Chapter 31: Carpus Fractures and Dislocations

Andrew D. Duckworth, David Ring

Chapter Outline

Introduction to Carpal Fractures and Dislocations

Carpal injuries most frequently occur in young active patients and are not very common overall. We talk about them and study them disproportionately to their frequency because they can be difficult to manage. For instance, fractures of the scaphoid are notorious for nonunion and sometimes the fracture is initially not visible on radiographs. The diagnosis of true fractures among suspected scaphoid fractures remains a dilemma in spite of advances in imaging because even the most sophisticated imaging has false positives and false negatives, because true fractures are uncommon, and because there is no consensus reference standard for true fractures. The use of clinical predictions rules and latent class analysis, accepting that the best we can do is to define and refine the probability of a fracture, may help. 
Nondisplaced scaphoid waist fractures have traditionally been treated in below-elbow casts including the thumb for nearly 3 months and issues with union persist. Screw fixation is an appealing option, but research suggests that with an accurate diagnosis of displacement, shorter less cumbersome methods of immobilization may suffice. Proximal pole fractures and displaced waist fractures are more routinely operated on, while distal pole fractures are treated symptomatically. Perilunate dislocations and fracture-dislocations are serious injuries, but effective treatment can maintain a mobile, useful wrist. Intercarpal ligament injuries and carpal malalignment remain confusing and debatable with many options for patients and surgeons to consider, and many questions worthy of study. 

Anatomy and Kinematics of Carpal Fractures and Dislocations

An understanding of the anatomy and kinematics of the eight carpal bones is essential for the diagnosis and management of carpal injuries. Advanced imaging techniques have increased our knowledge of the three-dimensional (3D) movements of the carpus, including their individual and combined contributions to wrist motion and stability. 

Osseous and Ligamentous Anatomy of Carpal Fractures and Dislocations

The carpus encompasses two rows of eight bones (Fig. 31-1) that serve as a bridge between the forearm and the hand, providing movement at the wrist joint, while also retaining a notable degree of stability.44,246,247,283,300,516 The proximal carpal row from radial to ulnar includes the scaphoid, lunate, and triquetrum. It is referred to as the key intercalated segment between the forearm and the distal row of the carpus, which is relatively fixed to the metacarpals distally, and movement results from the shape of the bones, their interaction with other bones, and the various ligamentous attachments.247,277,283,502,530 Through these articulations the proximal carpal row provides wrist joint movement and congruency, as well as force transmission between the forearm and the hand.43,46,300 To enable this to occur, the position and orientation of the scaphoid, lunate, and triquetrum is dynamic through their ligamentous attachments, as the proximal row has no direct tendinous attachments.246,247,283 Although the pisiform bone may provide stability to the proximal carpal row through the pisotriquetral joint, it should not theoretically be considered to be within the proximal carpal row as it is a sesamoid bone enclosed within the sheath of the flexor carpi ulnaris tendon.43,299 
Figure 31-1
The wrist is composed of two rows of bones that provide motion and transfer forces.
 
C, capitate; H, hamate; L, lunate; S, scaphoid; T, triquetrum; P, pisiform; Td, trapezoid; Tm, trapezium.
C, capitate; H, hamate; L, lunate; S, scaphoid; T, triquetrum; P, pisiform; Td, trapezoid; Tm, trapezium.
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Figure 31-1
The wrist is composed of two rows of bones that provide motion and transfer forces.
C, capitate; H, hamate; L, lunate; S, scaphoid; T, triquetrum; P, pisiform; Td, trapezoid; Tm, trapezium.
C, capitate; H, hamate; L, lunate; S, scaphoid; T, triquetrum; P, pisiform; Td, trapezoid; Tm, trapezium.
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The distal carpal row from radial to ulnar includes the trapezium, trapezoid, capitate, and hamate.44,246,283,300,516 The distal row articulates with the proximal carpal row, and distally with the five metacarpals of the hand by forming a transverse arch on which they are supported. The trapezium articulates with the first metacarpal, the trapezoid with the second, the capitate with the third, and the hamate articulates with the fourth and fifth. The capitate and trapezoid are tightly connected to the metacarpals, whereas there is 30 to 40 degrees of flexion–extension and rotation at the metacarpotrapezial joint. Motion at the distal carpal row is controlled by the extrinsic wrist flexors and extensors. 

Ligaments of the Carpus

The ligaments of the wrist are predominantly contained within the joint capsule. The inherent stability of the carpal rows, combined with the degree of movement achieved at the wrist joint, is predominantly due to the support of the extrinsic (Table 31-1) and intrinsic (Table 31-2) ligaments that reinforce the capsule of the carpus.43,46,102,283,300,476,516 Buijze et al.71 reviewed 58 anatomical studies and found that apart from the scaphocapitate ligament, the carpal ligaments are not described consistently. 
 
Table 31-1
The Extrinsic Ligaments of the Carpus
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Table 31-1
The Extrinsic Ligaments of the Carpus
Ligament Origin Insertion(s) Comments
Transverse carpal43,48,71,92,344,352,363,457 Volar scaphoid tuberosity and trapezial ridge Hook of hamate and pisiform Extra-articular ligament
Supports proximal carpal arch
Contains flexor tendons
Midportion of flexor retinaculum
Radiosca phocapitate43,44,46,251,425,430,431,432,449,479 Radial styloid at the level of the scaphoid fossa Volar capitate No scaphoid attachment
Crosses scaphoid (part of arcuate ligament) allowing rotation
Secondary stabilizer of scapholunate joint
Separate radioscaphoid ligament debated
Reinforces radial joint capsule
Radioscapholunate39,41,43,46,221,300,340,476 Distal radius ridge between scaphoid and lunate fossae Proximal scaphoid and lunate Pedicle derived from anterior interosseous artery, radial artery, and anterior interosseous nerve
Neurovascular supply to scapholunate IOM
Weak ligament, some consider not a true extrinsic ligament
Long/short radiolunate42,43,46,300,345,476 Radial styloid volar rim Lunate (palmar horn) and triquetrum Lies parallel to the radioscaphocapitate ligament
Passes anterior to proximal pole of scaphoid
Radial collateral42,43,46,251,319,476 Radial styloid dorsal/volar rim Scaphoid waist Many question existence of collateral ligaments
Some consider it part of the RSC ligament
Dorsal radiocarpal42,43,46,319,433,434,447,476,513,514 Distal radius, Lister tubercle Lunate, lunotriquetral ligament, triquetrum (dorsal tubercle) Origin debated
Possible insertion scaphoid (dorsal radioscaphoid ligament)
Role in scapholunate stability
Dorsal intercarpal42,43,46,319,340,414,424,447,476,513,514 Dorsoradial triquetrum Dorsoradial groove of scaphoid Multiple other insertions suggested (trapezium, trapezoid, lunate, capitate)
Ulnotriquetral43,46,300,476 Palmar edge TFCC Proximal/ulnar surfaces of the triquetrum Proximally, minimal distinction with ulnolunate ligament
May have fibers attached to ulnar styloid
Orifice provides communication between radiocarpal and pisotriquetral joint
Ulnolunate43,46,300,476 Palmar edge TFCC Palmar cortex of the lunate Continuous with short radiolunate ligament
Ulnocapitate43,46,300,476 Ulnar head, fovea region Capitate May act as ulnar anchor for the carpus
10% insertion on capitate, remainder arcuate ligament
Reinforces palmar region of the LT interosseous ligament
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Table 31-2
The Intrinsic Ligaments of the Carpus, Excluding the Distal Interosseous Ligaments
Ligament Origin Insertion(s) Comments
Scaphotrapezium-trapezoid43,44,46,48,134,329,345,430,431,432,476 Distal pole of scaphoid Proximal palmar aspect of trapezium/trapezoid Insertion on trapezoid is controversial
Secondary stabilizer scapholunate joint
Prevents extreme scaphoid flexion
Scaphocapitate43,46,134,344,345 Distal pole of scaphoid Radial volar body of the capitate Origin large surface area distal scaphoid
Triquetrocapitate43,46,477 Distal/radial corner of triquetrum Ulnar body of the capitate Continuation of ulnotriquetral ligament
Triquetrohamate43,46,477 Distal palmar cortex of the triquetrum Palmar aspect body of the hamate Continuation of ulnotriquetral ligament
Scapholunate37,40,43,45,46,67,340,428,448,453,476,497
Dorsal Dorsal lateral horn Lunate Ulnar-dorsal aspect proximal pole scaphoid Transverse strong thick (2–4 mm) fibers
Merges with dorsal intercarpal distally
Palmar Dorsal lateral horn Lunate Ulnar-dorsal aspect proximal pole scaphoid Histologically comparable to dorsal portion but oblique fibers, thinner (1–2 mm) and less stiff
Proximal Dorsal lateral horn lunate Ulnar-dorsal aspect proximal pole scaphoid Fibrocartilaginous membrane
Merges with adjacent articular cartilage
Widest, thinnest (1 mm), weakest section
Lunotriquetral43,46,340,398,476
Dorsal Lunate Triquetrum Transverse fibers but thinner and less stiff than palmar bundle
Palmar Lunate Triquetrum Transverse strong thick bundle of fibers
Interdigitates with ulnocapitate ligament
Proximal Lunate Triquetrum Fibrocartilaginous membrane similar to scapholunate proximal portion
 

Data from Duckworth AD, Ring D, McQueen MM. Assessment of the suspected fracture of the scaphoid. J Bone Joint Surg Br. 2011;93:713–719, reprinted with permission.

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Extrinsic Ligaments.
The extrinsic ligaments of the carpus (Fig. 31-2) connect the carpal bones to the forearm bones (proximally) and the metacarpals (distally) (Table 31-1). They are often difficult to distinguish from the fibrous capsule of the wrist on dissection; however, they are out with the articulations of the joint. 
Figure 31-2
 
A: The extrinsic palmar ligaments of the carpus. B: The extrinsic dorsal ligaments of the carpus. (Part B redrawn from Duckworth AD, Buijze GA, Moran M, et al. Predictors of fracture following suspected injury to the scaphoid. J Bone Joint Surg Br. 2012;94-B(7):961–968.)
A: The extrinsic palmar ligaments of the carpus. B: The extrinsic dorsal ligaments of the carpus. (Part B redrawn from Duckworth AD, Buijze GA, Moran M, et al. Predictors of fracture following suspected injury to the scaphoid. J Bone Joint Surg Br. 2012;94-B(7):961–968.)
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Figure 31-2
A: The extrinsic palmar ligaments of the carpus. B: The extrinsic dorsal ligaments of the carpus. (Part B redrawn from Duckworth AD, Buijze GA, Moran M, et al. Predictors of fracture following suspected injury to the scaphoid. J Bone Joint Surg Br. 2012;94-B(7):961–968.)
A: The extrinsic palmar ligaments of the carpus. B: The extrinsic dorsal ligaments of the carpus. (Part B redrawn from Duckworth AD, Buijze GA, Moran M, et al. Predictors of fracture following suspected injury to the scaphoid. J Bone Joint Surg Br. 2012;94-B(7):961–968.)
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The extrinsic palmar radiocarpal ligaments (Fig. 31-2A) include the transverse carpal, radioscaphocapitate (RSC), radioscapholunate (ligament of Testut; RSL), radial collateral, long radiolunate (radiolunotriquetral; RLT), and the short radiolunate ligaments.5,43,46,63,286,300,355,426,476 The extrinsic ulnocarpal ligaments include the ulnotriquetral (dorsal and palmar), ulnolunate, and ulnocapitate ligaments.5,43,46,63,286,300,355,426,476 These palmar ligaments predominantly originate from a lateral position on the radial-palmar facet of the radial styloid and head in a distal ulnar direction, where they assemble with the palmar ulnocarpal ligaments originating medially from the distal ulna and triangular fibrocartilage complex (TFCC). The strong oblique extrinsic palmar radial ligaments prevent the carpus from translating medially on the angulated slope of the distal radius through two V-shaped ligamentous bands.38,42,512,565 One is proximal (long radiolunate, RSL, ulnolunate, ulnotriquetral) and connects the forearm to the proximal carpal row and one is distal (RSC, ulnocapitate) and connects the forearm to the distal carpal row. Between the radial (RSC) and ulnar palmar ligaments (long radiolunate) there is a V-shaped interligamentous sulcus over the capitolunate articulation, which is an interval of capsular weakness known as the space of Poirier. Maximal space is seen when the wrist is dorsiflexed, with the space almost disappearing in palmar flexion. This is of clinical relevance during dorsal dislocations as it is through this area of weakness that the lunate displaces into the carpal canal. The arcuate ligament is found in the central third of the palmar joint capsule and is thought to be formed from the interdigitation of transverse fibers of the RSC, ulnocapitate, triquetrocapitate, and volar scaphotriquetral ligaments.43,46,71,300,476 This ligament forms a support sling for the midcarpal region, in particular the head of the capitate, which is thought to improve midcarpal movement while also delivering carpal stability. Alternate names for the arcuate ligament include the deltoid ligament, palmar distal V ligament, or Weitbrecht oblique ligament.46,71 Controversy exists regarding the existence of individual forms of some of the ligaments that make up the arcuate ligament, in particular the volar scaphotriquetral ligament.46,425,449 
The extrinsic dorsal carpal ligaments (Fig. 31-2B) include the dorsal radiocarpal (DRC) ligament, which may also be known as the dorsal radioulnotriquetral ligament or the dorsal radiotriquetral ligament, and the dorsal intercarpal ligament, which form a V-shaped configuration. The ulnodorsal capsule of the wrist is reinforced by the ulnolunate and ulnotriquetral ligaments and the floors of the fifth and sixth extensor compartments.5,43,46,63,286,300,355,426,444,513 Some studies have suggested an essential role of the dorsal carpal ligaments in scapholunate stability.147,317,433,434 
Intrinsic Ligaments.
The intrinsic ligaments connect the individual carpal bones to one another (Fig. 31-3 and Table 31-2). The ligaments are intra-articular short fibers that connect and hold the carpal bones of both the proximal and distal rows to each other. There is a contiguous merging of the interosseous ligaments with the joint articular cartilage. The intrinsic ligaments include the palmar midcarpal ligaments (scaphotrapeziotrapezoid, scaphocapitate, triquetrocapitate, triquetrohamate), the proximal interosseous ligaments (scapholunate, lunotriquetral), and the distal interosseous ligaments (trapeziotrapezoid, trapeziocapitate, capitohamate).43,46,63,286,300,355 Ligaments associated with the pisiform include the pisotriquetral ligament that bridges the pisotriquetral joint, and the pisohamate ligament, which is an extension of flexor carpi ulnaris.43,46 
Figure 31-3
 
A: The palmar intrinsic ligaments—scaphotrapeziotrapezoid ligament (STT), scaphocapitate ligament (SC), triquetrocapitate ligament (TC), and triquetrohamate ligament (TH). B: The dorsal intrinsic ligaments—capitohamate ligament (CH), capitotrapezoid ligament (CT), lunotriquetral ligament (LT), scapholunate ligament (SL), trapeziotrapezoid ligament (TT). The dorsal intercarpal ligament is not shown. (From: Berger RA, Weiss APC. Hand Surgery. 1st ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2003.)
A: The palmar intrinsic ligaments—scaphotrapeziotrapezoid ligament (STT), scaphocapitate ligament (SC), triquetrocapitate ligament (TC), and triquetrohamate ligament (TH). B: The dorsal intrinsic ligaments—capitohamate ligament (CH), capitotrapezoid ligament (CT), lunotriquetral ligament (LT), scapholunate ligament (SL), trapeziotrapezoid ligament (TT). The dorsal intercarpal ligament is not shown. (From: Berger RA, Weiss APC. Hand Surgery. 1st ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2003.)
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Figure 31-3
A: The palmar intrinsic ligaments—scaphotrapeziotrapezoid ligament (STT), scaphocapitate ligament (SC), triquetrocapitate ligament (TC), and triquetrohamate ligament (TH). B: The dorsal intrinsic ligaments—capitohamate ligament (CH), capitotrapezoid ligament (CT), lunotriquetral ligament (LT), scapholunate ligament (SL), trapeziotrapezoid ligament (TT). The dorsal intercarpal ligament is not shown. (From: Berger RA, Weiss APC. Hand Surgery. 1st ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2003.)
A: The palmar intrinsic ligaments—scaphotrapeziotrapezoid ligament (STT), scaphocapitate ligament (SC), triquetrocapitate ligament (TC), and triquetrohamate ligament (TH). B: The dorsal intrinsic ligaments—capitohamate ligament (CH), capitotrapezoid ligament (CT), lunotriquetral ligament (LT), scapholunate ligament (SL), trapeziotrapezoid ligament (TT). The dorsal intercarpal ligament is not shown. (From: Berger RA, Weiss APC. Hand Surgery. 1st ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2003.)
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On the radial side of the wrist the V-shaped scaphotrapezium-trapezoid ligament is found, providing stability to the scaphoid-trapezium-trapezoid articulation as well as the scaphoid itself.43,44,46,48,134,329,345,476 The V-shape is from the scaphotrapezial component of the ligament. Although insertion on the trapezoid bone is contested, recent studies have suggested the existence of two distinct ligaments: the scaphotrapezoid and scaphotrapezium ligaments, with the former thinner and less robust.43,44,46,251,345 However, some have suggested that the soft tissue present is capsule.134 Adjacent to the scaphotrapezium-trapezoid ligament is the scaphocapitate, which is a large robust ligament that provides midcarpal stability with fibers running in parallel to the RSC ligament.43,46,134,344,345 One recent study analyzed eight fresh-frozen cadavers using 3D CT and cryomicrotome imaging to better define the osseous and ligamentous anatomy of the scaphoid.67 They concluded that the scaphocapitate ligament was the thickest ligament of all those that attached to the scaphoid, with a mean thickness of 2.2 mm. On the ulnar side of the wrist, the remaining palmar midcarpal ligaments are the triquetrocapitate and triquetrohamate ligaments.43,46,477 
The proximal interosseous scapholunate and lunotriquetral ligaments are found deep within the carpus and are considered the two most important intrinsic ligaments as they are critical to carpal stability.183 The scapholunate interosseous ligament is a strong stiff C-shaped ligament that plays a vital role in carpal stability, with the thick and strong dorsal portion containing transversely oriented collagen fascicles key to the stability of the scapholunate joint.37,40,43,45,46,67,340,428,448,453,476,497 The palmar/volar and proximal/central portions act as secondary stabilizers, contributing primarily to rotational stability of the joint.40 Recent studies have demonstrated that the scapholunate interosseous ligament is the primary stabilizer of the scapholunate joint, with the scaphotrapezium-trapezoid ligament and the RSC ligament secondary stabilizers,430432 and the dorsal carpal ligaments likely having a tertiary role.147,317,433,434 The lunotriquetral ligament interdigitates with three extrinsic ligaments: the ulnotriquetral, ulnolunate, and radiolunate ligaments.43,46,340,398,476 The thickest and strongest zone of the lunotriquetral ligament is found palmarly.43,340,398 A stronger kinematic relationship than the scapholunate ligament is seen due to the tight association of its fibers.43,300,398,476 The scaphotriquetral ligament is a distal extension of the scapholunate and lunotriquetral ligaments.43 
The distal interosseous ligaments have a comparable structure to the proximal interosseous ligaments, with both palmar and dorsal fibers.43,46,396,397,476 The trapeziotrapezoid and trapeziocapitate ligaments similarly span their respective articulations, but with the latter having a deep ligament that bridges the joint. The capitohamate ligament spans only the distal part of the capitohamate joint articulation and again is reinforced by a large deep ligament that has extensions to the middle and ring finger metacarpals. 

Neurovascular Anatomy of Carpal Fractures and Dislocations

The neurovascular supply to the carpus is through the regional vasculature and nerves.47,164,185,186,298,366,474 Innervation is via the anterior interosseous and posterior interosseous nerves. Circulation to the carpus is composed of an extraosseous and intraosseous vasculature via both dorsal and palmar vascular systems, which are branches of the radial, ulnar, anterior interosseous, and deep palmar arch arteries (Fig. 31-4).57,164,185,186,366 The extraosseous arterial supply is formed by an anastomotic network of dorsal and palmar transverse arches connected longitudinally from their medial and lateral borders by the radial, ulnar, and anterior interosseous arteries.164,185,186,366,474 The three dorsal transverse arches of the carpus include the radiocarpal, the intercarpal, and the basal metacarpal arches.164 The three palmar transverse arches of the carpus include the radiocarpal, the intercarpal, and the deep palmar arches.164 For all of these arches, their presence in cadaveric specimens is inconsistent.164 
Figure 31-4
Schematic drawing of the arterial supply of the palmar aspect of the carpus.
 
Circulation of the wrist is obtained through the radial, ulnar, and anterior interosseous arteries and the deep palmar arch. 1, palmar radiocarpal arch; 2, palmar branch of anterior interosseous artery; 3, palmar intercarpal arch; 4, deep palmar arch; 5, recurrent artery.
Circulation of the wrist is obtained through the radial, ulnar, and anterior interosseous arteries and the deep palmar arch. 1, palmar radiocarpal arch; 2, palmar branch of anterior interosseous artery; 3, palmar intercarpal arch; 4, deep palmar arch; 5, recurrent artery.
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Figure 31-4
Schematic drawing of the arterial supply of the palmar aspect of the carpus.
Circulation of the wrist is obtained through the radial, ulnar, and anterior interosseous arteries and the deep palmar arch. 1, palmar radiocarpal arch; 2, palmar branch of anterior interosseous artery; 3, palmar intercarpal arch; 4, deep palmar arch; 5, recurrent artery.
Circulation of the wrist is obtained through the radial, ulnar, and anterior interosseous arteries and the deep palmar arch. 1, palmar radiocarpal arch; 2, palmar branch of anterior interosseous artery; 3, palmar intercarpal arch; 4, deep palmar arch; 5, recurrent artery.
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The incidence of avascular necrosis (AVN) following injury to the carpal bones is related to their complex intraosseous blood supply.57,164,185,186,366 Original work documented that the vascular supply of most carpal bones enters the distal half, leaving the proximal half at risk of AVN. The vascular supply of each carpal bone is shown in Table 31-3. From this, three general patterns of intraosseous vascularization have been described and help with identifying the carpal bones at risk of osteonecrosis.57,164,184186,366 
  1.  
    The scaphoid, capitate, and about 20% of all lunates are supplied by a single vessel increasing their risk to AVN.
  2.  
    The trapezium, triquetrum, pisiform, and 80% of lunates receive nutrient arteries through two nonarticular surfaces and have consistent intraosseous anastomoses; therefore, reducing the risk of AVN.
  3.  
    The trapezoid and 50% of hamates lack an intraosseous anastomosis and are at risk of avascular fragments.
 
Table 31-3
The Vascular Supply to All the Carpal Bones
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Table 31-3
The Vascular Supply to All the Carpal Bones
Carpal Bone Vascular Supply Comments
Scaphoid57,164,185,186,366 Scaphoid branches of the radial artery:
  •  
    Dorsal branch supplies 70–80% proximally
  •  
    Volar branch supplies 20–30% distally
No perforators at waist, cartilage, or SL ligament
All surgical approaches potentially endanger some of the arterial branches
Lunate57,164,182,186,366,542 ∼80% receive vessels from palmar and dorsal surfaces
  •  
    Dorsal originate from radiocarpal arch, intercarpal arch, and rarely dorsal branch of anterior interosseous

∼20% receive vessels from palmar surface only
  •  
    Palmar originate from radiocarpal arch, intercarpal arch, branches of anterior interosseous and ulnar recurrent arteries
Large articulating surface with nonperforators
Proximal pole has marginally less vascularity
Three intraosseous patterns:
  •  
    Y (59%; dorsal or palmar)
  •  
    I (30%; one dorsal, one palmar)
  •  
    X (10%, two dorsal, two palmar)
Triquetrum164,366 Branches of ulnar artery, dorsal intercarpal arch, palmar intercarpal arch
  •  
    Dorsal vessels supply 60%
  •  
    Palmar vessels supply 40%
Vessels enter through two (dorsal ridge/palmar oval facet) nonarticulating surfaces
Dorsal–palmar anastomoses found in 86%
Pisiform164,366 Branches of ulnar artery Two entry points for vessels:
  •  
    Proximal pole inferior to triquetral facet
  •  
    Distal pole inferior to articular facets

Proximal–distal anastomoses found
Trapezium164,366 Branches of radial artery
  •  
    Dorsal supply predominates
Vessels enter through three (dorsal/lateral/palmar tubercle) nonarticulating surfaces
Dorsal–lateral–palmar anastomoses found
Trapezoid164,366 Branches from the dorsal arch, the intercarpal arch, the basal metacarpal arch, and the radial recurrent artery
  •  
    Dorsal vessels supply 70%
  •  
    Palmar vessels supply 30%
Vessels enter through two (dorsal/palmar) nonarticulating surfaces
Capitate164,366 Branches of the dorsal intercarpal arch, dorsal basal metacarpal arch, palmar intercarpal arch, and ulnar recurrent artery Vessels enter through two (dorsal/palmar) nonarticulating surfaces
In 1/3 the supply to the capitate head is solely from the palmar side
Dorsal–palmar anastomoses found in 30%
Hamate164,366 Branches of the dorsal intercarpal arch, the ulnar recurrent artery, and the ulnar artery
  •  
    Dorsal vessels supply dorsal 30–40%
Vessels enter through three (dorsal/palmar/medial) nonarticulating surfaces
Dorsal–palmar anastomoses found in 50%, but no anastomoses with medial vessels
 

Data from Duckworth AD, Ring D, McQueen MM. Assessment of the suspected fracture of the scaphoid. J Bone Joint Surg Br. 2011;93:713–719, reprinted with permission.

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Kinematics of Carpal Fractures and Dislocations

The study of carpal kinematics began in the late 1800s using plain radiographs, and knowledge has advanced through in vitro cadaveric work, as well as employing advanced imaging techniques such as 3D CT. 
The biomechanics of the wrist joint need to allow for load transmission from the hand to the forearm and a wide range of motion, while also achieving stability throughout. Two predominant articulations are found at the wrist joint and include the proximal carpal bones (scaphoid, lunate, triquetrum) with the distal radius and ulna, which is considered as the key intercalated segment and provides principally extension and ulnar deviation at the wrist.246,247,502,530 The second articulation is between the proximal and distal carpal rows and provides predominantly flexion and radial deviation. Motion predominantly occurs in two planes, with flexion–extension at approximately 70 degrees in both directions, and radioulnar deviation at approximately 20 and 40 degrees respectively.246,247,283,516 The adjacent radioulnar joint provides a substantial rotatory arc of approximately 140 degrees around the longitudinal axis of the forearm.282,364,365 
Although many theories have been described, there are two predominant theories used to explain carpal kinematics, which are known as the columnar and the oval-ring or row theories.179,183 The columnar theory is the oldest, described by Navarro (Fig. 31-5).349 He observed motion between the proximal carpal row bones, predominantly from data on birds, and put forward the theory of three longitudinal columns: 
  1.  
    A mobile lateral (radial) column consisting of the scaphoid, trapezium, and trapezoid
  2.  
    A central flexion–extension column consisting of the lunate, capitate, and hamate
  3.  
    A rotational medial (ulnar) column consisting of the triquetrum and pisiform
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Figure 31-5
The columnar theory of carpal kinematics.
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This theory goes some way to explaining the load transmission of the wrist but not synchronous motion. Taleisnik476 put forward a modification of this theory by including the trapezium and trapezoid (i.e., lunate + distal carpal row) to the central column, as well as removing the pisiform from the medial column. With this theory flexion and extension occur through the central column, but he suggested that the scaphoid was an essential stabilizer for the midcarpal joint (radial column), the triquetrum (triquetrohamate joint) was the pivot point for rotation of the carpus, and that radial and ulnar deviation was facilitated through rotation of the scaphoid laterally and the triquetrum medially. 
The alternative oval-ring theory combines the theories of the carpal row and oval-ring concept (Fig. 31-6).275,276,283 The key concepts for this theory include the proximal intercalated segment, variable geometry, as well as the synchronous and reciprocating motion of the carpal rows. What is key to providing versatility to the wrist joint, combined with the ability to remain stable throughout, is the proximal intercalated segment (proximal carpal row).179,246,247,266,502,530 The primary axis for the combined motion of the carpus has been found to be within the head/neck of the capitate, which is not a singular point, but rather an oblique screw axis.246,247,283,516,563 The scaphoid is found on an axis 45 degrees to the longitudinal axis that passes through the lunate and capitate, and provides stability to the midcarpal joint while also stabilizing the central column. By virtue of its obliquity, the scaphoid will flex when under compression and exerts a similar force on the lunate. The lunate; however, is also under the influence of the triquetrum, which inherently prefers to extend. For this reason, the lunate may be thought of being in a state of dynamic balance between two antagonists, tending to lie in the position of least mechanical potential energy. 
Figure 31-6
The oval (A) and row (B) theories of carpal kinematics.
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The movement of the individual components of the proximal carpal row allows the length and contour of the proximal carpal row to be dynamic, providing extreme movements at the wrist while also maintaining stability around the longitudinal axis.246,247,283,502,516,530 This concept is known as the variable geometry of the proximal carpal row. To provide such a degree of motion, the individual carpal bones are multirotational moving not only up and down and back and forth, but also spinning and rolling about their own axes.246,247,283,516 
During flexion and extension of the wrist, each carpal row bone angulates in the same direction with nearly equal amplitude and in a synchronous fashion, a concept known as synchronous angulation (Fig. 31-7).64,246249,283,306,325,413,516,549,563 However, the amplitude of movement is different for the bones of each column.79 Recent studies using 3D noninvasive imaging have re-examined previous work analyzing the radiocarpal and midcarpal contributions to wrist flexion and extension.64,248,249,306,325,413,549,563 Sarrafian et al.413 documented that for flexion ∼40% is at the radiocarpal joint with ∼60% at the midcarpal joint, and that in extension ∼66.5% is at the radiocarpal joint with ∼33.5% at the midcarpal joint. More recent studies have documented that in flexion 62% to 75% of wrist motion occurred at the radioscaphoid joint, with 31% to 50% at the radiolunate joint.249,325,549 In extension, 87% to 99% of wrist motion has been shown to occur at the radioscaphoid joint, with 52% to 68% at the radiolunate joint. 
Figure 31-7
Conjunct rotation of the entire proximal intercalated row occurs in flexion during radial deviation (upper left).
 
The axes of the radius and carpal rows are collinear in neutral (middle left), and the proximal row extends with ulnar deviation (lower left). Angulatory excursions of the proximal and distal rows are essentially equal in amplitude and direction during extension (upper right) and flexion (lower right). This has been described as synchronous angulation.
The axes of the radius and carpal rows are collinear in neutral (middle left), and the proximal row extends with ulnar deviation (lower left). Angulatory excursions of the proximal and distal rows are essentially equal in amplitude and direction during extension (upper right) and flexion (lower right). This has been described as synchronous angulation.
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Figure 31-7
Conjunct rotation of the entire proximal intercalated row occurs in flexion during radial deviation (upper left).
The axes of the radius and carpal rows are collinear in neutral (middle left), and the proximal row extends with ulnar deviation (lower left). Angulatory excursions of the proximal and distal rows are essentially equal in amplitude and direction during extension (upper right) and flexion (lower right). This has been described as synchronous angulation.
The axes of the radius and carpal rows are collinear in neutral (middle left), and the proximal row extends with ulnar deviation (lower left). Angulatory excursions of the proximal and distal rows are essentially equal in amplitude and direction during extension (upper right) and flexion (lower right). This has been described as synchronous angulation.
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During radioulnar deviation, the proximal row exhibits a secondary out-of-plane angulation (sagittal plane) in conjunction to the synchronous motion occurring in the coronal plane.64,248,306,325,563 In radial deviation the proximal carpal row flexes and the capitate extends (reciprocal motion). Flexion of the obliquely orientated scaphoid, as the trapezium and trapezoid approach the radius, is transmitted through the dorsal scapholunate ligament and onto the lunate and triquetrum, when flexion is at 10 to 20 degrees. In ulnar deviation the proximal carpal row extends and the capitate flexes, along with the proximal migration of the hamate, forcing the triquetrum to displace palmarly and extend, bringing the lunate with it. Recent studies have demonstrated that associated pronation (radial deviation) and supination (ulnar deviation) of the proximal carpal row is minimal.248,325 These studies have also demonstrated that radial and ulnar deviation occurred primarily at the midcarpal joint, accounting for ∼60% and ∼85% of the movement respectively. 
One study has suggested that as the wrist moves into ulnar deviation, the unique helicoidal shape of the triquetrohamate joint forces the distal carpal row to translate dorsally and the triquetrum to tilt into extension, leading to extension of the proximal carpal row.530 The converse occurs during radial deviation. 

Pathoanatomy of Carpal Fractures and Dislocations

An injury to the carpus commonly occurs following a mechanism in which an axial compression force is applied to the wrist, commonly leading to hyperextension where the palmar ligaments undergo tension and the dorsal articulations are subject to shear stresses.255,279,302,529 It has been demonstrated that both the degree of force applied to the wrist and the degree of wrist radial or ulnar deviation will determine whether a ligament injury, a fracture, or both, occur. Minor injuries, such as ligamentous sprains, frequently result from a low-energy injury. However, one study has demonstrated a relationship between a low-energy simple fall in women and sustaining a scaphoid fracture.136 Higher-energy injuries that involve a more considerable force result in either a fracture to one or more of the carpal bones and/or a ligamentous disruption, with both intrinsic and extrinsic ligaments potentially involved.255,279,302,529 Variations in bone quality, the direction and magnitude of the deforming force and the position of the wrist at the time of injury explain the variety of injuries that can occur. 

Carpal Fractures

Fracture of the Scaphoid.
Any shear strain that travels across the midcarpal joint is transferred through the scaphoid and may cause a fracture and/or dislocation. Fracture of the scaphoid has been shown to occur when the wrist is dorsiflexed to ≥95 degrees and radially deviated to ≥10 degrees.255,279,302,529 In this position the proximal pole of the scaphoid is held firmly between the radius, capitate, RSC ligament, and the palmar capsule (Fig. 31-8).302,529 With the wrist radially deviated the RSC ligament is relaxed and unable to relieve the increasing force being applied to the radiopalmar aspect of the scaphoid.302,529 When axial loading and/or dorsal compression of the scaphoid occurs in this position, the scaphoid will fracture, most frequently through the waist as it is subject to the maximal bending movement.173,529 
Figure 31-8
The schematic above demonstrates the progression to fracture of the scaphoid during a hyperextension injury to the wrist.
 
The proximal pole of the scaphoid is trapped between the radius and tense palmar extrinsic ligaments, with the force concentrated at the scaphoid waist leading to fracture.
The proximal pole of the scaphoid is trapped between the radius and tense palmar extrinsic ligaments, with the force concentrated at the scaphoid waist leading to fracture.
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Figure 31-8
The schematic above demonstrates the progression to fracture of the scaphoid during a hyperextension injury to the wrist.
The proximal pole of the scaphoid is trapped between the radius and tense palmar extrinsic ligaments, with the force concentrated at the scaphoid waist leading to fracture.
The proximal pole of the scaphoid is trapped between the radius and tense palmar extrinsic ligaments, with the force concentrated at the scaphoid waist leading to fracture.
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The degree of force and position of the wrist at the time of injury are the likely determinants for the type and severity of scaphoid fracture. Herbert213 suggested that wrist deviation may predict the location of the fracture as the line of the midcarpal joint crosses the proximal pole in radial deviation and the distal pole in ulnar deviation. Fractures of the waist are usually the result of shear forces across the scaphoid, while tubercle fractures appear to be caused by either compression or avulsion.156,377 Compson96 suggested that the size of a proximal pole fracture was dependent on the level of the proximal extent of the joint facet with the capitate, which is the most variable aspect of scaphoid anatomy. Smaller proximal pole fractures can also be caused by an avulsion of the attachment of the scapholunate ligament. 
With an unstable displaced scaphoid fracture, the kinematics of the wrist are altered. Joint compressive forces, trapezium-scaphoid shear stress and capitolunate rotation moments all act upon the scaphoid, leading to a dissociation of the proximal and distal carpal rows that permits the natural tendency of the two carpal rows to fail by collapsing, assuming a lunate-extended posture. The scaphoid will assume an anteverted position, the lunate and triquetrum sublux forward and rotate dorsally, and the capitate and hamate sublux dorsally and proximally, producing the dorsal intercalated segment instability (DISI) deformity (see Carpal Ligament Injuries section below). This is demonstrated clinically by the collapse pattern seen with chronic scaphoid nonunion, a condition known as scaphoid nonunion advanced collapse (SNAC) appearing as a DISI deformity.109,411,446 The proximal and distal fracture fragments can collapse giving a characteristic flexed or “humpback” position on radiographs with an intrascaphoid angle of greater than approximately 30 degrees.411 
Fracture of the Capitate.
It has been suggested that fracture of the capitate occurs through one of three potential mechanisms: 
  1.  
    Scaphocapitate syndrome154,296,314: Occurs with a violent blow directed to the radial styloid which first fractures the scaphoid and then the capitate but produces no dislocation. The capitate fragment can be rotated 90 to 180 degrees, with the articular surface displaced anteriorly or facing the fracture surface of the capitate neck.510 Some have questioned the nomenclature with reports suggesting a scaphoid fracture does not always occur.24
  2.  
    Anvil mechanism: An axial load with the wrist in dorsiflexion, forcing the capitate onto the dorsal rim of the radius. The dorsal border of the radius will impinge on the capitate and cause a fracture through its waist.
  3.  
    Direct blow or crush injury.
Fracture of the Lunate.
Fracture of the lunate commonly occurs following a hyperextension injury to the wrist. In extension, the lunate is displaced onto the palmar aspect of the lunate fossa and rotated dorsally.429,549 The capitate pushes against the palmar aspect of the lunate, and at the same time moves it into an ulnar direction, which is countered by the RSL ligament. When the forearm is pronated and there is an ulnar minus variant, the support offered by the TFCC and ulnar head will be reduced and the compressive stresses across the proximal convexity of the lunate are altered between the TFCC and the radial articular surface.204,534 The reduced ulnar support may also allow proximal displacement of the triquetrum placing further tensile stress on the lunate surface through the lunotriquetral ligament. This chain of events can eventually result in a transverse fracture of the lunate in the sagittal plane.204,534 
Avulsions of the dorsal pole of the lunate are often associated with scapholunate dissociation (SLD) and are thus likely secondary to tension placed on the scapholunate ligament. Avulsion fractures of the ulnar aspect of the palmar pole of the lunate are frequently associated with a perilunate dislocation and are thus likely secondary to tension placed on the lunotriquetral ligament (see below). 
In the above scenarios, stress may be placed on the vasculature of the lunate (Table 31-3) prior to a fracture occurring, leading to the development of Kienböck disease. There is considerable evidence that the mechanisms of fracture are also associated with the development of Kienböck disease, with Kienböck disease known to be secondary to trauma, ulnar variance, and impaired vascularity.33,182,265 

Carpal Ligament Injuries

Carpal instability usually follows a high-energy injury leading to the wrist undergoing a force associated with hyperextension, ulnar deviation, and intercarpal supination.301304 This can lead to an interruption of the oval ring, commonly in the proximal carpal row, leading to instability. The most common pattern of injury is associated with a perilunate dislocation or fracture dislocation (see below). 
Although several systems exist, three interrelated classification systems are commonly used for defining carpal instability and are useful in understanding the pathoanatomy of the injury. The three classifications include intercalated segment instability,277,278 static versus dynamic instability,476 and dissociative versus nondissociative instability (Table 31-4). Linscheid described instability in relation to the appearance of the lunate and the intercalated segment on standard lateral radiographs (Fig. 31-9).277 When the dynamic kinematic relationship between the scaphoid, lunate, and triquetrum is disrupted by either a fracture and/or a ligamentous injury, instability of the wrist ensues with loss of synchronous motion and intercarpal contact patterns. The lunate will flex with loss of ulnar support from the triquetrum and when in a fixed position of flexion of greater than 15 degrees, volar intercalated segment instability (VISI) has occurred. When the opposite occurs and the lunate falls into fixed extension of more than 10 degrees, DISI has occurred. The fixed malpositioning of the lunate, even in radial and ulnar deviation of the wrist, affects the functioning of the proximal intercalated segment and thus the kinematics of the wrist. With persistent instability, degenerative changes will ensue as a consequence of increased shear forces and abnormal contact between the individual carpal bones.15,267,524,527 
Figure 31-9
Schematic drawing of carpal instability.
 
A: Normal longitudinal alignment of the carpal bones with the scaphoid axis at an approximately 45-degree angle to the axes of the capitate, lunate, and radius. B: DISI deformity (scapholunate angle >60 degrees). C: VISI deformity (scapholunate angle <30 degrees).
A: Normal longitudinal alignment of the carpal bones with the scaphoid axis at an approximately 45-degree angle to the axes of the capitate, lunate, and radius. B: DISI deformity (scapholunate angle >60 degrees). C: VISI deformity (scapholunate angle <30 degrees).
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Figure 31-9
Schematic drawing of carpal instability.
A: Normal longitudinal alignment of the carpal bones with the scaphoid axis at an approximately 45-degree angle to the axes of the capitate, lunate, and radius. B: DISI deformity (scapholunate angle >60 degrees). C: VISI deformity (scapholunate angle <30 degrees).
A: Normal longitudinal alignment of the carpal bones with the scaphoid axis at an approximately 45-degree angle to the axes of the capitate, lunate, and radius. B: DISI deformity (scapholunate angle >60 degrees). C: VISI deformity (scapholunate angle <30 degrees).
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Table 31-4
Classifications of Carpal Instability
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Table 31-4
Classifications of Carpal Instability
Classification Description Examples
Dorsal intercalated segment instability (DISI) Lunate extends, dorsal displacement of the capitate
Scapholunate angle >60 degrees
Capitolunate angle >15 degrees
Radiolunate angle >10–15 degrees in dorsal direction
Scapholunate dissociation
Displaced scaphoid fracture
Scaphoid pseudarthrosis
Volar intercalated segment instability (VISI) Lunate flexes, volar displacement of the capitate
Scapholunate angle <30 degrees
Capitolunate angle >30 degrees
Radiolunate angle >10–15 degrees in volar direction
Lunotriquetral dissociation
Multiple complex carpal instability
Dissociative Instability due to injury within carpal row (intrinsic ligament injury) Scaphoid fracture
Scapholunate dissociation
Perilunate dislocation
Nondissociative Instability due to injury between the carpal rows (extrinsic ligament injury) Radiocarpal instability
Midcarpal instability
Barton fracture-dislocations
Die-punch fracture dislocations
Combined Combination of dissociative and nondissociative
Static instability Standard (PA and lateral) nonstress views demonstrate carpal malalignment/instability
Dynamic instability Standard nonstress views demonstrate no carpal malalignment/instability, but positive stress views
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Dissociative instabilities of the carpus involve an isolated ligament disruption between two connected carpal bones (injury to major intrinsic ligament), with or without an associated bony disruption; for example, SLD ± a fracture of the scaphoid.102,183,553 Nondissociative instabilities of the carpus include subluxations or incomplete dislocations of the entire carpus (radiocarpal subluxation or dislocation) that may be purely ligamentous (injury to major extrinsic ligament), but more commonly include a fragment of the distal radius.183 These dislocations are frequently a palmar or dorsal Barton fracture-dislocation, or a radial styloid fracture-dislocation; for example, a chauffeur’s fracture. DISI and VISI instabilities may be either dissociative or nondissociative depending on the degree of damage to the ligamentous connections of the proximal carpal row. 
Static instability occurs when carpal malalignment and instability is found on standard PA and lateral radiographs of the wrist. With dynamic instability, carpal malalignment and instability is only apparent using specified clinical physical provocation tests and when stress radiographs are positive (normal standard radiographs). The term adaptive carpal instability relates to the development of carpal instability due a cause unrelated to the carpus; for example, carpal malalignment following a severe malunion of a distal radius fracture. 

Perilunate Dislocation and Fracture-Dislocation

Perilunate dislocations and fracture-dislocation predominantly follow a high-energy mechanism of hyperextension, ulnar deviation, and intercarpal supination injury to the wrist.301304 There are rare cases of reversed perilunate instability, when the wrist is pronated at the time of impact thus adding an external force to the hypothenar region, forcing the wrist into extension and radial deviation. For these cases the lunotriquetral ligament injury occurs first and the scapholunate ligament may remain intact.274,384 
Perilunate dislocations can be subdivided into two subgroups:239,324 
  1.  
    Lesser-arc perilunate dislocations: Pure ligamentous injuries around the lunate
  2.  
    Greater-arc perilunate dislocations: Ligamentous injuries associated with a fracture of one or more of the bones around the lunate
Mayfield suggested that carpal instability predominantly occurs in relation to the lunate, which is the carpal keystone.301304 He put forward a pathoanatomic classification associated with progressive perilunate instability from a radial to ulnar direction (Fig. 31-10). 
  •  
    Stage I: Scaphoid fracture, SLD, or both
    •  
      As the distal carpal row is violently extended, supinated, and ulnarly deviated, the scaphotrapezium-trapezoid and scaphocapitate ligaments are tightened causing the scaphoid to extend. As the scaphoid extends, the scapholunate ligament transmits the force to the lunate, which cannot rotate as much as the scaphoid because it is constrained by the palmarly located radiolunate and ulnolunate ligaments. As a consequence, a scaphoid fracture or a progressive elongation and tearing of the scapholunate and palmar RSC ligaments may occur, potentially leading to complete SLD.
  •  
    Stage II: Lunocapitate disruption
    •  
      If the extension-supination force on the wrist persists once the proximal carpal row has been dislocated, transmission of the force distally to the capitate may lead to displacement and eventual dislocation dorsally through the space of Poirier. It is followed by the rest of the distal carpal row and the radial-most portion of the dislocated proximal carpal row. This may be the complete scaphoid or just its distal fragment.
  •  
    Stage III: Lunotriquetral disruption
    •  
      If the extension-supination force to the wrist persists, once the capitate is displaced dorsally lunotriquetral (most common), ulnotriquetral, and/or triquetrum-hamate-capitate ligament disruptions may occur. Stage III is complete when the palmar lunotriquetral ligament, including the medial expansions of the long radiolunate ligament, is completely disrupted and the joint has displaced.
  •  
    Stage IV: Perilunate dislocation
    •  
      If the extension-supination force to the wrist persists and the dorsally displaced capitate is pulled proximally, pressure is applied onto the dorsal aspect of the lunate, forcing it to dislocate in a palmar direction due to injury to the DRC ligament. As the palmar ligaments are much stronger than the dorsal capsule such a dislocation seldom involves a pure palmar displacement of the lunate, but rather a variable degree of palmar rotation of the bone into the carpal tunnel using the intact palmar ligaments as a hinge.
Figure 31-10
The Mayfield stages of progressive perilunate instability.
 
Stage I results in SL instability. Stages II to IV result in progressively worse perilunate instability.
Stage I results in SL instability. Stages II to IV result in progressively worse perilunate instability.
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Figure 31-10
The Mayfield stages of progressive perilunate instability.
Stage I results in SL instability. Stages II to IV result in progressively worse perilunate instability.
Stage I results in SL instability. Stages II to IV result in progressively worse perilunate instability.
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Lunate dislocation is the end stage of progressive perilunate dislocation. Along with ligamentous disruptions, fractures of the radial styloid, scaphoid, capitate, and the ulnar styloid can occur. 

Epidemiology of Carpal Fractures and Dislocations

When compared to fractures of the distal radius and hand, fractures of the carpus are uncommon, particularly those injuries not involving the scaphoid. There are minimal data documenting the global epidemiology of these injuries. The majority of literature is in relation to the epidemiology of scaphoid fractures, which is discussed later. An issue with many of the epidemiological studies in this area is that the majority of the data is collected retrospectively leading to inaccuracies in diagnosis and classification. Furthermore, many studies are performed within specific patient populations; for example, military, leading to wide ranging results regarding incidence, age, gender, and modes of injury. 

Carpal Fractures

Using data that is presented in Chapter 3 on fracture epidemiology from the Edinburgh 2010 to 2011 database, carpal fractures are relatively frequent accounting for 2.8% of all fractures with an annual incidence of 37.5/105 population per year. From the early 1900s Stimson462 quoted a prevalence for carpal fractures of 0.2% of all fractures, although he acknowledged that the number of carpal fractures, particularly those of the scaphoid, was probably higher. Data from the past 60 years is consistent, with a prevalence ranging from 2% to 3% of all fractures.107,148 
The mean age at the time of injury for all carpal fractures ranges from 35 to 40 years and a male predominance is seen.218,227,507 Overall, fractures of the carpus have a type A fracture curve (Chapter 3) with a bimodal distribution involving younger males and older females. A fall from standing height accounts for almost two-thirds of all injuries, with other modes of injury including sports, direct blow, assault, and motor vehicle collision (MVC).218,227,507 
It is consistently documented that scaphoid fractures and fractures of the triquetrum account for over 90% of all carpal fractures, with injuries to the hamate, pisiform, lunate, capitate, trapezium, and trapezoid being rare.218,227,507 Fractures of the scaphoid, hamate, pisiform, and trapezium appear to occur predominantly in younger males, with the mean age ranging from 29 to 43 years and a male predominance ranging from 66% to 100%. These data are consistent with a type B fracture distribution curve (Fig. 31-11). Triquetral fractures appear to be a different fracture to other fractures of the carpus, occurring at a mean age of 51 years with an approximately equal gender distribution, thus most closely fitting a type A fracture distribution curve. One study analyzed the epidemiology of scaphoid fractures against that of the other carpal fractures and found youth and male gender to be associated with a fracture of the scaphoid.218 
Figure 31-11
A type B fracture distribution curve for fractures of the scaphoid as seen in Edinburgh from 2007 to 2008.
 
(Reprinted with permission from: J Trauma Acute Care Surg. 2012;72(2):E41–E45.)
(Reprinted with permission from: J Trauma Acute Care Surg. 2012;72(2):E41–E45.)
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Figure 31-11
A type B fracture distribution curve for fractures of the scaphoid as seen in Edinburgh from 2007 to 2008.
(Reprinted with permission from: J Trauma Acute Care Surg. 2012;72(2):E41–E45.)
(Reprinted with permission from: J Trauma Acute Care Surg. 2012;72(2):E41–E45.)
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Injuries Associated with Carpal Fractures and Dislocations

Associated injuries are seen in approximately 7% of cases, with a fracture of the proximal or distal radius accounting for over 90% of all associated fractures. One study has demonstrated that of all patients with a carpal fracture only 7% sustain multiple carpal fractures, with almost half of these perilunate fracture-dislocations and over 90% involving a fracture to the scaphoid.218 Work from Edinburgh on dislocations has demonstrated that perilunate dislocations have an incidence of 0.5/105 population per year, occurring at a mean age of 26 years, and are frequently seen in males. Two studies have demonstrated that high-energy mechanisms are a risk factor for sustaining an associated injury following a fracture of the carpus.136,218 Open carpal fractures are noted to be rare,106,218 with only one documented in a 15-year study of 2,386 open fractures.106 

Diagnosis of Carpal Injuries

Mechanism of Injury of Carpal Fractures and Dislocations

An injury to the carpus commonly occurs following a mechanism in which an axial compression force is applied to the wrist, commonly leading to hyperextension where the palmar ligaments undergo tension and the dorsal articulations are subject to shear stresses.255,279,302,529 Given this, the most common mode of injury is a fall on the outstretched hand when an individual straightens the arm for protection and the body mass and external forces are placed across the wrist joint. Less common mechanisms occur when a forced is applied across the wrist when it is in palmar flexion. Most carpal instabilities, in particular perilunate dislocations, occur as a consequence of a high-energy injury; for example, a fall from a height on the outstretched hand or a motor vehicle accident. 

Clinical Assessment and Diagnosis of Carpal Injuries

Patients with an injury to the carpus will commonly have wrist pain as their primary presenting complaint. Clinical examination uses a combination of clinical signs along with special tests to help determine the diagnosis; however, pain, swelling, and ecchymosis around the region of the carpus may be present in the acute phase. A full examination of the contralateral wrist can often be helpful, particularly when assessing for instability. The most constant and dependable sign of carpal injury is well-localized tenderness.56,173 
  •  
    Anatomical snuffbox (ASB): Scaphoid injury
  •  
    Distal to Lister tubercle: Scapholunate and lunate injuries
  •  
    Dorsal margin, fingerbreadth distal to the ulnar head: Triquetral, lunotriquetral ligament and triquetrohamate ligament injuries
Changes in alignment of the hand, wrist, and forearm may be clinically evident on inspection of the extremity. Swelling over the proximal carpal row is suggestive of a ligament avulsion with or without an associated fracture. With carpal instability and/or dislocation a gross deformity may be apparent; for example, a marked prominence of the entire carpus dorsally is suggestive of a perilunate dislocation. Compressive stresses applied actively or passively may produce pain at the site of damage and cause a palpable and audible snap, click, shift, catch, or clunk, which may also be appreciated on movement of the wrist. Stress loading the wrist with compression and motion from radial to ulnar deviation may simulate midcarpal instability (MCI) and produce a “catch-up clunk” as the proximal row of carpal bones snap from flexion to extension. It should be noted that tendon displacements with audible snaps are easily produced in some patients but are seldom symptomatic. Despite poor diagnostic performance characteristics due to the rarity of these injuries, the following special tests are proposed as aids to the diagnosis of carpal ligament injury. 
  •  
    Scaphoid shift test (Fig. 31-12)370,523,528,547,548
    •  
      Pressure applied over scaphoid tubercle, wrist moving from radial to ulnar deviation
    •  
      Positive if there is a “clunk” as the scaphoid subluxes dorsally out of the scaphoid fossa (up to 30% of normal wrists have positive test)140
    •  
      Diagnostic of scapholunate disruption
  •  
    Midcarpal shift test153,276
    •  
      Pressure applied over dorsum of the capitate, wrist moving from radial to ulnar deviation
    •  
      Positive if there is a “clunk” as the lunate reduces from the palmar-flexed position
    •  
      Diagnostic of MCI
  •  
    Lunotriquetral ballottement384
    •  
      Lunate fixed with the thumb and index finger of one hand while the triquetrum is displaced palmarly and dorsally with the thumb of the other hand
    •  
      Positive if painful
    •  
      Diagnostic of lunotriquetral instability or arthritis
  •  
    Lunotriquetral shear test
    •  
      Dorsally directed pressure to the pisiform (directly palmar to the triquetrum) and a palmarly directed pressure to the lunate (just distal to the palpable dorsoulnar corner of the distal radius)
    •  
      Positive if results in reproducing patients pain along with palpable crepitation or clicking
    •  
      Diagnostic of lunotriquetral instability
Figure 31-12
The scaphoid shift test: Pressure is applied to the palmar aspect of the scaphoid tubercle while moving the wrist from an ulnar to radial deviation.
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Imaging for Carpal Fractures and Dislocations

Radiographs

The four standard views commonly employed in the assessment of scaphoid fractures can be used to detect most injuries to the carpus.85,170 These include neutral posteroanterior (PA) and lateral radiographs, along with a 45-degree radial oblique and a 45-degree ulnar oblique views (Fig. 31-13). Additional extension and flexion views are advocated for detecting intercarpal ligament injury, along with a clenched fist and stress views.183 Some authors also advocate contralateral wrist views because of the wide range of normal alignment. The standard neutral PA and lateral radiographs are useful for determining the presence of clear fractures and assessing carpal alignment, but are often poor for scaphoid fracture detection due to the tubercle overhang on the PA and the overlap on the lateral.96 The 45-degree radial oblique, 45-degree ulnar oblique, ulnar deviated PA, Ziter (Fig. 31-14), and carpal box or tunnel views are purported to improve the ability to diagnose a fracture, particularly of the scaphoid, and are discussed later.96,170,399,400,401,566 The VISI and DISI patterns of carpal malalignment are commonly detected using standard neutral lateral radiographs, with additional views in maximal radial and ulnar deviation if the diagnosis is in doubt. 
Figure 31-13
The four scaphoid views (PA, true lateral, radial oblique, ulnar oblique) detect most carpal fractures.
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Figure 31-14
Ziter view is an additional image that can aid in the diagnosis of scaphoid fractures.
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For the normal carpus with the wrist and hand in a neutral position, in the coronal (PA) plane a line drawn through the axis of rotation parallel with the anatomic axis of the forearm will pass through the head and base of the third metacarpal, the capitate, the radial aspect of the lunate, and the center of the lunate fossa of the radius.306,563 In the sagittal (lateral) plane with the wrist and hand in a neutral position, a line will pass through the longitudinal axis of the index finger metacarpal, capitate, lunate, and the radius, with the scaphoid lying on an axis at a 45-degree angle to this line.306,563 Standard radiographs should demonstrate a constant space between the scaphoid, lunate, and triquetrum throughout the range of wrist motion. Knowledge of these facts can aid in the diagnosis of carpal fracture displacement, instability, and collapse: 
  •  
    Intercarpal, carpometacarpal, and radiocarpal joint spaces (neutral PA view)
    •  
      Assessment of joint space between the individual carpal bones, the carpal bones and the metacarpals, and the carpal bones and radius
    •  
      Space is normally ≤2 mm, with ligament disruption suspected at >3 mm and often diagnostic at >5 mm
    •  
      Clenched fist views can accentuate the gap if equivocal
  •  
    Gilula lines (Fig. 31-15) (neutral PA view)193
    •  
      Arc 1 runs along the proximal articular surface of the proximal carpal row
    •  
      Arc 2 runs along the distal articular surface of the proximal carpal row
    •  
      Arc 3 runs along the proximal cortical margins of the capitate and hamate
    •  
      Three carpal arcs that produce smooth curves when drawn, with a broken arc diagnostic of a fracture and/or instability, particularly perilunate fracture dislocations
    •  
      With lunotriquetral dissociation, an intercarpal gap may not be seen but a break in the normal carpal arc of the proximal carpal row is evident
  •  
    Carpal-height ratio = carpal height/length of third metacarpal (neutral PA view) (Fig. 31-16)
    •  
      One method of measuring carpal height is to measure the distance between the base of the third metacarpal to the subchondral sclerotic line of the articular surface of the distal radius. The line should bisect the middle of the radius and metacarpal.
    •  
      Used to quantify carpal collapse with the normal ratio 50% (45% to 60%) and less than 45% indicative of carpal collapse
    •  
      One study has suggested gender specific normal values520
    •  
      Limited diagnostic value for carpal instability
    •  
      Alternate method uses height of the capitate instead of the third metacarpal348
  •  
    Inter- and intracarpal angles (neutral lateral view) (Table 31-4)
    •  
      Scapholunate angle (normal 45 degrees, range 30 to 60)
      •  
        Angle created by the longitudinal axes of the scaphoid and the lunate (Fig. 31-17)
      •  
        Long axis of the scaphoid is a line tangential to the palmar convex surfaces of the proximal and distal poles of the scaphoid
      •  
        Long axis of the lunate is a line perpendicular to the line connecting the dorsal and palmar lips of the lunate
      •  
        DISI pattern greater than 60 degrees, VISI pattern when less than 30 degrees; greater than 80 degrees is diagnostic of carpal (scapholunate) instability183,277
    •  
      Capitolunate angle (normal <15 degrees): Greater than 15 to 20 degrees is suggestive of carpal instability (Fig. 31-9)
    •  
      Radiolunate angle (normal <15 degrees): Greater than 15 to 20 degrees is suggestive of carpal instability
Figure 31-15
Gilula lines.
 
A: AP views show three smooth Gilula arcs in a normal wrist. These arcs outline proximal and distal surfaces of the proximal carpal row and the proximal cortical margins of capitate and hamate. B: Arc I is broken, which indicates an abnormal lunotriquetral joint due to a perilunate dislocation. Additional findings are the cortical ring sign produced by the cortical outline of the distal pole of the scaphoid and a trapezoidal shape of the lunate.
A: AP views show three smooth Gilula arcs in a normal wrist. These arcs outline proximal and distal surfaces of the proximal carpal row and the proximal cortical margins of capitate and hamate. B: Arc I is broken, which indicates an abnormal lunotriquetral joint due to a perilunate dislocation. Additional findings are the cortical ring sign produced by the cortical outline of the distal pole of the scaphoid and a trapezoidal shape of the lunate.
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Figure 31-15
Gilula lines.
A: AP views show three smooth Gilula arcs in a normal wrist. These arcs outline proximal and distal surfaces of the proximal carpal row and the proximal cortical margins of capitate and hamate. B: Arc I is broken, which indicates an abnormal lunotriquetral joint due to a perilunate dislocation. Additional findings are the cortical ring sign produced by the cortical outline of the distal pole of the scaphoid and a trapezoidal shape of the lunate.
A: AP views show three smooth Gilula arcs in a normal wrist. These arcs outline proximal and distal surfaces of the proximal carpal row and the proximal cortical margins of capitate and hamate. B: Arc I is broken, which indicates an abnormal lunotriquetral joint due to a perilunate dislocation. Additional findings are the cortical ring sign produced by the cortical outline of the distal pole of the scaphoid and a trapezoidal shape of the lunate.
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Figure 31-16
Carpal-height ratio, which is calculated by L2/L1.
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Figure 31-17
The scapholunate angle is created by the long axis of the scaphoid and a line perpendicular to the capitolunate joint.
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Secondary Imaging Modalities

Secondary imaging modalities are predominantly used in the assessment of scaphoid fractures and the diagnosis of intercarpal ligament injury and any associated instability (Table 31-5). For carpal fractures, further imaging is used for diagnosis, determining displacement, or in the assessment and management of malunions, nonunions, or bone loss. Detailed discussion of the use of secondary imaging modalities for fractures of the scaphoid is discussed in the scaphoid fracture section. 
 
Table 31-5
Secondary Imaging Modalities for Carpal Injuries
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Table 31-5
Secondary Imaging Modalities for Carpal Injuries
Modality Use(s)
USS Suspected carpal fractures, ligament injuries
CT (2D/3D) Suspected carpal fractures, fracture displacement, malunion, nonunion, and bone loss
3D imaging is useful in reconstructive procedures for malunions and nonunions
Dynamic CT is used by some for ligament injuries
Bone scintigraphy Suspected carpal fractures, avulsion injuries
Arthrography ± videofluoroscopy Ligament injuries
MR imaging (MRI) Suspected carpal fractures, AVN of carpal bones, ligament injuries
Wrist arthroscopy Suspected carpal fractures, fracture displacement, ligament injuries
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The following are measures of scaphoid fracture displacement, primarily assessed on CT and/or MR imaging:18,30 
  •  
    Lateral intrascaphoid angle (normal 30 degrees ± 5 degrees; sagittal view)
    •  
      Angle created by lines drawn perpendicular to the proximal and distal articular surfaces/poles of the scaphoid (Fig. 31-18A)
    •  
      An angle greater than 35 degrees is used as a cut-off for displacement18
  •  
    AP intrascaphoid angle (normal 40 degrees ± 5 degrees; coronal views)
    •  
      Angle created by lines drawn perpendicular to the proximal and distal articular surfaces
  •  
    Dorsal cortical angle (normal 140 degrees, abnormal >160 degrees; sagittal view)
    •  
      Angle created by tangential lines drawn along the dorsal cortices of the proximal and distal scaphoid fragments (Fig. 31-18B)
  •  
    Scaphoid height-to-length ratio (normal 0.60, abnormal >0.65; sagittal view)
    •  
      Ratio of the lines measuring the height and length of the scaphoid
    •  
      The length is determined by a palmar line drawn from the most proximal to the most distal edge of the scaphoid (Fig. 31-18C)
    •  
      The height is the maximal point with a line perpendicular to the length line
Figure 31-18
 
A: Lateral intrascaphoid angle measurement. B: Dorsal cortical angle measurement. C: Scaphoid height-to-length ratio measurement.
A: Lateral intrascaphoid angle measurement. B: Dorsal cortical angle measurement. C: Scaphoid height-to-length ratio measurement.
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Figure 31-18
A: Lateral intrascaphoid angle measurement. B: Dorsal cortical angle measurement. C: Scaphoid height-to-length ratio measurement.
A: Lateral intrascaphoid angle measurement. B: Dorsal cortical angle measurement. C: Scaphoid height-to-length ratio measurement.
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Bain et al.30 determined the intra- and interobserver reliability of the lateral intrascaphoid angle to be poor and poor to moderate respectively, the dorsal cortical angle to be moderate to excellent for both, and the height-to-length ratio was excellent and moderate to excellent respectively. 

Diagnosis of Carpal Injuries: Pearls and Pitfalls

  •  
    Standard scaphoid radiographic views detect most carpal injuries
  •  
    DISI pattern is most commonly associated with displaced scaphoid fractures and SLD
  •  
    Perilunate dislocations can be missed
  •  
    Assessment of Gilula’s line can aid in the diagnosis of perilunate dislocations
  •  
    CT is useful in the diagnosis of suspected carpal fractures and assessment of union
  •  
    MRI is useful in detecting suspected fractures and AVN of the carpus
  •  
    Wrist arthroscopy can be used as an aid to the diagnosis of ligament injuries and fracture displacement

Scaphoid Fractures

The name scaphoid comes from the Greek word “skaphos” meaning boat, a reference to the shape of the bone.173 Acute scaphoid fractures were first described by Cousin and Destot in 1889, with subsequent descriptions by Mouchet and Jeanne in 1919.173 The position of the scaphoid on the radial side of the wrist, as the proximal extension of the thumb ray, makes it vulnerable to injury. 
Some nondisplaced fractures of the scaphoid are not visible on radiographs taken at the time of injury (occult scaphoid fracture). Patients with radial-sided wrist pain and tenderness after a fall are often suspected of having an occult scaphoid fracture. The suspected scaphoid fracture remains a problematic clinical scenario despite advances in both knowledge and radiologic imaging. The mind-set and thrust of research in recent years has been aimed to find the optimal radiological test so that no fractures are missed, and to establish an early definitive diagnosis thus limiting immobilization, restrictions, and the number of further clinical assessments.132,168,194,209,235,307,490,506 However, despite advocates for the various secondary imaging modalities, a clear answer to the problem has not emerged. 
Displaced, comminuted, and unstable fractures of the scaphoid are routinely managed with surgical intervention. Much of the current controversy surrounds the undisplaced or minimally displaced acute fractures. Current opinion is that patients with undisplaced fractures of the scaphoid need protection and cast immobilization for 6 to 12 weeks, accounting for a considerable loss of time and productivity in a predominantly young and active population.31,171,307,404,405 Advocates for early operative intervention claim that screw fixation not only limits the need for a cast, but may also allow earlier return to sports and work.66,307,368,560 

Clinical Anatomy of Scaphoid Fractures

The scaphoid bone is located in the proximal carpal row on the radial aspect of the wrist and is a small irregular S-shaped tubular bone.44,67,71 It lies entirely within the wrist joint and is located at a 45-degree plane to the longitudinal and horizontal axes of the wrist. It has a reduced capacity for periosteal healing and an increased tendency for delayed union and nonunion because just over 80% of its surface is articular cartilage. 
The scaphoid is ridged across its nonarticular dorsoradial surface, along which the critical dorsal ridge vessels traverse. The ridge is the insertion point for both the dorsal component of the scapholunate ligament (Table 31-2) and the intercarpal ligament (Table 31-1). The distal pole is pronated, flexed, and ulnarly angulated with respect to the proximal pole. Articulations are with the trapezium/trapezoid (distal surface), radius (proximal/lateral surface), capitate (medial surface), and lunate (medial surface).44,67,71 
The ligamentous attachments of the scaphoid are predominantly found on the nonarticular dorsoradial surface. The short intrinsic ligaments provide stability to the scaphoid through attachments to the other carpal bones, in particular the lunate, and merge with the extrinsic ligaments and capsule of the wrist.43,44,46,53,67,71,300,476 The RSC ligament does not attach to the bone itself but crosses the waist, acting as a sling across it and allowing it to rotate.43,44,46,251,425,430432,449,476 There are no tendon attachments to the scaphoid.283 Through these articulations and soft tissue attachments the scaphoid acts as a midcarpal joint “bridge” linking and synchronizing the motions of the proximal and distal carpal rows as part of the key intercalated segment.44,246,247,434,530 Motion of the scaphoid includes rotation proximally and gliding distally, while providing stability to the midcarpal joint. 

Vascular Supply

The potential for nonunion of the scaphoid is often ascribed to the meager, largely retrograde blood supply (Table 31-3),57,164,185,186,366,474 through soft tissue attachments via two vascular pedicles originating from the scaphoid branches of the radial artery (Fig. 31-19).44,185,186,366 
  •  
    Dorsal branch: Enters via the small foramina along the spiral groove and dorsal ridge of the scaphoid and supplies 70% to 80% of the scaphoid proximally, including the proximal pole.
  •  
    Volar branch: Enters via the scaphoid tubercle and supplies the remaining 20% to 30% of distal scaphoid.
Figure 31-19
The vascular supply of the scaphoid is provided by two vascular pedicles.
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It should be noted that the waist of the scaphoid has been shown to have minimal or no perforating vasculature.185 Furthermore, no vessels perforate the proximal dorsal cartilaginous area or through the scapholunate ligament.164 For the detailed pathoanatomy of injury please see Page 999. 

Epidemiology and Etiology of Scaphoid Fractures

Acute scaphoid fractures account for 2% to 3% of all fractures, approximately 10% of all hand fractures and between 60% and 80% of all carpal fractures.173,226,270 The incidence of scaphoid fractures quoted in the literature is inconsistent with a range from 1.5 to 121 fractures per 100,000 persons per year.136,226,242,270,506,509,546,558 It is most probable that the wide variation documented is due to the use of predominantly retrospective data, analysis of specific patient populations; for example, military, as well as the limitation of many large datasets to distinguish between a true and suspected fracture.226,242,270,506,509,546,558 The lower quoted incidences appear to be more in keeping given that the average incidence of fractures of the distal radius is 195 per 100,000 population per year.107,509 A recent study from Edinburgh documented the epidemiology of true radiographically confirmed acute fractures of the scaphoid in a defined adult population using a prospective dataset and found an annual incidence of 29 per 100,000 per year,136 which is consistent with previous studies from Scandinavia quoting an annual incidence of 26 to 39 per 100,000 per year.242,270 The mean age in the literature ranges from 25 to 35 years, with males significantly younger at the time of injury compared to females suggesting scaphoid fractures most closely fit a type B fracture distribution curve (Fig. 31-11). A male predominance is seen with a male-to-female ratio of approximately 2.5:1.136,226,242,270,506,509,546,558 Two studies have documented male sex as a risk factor associated with a true fracture.135,235 
Scaphoid fractures usually occur after a fall on to the outstretched hand or during sports,136,235,270,509 with two studies reporting that sports injuries are associated with a true fracture.135,235 One study has documented that a low-energy fall from standing height has been shown to occur more frequently in females, with males more likely to sustain their fracture after a high-energy injury such as sports or a motor vehicle collision.136 This is in keeping with the younger age at which fracture occurs in males. Sports noted to cause increased risk include football, basketball, cycling, and skateboarding depending on the study origin.136,509 Fractures of the scaphoid are being increasingly documented after punching or assault-related injuries.224,468 
An exact understanding of the epidemiology and etiology of fractures of the scaphoid is essential when considering the diagnosis of the suspected scaphoid fracture, in particular the use of further imaging modalities such as CT or MRI. Given the increasing evidence for earlier return to function following fixation of the scaphoid,66,307 it is important to consider that the population affected is predominantly young and active, with these patients more frequently sustaining unstable injuries. 

Scaphoid Fractures Clinical Assessment and Diagnosis

The diagnosis of a fracture to the scaphoid is made by a combination of clinical history, examination, and radiographic assessment. Patients classically present with wrist pain following a fall onto the outstretched hand, with almost 90% recalling a hyperextension injury. Clinical examination uses a combination of clinical signs (Table 31-6). Generally pain, swelling, ecchymosis, and tenderness around the region of the scaphoid may be present in the acute phase. Standard four-view radiographs are subsequently used to confirm the diagnosis. 
Table 31-6
The Sensitivity, Specificity, Positive Predictive Value and Negative Predictive Value of Clinical Signs of Scaphoid Fractures
Sensitivity (%) PPV (%) Specificity (%) NPV (%)
ASB tenderness 100 30 19 100
Scaphoid tubercle tenderness 100 34 30 100
Longitudinal thumb compression 100 40 48 100
Reduced thumb movement 66 41 66 85
ASB swelling 61 50 52 58
ASB pain in ulnar deviation/pronation 83 44 17 56
ASB pain in radial deviation/pronation 70 45 31 56
Pain on thumb/index pinch 48 44 31 41
Scaphoid shift (Kirk-Watson) test 66 49 31 69
 

PPV, positive predictive value; NPV, negative predictive value; ASB, Anatomical snuffbox.

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However, up to 30% to 40% of scaphoid fractures are not identified on initial assessment and investigation with standard four-view radiographs and are thus classified as having a suspected fracture.31,62,170,172,173,255,393,505,517 Patients who are subsequently found to have a fracture confirmed on repeated assessment and radiologic imaging, most frequently at 10 to 14 days post injury, are said to have had an occult fracture of the scaphoid.23,60,168,170,261,311,393 In these cases, the treating surgeon must balance employing immobilization and restriction of activities in a predominantly young and active population against the risks of nonunion and arthrosis associated with an undiagnosed and untreated scaphoid fracture.104,250,405 

Symptoms

Patients present with a history of hyperextension to the wrist, often following a fall, sports, or punch injury. It is important to determine a history of previous trauma to the scaphoid and not treat a nonunion as if it is an acute fracture. The main complaint is of radial-sided wrist pain, with localized tenderness over the scaphoid in the region of the ASB. 

Signs

No single sign has been found to be adequately sensitive or specific (Table 31-6).150,167,200,350,371,376,505,517 The first studies in this area analyzed the sensitivity and specificity of the classic individual clinical signs. ASB tenderness is over sensitive and has poor specificity. In a study of 246 patients with a suspected fracture of the scaphoid, ASB tenderness was found to have a sensitivity of 90% and a specificity of 40%, with scaphoid tubercle tenderness having a sensitivity of 87% and specificity of 57%.167 From another study that performed a prospective analysis of 73 patients with a suspected scaphoid fracture, the sensitivity and specificity of ASB pain on ulnar deviation of the pronated wrist was calculated.376 That individual sign had a negative predictive value (NPV) of 100% and the authors concluded that patients with a negative test could be safely discharged at presentation as they did not have a scaphoid fracture. 
Further studies aimed to improve the diagnostic performance characteristics, in particular specificity of the clinical signs, by combining them. Parvizi et al.371 performed a prospective study of 215 consecutive patients and demonstrated that the use of one clinical sign in isolation was insufficient for the diagnosis of a fracture, but that a combination of ASB tenderness, scaphoid tubercle tenderness, and ASB pain on longitudinal compression of the thumb generated a sensitivity of 100% and a specificity of 74%. However, these findings were only valid for the first 24 hours after injury. 
Recent studies have examined alternative clinical signs as predictors of a fracture of the scaphoid. Unay et al. analyzed 10 clinical examination maneuvers on 41 patients with suspected scaphoid fractures and used MRI to determine the presence or absence of a fracture. They demonstrated that pain on thumb-index finger pinch and ASB pain on pronation of the forearm were most suggestive of a true scaphoid fracture.505 Duckworth et al.135 determined that the best predictors of fracture within 72 hours of injury were the absence of pain on ulnar deviation of the wrist and pain on thumb-index finger pinch, with scaphoid tubercle tenderness most predictive at week two. 

Radiographs

Neutral PA and lateral radiographic views are useful for ascertaining carpal alignment and the assessment of perilunate fracture-dislocations; however, they are poor at fracture detection, particularly with the tubercle overhang found on the neutral PA view.85,96 Views suggested to improve the ability to diagnose a scaphoid fracture are demonstrated in Table 31-7.85,96,170,566 
Table 31-7
Additional Radiographic Views Used in the Assessment of Scaphoid Fractures
Radiologic View Advantages
Ulnar-deviated Detection of proximal pole fractures
45-degree ulnar oblique (semipronated) Detection of oblique sulcal, waist (in particular displacement), and tubercle fractures
45-degree radial oblique (semisupinated) Detection of proximal pole fractures, humpback deformities, and avulsion fractures
Ziter view Detection of waist fractures as beam at right angles to long axis
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Ziter view, or the “banana view,” uses a PA view of the wrist in ulnar deviation with 20-degree tube angulation to the elbow (Fig. 31-14).566 This modified view can aid in the identification of scaphoid waist fractures, although fractures oblique to the beam are not well identified. Carpal box views have been shown to increase agreement in the interpretation of the standard four-view scaphoid radiographs from 36% to 55%, although they are not routinely utilized.400,401 Some authors also suggest comparative views of the contralateral uninjured wrist can aid in the diagnosis of the suspected fracture.1 
Some studies have suggested that when clinical and radiographical assessment is carried out by experienced surgeons, all suspected scaphoid fractures can be detected within 6 weeks of injury.31,170 However, the vast majority of the literature consistently indicates that up to 30% to 40% of scaphoid fractures are not identified on initial assessment and investigation with four-view radiographs.31,62,170,172,173,255,393,505,517 Standard four-view scaphoid radiographs have been demonstrated to have low inter- and intraobserver reliability for the diagnosis of suspected scaphoid fractures.491,492 Repeated radiologic assessment has been documented to have low sensitivity, with one study only detecting 50% of suspected scaphoid fractures.172 Barton suggested three possible reasons why standard scaphoid radiographs are often misinterpreted.31 
  1.  
    A dark line may be formed by the dorsal lip of the radius overlapping the scaphoid
  2.  
    The presence of a white line formed by the proximal end of the scaphoid tuberosity
  3.  
    The dorsal ridge of the scaphoid may appear bent on the semisupinated view
Soft tissue signs of a scaphoid fracture on plain radiographs include the scaphoid fat pad sign (distortion or loss of adjacent fat stripes over the radial aspect of the scaphoid on the PA view with the wrist in ulnar deviation) and the pronator fat pad/stripe sign (a prominent pronator quadrates fat pad over the volar aspect of the wrist on the lateral view). Although there are advocates for these soft tissue signs,268 most have demonstrated them to be unreliable detectors for the presence of a suspected scaphoid fracture.23,123 Given the difficulty with confidently diagnosing a scaphoid fracture on standard radiographs, when clinical suspicion is present but radiographs are negative, immobilization is recommended with repeat examination and radiographs performed within 10 to 14 days of injury. The delay may lessen both tenderness and anxiety leading to a better examination. 

Ultrasound

Ultrasound is a noninvasive and relatively inexpensive technique for diagnosing scaphoid fractures; however, it is operator dependent and has been shown to be least effective in detecting true fractures with a sensitivity ranging from 37% to 93% and a specificity ranging from 61% to 91%.88,110,235,337,423 There are advocates for the use of high–spatial-resolution sonography for detecting the suspected scaphoid fracture, with the sensitivity rising up to 100% and the specificity as high as 91%.168,214 Others have suggested it to be a useful precursor to further imaging modalities when used in the emergency department.373 

Bone Scintigraphy

There are strong advocates for bone scintigraphy34,35,490,491; however, most authors feel that the specificity is too low when compared to both CT and MRI.59,162,391,394,559 Beeres et al.35 analyzed 100 patients with a suspected fracture and found bone scintigraphy had a sensitivity of 100% and a specificity of 90%, concluding that there was no advantage to MRI over this modality. Further work from this group found similar results when comparing CT with bone scintigraphy.391 However, Fowler et al.162 found in 43 patients with suspected scaphoid fractures that bone scintigraphy was inferior to MRI for both sensitivity and specificity, using 1-year follow-up as the reference standard. 

CT

Many authors advocate the use of CT for diagnosing true fractures among suspected scaphoid fractures,59,108,292,504,562 although some have cautioned against its use for undisplaced fractures.3 In an analysis of 47 patients with a suspected scaphoid fracture, using 2-week radiographs and/or MRI as the reference standard, CT was found to be 94.4% sensitive and 100% specific with an NPV of 96.8% and a positive predictive value (PPV) of 100%.198 CT has also been shown to be useful in detecting other injuries around the wrist, particularly in the acute assessment of the suspected fracture.461,504 In a study of 28 patients with a suspected scaphoid fracture who underwent CT, undisplaced fractures of the distal radius or carpus were demonstrated in 36% of patients.504 Stevenson et al. performed a retrospective analysis of 84 patients with suspected scaphoid fractures who underwent CT within 14 days of injury. Fifty-four scans were normal. Of the 30 abnormal scans the authors found that 7% were occult scaphoid fractures, 18% were occult carpal fractures (triquetrum, capitate, lunate), and 5% were distal radius fractures.461 Overall, approximately one-third of CT scans for suspected scaphoid fractures found other wrist injuries. 
To determine the intraobserver and interobserver reliability of CT for the diagnosis of an undisplaced scaphoid fracture, one study used eight observers to evaluate CT scans from 30 patients.3 Although they found substantial intraobserver and interobserver reliability, they also noted a high false-positive rate, possibly from the misinterpretation of vascular channels as a unicortical fracture (Fig. 31-20). A very recent study has reported a kappa value of only 0.51 (moderate agreement) for the interobserver reliability among radiologists when using CT for the diagnosis of scaphoid fractures.116 
Figure 31-20
Sagittal CT slice demonstrating an undisplaced fracture of the scaphoid waist, although this could be mistaken for a vascular channel.
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MRI

For the suspected scaphoid fracture, MRI is argued to be the best investigation, although some institutions have limited access and there are inconsistencies regarding cost efficiency.65,132,171,194,209,235,261,379,559 In a prospective blind study in which MRI scans were performed within 72 hours of injury in 32 patients with a suspected scaphoid fracture, it was found that the sensitivity and specificity of MRI were 100%, with potential savings of $7,200 per 100,000 of the population through avoiding unnecessary immobilization and review.171 This study used clinical and/or radiographic follow-up at 6 weeks as their reference standard. A more recent randomized controlled trial allocated 84 patients with a suspected scaphoid fracture to early MRI and discharge if no injury, or to standard reassessment in clinic 10 to 14 days after injury.372 They found no difference between the two groups in terms of mean management costs, pain, patient satisfaction, and time off work or sports. 
Although MRI is the most successful secondary imaging modality to date in terms of performance characteristics, in low prevalence situations the PPV has been found to be only 88% and recent work has documented the potential for false-positive MRI scans.117 Ring and Lozano-Calderon394 performed an analysis to determine the diagnostic performance characteristics of the various secondary imaging modalities utilized in the assessment of the suspected scaphoid fracture (Table 31-8). Using Bayesian formulae and an average published prevalence of scaphoid fractures among suspected fractures of 7%, the NPV for MRI was 88%, meaning that around 12% of patients with a suspected scaphoid fracture undergo an MRI that is interpreted as demonstrating a fracture when they may not actually have a fracture. A recent analysis of MRI scans in healthy individuals also highlighted the potential for false-positive MRI scans, with benign abnormalities diagnosed as fractures by numerous blinded radiologists.117 This study concluded that MRI is not a suitable reference standard for true scaphoid fractures among patients with suspected fractures. 
Table 31-8
The Sensitivity, Specificity, Accuracy as well as the Average Prevalence Adjusted PPV and NPV for Various Imaging Modalities as Determined by Ring et al. for Suspected Fractures of the Scaphoid
Imaging Modality (Number of Studies Assessed) Sensitivity (%) Specificity (%) Accuracy (%) PPV NPV
Ultrasound (n = 4) 93 89 92 0.38 0.99
Bone scintigraphy (n = 18) 96 89 93 0.39 0.99
CT (n = 8) 94 96 98 0.75 0.99
MRI (n = 22) 98 99 96 0.88 1.00
 

From Duckworth AD, Ring D, McQueen MM. Assessment of the suspected fracture of the scaphoid. J Bone Joint Surg Br. 2011;93-B(6):713–719.

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A prospective cohort study that again used 6-week radiographs as the reference standard demonstrated that CT and MRI had comparable diagnostic performance characteristics for detecting true fractures among suspected scaphoid fractures, with the PPV for CT being 76% compared to 54% for MRI.292 This study also questioned whether or not bone edema on MRI and small unicortical lines on CT are diagnostic of a true scaphoid fracture. The rate of scaphoid bone bruising (Fig. 31-21) on MRI leading to occult fracture has been documented to be 2% in one study.487 
Figure 31-21
MRI demonstrating scaphoid bone bruising but no fracture.
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Current Practice

Despite many advocates, the optimal imaging modality is not known. One paper has recently presented a meta-analysis of 26 studies to determine the prevalence adjusted diagnostic performance characteristics of bone scintigraphy, CT, and MRI for suspected scaphoid fractures.559 Of the 26 studies, 9 used 6-week radiographic follow-up as their reference standard. Bone scintigraphy and MRI were shown to have comparable high sensitivity rates, though MRI was more specific (Table 31-9). 
Table 31-9
The Sensitivity and Specificity as Determined by Yin et al. of Different Imaging Techniques in the Diagnosis of Occult Fractures of the Scaphoid
Imaging Modality (Number of Studies Assessed) Sensitivity (%) Specificity (%)
Bone scintigraphy (n = 15) 97 89
CT (n = 6) 93 99
MRI (n = 10) 96 99
 

From Duckworth AD, Ring D, McQueen MM. Assessment of the suspected fracture of the scaphoid. J Bone Joint Surg Br. 2011;93-B(6):713–719; with data from Yin ZG, Zhang JB, Kan SL, et al. Diagnosing suspected scaphoid fractures: A systematic review and meta-analysis. Clin Orthop Relat Res. 2010;468:723–734.

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National guidelines of some professional associations, as well as advocates for MRI, suggest an overly optimistic assessment for its use. The Royal College of Radiologists (UK) recommends that on current evidence bone scintigraphy, CT, and MRI are comparable for triaging the suspected acute scaphoid fracture.403 However, the American College of Radiology (ACR) concludes radiographs and MRI should be utilized.19 An international survey of 105 hospitals worldwide was performed to determine their own imaging protocol for the suspected scaphoid fracture and reported a high rate of inconsistency among the hospitals with only 22% found to have a fixed protocol.201 

Assessing Diagnostic Tests

Given the combination of oversensitive clinical signs and no consensus gold standard for diagnosing a scaphoid fracture, most patients with a suspected fracture of the scaphoid receive more protection and diagnostic testing than is required.31,150,167,170,200,371,376 This can lead to issues with wrist stiffness and costs to both the healthcare system and the patient with time off work and sports in a predominantly young, healthy, and active patient group.132,438,490,506 
It has been proposed that the assessment of the various diagnostic tests for the assessment of the suspected scaphoid fracture must account for two important issues.137,394 The first is the low prevalence of true fractures among suspected fractures, which greatly lowers the probability that a positive test will correspond with a true fracture as false positives are nearly as common as true positives.3,137,226,235,255,270,390,394 Research has documented that between 5% and 20% of patients who attend the emergency department with a suspected scaphoid fracture are ultimately found to have a true fracture.3,226,235,255,270,390,394 Given that false positives and false negatives are 5% to 10% for most diagnostic tests, this low prevalence of disease among assessed patients leads to low PPVs according to Bayes theorem even when the diagnostic test is both highly sensitive and specific (Fig. 31-22).16,394 
Figure 31-22
The relationship between fracture prevalence and the positive predictive value of diagnostic tests, in this case, CT.
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The second issue relates to the fact that the calculation of the diagnostic performance characteristics (sensitivity, specificity, PPV and NPV, and accuracy) for the various imaging modalities using a traditional formula requires a consensus reference standard for the presence or absence of a fracture.16,17 The most frequently used standard in the literature is the absence of a fracture on radiographs at 6 weeks post injury.3,170,338,394,559 However, given the lack of consensus, an alternative method for calculating diagnostic performance characteristics based on a statistical method that identifies clinical factors that tend to associate (latent classes) in patients with a high probability of fracture is preferable.3,338,394 This technique has been applied to the diagnosis of carpal tunnel syndrome,263 as well as in two recently published studies on the assessment of the suspected scaphoid fracture.72,135 These studies found small but potentially important differences between the results obtained using traditional formula and those obtained using latent class analysis.72,135 
The upshot of the issues raised by the low prevalence and lack of consensus reference standard is that there will likely always be a small probability of missing a true fracture among suspected scaphoid fracture. If patients, doctors, and society can accept an approximate 1% chance of missing a true fracture, we may have adequate management strategies at the current time. It is not clear that imaging technology will improve these odds because better imaging has findings which are difficult to interpret. The best option might be to increase the pretest odds of a fracture before ordering advanced imaging, and this can be done by applying a clinical prediction rule to determine when to order further imaging. 

Clinical Prediction Rules

The benefit of clinical prediction rules in medicine to guide, but not dictate, management of patients is well documented.285,387 It has been suggested that an important step to improving the diagnostic performance characteristics of the various imaging modalities for the suspected scaphoid fracture would be to increase the prevalence of the true scaphoid fracture among suspected fractures through the development and promotion of clinical prediction rules.137,394 These rules would incorporate a combination of demographic and clinical risk factors predictive of a true scaphoid fracture. Implementation of these rules could potentially increase the prevalence of true scaphoid fractures among suspected fractures and subsequently allow the utilization of sophisticated secondary imaging in high risk patients, potentially leading to improved diagnostic performance characteristics of diagnostic imaging. 
Two studies have demonstrated the potential of clinical prediction rules to improve the management of suspected scaphoid fractures. One study from Holland analyzed 78 patients with a suspected scaphoid fracture and determined using multivariate analysis that a reduction in extension of greater than 50%, supination strength of ≤10%, and the presence of a previous fracture were most predictive of a true fracture.390 A recent prospective study from Edinburgh and Boston analyzed 223 patients with a clinically suspected or radiographically confirmed scaphoid fracture, using radiologic imaging at 6 weeks as their reference standard.135 They demonstrated that risk factors for a true fracture were male gender, sports injury, ASB pain on ulnar deviation of the wrist, and pain on thumb-index finger pinch at presentation, as well as persistent scaphoid tubercle tenderness at 2-week review. They incorporated these signs to develop clinical prediction rules that can guide assessment of these patients (Fig. 31-23). Ultimately, this study demonstrated that clinical prediction rules have a substantial and meaningful influence on the probability of a suspected scaphoid fracture. 
Figure 31-23
(Reprinted with permission from: J Bone Joint Surg Br. 2012;94(7):961–968, Figure 2.)
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Figure 31-23
A potential management algorithm for suspected scaphoid fractures based on a clinical prediction rule developed by Duckworth et al.
(Reprinted with permission from: J Bone Joint Surg Br. 2012;94(7):961–968, Figure 2.)
(Reprinted with permission from: J Bone Joint Surg Br. 2012;94(7):961–968, Figure 2.)
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Classification and Associated Injuries of Scaphoid Fractures

There are several classification systems available for fractures of the scaphoid. These include the following. 
  •  
    Russe classification407
  •  
    AO classification
  •  
    Herbert and Fisher classification211
  •  
    Mayo classification100
The Russe classification predicts instability according to the inclination of the fracture line; for example, vertical oblique fractures. The AO classification breaks the fracture down into simple anatomic location (distal pole, waist, proximal pole) and comminution. 
Herbert and Fisher211 proposed a classification intended to identify those fractures most applicable for operative fixation and is commonly used throughout the literature (Table 31-10 and Fig. 31-24). Type A fractures are stable fractures that often appear incomplete (unicortical), are associated with good union rates, and minimal treatment is required. Type B fractures include any acute bicortical fracture and are defined as unstable and hence will most likely require surgery due to the potential for displacement in plaster and delayed union. There are now two studies that have demonstrated that displaced waist of scaphoid fractures (Herbert B2) account for over one-third of all fractures,61,136 with one of these studies demonstrating that unstable Herbert type-B injuries were significantly more common in younger patients following a high-energy injury.136 Type C and Type D fractures are associated with delayed and nonunion respectively. Characteristics of Type C delayed union are defined as widening of the fracture line, development of cysts adjacent to the fracture, and relative density of the proximal fragment. 
Figure 31-24
Schematic drawing of Herbert and Fisher classification of scaphoid fractures.
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Table 31-10
The Prevalence of Different Herbert and Fisher Fracture Types of Acute Scaphoid Fractures
Herbert Classification Prevalence (%)136
Type A: Stable acute fractures 31.1
A1 (tuberosity) 14.6
A2 (unicortical waist) 16.5
Type B: Unstable acute fractures 68.9
B1 (distal oblique/pole) 21.2
B2 (complete waist) 36.4
B3 (proximal pole) 6
B4 (transscaphoid perilunate fracture dislocation) 2
B5 (comminuted) 3.3
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Some argue the most useful classification for guiding treatment, particularly for displaced fractures, is the Mayo classification.100,125 The criteria for instability they set out are as follows: 
  •  
    >1 mm of fracture displacement103,143
  •  
    A lateral intrascaphoid angle of >35 degrees (see below)
  •  
    Bone loss or comminution
  •  
    Fracture malalignment
  •  
    Proximal pole fractures
  •  
    DISI deformity
  •  
    Perilunate fracture-dislocation
A criticism of all these classifications is that they do not clearly consider the extent of associated soft tissue injuries. 

Diagnosis of Displacement and Instability

Assessment of scaphoid fracture displacement and instability is essential, given the higher rates of nonunion associated with nonoperative management.143 All displaced fractures are unstable. A very small percentage of patients have a nondisplaced fracture (no radiologic signs of displacement) but are unstable (fracture fragments move easily with probing or external pressure on the distal pole of the scaphoid during wrist arthroscopy). There are various methods for determining scaphoid fracture displacement (Table 31-11). As with the assessment of the suspected scaphoid fracture, the various imaging modalities are hindered by the low prevalence of displaced scaphoid fractures among all fractures. This leads to all modalities being better at excluding displacement rather confirming it. 
Table 31-11
The Sensitivity, Specificity, Accuracy as well as the PPV and NPV for Various Imaging Modalities Used in the Assessment of Scaphoid Fracture Displacement
Imaging Modality Sensitivity (%) Specificity (%) Accuracy (%) PPV NPV
Radiographs 75 72 64 10 97
CT 72 80 80 13 98
Radiographs + CT 80 73 73 16 99
 

From: Dias JJ, Singh HP. Displaced fracture of the waist of the scaphoid. J Bone Joint Surg Br. 2011;93:1433–1439.

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Standard scaphoid radiographs can be used to determine displacement in terms of translation, step-off, gap, rotation, and angulation (Fig. 31-25)125; however, some question the validity of its use with only moderate interobserver reliability being reported.47,50,121 Some authorities advocate the use of wrist motion views to demonstrate displacement, with the length of the scaphoid determined by comparing ulnar and radial deviation views in both wrists. Assuming that the two views are identical, any difference in length is indicative of a scaphoid deformity as a consequence of either a fracture and/or a ligament injury. When displacement and instability is suspected, careful assessment of the lateral radiograph for the position of the lunate (Fig. 31-17) and intrascaphoid angulation (Fig. 31-18) is essential,50,121 with repeat radiographs recommended as displacement may occur over time. 
Figure 31-25
A displaced and comminuted fracture through the waist of the right scaphoid.
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CT is more accurate and reliable than radiographs for the diagnosis of scaphoid fracture displacement,287,343 but it is unclear whether routine CT scanning improves outcomes. One study determined that CT had a low sensitivity in the diagnosis of radial/ulnar scaphoid displacement, while radiographs had a low sensitivity in the diagnosis of volar/dorsal displacement.486 Useful measurements include the following: 
  •  
    Fracture displacement103,143
    •  
      Step ≥1 mm at dorsal or radial cortices
    •  
      Gap ≥1 mm (sagittal or coronal views)
Lozano-Calderon et al.287 analyzed the diagnostic performance characteristic of radiographs and/or CT for detecting the displacement of acute scaphoid fractures. They concluded that CT improved the reliability of detecting scaphoid fracture displacement but with an accuracy still <80% with the utilization of CT limited by the low prevalence of displaced fractures. One study found that quantitative measurements of scaphoid fracture displacement using CT had limited intra- and interobserver reliability,395 and others have suggested that measurement is influenced by the image plane and the thickness of the slices used.388,446 However, one recent study has suggested that training can lead to a slight increase in reliability for detection of displacement using such methods.68 
Alternate methods of determining fracture displacement include USS, MRI, or wrist arthroscopy.50,70 One study has reported 100% specificity for determining scaphoid fracture instability when using USS; however, this is noted to be very user dependent.124 A recent study analyzed 58 consecutive patients with a scaphoid fracture who underwent arthroscopy-assisted operative fracture fixation.70 They found a significant correlation between radiographic comminution (>2 fragments) and arthroscopically determined displacement and instability. Using arthroscopy as the reference standard (Fig. 31-26), one study has found that radiographs and CT cannot be relied on to accurately diagnose scaphoid fracture displacement and/or instability.69 This study was novel in making a clear distinction between displacement and instability, noting a few radiologically well-aligned fractures that were unstable on arthroscopic visualization. To our knowledge, there are no data regarding the prognosis of well-aligned unstable fractures. 
Figure 31-26
Arthroscopic diagnosis of scaphoid fracture displacement.
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Associated Injuries

Associated injuries occur in approximately 10% of all scaphoid fractures, commonly following a high-energy mode of injury, and proximal radial fractures are most frequently seen.136,541 Fractures of the distal radius can occur, as can perilunate dislocations and transscaphoid perilunate fracture-dislocations.136,218 A concomitant fracture of the distal radius can be indicative of more serious ligamentous disruption and carpal instability.228 It is essential to consider that a radiograph never accurately exposes the true degree of joint and ligament damage. 
Recent studies have aimed to document the incidence of associated ligamentous injuries given the increased use of wrist arthroscopy in the management of scaphoid fractures. Caloia et al.77 documented an associated ligamentous and/or bony injury in 63% of the 24 acute scaphoid fractures in their series. In a more recent study of 41 scaphoid waist fractures, fresh intrinsic ligament injuries were found in 34 cases, with 29 cases a scapholunate ligament injury (complete rupture in 10). Interestingly, there was no significant difference in the rate of ligament injury between nondisplaced and displaced scaphoid fractures.243 The clinical relevance of these associated ligamentous injuries is yet to be determined. 

Authors’ Preferred Management—Imaging and Diagnosis of Displacement

 
 

Given the low prevalence of displacement and instability, we feel comfortable relying on radiographs that demonstrate no gapping or translation at the fracture, and no dorsal tilting of the lunate, if the patient agrees that a very small risk of healing problems is preferable to the radiation and other downsides of CT. If there is any uncertainty, we order CT in the planes defined by the long axis of the scaphoid.

Authors’ Preferred Management—Acute Scaphoid Fractures

 
 
Suspected Scaphoid Fractures
 

Patients with a suspected occult scaphoid fracture are re-evaluated after 1 to 2 weeks of immobilization in a forearm cast or splint. An examination by a specialist after the injury has become less painful substantially decreases the probability of a scaphoid fracture in most circumstances. If the probability of a fracture remains unacceptable (a decision shared with the patient) and new scaphoid specific radiographs are also normal, the patient can either continue with immobilization (6 weeks of splint immobilization with normal scaphoid radiographs is likely sufficient) or advanced imaging (typically CT or MRI) can be used to attempt to exclude a fracture and avoid additional immobilization and activity restrictions. The higher the pretest odds of a fracture, the more likely an imaging diagnosis of a fracture will correlate with a true fracture. The lower the pretest odds; for example, “rule out” rather than “confirm,” the less likely that a radiologic diagnosis of a fracture will correspond with a true fracture. Patients with more pressing needs to diagnose a fracture (some athletes and other occupations) can be considered for more sophisticated imaging early on, keeping in mind the limitations of this diagnostic strategy.

 
Scaphoid Tubercle Fractures
 

For tubercle fractures, we recommend 3 to 4 weeks in a splint followed by active mobilization.

 
Nondisplaced Scaphoid Fractures
 

We recommend as standard a below-elbow cast with the thumb free for nondisplaced stable scaphoid fractures. If there is any doubt about the presence of displacement, particularly if there is fragmentation at the fracture line, we would progress to a CT scan. Based more on tradition than data, the duration of immobilization is 8 to 10 weeks. Radiographs and clinical examination should not be used to determine duration of immobilization because they are unreliable for diagnosis of union. Return to sport and use of the hand with force is delayed until there is clear radiographic evidence of union or 4 to 6 months have passed. At this point it is reasonable to “put things to the test” no matter what the radiographs show since additional protection is unlikely to facilitate union.

 

We offer patients with nondisplaced or minimally displaced fractures the option of percutaneous screw fixation, including a balanced discussion on the risks and benefits of surgery based on the best available evidence. One of us prefers a volar approach to percutaneous fixation and the other uses either a dorsal or a volar approach. We feel the advantages of the volar approach are that the scaphoid tubercle is very superficial, the wrist can be maintained in neutral which makes imaging easier and decreases the chance of bending the guidewire, and there is no need to open the radiocarpal joint. On the other hand, care must be taken to ensure that an overhanging trapezium does not cause the surgeon to insert the screw too superficially (too volar) or too vertical. There may also be a risk of later scaphotrapezial arthrosis. Using this approach, the surgeon must be prepared to place the screw through the overhang of the trapezium which is usually extra-articular. If the screw is placed too vertically in the sagittal plane, the screw tip may penetrate the dorsal radial scaphoid cortex, which both endangers the radioscaphoid cartilage and usually provides inadequate fixation of the proximal fragment.

 

We feel the advantages of a dorsal approach include easier central placement in the proximal pole and body of the scaphoid. Disadvantages include the need to keep the wrist in a flexed position, greater risk of bending the guidewire, risk to digital extensor tendons, and creation of a hole in the scaphoid articular surface. The starting point of the wire can be identified arthroscopically and a large bore needle used as a guidewire or this can be done entirely with the image intensifier. The hand is placed on top of a stack of towels on the image intensifier to maintain the wrist in flexion to provide access to the starting point and limit the potential for bending the wire. The wrist is kept flexed and the images are perpendicular to the carpus. After determining the length of the screw, the wire is placed into the trapezium to prevent unintended extraction if predrilling is used.

 

Some surgeons allow patients to return to sports and forceful activity sooner after screw fixation than they would after cast treatment (sometimes within a few weeks of screw placement), but we do not recommend that approach. Postoperatively, a bandage is applied and usually a cast is not required. Noncontact sports are allowed immediately. Contact sports, heavy lifting, or axial loading of the wrist can commence progressively 6 weeks after surgery.

 
Unstable and/or Displaced Scaphoid Fractures
 

Arthroscopic-assisted fixation or ORIF of the scaphoid is recommended if there is any gapping or angulation in the scaphoid, even if the fracture appears stable and impacted, because our impression is that displaced fractures are unstable and should be managed operatively.543 If reduction can be achieved and monitored arthroscopically percutaneous fixation is possible, but we feel the standard treatment is open reduction and internal fixation. Reduction is facilitated by the use of K-wires used as joysticks in each fragment as well as other instruments used to push and guide the fragments into position. Bone grafting is considered in the face of comminution.

 

A splint is applied for comfort after operative fixation. In most cases the splint is maintained until suture removal about 2 weeks later. In unreliable patients or some very unstable or very proximal fractures a cast may be used for 4 to 8 weeks. Return to sports is risky until the fracture is healed (at least 2 to 3 months). Patients who wish to return sooner must agree to assume the associated risks.

 
Proximal Pole Scaphoid Fractures
 

For proximal pole fractures we recommend operative treatment using a small open dorsal approach to check alignment in case the fracture is unstable.442 We prefer a straight 3-to 4-cm incision centered over the dorsal aspect of the wrist after checking the level of the scapholunate junction with the fluoroscope. The extensor pollicis longus tendon can usually be left in place. The dorsal capsule is then incised and the scaphoid exposed. Care is taken to avoid injury to the dorsal ridge vasculature during the approach. For unstable fractures, bone grafting might be considered to stimulate union. A compression screw is applied over a guidewire, using a second wire to control rotation if the fragment is unstable. Our postoperative protocol is as for unstable/displaced fractures.

Management of Scaphoid Fractures

Suspected Scaphoid Fractures

For suspected fractures, distal pole/tubercle fractures, and undisplaced waist fractures early diagnosis is important. If the diagnosis is confirmed at the time of injury following the use of secondary imaging; for example, CT or MRI, the patient is treated as an undisplaced scaphoid fracture. This is usually with a simple below-elbow forearm cast with or without thumb immobilization for 6 weeks, with check scaphoid radiograph views obtained at the time of cast removal. When there are persistent clinical and radiologic signs of a fracture, further immobilization in a cast for an additional 2 weeks is recommended. When secondary imaging is not used at presentation, repeat assessment and radiologic imaging, most frequently at 10 to 14 days post injury, is usually performed. In the interim, a below-elbow forearm cast with (scaphoid cast) or without (Colles cast) thumb immobilization should be applied until the diagnosis is confirmed or refuted. 

Scaphoid Tubercle Fractures

Nonoperative management is routinely employed for scaphoid tubercle fractures (Herbert A1).122,127,232 Scaphoid tubercle fractures are a generally benign avulsion injury. Although some authors suggest that splinting is adequate, others prefer cast immobilization for 4 weeks. Tubercle fractures managed with casting can have radiographs that show persistent displacement and fibrous union causing no disability, although these findings are more commonly seen in fractures treated without immobilization.320 

Nondisplaced Scaphoid Fractures

Nonoperative Versus Operative Management.
Controversy exists regarding the management techniques for nondisplaced or minimally displaced waist fractures (Herbert A2, B1, and B2). Studies in this area often include both nondisplaced and so-called minimally displaced fractures. Nondisplaced scaphoid fractures are usually stable, although there is no gold standard for confirming this, and achieve union rates between 95% and 99% when managed conservatively.54 Some authors suggest that cast immobilization is the method of choice for the primary treatment of undisplaced or minimally displaced fractures of the scaphoid.122,127,232 Variable rates (3% to 20%) of subsequent displacement in cast are reported,91,272 due to a lack of consensus regarding the appropriate imaging modality to use and the criteria for displacement. 
However, there is an increasing body of evidence to support early percutaneous screw fixation of these fractures, with advocates citing a minimally invasive technique associated with a low complication rate, a shorter time to union by over a month, a more rapid improvement in functional testing, as well as an earlier return to sports and work, all in a predominantly young and active population.55,206,231,307,368,409,560 The shorter time to union is difficult to assess given radiographs are known to be unreliable. 
Herbert and Fisher211 reported an overall incidence of nonunion after conservative treatment at 50% and subsequently advocated the use of internal fixation for scaphoid fractures with a newly designed screw. More recently, there have been several studies advocating the use of early fixation for nondisplaced or minimally displaced fractures of the scaphoid,206,231,368,560 with now several randomized controlled trials directly comparing the two treatment modalities (Table 31-12).6,27,55,127,307,409,515 
Table 31-12
Details of Current PRCTs Comparing Operative and Nonoperative Management for Undisplaced or Minimally Displaced Fractures of the Scaphoid
Study (Follow-up) Mean Age (yr) Male/Female (%) Treatment (n) Fracture Type (Displaced) Key Findings and Recommendations
Conservative Operative
Adolfsson et al.6 (Min 16 wks) 31 74/26 28 23 Herbert B1, B2 (none) No significant difference for rate of union or time to union
Operative group had a significantly better range of motion at 16 wks, grip strength no difference
Arora et al.27 (Min 24 wks) 33 73/27 24 23 Herbert B2 (none) No significant difference in the range of wrist motion or grip strength
Operative group had a better mean DASH score, a faster time to union and a faster return to work
Bond et al.55 (Mean 25 mos) 24 88/12 14 11 Herbert A2, B2 (none) No significant difference in the range of wrist motion or grip strength
Operative group had a significantly faster average time to union and average time to return to work
Patient satisfaction high in both groups
Dias et al.127 (Min 1 yr) 30 90/10 44 44 Herbert A2, B2, B5 (11 minimally displaced) Operative group had significantly better range of motion, patient evaluation measure and grip strength at 8 wks, with significantly better grip strength at 12 wks
No significant difference between groups with respect to any other outcome measure at any other time
Return to work same in both groups
Rate of nonunion was higher in conservative group, rate of complications (predominantly scar sensitivity) higher in operative group
McQueen et al.307 (Min 1 yr) 29 83/17 30 30 Herbert B1, B2 (7 minimally displaced) Operative group had significantly faster time to union
Trend towards a higher rate of nonunion in the nonoperative group
Operative group had a significantly more rapid return of function, sport and, work
Saeden et al.409 (Min 12 yrs) 33 79/21 30 31 AO C2, C3 (none) Return to work faster in operative group for blue-collar occupations
No differences with respect to function, union, or carpal arthritis
Operative group had a higher rate of scaphotrapezial joint arthritis but this did not correlate with subjective symptoms
Vinnars et al.515 (Mean 10 yrs) 31 78/22 42 41 Herbert A2, B1, B2, B3 (none) Operative group had a significant increase in rate of scaphotrapezial joint arthritis
No differences in limb-specific outcome scores were found
Range of motion and grip strength were greater (not significant) in the conservative group
 

Adapted from: Doornberg JN, Buijze GA, Ham SJ, et al. Nonoperative treatment for acute scaphoid fractures: A systematic review and meta-analysis of randomized controlled trials. J Trauma. 2011;71:1073–1081.

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McQueen et al. in their prospective randomized trial of 60 patients (30 percutaneous fixation, 30 casts) followed-up for 1 year reported a significantly decreased time to union with a more rapid return of function, sport, and full-time work when compared with those managed conservatively.307 Low complication rates were also reported with the surgical technique. Arora et al.27 found similar results in their prospective study of percutaneous fixation with comparable costs for both techniques; however, Davis et al.112 reported cost savings of almost $6,000 in favor of surgical fixation. 
Saeden et al. performed a long-term prospective randomized 12-year follow-up study comparing ORIF and nonoperative management and found an earlier return to function in the operative group, recommending surgery be offered to young and active patients.409 This study did report an increased rate of radiologic signs of scaphotrapezial joint arthritis in the operative group, but this did not correlate with subjective clinical findings. Dias et al.127 randomized 88 patients (44 ORIFs, 44 casts) and followed them for 1 year following injury. They reported superior earlier results in the operative group across many of the outcome measures. There were 10 (23%) patients in the conservative arm that developed nonunion compared to none in the operative group. There was a 30% complication rate in the operative group but all were minor, with the vast majority related to the scar due to the open technique. Despite these findings, the authors concluded that undisplaced or minimally displaced scaphoid waist fractures should be managed in a cast. 
Three of four recent systematic reviews with meta-analysis have concluded that on current evidence neither method is clearly superior, not only with surgical management associated with improved functional outcome, a more rapid return to function/sports/work and superior union rates, but also with a significantly increased rate of complications.13,66,232,470 However, these reviews included “minimally displaced” fractures and combined ORIF and percutaneous fixation under one umbrella for surgical management, with ORIF more commonly associated with complications.127 
Technique—Nonoperative Management.
For nondisplaced, minimally displaced or selected displaced fractures (see below), a below-elbow forearm cast with or without thumb immobilization can be used for 2 weeks, and then clinical review is recommended with further scaphoid radiograph views mandatory as surgery may be necessary if the fracture has displaced. When in doubt, further imaging is recommended. If the fracture remains undisplaced, a cast can be reapplied until fracture union is confirmed clinically and radiographically. There is a general consensus that most stable scaphoid fractures unite in 6 to 8 weeks with cast immobilization; however, examination and radiographs are unreliable so duration of immobilization is based ultimately on surgeon preference.126 However, bone consolidation can take 12 to 16 weeks and some fractures will not have healed even after this time. 
One of the important questions regarding the nonoperative management of scaphoid fractures is the type of cast to be applied—an above-elbow cast, a Colles cast (below elbow without thumb immobilization), or a scaphoid cast. Three recent systematic reviews have concluded that on current evidence there is no advantage to any of these methods.13,131,470 Although some authors still advocate the use of above-elbow casts, two randomized studies have demonstrated no significant advantage in the use of above-elbow casts.10,188 In a further nonrandomized prospective study it was found that using an above-elbow cast may cause increased movement at the fracture site.259 
The remaining debate is whether to use a scaphoid cast or a Colles cast. Prior to 1942, Bohler et al.54 proposed the use of an unpadded dorsal backslab, but then changed the cast to include the proximal phalanx of the thumb—the scaphoid cast. Since then, there have been several studies demonstrating no difference between the two techniques. In one cadaveric study it was found that provided the wrist was not in ulnar deviation, the position of the thumb had no influence on the fracture gap.557 Hambidge et al.208 randomly allocated 121 acute scaphoid fractures for conservative treatment in a Colles cast with the wrist immobilized in either 20 degrees flexion (n = 58) or 20 degrees extension (n = 63). They found no difference between groups in terms of union rates, wrist flexion, or grip strength but did find that the wrists which had been immobilized in flexion had a greater reduction in wrist extension. 
There are now two large prospective randomized trials (one published and one to be published) comparing the Colles cast and scaphoid cast for an acute fracture of the scaphoid, with both having demonstrated no advantage to either method.91 For this reason, the use of Colles casts or forearm casts, rather than scaphoid casts, is advocated. 
Technique—Percutaneous Fixation.
For undisplaced or minimally displaced fractures, percutaneous fixation is superior to ORIF providing superior union rates, faster functional recovery, and reduced surgical morbidity; for example, scar, complex regional pain syndrome (CRPS).125,127,212,388 Percutaneous fixation is a simple technique and can be performed through either a volar or a dorsal approach, with neither reported to provide a superior outcome.2,133,238,347 
Some feel it is easier to get the screw in the center of the scaphoid using the dorsal approach, particularly for fractures of the proximal pole.205 The dorsal approach is often described utilizing a small open incision citing an increased risk to tendons or nerves, in particular the posterior interosseous nerve, extensor digitorum communis to the index finger, and extensor indicis proprius,2 but the senior author and other advocates like Slade use a fully percutaneous approach.442 Slade placed the wrist in a traction tower to facilitate arthroscopy and used a mini image intensifier placed lateral. The senior author of this chapter places the mini C-arm vertically, stacks towels on the collector to keep the wrist bent with the carpus perpendicular to the beam. Slade and Geissler found the starting point for the screw through the arthroscope and suggested marking the spot with a large gauge needle that could be used as a guide for wire insertion. The senior author finds the starting point under the image intensifier. Slade advanced the guidewires out the volar surface of the thumb to get the wire out of the wrist, facilitating a PA view of the wrist without risking bending the wire. The senior author keeps the wrist flexed to at least 45 degrees to avoid bending the wire and takes radiographs perpendicular to the scaphoid rather than the distal radius. Slade placed the scaphoid in the image intensifier with some wrist flexion and enough rotation so that the distal and proximal poles of the scaphoid overlap creating a near circular image in which the guidewire for the screw should be dead central. The senior author finds that view unpredictable and unreliable and uses real-time 360 imaging to judge the position of the screw, again, keeping the wrist flexed. 
With the volar approach (Fig. 31-27), a potential disadvantage is an increased prevalence of later scaphotrapezial osteoarthrosis; however, this is commonly asymptomatic and has no impact on the final outcome.515 For the volar approach, the hand is placed on a radiolucent table or with care directly on the collector of a small image intensifier with the shoulder abducted and the forearm in supination. The wrist is extended over a roll. The correct placement of the guidewire is crucial to the success of the procedure. It helps to remember that the scaphoid lies in a 45-degree plane to both the longitudinal and horizontal axes of the wrist. The incision point for the volar approach is found approximately 1 cm distal and radial to the scaphoid tubercle with entry point on the scaphoid tubercle. A 4- to 5-mm skin incision is made or the guidewire can be inserted percutaneously and an incision made around the wire just large enough for the screw to pass once the wire position is acceptable. In a few cases with an overhanging trapezium, it may be necessary to insert the guidewire through the trapezium, which does not seem to result in added morbidity.190,191,308 The tip of the guidewire is placed on the scaphoid tubercle. The optimal entry point is one that will allow central placement of the screw in the proximal pole of the scaphoid. For the volar approach, this is often relatively radial on the distal pole. The guidewire is inserted at a 45-degree angle in both planes (roughly in line with the radially and palmarly abducted thumb metacarpal) aiming the tip at the apex of the proximal pole. The image intensifier is used to check wire placement utilizing anteroposterior, lateral and both supinated and pronated oblique views.173 
Figure 31-27
Percutaneous stabilization of scaphoid fracture.
 
A: A fracture through the waist of the scaphoid. B: The wrist should be dorsiflexed prior to insertion of the K-wire and a 4-5 mm incision is made in the skin crease, sufficient for the insertion of the screw. C: The K-wire is inserted at a 45-degree angle in both planes and the position is checked using fluoroscopy. D, E: A second K-wire can be used if the position of the first wire is not quite adequate, or if there is concern regarding potential rotation of the fracture fragments. F: Insertion of the self-drilling, self-tapping variable pitch scaphoid screw using fluoroscopy to avoid rotation of fracture fragments. G: Postoperative views demonstrate good compression of the fragments and satisfactory position of the screw on all views.
A: A fracture through the waist of the scaphoid. B: The wrist should be dorsiflexed prior to insertion of the K-wire and a 4-5 mm incision is made in the skin crease, sufficient for the insertion of the screw. C: The K-wire is inserted at a 45-degree angle in both planes and the position is checked using fluoroscopy. D, E: A second K-wire can be used if the position of the first wire is not quite adequate, or if there is concern regarding potential rotation of the fracture fragments. F: Insertion of the self-drilling, self-tapping variable pitch scaphoid screw using fluoroscopy to avoid rotation of fracture fragments. G: Postoperative views demonstrate good compression of the fragments and satisfactory position of the screw on all views.
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A: A fracture through the waist of the scaphoid. B: The wrist should be dorsiflexed prior to insertion of the K-wire and a 4-5 mm incision is made in the skin crease, sufficient for the insertion of the screw. C: The K-wire is inserted at a 45-degree angle in both planes and the position is checked using fluoroscopy. D, E: A second K-wire can be used if the position of the first wire is not quite adequate, or if there is concern regarding potential rotation of the fracture fragments. F: Insertion of the self-drilling, self-tapping variable pitch scaphoid screw using fluoroscopy to avoid rotation of fracture fragments. G: Postoperative views demonstrate good compression of the fragments and satisfactory position of the screw on all views.
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Figure 31-27
Percutaneous stabilization of scaphoid fracture.
A: A fracture through the waist of the scaphoid. B: The wrist should be dorsiflexed prior to insertion of the K-wire and a 4-5 mm incision is made in the skin crease, sufficient for the insertion of the screw. C: The K-wire is inserted at a 45-degree angle in both planes and the position is checked using fluoroscopy. D, E: A second K-wire can be used if the position of the first wire is not quite adequate, or if there is concern regarding potential rotation of the fracture fragments. F: Insertion of the self-drilling, self-tapping variable pitch scaphoid screw using fluoroscopy to avoid rotation of fracture fragments. G: Postoperative views demonstrate good compression of the fragments and satisfactory position of the screw on all views.
A: A fracture through the waist of the scaphoid. B: The wrist should be dorsiflexed prior to insertion of the K-wire and a 4-5 mm incision is made in the skin crease, sufficient for the insertion of the screw. C: The K-wire is inserted at a 45-degree angle in both planes and the position is checked using fluoroscopy. D, E: A second K-wire can be used if the position of the first wire is not quite adequate, or if there is concern regarding potential rotation of the fracture fragments. F: Insertion of the self-drilling, self-tapping variable pitch scaphoid screw using fluoroscopy to avoid rotation of fracture fragments. G: Postoperative views demonstrate good compression of the fragments and satisfactory position of the screw on all views.
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A: A fracture through the waist of the scaphoid. B: The wrist should be dorsiflexed prior to insertion of the K-wire and a 4-5 mm incision is made in the skin crease, sufficient for the insertion of the screw. C: The K-wire is inserted at a 45-degree angle in both planes and the position is checked using fluoroscopy. D, E: A second K-wire can be used if the position of the first wire is not quite adequate, or if there is concern regarding potential rotation of the fracture fragments. F: Insertion of the self-drilling, self-tapping variable pitch scaphoid screw using fluoroscopy to avoid rotation of fracture fragments. G: Postoperative views demonstrate good compression of the fragments and satisfactory position of the screw on all views.
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When the wire is in a good position in the scaphoid (and the alignment of the scaphoid is confirmed for minimally displaced fractures), an attempt is made to measure the screw. The length of the screw should be measured carefully and several millimeters subtracted from the measured length to avoid prominence at either end. It is useful to estimate the length of the scaphoid based on preoperative measurement. Through a percutaneous insertion (incision just large enough to pass the screw) measurement can be difficult using the sleeve measure, but one can use a second wire of the same length and measure the difference. Some then drill the guidewire into the trapezium to anchor it. Predrilling is used depending on the type of screw. The drill is passed over the wire, stopping if there is any resistance as this may indicate a bend in the wire that will lead to drill or wire breakage. Even if the screw is self-drilling there is a risk of distraction of the fracture and so if predrilling is not used the progress of the screw should be monitored using image intensification to ensure that no rotation or distraction occurs at the fracture site. If distraction occurs, the screw is removed and the track drilled. If there is a bend, the wire can usually be further advanced so that the drill passes over a nonbent part of the wire. After drilling, the screw is advanced under image intensification. It is important to judge screw length prior to fully seating the screw. The wire is then removed, and central positioning of the screw without joint penetration at the radiocarpal joint or prominence at the scaphotrapezial joint should be confirmed with AP, lateral, supinated, and pronated views of the wrist.173 
There are a number of screws available that vary in size and pitch variation and can be partially, fully or tip threaded, and with or without ancillary techniques for achieving compression (e.g., special screw drivers or even mobile parts of the screw). Biomechanical studies support the common sense view that larger screws are stronger32,89,198,207,357,466; however, there is no evidence that the type of screw affects the outcome with the exception that cannulated screws have been shown to improve central placement of the screw when compared with the Herbert screw.503 

Unstable and/or Displaced Scaphoid Fractures

Surgical treatment is routinely employed for displaced scaphoid fractures (Herbert B1, B2), comminuted fractures (Herbert B5), and fractures associated with carpal instability and/or a dislocation (Herbert B4). Unstable or displaced fractures of the scaphoid, as well as proximal pole fractures, have an increased rate of redisplacement,91 delayed union, and nonunion143 when managed with cast immobilization alone.73,367,551 A recent systematic review of displaced scaphoid fractures found a four times higher risk of nonunion when compared with undisplaced fractures following conservative management, with nonunion seventeen times more likely if a displaced fracture of the scaphoid is managed nonoperatively.436 
It is debatable whether some displaced unstable scaphoid fractures can be treated in a cast.73,367,551 Since displacement is the primary and only evidence-based risk factor for nonunion, displaced fractures should be strongly considered for either open or arthroscopic-assisted reduction plus internal fixation. Some patients may not be suitable for an operation; for example, noncompliant patients, elderly patients with or without significant medical comorbidities.173 The consequence of managing these patients nonoperatively is not completely clear and it may be that in the elderly patient nonoperative management provides a comparable outcome to operative treatment, without the risks associated with surgery. Rates of redisplacement range from 12% to 22%,10,91,103,143 union 50% to 90%,10,103,125,409 and the development of osteoarthritis 16% to 31%.122,409 
Technique—ORIF.
McLaughlin305 was the first to report the use of primary ORIF for fractures of the scaphoid, and subsequently positive results have been reported in many studies.388 Displaced fractures are treated with either ORIF or arthroscopically assisted percutaneous fixation. There must be direct visualization of fracture reduction as the strange shape of the scaphoid and complex carpal anatomy makes image intensification inadequate. Some fractures reduce with radial deviation and extension, but many require direct manipulation which can be facilitated by the use of K-wires inserted into each fracture fragment. Both dorsal and volar approaches have been reported with success, with the palmar exposure limiting potential damage to the vascular supply, but the dorsal approach providing improved access to proximal fractures.125,212,297 Once the fracture is reduced, screw placement is as described for percutaneous fixation. 
For the volar approach, most use an incision across the transverse wrist creases in line with the flexor carpi radialis (FCR) tendon. The incision starts distal to the distal pole of the scaphoid and is about 5 cm in length. The FCR tendon sheath is opened and the tendon is retracted in an ulnar direction. The superficial radial artery is either retracted distally or ligated. The wrist capsule is isolated and divided in line with the scaphoid, starting at the distal pole and ending as soon as the fracture is visualized, preserving as much of the RSC ligament as possible. The fracture is aligned and provisionally secured with a wire. Usually a volar screw is inserted as described above, but it is also possible to put in a dorsal screw percutaneously at this point.173 
Technique—Arthroscopic-assisted Reduction and Fixation.
Some authors advocate arthroscopic-assisted reduction and fixation, with high union rates reported and the added advantage of being able to assess for the presence of associated soft tissue injuries.181,427,440,441,443,482 However, disadvantages are similar to that with the open technique and include a steep learning curve, extensor tendon damage, poor fracture reduction, nerve injury, and scaphotrapezial or radioscaphoid joint damage.125,441 Ultimately, it is not clear that arthroscopic-assisted surgery has any advantages over open and might be more difficult and time consuming. Once the fracture is reduced, care must be taken not to flex, distract, translate, or rotate the fragments when inserting the screw and gaining compression. 
For this technique, the fracture is best seen through a midcarpal portal, usually employing the 4/5 midcarpal portal. Angulation, translation, and gapping can be seen on the capitate articular surface of the scaphoid, but on the radial side is not seen. A reduction maneuver of extension and radial deviation with volar wire stabilization of the scaphoid often restores alignment. If a manipulative reduction is insufficient the K-wire is withdrawn to the volar side of the fracture and retained for later advancement across the reduced fracture. Additional K-wires in one or both fragments, as well as percutaneously inserted snaps or elevators, can help restore alignment. The volar wire is then advanced to stabilize the fracture. A screw is then placed percutaneously as described above. 

Proximal Pole Scaphoid Fractures

A meta-analysis has demonstrated that the relative risk of nonunion for proximal pole fractures (Herbert B3) was 7.5 times more when compared with more distal fractures when all were managed nonoperatively (Fig. 31-28).141 Temporary interruption of the blood supply to the proximal fragment is virtually certain with proximal pole fractures but, if stabilized, the proximal pole has the capacity to revascularize and heal.187,290 Proximal pole fractures are uncommon and the use of operative management is based on intuition more than data. 
Figure 31-28
A fracture through the proximal pole of the scaphoid.
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Technique—ORIF. For proximal pole fractures, most authors recommend operative treatment using a small open dorsal approach to ensure alignment and to allow access to the proximal fragment.442 Commonly, a straight 3- to 4-cm incision is centered over the dorsal aspect of the wrist after checking the level of the scapholunate junction with the fluoroscope. The extensor pollicis longus tendon is routinely unmoved. The dorsal capsule is then incised and the scaphoid exposed. Care is taken throughout this approach to avoid injury to the dorsal ridge vasculature. Otherwise, the technique for fixation is as for ORIF above. 

Complications of Scaphoid Fractures: Scaphoid Malunion

Some displaced scaphoid fractures can malunite, usually with a humpback deformity (Fig. 31-29). Pronation or ulnar translation of the distal fragment is less commonly seen.125 The effect of this malalignment on symptoms and wrist function is debatable.18,342 One cadaveric study has suggested that scaphoid malunion results in a notable reduction in wrist motion,74 and a few small series of osteotomy for scaphoid malunion have reported improved motion and function with decreased symptoms.289 However, studies of nonunions treated with no attempt to correct alignment (e.g., with Russe grafts) found no correlation of function or arthrosis with scaphoid malalignment in both the short and long term.160,383 
Figure 31-29
The intrascaphoid angle measures 67 degrees.
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Figure 31-29
CT scan of a scaphoid fracture that has healed with a humpback deformity.
The intrascaphoid angle measures 67 degrees.
The intrascaphoid angle measures 67 degrees.
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Clinical Assessment and Diagnosis

Patients with scaphoid malunion are believed to be at risk of wrist pain, reduced wrist extension and diminished grip strength.74,342 One study has demonstrated that the loss of wrist extension is proportional to the angular deformity,74 while another has suggested that the degree of DISI deformity correlates with symptom severity.342 Standard radiographs are the first line of investigation, with further imaging in the form of CT to better delineate the deformity. Useful measurements include the following: 
  •  
    Lateral intrascaphoid angle (Fig. 31-18A): An angle greater than 35 degrees is used as a cut-off for displacement18; noted to have poor interobserver reproducibility on both CT and MRI.30,395
  •  
    Height-to-length ratio (Fig. 31-18C): Found to have the best reproducibility for assessing angulation.30,395
Alternate measurements found to be of limited use include the dorsal cortical angle (Fig. 31-18B) and the AP intrascaphoid angle.18 It should be noted that both short- and longer-term retrospective studies have demonstrated no correlation between any outcome measure and the degree of radiologic deformity.160,383 

Management

The clinical consequences of malunion are not completely clear. Forward et al.160 reported on the clinical outcome at 1 year of 42 consecutive patients with a malunited scaphoid waist fracture that had all been managed nonoperatively and found no significant correlation between any outcome measures (range of motion, grip strength, PROMs) and any of the three measures of malunion (height-to-length ratio, dorsal cortical angle, lateral intrascaphoid angle). Similar results have been reported in the longer term.383 
An osteotomy is considered when there is objective impairment (e.g., loss of extension) that seems directly related to the scaphoid malalignment.146,155 Lynch et al. reported a technique of corrective osteotomy that corrects the intrascaphoid angles, restores palmar length to the scaphoid, and reduces DISI deformity of the carpus.281,289 They claim that this method could potentially prevent or delay the onset of arthritis in young patients with high functional demands. 

Complications of Scaphoid Fractures: Scaphoid Nonunion

Scaphoid nonunion leads to a specific type of post-traumatic wrist arthrosis labeled scaphoid nonunion advance collapse (SNAC) similar to the arthrosis that develops after scapholunate ligament injury.290 The development of SNAC (Fig. 31-30) is extremely variable in terms of the rapidity of progression and the association with pain, stiffness, disability, or union. One rationale for operative treatment to gain union of the scaphoid is to delay or prevent arthritis, but it is unclear if union can achieve these goals, particularly if the nonunion is more than a year old. 
Figure 31-30
Scaphoid nonunion advanced collapse (SNAC) of the left wrist.
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Epidemiology and Etiology

The natural history of scaphoid fracture nonunion is unknown as the majority of patients represent due to new or on-going symptoms. The quoted rate of nonunion is variable due to a lack of agreement regarding the criteria for union and the imaging modality that should be used. Nonunion is said to occur in approximately 10% of all scaphoid waist fractures, but the rate is much lower for nondisplaced fractures and approaches zero when a nondisplaced fracture is adequately treated and protected.50,73 Displaced fractures have a 50% nonunion rate, with an increased rate also seen with proximal pole fractures (Table 31-13 and Fig. 31-31).31,99,121,143,471 Other proposed risk factors for nonunion of scaphoid waist fractures include delayed diagnosis or treatment.104,141,269,367,405,551 
Figure 31-31
An established scaphoid proximal pole fracture nonunion found on MRI.
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Table 31-13
Rates of Scaphoid Fracture Nonunion Based on Fracture Type and Management Used
Fracture Type Management
Nonoperative Operative
Undisplaced/minimally displaced 1–5% 0–2%
Displaced 10–50% 0–7%
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Pathoanatomy and Classification

Fisk156 described the triplane angulation and subsequent humpback deformity of the scaphoid that results from established nonunion where the proximal scaphoid rotates dorsally into extension and the distal part faces downward in flexion. Impingement between the palmar-flexed scaphoid distal pole and the radial styloid process leads to the development of radiocarpal osteoarthritis.173 At the same time, the unsupported carpus collapses into a DISI deformity with increasing subluxation and secondary arthritis of the midcarpal joint (Fig. 31-32). The articulation of the proximal pole with the radius and the radiolunate joint are relatively spared. 
Figure 31-32
An established scaphoid nonunion with associated DISI deformity.
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Some scaphoid nonunions have minimal or no deformity, there seems to be a firm fibrous union between the fracture fragments, and the progression to symptoms and the necessity for treatment is unclear.73,126,128,367 According to the Herbert and Fisher classification (Fig. 31-24), Type D1 fractures are scaphoid fibrous nonunions that commonly occur in stable fractures following cast immobilization.211 
Type D2 fractures are an established sclerotic scaphoid nonunion. These injuries are usually unstable with a progressive deformity that leads to the development of wrist arthritis (SNAC).73,126,128,367 Two patterns of nonunion displacement have been described, dorsal or volar, with the location of the fracture line relative to the dorsal apex of the scaphoid ridge predictive of the pattern.328,358,359 Distal scaphoid waist fractures, with large triangular bone defects, are associated with the volar pattern, with the development of a humpback and/or DISI deformity. Proximal scaphoid waist fractures, with much smaller flat crescent-shaped bone defects, are associated with the dorsal pattern.173 Similarly, one study has found that carpal instability after a scaphoid fracture nonunion is related to whether the fracture line passes distal or proximal to the scaphoid apex.327 

Clinical Assessment and Diagnosis

Many scaphoid nonunions are unnoticed fractures that present with symptoms either gradually or after a later fall.250 Missed diagnosis is not uncommon and often results in additional morbidity from secondary changes, including nonunion, collapse deformity, and degenerative arthritis.290 Patients usually have radial-sided wrist pain, reduced wrist motion with pain at the limits of motion, and reduced grip strength.73,74,250,367 
Imaging.
A radiographic diagnosis of nonunion cannot be made confidently until 6 to 12 months after injury,126,128 although some may argue that union can be confirmed if the patient is asymptomatic and the original fracture line is no longer visible.121 Prior to that time radiographs may demonstrate the classic findings of nonunion, including widening of the fracture gap, cystic changes, and fracture line sclerosis even when the fracture is healing.73,126,128 Radiographs can be compared with images of the opposite unaffected wrist, particularly for preoperative planning. Other options for diagnosing nonunion include USS, CT, or MRI. One study investigated the use of real-time linear USS in determining fracture site movement in 27 patients with a scaphoid nonunion, of which 24 had had surgical treatment, and found the technique to be 100% specific for visualization of movement at the fracture site although it was of no benefit in assessing proximal pole nonunion.124 
Although MRI is utilized in the diagnosis of scaphoid AVN, it has not been found to be superior to CT for assessing fracture nonunion, alignment, and for comparison of findings before and after nonunion surgery.21,309,326,420,435 Sagittal images from scans are considered to provide the best method of evaluating the location of the nonunion and the degree of collapse. The lateral intrascaphoid angle and the height-to-length ratio of the bone help determine angulation and collapse of the scaphoid, with an angle of more than 35 degrees associated with an increased incidence of arthrosis even in nonunions that eventually progress to union. One study has documented a good correlation between preoperative proximal pole sclerosis on CT with AVN and subsequent fracture union, with a specificity of 100%, but with a sensitivity of 60% and an accuracy of 74%.450 CT is also cheaper and more readily available in many centers. The only definitive test for confirming AVN is the observation at surgery of the presence or absence of bleeding from bone. 

Management

The quoted union rate following treatment for scaphoid fracture nonunion is wide ranging, with a recent systematic review concluding an 80% union rate for bone grafting without fixation and an 84% rate for grafting with internal fixation.339 
The goals of management are to relieve symptoms, correct the carpal deformity, achieve union, and hopefully delay the onset of wrist arthrosis.73,367 The major principles to follow are the following:173 
  1.  
    Make an early diagnosis
  2.  
    Perform a complete resection of the nonunion
  3.  
    Correct the deformity secondary to carpal collapse and carpal instability
  4.  
    Preserve the blood supply throughout
  5.  
    Achieve bone apposition by an inlay graft
  6.  
    Achieve stability with screw fixation
Treatment options include bone grafting, fixation without bone grafting, fixation with either a vascularized or a nonvascularized graft, and finally wrist salvage procedures (Table 31-14). There is limited data on the ability of current techniques to either reduce symptoms or limit the onset of wrist arthrosis, as well as when salvage procedures should be utilized primarily.73 Poor prognostic indicators are a prolonged nonunion time, prior failed surgery requiring revision, the more proximal the nonunion, and the absence of punctate bleeding at the proximal pole during surgery.380,478,479 Generally, the number of punctuate bleeding points is a good indicator of bone vascularity. When the proximal pole is completely avascular, the likelihood of successful healing with a graft is virtually nil and an alternative salvage procedure should be considered.197,380,478 
 
Table 31-14
Wrist Salvage Procedures for Scaphoid Nonunion
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Table 31-14
Wrist Salvage Procedures for Scaphoid Nonunion
Fracture Type Comments
Partial or complete scaphoidectomy Excision of larger fragments (>8 mm) lead to wrist weakness and poor outcome177
Scaphoid replacement Worth considering in selected patients
Silicone implants abandoned due to progressive silicone arthritis in many cases and long-term results mixed90,145,210,469
Unless the midcarpal joint is stable and painless, replacement should be combined with a fusion across the midcarpal joint to prevent carpal subluxation173
Young and active patients are likely to complain of continued pain after this procedure and wrist arthrodesis is then often preferable
Wrist denervation Good pain relief, but may be temporary463
Proximal row carpectomy (PRC) Mixed results reported
Recent systematic review compared PRC with four-corner fusion335
Both procedures give improvements in pain and subjective outcome measures
PRC gives marginally superior motion and reduced complications
Risk of subsequent osteoarthritis is significantly higher in PRC
Wrist arthrodesis Indicated for radiocarpal and midcarpal osteoarthritis associated with severe pain, weakness, and reduced wrist motion
Good results, in particular pain relief and improved strength, reported in young patients with high functional demands225
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Stable Nonunions.
The stable scaphoid nonunion is characterized by a firm fibrous nonunion that prevents deformity, with the risk of osteoarthritis being small. The indications to manage patients surgically with a stable nonunion are limited to improvement in symptoms, prevention of progression to an unstable nonunion, or delaying the development of degenerative changes. The earlier the surgery is performed, the lower the incidence of secondary osteoarthritis.173 
For stable nonunions, structural graft support is not required, simply graft that will promote union; although some have suggested no graft at all is needed. Treating stable nonunions ordinarily gives good results using either an open or percutaneous technique.291,386 One scientific exhibit presented data on stable scaphoid delayed unions or nonunions (defined by nonunions that were well aligned and without extensive sclerosis or bone resorption at the nonunion site) that were treated by percutaneous screw fixation with good results.439 One study of 27 patients with established scaphoid nonunions (well-aligned fractures with extensive local bone resorption) managed with percutaneous screw fixation alone reported good results with all fractures uniting at an average of 3 months.291 Additional study is needed to determine which nonunions are amenable to this approach. 
Unstable Nonunions.
The quoted success rates of achieving union with internal fixation and bone grafting for unstable nonunions range from 60% to 95%.130,499 The differing rates may be explained by the heterogeneous nature of patient demographics, fracture nonunion characteristics, or the acknowledged difficulty in defining union.173 Two studies have implicated smoking as a reason for failure of nonunion surgery.130,284 
Techniques and Bone Grafting.
CT and radiographs of the opposite side can help determine the optimal size and shape of the bone graft required. The standard palmar approach (see above) with the advantage of avoiding damage to the blood supply can be used for most reconstructions of unstable scaphoid nonunions, except in fractures involving a small proximal pole fragment. Techniques of palmar and radiopalmar bone grafting have been developed to correct scaphoid malalignment and to restore normal scaphoid length. Failure to correct the humpback deformity results in intraoperative problems because the screw cannot be adequately placed and will cut out, leaving residual instability.173 Even if the nonunion heals, the malunited scaphoid has a twofold increase in degenerative arthritis compared with a scaphoid that has healed with correct alignment.500 Although AVN of the proximal fragment may potentially affect the healing potential of a scaphoid, diminished vascularity of the proximal scaphoid is not a contraindication to a palmar inlay bone graft.173 If fracture union can be achieved, the relative avascularity will improve. 
There are a number of methods of bone grafting in use but none has been found to be superior in terms of achieving union.73,499 Prior to the introduction of modern fixation methods the Matti-Russe inlay graft was used in the treatment of scaphoid nonunion (Fig. 31-33), but this technique does not usually correct malalignment.421 Anterior wedge grafting procedures, with initial reduction of the lunate and temporary pin fixation, are now in common use as humpback deformities can be corrected with this technique.144,496 Screw fixation has generally been found to give superior union rates when compared to K-wire fixation when using nonvascularized graft.73,313 No correlation between donor sites (iliac crest, distal radius) and union have been demonstrated.478,479 Some authors advocate taking corticocancellous graft from the anterolateral corner of the radial metaphysis rather than the iliac crest, as it allows harvesting from one incision with reduced donor site morbidity and comparable union rates.7,385 Cohen et al.93 recently reported good clinical and radiologic results in 12 patients with established scaphoid waist nonunions using ORIF with only cancellous interposition graft from the ipsilateral distal radius. Potential disadvantages of nonvascularized grafts include increased nonunion rates in the presence of AVN and short-term donor site morbidity associated with graft taken from the iliac crest.73 
Figure 31-33
Standard Russe bone graft.
 
His technique relied on packing a corticocancellous bone graft into a trough curetted through the volar cortex of both fragments. Because the volar cortex is often foreshortened by erosion of the fragments, loss of length is difficult to correct without introducing a cortical graft. Modified Russe winged graft can be impacted into a volar trough to lengthen the scaphoid.
His technique relied on packing a corticocancellous bone graft into a trough curetted through the volar cortex of both fragments. Because the volar cortex is often foreshortened by erosion of the fragments, loss of length is difficult to correct without introducing a cortical graft. Modified Russe winged graft can be impacted into a volar trough to lengthen the scaphoid.
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Figure 31-33
Standard Russe bone graft.
His technique relied on packing a corticocancellous bone graft into a trough curetted through the volar cortex of both fragments. Because the volar cortex is often foreshortened by erosion of the fragments, loss of length is difficult to correct without introducing a cortical graft. Modified Russe winged graft can be impacted into a volar trough to lengthen the scaphoid.
His technique relied on packing a corticocancellous bone graft into a trough curetted through the volar cortex of both fragments. Because the volar cortex is often foreshortened by erosion of the fragments, loss of length is difficult to correct without introducing a cortical graft. Modified Russe winged graft can be impacted into a volar trough to lengthen the scaphoid.
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Vascularized bone grafts from the distal radius (radial artery), distal ulna (ulnar artery), and based on the pronator quadratus (Fig. 31-34), have been described.460 Union rates following distal radial pedicle grafts range from 27% to 100%, with poor rates seen when used for AVN.73,459,464,564 New free vascularized grafts from the iliac crest and the medial femoral supracondylar zone have been reported, with one study documenting superior union rates of the medial femoral supracondylar graft when compared to a vascularized graft from the distal radius.240 
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Figure 31-34
Pronator quadratus graft.
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A recent randomized controlled trial compared vascularized (distal radius) with nonvascularized (iliac crest) bone grafting for scaphoid nonunion and found a 100% union rate in the nonvascularized group, with a rate of 85% in the vascularized group (p > 0.05).58 No significant differences were found in time to union or function. 

Authors’ Preferred Management—Scaphoid Fracture Nonunion

 
 

For a stable scaphoid nonunion, we prefer an open palmar approach using a straight incision as opposed to the curved incision described by Russe.173,407 The incision is based over or radial to the FCR from the scaphoid tubercle to the distal radius. The sheath of the FCR tendon is incised and the tendon retracted ulnarly. Directly beneath the tendon lies the palmar capsule of the wrist, just above the scaphoid. The capsule should be incised longitudinally. The superficial palmar branch of the radial artery is distal at the end of incision and needs to be ligated in cases of wider exposure of the distal scaphoid. Stable scaphoid nonunions might not be visible macroscopically and often need sharp division with the knife. It is useful to check the site of a nonunion as fusion of the proximal pole of the scaphoid with the lunate or the scaphoid distal pole and trapezium have been undertaken assuming that this joint was the site of nonunion. It is important to prepare the nonunion surfaces by removing any fibrous tissue and sclerotic bone. We usually leave the dorsal cartilage in place. This provides a hinge and facilitates assessment of scaphoid length. In most cases of stable nonunion, cancellous bone graft from the distal radius usually provides sufficient volume as structural support is not required, although iliac crest bone graft can be used if necessary. Screw fixation of the scaphoid is then used. Immobilization in a cast or splint is not required postoperatively except in occasional cases for pain relief.173

 

For an unstable nonunion, we feel a volar approach is necessary to correct the humpback deformity. The nonunion gap is exposed and debrided, and the fracture fragments are mobilized. It is best to leave a cartilage hinge posteriorly to provide a fulcrum around which the fragments may be hinged open although this is often not possible in older, unstable scaphoid fractures. If the hinge is released in an effort to regain all of the scaphoid length, the fracture fragments will become extremely unstable and difficult to align. Furthermore, the gap between the two fragments may be too great for the scaphoid to revascularize the proximal pole.500 The wrist is extended and the two fragments gently distracted with small spreaders. This maneuver usually achieves adequate correction of the carpal deformity and a satisfactory improvement in wrist extension. Provided that reasonable correction is achieved and that the wrist extends to at least 45 degrees, most patients achieve satisfactory clinical results. The fracture surfaces are excised with a small osteotome, burr, or curette. We prefer a corticocancellous wedge graft from the iliac crest. This is an interposition graft, which is inserted on the palmar surface and serves to bridge the fracture gap and correct any displacement or angulation of the scaphoid that has occurred. Vascularized bone grafts from the distal radius (radial artery) or distal ulna (ulnar artery) have also been described, though we would prefer the pronator quadratus graft.460 To correct angular deformity and restore normal scaphoid length, the amount of resection and size of the graft can be calculated preoperatively by CT scans. The indications for interposition grafting include gross motion at the nonunion site, scaphoid resorption, and loss of carpal height. Most commonly, the operative procedure involves an anterior interposition bone graft, with the size based on comparative scaphoid views of the opposite wrist and intraoperative measurements. The width and depth of the defect is measured and a graft of the exact size is removed from the iliac crest with an osteotome. Oscillating saws should not be used, as thermal necrosis of the graft can occur. With the wedge graft in place and the scaphoid reduced and held with a K-wire, a compression screw is inserted. Internal fixation with K-wires alone is usually not successful as compression is required to achieve union. However, if the graft shows a tendency to rotate, additional fixation with a K-wire may be required. If there is a severe or longstanding DISI deformity with an RL angle greater than 20 degrees, additional pinning of the lunate to radius for 6 to 8 weeks is advised.155 It may be difficult to completely correct carpal instability in longstanding cases, and these patients may be better served by various salvage procedures. Finally, a partial radial styloidectomy can be performed in patients with radiologic signs of stage I radioscaphoid arthritis, this being arthritis that is limited to the scaphoid and radial styloid. This is undertaken to relieve pain arising from arthritic joints or osteophyte impingement. If there are no radiologic signs of arthritis, a styloidectomy should not be undertaken at the same time as a scaphoid reconstruction often relieves symptoms.173

 

With stable fixation, postoperative immobilization is usually not required but a Colles cast can be used if there is doubt about stability or if pins have been used across the radiocarpal joint.

Complications of Scaphoid Fractures: Scaphoid AVN

AVN of the scaphoid can occur as a late complication of scaphoid fractures, especially those involving the proximal pole. Occasionally, AVN may occur without a fracture, either as a complication of SL ligament injury or as an idiopathic condition known as Preiser disease. 

Clinical Assessment and Diagnosis

The typical symptoms of AVN are increasing pain and stiffness of the wrist. Standard radiographs demonstrate a small, deformed proximal pole fragment with cystic changes and areas of sclerosis. The value of MRI to diagnose AVN in the routine management of scaphoid nonunions is debated. Current best evidence has not demonstrated that MRI can reliably or accurately diagnose AVN, with MRI findings not prognostic. 

Management

The natural history of scaphoid AVN is not known and it is not known if operative treatment can alter the natural course of the disease. One treatment option is a vascularized bone graft.28,367,522 Arora et al.28 reported the use of free vascularized iliac bone graft for the management of 21 patients with AVN and nonunion of the scaphoid for which conventional bone grafting had failed, achieving union and good symptom relief in 16 patients. 
The bone graft can be harvested dorsally through the second dorsal compartment of the distal radius, anteriorly in the form of a pronator quadratus graft, or from the second metacarpal. It is important to adhere to the basic principles of nonunion treatment with meticulous preparation and stabilization of the nonunion site. There has been one report of using arthroscopic debridement in managing these patients.312 

Directions for Future Research in Scaphoid Fractures

It is likely that we will never have a consensus reference standard for true fractures among suspected scaphoid fractures. More sophisticated imaging to date has simply identified more abnormalities that are difficult to interpret. Consequently, to move forward we may need to accept that we are ultimately dealing with probabilities rather than certainties in the diagnosis of fracture. Such an approach would no longer seek to diagnose the presence or absence of a fracture definitively. Rather, the goal would be optimal NPV and PPV with the ultimate aim of reaching certain accepted thresholds. Since the pretest odds of a fracture (or the prevalence of true fractures among suspected fractures) has a substantial effect on the PPV, future research should build on the attempts to develop clinical prediction rules that use demographic and clinical factors predictive of a true fracture to better identify patients in whom imaging will have an acceptable NPV and PPV. In addition, given the absence of an accepted reference standard, future research should use latent class analysis to estimate diagnostic performance characteristics. 
Regarding the decision between operative or nonoperative treatment of nondisplaced fractures of the scaphoid waist, the following issues merit further investigation: The safety of a shorter duration of cast wear and the use of casts or even splints that are less cumbersome (e.g., thumb free); differences in quality of life, cost effectiveness, and the safety of earlier return to work or sport; the definition, diagnosis, and prevalence of “minimally displaced” fractures of the scaphoid waist; and a comparison of operative and nonoperative treatment for this subset of fractures. 
Regarding scaphoid nonunion, more data is needed on the long-term outcome, including patient reported measures, following surgical intervention. There are also controversies regarding the use of vascularized bone grafts in reconstructive procedures, as well as when to progress to salvage procedures. 

Scaphoid Fractures: Pearls and Pitfalls

  •  
    Male gender and sports injuries are risk factors for an acute fracture of the scaphoid
  •  
    Clinical prediction rules might aid in the assessment of the suspected fracture
  •  
    Displacement of scaphoid fractures may be difficult to diagnose and CT or arthroscopy can be helpful
  •  
    The criteria for displacement, in particular minimal displacement, needs to be further investigated and better defined
  •  
    Nonoperative management is routinely employed for suspected scaphoid fractures and tubercle fractures
  •  
    Percutaneous fixation for undisplaced or minimally displaced waist fractures may reduce time in cast, increase the rate of return to function and increase the rate of union
  •  
    Surgical management is recommended for displaced scaphoid fractures, proximal pole fractures, comminuted fractures, and fractures that are part of a greater perilunate injury

Other Carpal Fractures

Triquetral Fractures

Triquetral fractures are the second most common fracture of the carpus,218,227,507 with avulsion fractures (representing in essence a benign “wrist sprain”) accounting for over 90% of all triquetral injuries.114,218 Less common patterns of fracture include the following: 
  •  
    Transverse fracture of the triquetrum as part of a perilunate dislocation, although more frequently dorsal displacement is seen14,273,412,452,555
  •  
    Impingement shear fracture type178,489
    •  
      Ulnar impaction: Ulnar styloid against the dorsal triquetrum, which occurs with the wrist in extension and ulnar deviation, particularly when a long ulnar styloid is present.
    •  
      Triquetrohamate impaction: Hamate against the posteroradial projection of the triquetrum, occurs through compression of the wrist in forced dorsal and ulnar extension while the forearm is pronated.

Clinical Assessment and Diagnosis

Patients present with pain and tenderness localized over the region of the triquetrum. Standard scaphoid views will detect most triquetral fractures, with dorsal avulsion fractures of the triquetrum often found on the oblique or lateral views.114 PA radiographs of the wrist are useful in identifying transverse body fractures; however, they will often not detect avulsion fractures of the triquetrum due to the normal superimposition of the dorsal lip on the lunate. Additional views that can aid the diagnosis include an oblique pronated lateral radiograph that will project the triquetrum even more dorsal to the lunate.114 Secondary imaging modalities are often not necessary, although CT for further delineation of body fractures is useful. Occult triquetral fractures can be identified when CT and MRI are used in the detection of occult scaphoid fractures.171 

Management

Triquetral avulsions are managed with a splint for comfort only and active self-assisted stretches as comfort allows to limit stiffness.114 Triquetral body fractures associated with carpal disruption often require internal fixation.273,412,437,452 

Lunate Fractures

Lunate fractures account for less than 1% of all carpal fractures and most occur as part of a perilunate injury.218,227,507 

Clinical Anatomy

The lunate is the middle bone of the proximal carpal row, acting as a keystone in the well-protected concavity of the lunate fossa of the radius, anchored on either side through interosseous ligaments that connect to the scaphoid and triquetrum.247,277,283,502,530 Distally, the convex capitate head fits into the concavity of the lunate. The joint reaction forces from the capitate and radius move the lunate ulnarly. The proximal pole of the hamate has a variable articular facet on the distal ulnar surface of the lunate, and ulnar deviation increases the degree of contact between these two bones. 
The vascular supply of the lunate is primarily through the proximal carpal arcade, with current literature suggesting that approximately 80% of lunates receive vessels from both the dorsal and palmar surfaces, with the remaining 20% from the palmar surface only (Table 31-3).57,164,182,186,366,542 It is said that this limited blood supply renders the lunate vulnerable to AVN,57,164,185,186,366 and yet AVN is almost unheard of after lunate or perilunate dislocations, presumably because the palmar radiocarpal arch usually remains intact as the dislocation is through the space of Poirier. The lunate blood supply is frequently endangered by common dorsal approaches to the wrist, but the blood supply from the palmar radiocarpal arch is usually sufficient. 
Kienböck Disease.
Kienböck disease is an eponym for idiopathic avascular osteonecrosis of the lunate.75,116 It usually has an insidious onset without a history of injury; however, diagnosis is sometimes made after a simple fall that fractures the necrotic bone.33,182 Osteonecrosis may be the result of interruption of the vascular supply to the lunate, which shows no radiographic evidence of injury until sclerosis and osteochondral collapse.33,182,265 The condition is more common in patients with an ulnar minus variant.173,204,534 
Some believe that unrecognized and untreated fractures of the lunate lead to Kienböck disease, predominantly due to the cadaveric work of Verdan who applied strong forces to cadaver bones and observed that the resulting fractures were not visible on standard radiographs but only on histology.33,173,182 However, others have questioned these findings, with one study suggesting that early venous congestion, not fracture, of the lunate was responsible for the pathogenesis of Kienböck disease.419 The lunate necrosis after perilunate dislocation is probably due to impairment of the arterial vasculature.173 

Clinical Assessment and Diagnosis

Most patients with fractures of the lunate have a history of a hyperextension injury such as a fall on the outstretched hand.81,229 Patients present with pain and tenderness localized over the region of the lunate and triquetrum. 
Imaging.
Standard scaphoid views are the primary investigation for suspected lunate fractures.114 Some injuries may be difficult to visualize early, as an undisplaced fracture can be obscured by superimposed structures.173 
  •  
    The palmar cortical line of the radial styloid is aligned with the division between the dorsal and palmar thirds of the lunate where a transverse fracture often occurs.
  •  
    The PA view of this is in a plane almost perpendicular to the fracture, which is overlapped by the rims of the distal radius and is therefore not apparent.
  •  
    The palmar horn of the lunate may also be hidden by the pisiform and scaphoid shadows.
Given this, there must be a low threshold for further imaging when the diagnosis is in doubt. Bone scan will be positive within 24 hours of injury. However, CT will provide the most precise detail regarding any fractures, as well as any osteonecrotic changes that may need to be differentiated from a primary fracture or secondary fracture associated with fragmentation. Arthroscopic examination permits a direct assessment, including of the articular surfaces and the intrinsic ligaments.173 
Classification.
Lunate fractures can be difficult to describe and part of the difficulty is that the fragmentation that occurs in Kienböck disease can be confused with fractures. However, acute fractures of the lunate were classified into five groups by Teisen and Hjarbaek.484 
  1.  
    Frontal fractures of the palmar pole with involvement of the palmar nutrient arteries
  2.  
    Osteochondral fractures of the proximal articular surface without substantial damage to the nutrient vessels
  3.  
    Frontal fractures of the dorsal pole
  4.  
    Transverse fractures of the body
  5.  
    Transarticular frontal fractures of the body
Fresh fractures of the lunate include dorsal and palmar horn avulsion fractures that occur more often in the radial corner than in the ulnar corner. Fractures of the body are usually transverse in the coronal plane. The more common of these is between the middle and palmar thirds of the body. 

Management

Nonoperative management in cast for approximately 4 weeks is suitable for most isolated lunate fractures,81,229 with nonunion rarely reported. A transverse fracture of the body will heal if it remains nondisplaced, particularly in adolescents. 
Indications for ORIF include displacement and/or associated carpal instability. If there is evidence of separation of the lunate fragments by the capitate, union will not occur and the risk of AVN is markedly increased.78,258,323 Although the efficacy of internal fixation of the lunate is unproven and the obstacles to successful reduction and fixation are substantial, the consequences of inaction are as to be expected. Distraction with an external fixator may facilitate reduction of the lunate fragments, particularly in the chronic setting.83 
Nonunion of a lunate body fracture is rare, as most will progress to Kienböck disease. If this does occur, the treatment includes radial shortening, radial wedge osteotomy, or ulnar lengthening in the early stages, with carpal arthodesis if the condition is advanced.11,111,151,173,195,310,483,537 

Other Carpal Fractures

Carpal fractures other than those of the scaphoid, lunate and triquetrum are rare. The known facts about these are summarized in Table 31-15
Table 31-15
Epidemiology, Etiology, Diagnosis and Management of Trapezium, Trapezoid, Capitate, Hamate, and Pisiform Fractures
Fracture Epidemiology and Etiology Clinical Assessment and Diagnosis Management and Complications
Trapezium Rare, <5% of all carpal fractures218,467
Body (vertical), tuberosity or avulsion fracture types
Ridge avulsion occur following forceful deviation, traction or rotation on capsular ligaments or flexor retinaculum330
Tuberosity fractures associated with fractures of the hook of the hamate, or with dislocation of the hamate, due to the attachments of the flexor retinaculum199,230,236,498
Articular surface fractures can be associated with dislocation or fracture-dislocation of the first CMCJ176,230,330
Localized pain and tenderness
Standard scaphoid views primary investigation
Carpal tunnel views for tuberosity fractures230
Associated scaphoid fractures reported222,508
Secondary imaging modalities for associated complex injuries
Undisplaced: Scaphoid cast
Displaced/dislocation: CRIF381 or ORIF165,176,321,494
Recent report of the use of arthroscopy540
60% reported to have an unsatisfactory outcome105
Nonunion (ridge fractures): Excision
Trapezoid Least common carpal fracture (<1%)218
Fracture patterns include sagittal, coronal, or crush244
Vast majority undisplaced244
Dislocations can occur in both directions76,175,244,346,458
Associated fractures in one-third of cases244
Strong ligamentous attachments mean high-energy injuries required for injury (e.g., RTA, crush, sports), with axial loading, forced flexion, forced extension, and direct blow all described244,293,318
Localized pain and tenderness (e.g., base of second metacarpal)
Symptoms and signs can be minimal and imitate a scaphoid fracture244
Standard scaphoid views primary investigation
Oblique views can aid diagnosis
Overlap of carpals can make diagnosis difficult353
Coronal fractures rarely detected on radiographs244
CT/MRI for diagnosis in over 80% of cases244
Undisplaced (<2 mm): Vast majority, scaphoid cast
Excellent results often achieved even with delayed treatment202,244,341
Displaced ± dislocation or delayed union: ORIF or excision76,346,378,408,521
Capitate Controversy regarding frequency, <1% carpal fractures75,218
Mechanism injury includes direct blow/crush, scaphocapitate syndrome154,296,314 or the anvil mechanism theory of injury (see Pathoanatomy)
Direct blow or crush injuries are often associated with injury to the other carpal bones and/or the metacarpals
Localized pain and tenderness
Standard scaphoid views primary investigation
Lateral views useful for determining displacement and rotation of the head
Dynamic studies for displacement
CT/MRI for occult fractures8,115,356
Undisplaced: Heals without immobilization, scaphoid cast
Displaced ± dislocation: ORIF166,382,392,488,510
Nonunion rare when undisplaced98,561
AVN possible with displaced fractures294,495
Hamate Rare, <5% of all carpal fractures, third most common218
Hook (most common), body or dorsoulnar flake fracture types161,354,536,567
Hook fracture is commonly a sports (racket sports and golf)-related injury9,152,161,169,203,369,519 (Fig. 31-35)
Body or coronal fractures are commonly seen in young men following a punch injury. Associated fracture or fracture-dislocation of metacarpals frequent536
Flake or avulsion fractures usually occur following a low-energy fall or direct blow
Localized pain and tenderness, though often minimal
Ulnar nerve lesion (deep branch of ulnar nerve passes around hook of hamate)161,169,451
Tendon rupture with chronic presentations315,485,556
Standard scaphoid views primary investigation
Loss of bone contour is suspicious of dislocation
One study suggested three signs indicative of a hook fracture354:
  1.  
    Absence of the hook
  2.  
    Sclerosis of the hook
  3.  
    Lack of cortical density

Oblique and carpal tunnel views improving chance of diagnosing hook fractures245,262
Important to distinguish from os hamulus proprium
Alternate view with maximal radial deviation of the wrist and maximal abduction of the thumb49
CT/MRI for suspected fractures22,245,375
Undisplaced: Cast with good results reported519,535,536
Displaced ± dislocation ± nerve lesion: Excision or ORIF 9,220,417,451,519 ± decompression of Guyon canal
With excision some authors advocate bone grafting to preserve the pulley effect on the flexor tendons526
One study determined a concomitant soft tissue lesion was predictive of a poorer outcome220
Nonunion (more common with hook fractures) can lead to chronic pain and little finger flexor tendon injury. Manage with excision or OIRF ± bone grafting418,556
Pisiform Rare, <5% of all carpal fractures218
Predominantly body fractures218
Dislocation is rare119,336,415
Commonly sports-related fractures and often missed262
Localized pain and tenderness336
Ulnar nerve lesion (terminal branch division at pisiform)
Standard scaphoid views primary investigation
Lateral in 20 to 45 degrees of supination and carpal tunnel views aid diagnosis262
Subluxation of pisotriquetral joint diagnosed with ≥1 of
  1.  
    joint space <4 mm width
  2.  
    loss of parallelism >20 degrees
  3.  
    proximal or distal override of pisiform <15% width of joint surfaces
Cast treatment usually sufficient
Excision through a volar approach for painful nonunion (rare)26,95,336
Complications of excision may include reduction of grip strength/wrist flexion, hammer syndrome, ulnar nerve neuropathy26; however, some studies have disputed the loss in wrist function264
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Authors’ Preferred Management—Other Carpal Fractures

 
 

For the vast majority of isolated, undisplaced or minimally displaced carpal fractures we prefer nonoperative management. We routinely use a standard Colles cast or wrist splint, depending on the requirements of the patient, for a period of approximately 4 weeks followed by routine mobilization. For simple avulsion fractures, immediate motion and a splint as required for discomfort is sufficient. For displaced fractures, which are routinely associated with other osseous or soft tissue injuries of the carpus, we prefer closed or open reduction, with internal fixation.

Directions for Future Research in Other Carpal Fractures

There is sparse literature on all the “other carpal fractures.” Exact details regarding epidemiology, diagnosis using standard radiographs, as well as short-term and long-term outcomes following both conservative and operative management is not known. 

Other Carpal Fractures: Pearls and Pitfalls

  •  
    Triquetral fractures are the second most common carpal fracture following a fracture of the scaphoid
  •  
    Routine scaphoid radiographs detect most carpal injuries
  •  
    A thorough assessment for other osseous and ligamentous injuries of the carpus is necessary
  •  
    The vast majority of the other carpal fractures can be managed nonoperatively with good results

Carpal Ligament Injuries

There are various classifications for carpal malalignment and carpal ligament injuries, which are discussed on Pages 1000–1002. A variety of imaging modalities are utilized when carpal ligament injury is suspected. Standard scaphoid radiographs with additional deviated views of the wrist, and possibly a clenched fist PA view form the primary investigation. MRI is imperfect for carpal ligament injuries and wrist arthroscopy is considered the reference standard, but it is not clear what to do with the so-called “partial” injuries and how these can be distinguished from normal variations or age-related changes. 

Scapholunate Dissociation of Carpal Ligament Injuries

Etiology

SLD is the most common form of carpal ligament injury, with dynamic scapholunate instability the most common cause of instability in adolescents and young adults.183,475,544 Instability can occur in isolation or in association with a fracture of the carpus or distal radius.84,149,331,332,362,416,511 The most common mechanism of injury involves hyperextension of the wrist with associated ulnar deviation and intracarpal supination leading to injury of the scapholunate interosseous and palmar ligaments.301304 A previous injury, repetitive strain on the carpus, or the presence of acute or chronic synovitis appears to alter the magnitude of force required to cause ligamentous disruption, so much so that the presenting event may be following a trivial injury.173 
SLD describes a spectrum of injuries ranging from ligamentous sprains through to dislocation of the scaphoid. A variety of ligament disruptions can occur including one or more of the scapholunate interosseous ligament, the RSL ligament, the RSC ligament, the scaphotrapezium-trapezoid ligament, the DRC ligament, and the dorsal intercarpal ligament.173 Disruption of the scapholunate interosseous ligament leads to dyskinesia between the scaphoid and the lunate, ultimately resulting in progressive widening of the scapholunate joint with time.480 The clinical consequences of the injury depend on the tightness or laxity of the capsuloligamentous system of the wrist, as well as the presence of any associated palmar radiocarpal or midcarpal ligament damage.173 

Clinical Assessment and Diagnosis

Patients will often present with localized wrist pain and swelling following a fall onto an outstretched hand, with the wrist undergoing a forced hyperextension.37,331,332,518 There will be tenderness in the region of the scaphoid and lunate. Movement of the wrist may be minimal, with pain on flexion–extension or radioulnar deviation and an audible clunk or click heard. A full assessment of the entire carpus and distal radius and ulna is necessary as there may be an associated fracture. A clinical deformity at the wrist may be apparent and a full neurovascular assessment is imperative, as acute carpal tunnel syndrome can occur with associated carpal fractures and dislocations.331,332 
Clinical findings can be subtle, and the classic features of carpal instability may not be apparent without provocative stress testing. A simple general provocative maneuver is a vigorous grasp that induces pain, an audible clunk or click, a dorsal deformity in the region of the proximal scaphoid, and reduced power with repetitive grip strength testing. A positive Kirk-Watson (scaphoid shift) test is highly suggestive of scapholunate instability (Fig. 31-12), although not absolutely specific for SLD as it may reposition the entire proximal carpal row if the row, rather than the individual scaphoid, is unstable.370,523,528,547,548 In addition, in individuals with lax ligaments there may be false-positive signs of dorsal subluxation of the scaphoid that are not pathologic. Generalized ligamentous laxity may be present in patients with true SLD as many wrists with an injury have some form of pre-existing ligamentous laxity.303 
Imaging.
The six standard views for carpal instability are mandatory in the assessment of suspected SL instability. Clenched fist views and contralateral wrist views can aid in the diagnosis. The following should be assessed (see Pages 1004–1008): 
  •  
    A scapholunate gap of >3 mm is suggestive of instability, with a gap >5 mm diagnostic of SLD if there is a positive cortical ring sign (Fig. 31-36). The increased gap between the scaphoid and lunate has been named the Terry Thomas sign (Fig. 31-36) after the gap-toothed smile of the British comedian.163 It is suggested that the gap should be compared to the uninjured opposite extremity,80 particularly in the absence of a dorsiflexed lunate, which is most likely nontraumatic.360
  •  
    The appearance of the scaphoid.
    •  
      A positive cortical ring sign is when the distal scaphoid tubercle is seen end-on with a PA view, suggestive that the scaphoid is flexed.80
  •  
    A scapholunate angle of >60 degrees is suggestive of instability, with an angle of >80 degrees diagnostic of SLD (Fig. 31-36).183,277
  •  
    The appearance of the lunate.
    •  
      DISI deformity (Fig. 31-36) where the lunate is extended (dorsally angulated) is associated with a SLD (Table 31-4).
    •  
      A normally positioned lunate projects as a quadrilateral shape on the neutral PA radiograph; however, the shape appears triangular when the lunate is malrotated and is often associated with a perilunate dislocation.
  •  
    A capitolunate or radiolunate angle of >15 degrees is suggestive of instability, with an angle >20 degrees diagnostic.
  •  
    Gilula lines for ligamentous instability (Fig. 31-15).
  •  
    Exclude associated fractures of the radius or carpus (Fig. 31-37), especially in younger patients.
    •  
      An ulnar positive variance of >2 mm in nonosteoporotic patients with an intra-articular fracture of the distal radius has been found to be predictive of a severe scapholunate injury.159
Figure 31-35
 
A: Radiograph of the right hand reveals a fracture through the hamate. B: 3D CT reconstruction confirms a fracture through the body of the hamate. C: Radiograph post ORIF.
A: Radiograph of the right hand reveals a fracture through the hamate. B: 3D CT reconstruction confirms a fracture through the body of the hamate. C: Radiograph post ORIF.
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Figure 31-35
A: Radiograph of the right hand reveals a fracture through the hamate. B: 3D CT reconstruction confirms a fracture through the body of the hamate. C: Radiograph post ORIF.
A: Radiograph of the right hand reveals a fracture through the hamate. B: 3D CT reconstruction confirms a fracture through the body of the hamate. C: Radiograph post ORIF.
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Figure 31-36
Scapholunate instability with an increased scapholunate gap (Terry Thomas sign) found on the AP view.
 
A DISI deformity and an increased scapholunate angle are found on the lateral view.
A DISI deformity and an increased scapholunate angle are found on the lateral view.
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Figure 31-36
Scapholunate instability with an increased scapholunate gap (Terry Thomas sign) found on the AP view.
A DISI deformity and an increased scapholunate angle are found on the lateral view.
A DISI deformity and an increased scapholunate angle are found on the lateral view.
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Figure 31-37
Radiographs of the wrist post manipulation for a fracture of the distal radius.
 
An increased scapholunate gap indicative of SLD is seen, and was confirmed intraoperatively.
An increased scapholunate gap indicative of SLD is seen, and was confirmed intraoperatively.
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Figure 31-37
Radiographs of the wrist post manipulation for a fracture of the distal radius.
An increased scapholunate gap indicative of SLD is seen, and was confirmed intraoperatively.
An increased scapholunate gap indicative of SLD is seen, and was confirmed intraoperatively.
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When these findings are not found on initial radiographs, stress testing with the provocative maneuvers discussed can be used with clenched-fist views or radioulnar stress views to determine the diagnosis and confirm dynamic SLD. Dynamic SLD is characterized by normal radiographs of the wrist, but with axial loading of the wrist a widening of the scapholunate gap is seen. Static instability is characterized by a widening of the scapholunate gap in an unloaded wrist and a scapholunate angle >60 degrees.317 
Secondary imaging modalities include fluoroscopy or cineradiography using standard and provocative stress motions.351,374 Arthrography has a high rate of false-positive and false-negative results and is therefore of limited use.493,518 MRI is helpful in determining the extent of ligament injury. Wrist arthroscopy can be used to determine the extent of ligament disruption and the presence of radioscaphoid arthritis, as well as to classify and treat the injuries.180,223,465,518 Arthroscopy has been shown to be effective in patients with suspected dynamic SLD (normal radiographs) for diagnosis and treatment in both acute and chronic cases, allowing assessment of both the ligaments, and midcarpal and radiocarpal joints.223,532 
Classification.
SLD encompasses a spectrum of injuries ranging from grade I ligament sprains, through all grades of ligament destabilization, to injuries of multiple ligaments, and finally dislocation.173 A greater-arc injury encompasses SLD with a fracture of the radial styloid. The classification of scapholunate instability considers whether the injury is acute or chronic and whether it is static or dynamic, as this can be helpful for guiding management. 
A static deformity does not occur with an isolated injury to the scapholunate ligament, is often only apparent on stress imaging; that is, dynamic instability.45,317,331,332 Static instability occurs when the ligament is injured in conjunction with a multiple ligament disruption. 
One study has described four grades of ligament injury according to arthroscopic findings.180 
  •  
    Grade I: Attenuation or hemorrhage of the ligament is seen from the midcarpal space but the bones are congruent. Conservative treatment is usually sufficient.
  •  
    Grade II: Incongruency between the carpal bones when viewed from the midcarpal space. Arthroscopic reduction and fixation is normally required.
  •  
    Grade III: Carpal malalignment in both carpal spaces with a gap between the carpal bones allowing entry of a 1-mm probe. Arthroscopic ± open reduction with fixation is required.
  •  
    Grade IV: Carpal malalignment in both carpal spaces with gross instability and a gap between the carpal bones allowing entry of a 2.7-mm arthroscope. Open reduction and fixation is needed.
An alternative classification was put forward by Kuo and Wolfe,260 which was subsequently used to define treatment (Table 31-16).252 
Table 31-16
An Alternate Classification for SLD, with an Aim to Guide Treatment, put Forward by Kuo and Wolfe
I. Occult II. Dynamic III. SL Dissociation IV. DISI V. SLAC
Ligaments Partial SL ligament Incompetent or complete SL ligament; partial volar extrinsics Complete SLIL, volar or dorsal extrinsics Complete SLIL, volar extrinsics, secondary changes in RL, STT, dorsal ligaments As stage IV
Radiographs Normal Abnormal on stress testing SL gap ≥3 mm, grossly abnormal on stress testing SL angle ≥60 degrees, SL gap ≥3 mm, RL angle ≥15 degrees, CL angle ≥15 degrees Progressive OA with pancarpal OA final stage
Management Pinning or capsulodesis Ligament repair with capsulodesis Ligament repair with capsulodesis vs. triligament reconstruction Reducible: Triligament reconstruction
Irreducible: Fusion
Proximal row carpectomy or fusion
 

CL, capitolunate; RL, radiolunate; SL, scapholunate.

 

Adapted from: Kitay A, Wolfe SW. Scapholunate instability: Current concepts in diagnosis and management. J Hand Surg Am. 2012;37:2175–2196 and Kuo CE, Wolfe SW. Scapholunate instability: Current concepts in diagnosis and management. J Hand Surg Am. 2008;33:998–1013.

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Management

With appropriate treatment, it is possible to avoid potential complications of an SLD injury including advanced scapholunate collapse and progressive, painful arthritis of the wrist. Different treatment options need to be considered on the basis of the duration since the injury, the extent of ligamentous involvement, and the presence of associated carpal instabilities and/or fractures. The grade of ligament injury can guide treatment, as described above. However, a better guide is the duration since injury, which is best defined as follows: 
  •  
    <4 weeks since injury = acute
  •  
    4 to 24 weeks since injury = subacute
  •  
    >6 months = chronic
The primary goals of treatment are stabilization of the carpal bones in good alignment allowing restoration of wrist mobility. The earlier ligament repair takes place the easier it is to perform a direct repair.173 
Acute SLD.
Patients with a grade I ligament injury but with no evidence of carpal instability can be managed effectively with cast immobilization. In patients with partial ligament tears but with instability present arthroscopically, cast immobilization is unsuitable as the scaphoid requires wrist extension to maintain reduction and the lunate requires wrist flexion.481 For these cases, percutaneous K-wire fixation in combination with cast immobilization for 8 weeks can be employed. One K-wire is placed from the scaphoid to the lunate and another from the scaphoid to the capitate. Pins can be placed into the scaphoid and lunate and used as joysticks to reduce the scapholunate joint.173 An 85% success rate in maintaining SL reduction has been reported in patients with a scapholunate interval that was greater than the unaffected wrist by 3 mm or less and in patients where the injury was less than 3 months old.538,539 Such injuries, even if not initially associated with obvious instability, can progress to scapholunate collapse.518 
When the carpus cannot be reduced by closed methods, open ligament repair and pin fixation is recommended in all cases of acute SLD. Cadaveric studies have demonstrated that reduction of the scapholunate articulation is essential to the recovery of normal wrist kinematics after SLD.480 Soft tissue repair and reconstruction are popular because they attempt to restore the normal kinematics of the wrist, with current literature demonstrating superior results of direct ligament repair over ligament reconstruction.36,94,316 The technique of repair has changed with the use of intraosseous suture retaining anchors allowing ligament attachment directly to the bone (Fig. 31-38).29,51,402 Results of primary open ligament repair by a dorsal approach are conflicting.51,271 Some authors advocate a combined dorsal and palmar approach suggesting improved reduction and outcome.139,295 
Figure 31-38
 
A–D: Ligament repair for scapholunate instability using anchors placed into the lunate (or scaphoid, depending on where the ligament has ruptured), and the ligament is sutured back into position.
A–D: Ligament repair for scapholunate instability using anchors placed into the lunate (or scaphoid, depending on where the ligament has ruptured), and the ligament is sutured back into position.
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Figure 31-38
A–D: Ligament repair for scapholunate instability using anchors placed into the lunate (or scaphoid, depending on where the ligament has ruptured), and the ligament is sutured back into position.
A–D: Ligament repair for scapholunate instability using anchors placed into the lunate (or scaphoid, depending on where the ligament has ruptured), and the ligament is sutured back into position.
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Bickert et al.51 reported on the short-term outcome of 12 patients following repair with a dorsal approach at a mean follow-up of 19 months and reported restoration of a normal scapholunate angle in 10 patients, with the mean range of motion at 78% of normal, the mean grip strength 81%, and 8 patients with an excellent or good result. However, no correlation was found between functional and radiologic results, although one of the two poor results was associated with lunate necrosis. Outcome in the long-term is unknown, although similar outcomes have been reported at 5 to 6 years following surgery.258 Some authors are advocates of management using an arthroscopic technique that can aid in confirming the diagnosis, as well as determine the location and extent of ligamentous damage; for example, palmar extrinsic ligament attenuation.257,538 However, whether this is superior remains unclear. 
Subacute SLD.
For subacute SLD, the addition of local tissue may be necessary if the ligament has retracted or is deficient.173 Blatt’s technique (Fig. 31-39) utilizes a proximally based dorsal capsular flap retracted onto the scapholunate articulation, and this is sutured as tightly as possible to the distal pole of the dorsal aspect of the scaphoid to act as a tether.52,334 This flap can be added to the ligament repair process described earlier by placing nonabsorbable sutures from the lunate ligament remnant into the capsular tissue and then out through the scaphoid. An alternative method is to use a strip of tendon from the radial wrist extensors (extensor carpi radialis longus or extensor carpi radialis brevis), but tendon tissue is not an ideal ligament replacement with capsular tissue routinely preferred.173 
Figure 31-39
Blatt’s technique of dorsal capsulodesis, with the scaphoid reduced a capsular flap is secured to the distal pole with an anchor.
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Through a palmar approach, direct ligament repair using nonabsorbable sutures can be performed. If there is deficient tissue, a section of the FCR can be used to augment the repair process by placing drill holes through the proximal scaphoid and radial half of the lunate and passing one-half of the FCR tendon in a circular fashion to reinforce the dorsal and palmar ligaments. The RSC and RSL ligaments may be advanced into the gap. With a large, complete ligament tear associated with a gap of 5 mm or more, adjunct palmar ligament repair is usually needed.173 A carpal tunnel incision extended slightly radially is performed, and the damaged area is identified with a probe inserted from a separate dorsal incision. The interval between the RSC ligament and the RSL ligament is developed. Sutures may then be placed with intraosseous anchors into the scaphoid proximal pole or remnants of the interosseous membrane, which are then used to pull the RSL ligament against the proximal pole to hold the over-reduction of the proximal scaphoid, which is stabilized by K-wires. The purpose of this palmar repair is to bring the dorsally subluxed and rotated proximal scaphoid in apposition with the palmar intracapsular ligaments.173 
Whether the approach is dorsal, palmar, or combined, tight repair of the capsular structures is required. Internal fixation for a period of 12 weeks is preferred, supplemented with a below-elbow cast. After cast removal, a splint is worn as muscle strength and joint motion are restored with the aid of physiotherapy as required. Return to work or sports are best delayed for a minimum of 6 months, with continued protection being used during sports activities. 
Chronic SLD.
The major issues associated with chronic SLD and instability are whether the ligaments can be directly repaired, whether any residual carpal dislocation is reducible, and whether the joint has developed arthritis. When possible, restoration of normal carpal anatomy by repair and reconstruction of the support ligaments of the wrist remains the preferred treatment. This requires sufficient local tissue for a repair and a correctable carpal instability. Partial or complete fusion of the wrist may be required when:173 
  •  
    there is a fixed carpal deformity; for example, the rotational subluxation of the scaphoid or DISI deformity cannot be reduced.
  •  
    the degree of ligament disruption and retraction precludes repair.
  •  
    there are local degenerative changes of the radiocarpal and midcarpal joints.
  •  
    the demands and expectations of the patient include heavy lifting or repetitive loading.
There are many techniques described to treat chronic scapholunate instability.52,173,422,472 Current techniques for ligament reconstruction include repair with the dorsal capsular flap procedure, a palmar ligament reefing procedure, or combined dorsal and palmar procedures that add flexor or extensor tendon tissue to the repair site.173 The goal of each of these repair techniques involves the addition of local tissue to provide a collagen framework for future stability.52,173,422,472 Soft tissue reconstructions have several theoretical advantages that make them attractive alternatives to other procedures. In contrast to arthrodeses, soft tissue reconstructions provide a greater range of intercarpal motion.472 
Tendon weave procedures and tenodeses (Fig. 31-40) have been attempted with variable success. Wrist extensor or flexor tendon augmentation procedures require placement of drill holes in bone. In this procedure, drill holes are carefully placed in a dorsal-to-palmar direction through the scaphoid and lunate. Tendon strips are then passed through these holes to attempt a reconstruction of the ligament. The large holes required to pass tendon grafts can lead to a fracture of the carpus.173 An alternative technique is to take part of an extensor or flexor tendon and pass it through the capitate, scaphoid, lunate, and distal radius.12 Another technique is the reconstruction of the dorsal part of the ligament using a bone-ligament-bone autograft; however, clinical results are not particularly convincing.533 
Figure 31-40
Tendon weaves and reconstructions proposed by various authors.
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The palmar approach for SL ligament repair (Conyers technique) is performed through a carpal tunnel incision.97 A probe or needle passed dorsal to palmar is helpful in locating the ligament tear and palmar ligament intervals. Flaps of RSC and RSL ligaments are reflected laterally and medially. Palmar cortical bone is removed from the capitate, distal radius, scaphoid, and lunate on either side of the scapholunate interval and the cartilage surfaces of the scaphoid and lunate are denuded to subchondral bone to encourage a strong syndesmosis. The scaphoid and lunate are then reduced and pinned with threaded wires that are left in place for at least 8 weeks. The palmar ligaments are carefully repaired overlapping the edges over the denuded cortical bone to ensure sound healing to bone. Motion is delayed 10 to 12 weeks to encourage adequate strength of the syndesmosis.173 
Several procedures have been designed to restrict rotatory subluxation of the scaphoid by creating a dorsal tether.52,86,280,422 A commonly used method of dorsal capsulodesis is the Blatt type of capsular reconstruction.52 Results of Blatt capsulodesis for chronic SLD are acceptable, although some clinical series have not reported favorable outcomes that could be a consequence of patient selection.120 Both short- and longer-term series have reported promising results with the use of a dorsal intercarpal ligament capsulodesis, which is a soft tissue reconstruction procedure based on the dorsal intercarpal ligament of the wrist.174,444,445,472 The theoretical advantage of this method is that it avoids a tether between the distal radius and the scaphoid, allowing the proximal carpal row to work as a functional unit. Wyrick et al.554 assessed the use of ligament repair and dorsal capsulodesis for static SLD and found that no patients were free of pain at follow-up. Their experience, along with others, has suggested that dorsal capsulodesis is likely more suited to patients with dynamic instability than for those with static instability. Static instability requires an intercarpal fusion.173 
Wrist Fusion.
Of the partial wrist fusions performed for wrist instability, the scaphotrapeziotrapezoidal (STT) fusion is frequently recommended in the literature.142,173,525 The purpose of this procedure is to stabilize the distal scaphoid and thereby hold the proximal pole more securely within the scaphoid fossa of the distal radius.173 Clinical studies have shown that STT fusion is reliable and effective, giving pain relief and reasonable functional results. Similar results have been recently reported for scaphocapitate fusion in the medium term.118 However, in the longer term, degenerative changes in adjacent joints may be a problem.158 Young active patients with chronic instability and severe arthritis can be treated with excision of the scaphoid and a four-corner fusion with arthrodesis of the capitate, lunate, hamate, and triquetrum. 
STT fusion can be performed through a transverse incision centered over the STT joint or through the universal longitudinal incision. If either STT fusion or the equivalent scaphocapitate fusion is undertaken, it is important to reduce the palmar-flexed scaphoid, close the SL interval, and maintain carpal height.118 The ideal flexion angle of the scaphoid is 45 degrees. Fixation of the STT or scaphocapitate joints is performed with K-wires, screws, or staples. Bone graft from the distal radius or iliac crest is placed between the decorticated distal scaphoid and the proximal surfaces of the trapezium and trapezoid (STT fusion), or between the medial articular surface of the scaphoid and the lateral surface of the capitate (scaphocapitate fusion). Once scaphoid alignment is achieved, cancellous bone graft is inserted and K-wires are placed to support the fusion area. Prereduction placement of K-wires into the scaphoid facilitates correct orientation after reduction.173 Immobilization after intercarpal fusion is usually for 8 weeks in a scaphoid cast, followed by a support splint for 4 to 6 weeks. CT scans of the wrist can help determine the degree of consolidation at the fusion site. 

Authors’ Preferred Management—SLD

 
 

We recommend primary repair and pin fixation for acute SLD using a dorsal approach.173 The approach is centered over Lister tubercle, reflecting the dorsal wrist capsule to preserve the dorsal intercarpal and dorsal radiotriquetral ligaments, using a radial-based capsular flap. The radial capsule is reflected from the scaphoid to its waist. The open technique allows direct visualization of the injured ligament, reduction, and ligament repair. Most often, the SL ligament is torn off the scaphoid, but still attached to the lunate. In rare cases, avulsion from the lunate or an oblique tear will be seen. Reduction of the lunate and scaphoid is performed with K-wire joysticks inserted in a dorsal-to-palmar direction. The rim of the proximal scaphoid is freshened to subcortical bone with a fine rongeur to facilitate ligament healing. Ideally, high-speed burrs should be avoided as thermal necrosis may occur. When the ligament remains attached to the lunate, intraosseous anchors are inserted into the waist of the scaphoid. The anchors are placed in such a position that the suture lies in a slightly oblique direction in order to resist the rotational forces between scaphoid and lunate.51 The sutures attached to the anchors are placed in the SL ligament in a palmar to dorsal direction. If anchors are not available, drill holes in the scaphoid are required to allow direct attachment of the ligament onto the scaphoid. When the sutures are positioned, the scaphoid and lunate are reduced with joysticks and held in the reduced position with K-wires. One K-wire is placed from the scaphoid to the lunate and another from the scaphoid to the capitate. The sutures are tied and the capsule repaired. A below-elbow cast is applied and retained for 12 weeks, when the K-wires are removed.

 

We prefer the Blatt’s technique of capsule reconstruction, using dorsal capsulodesis for the treatment of chronic scapholunate instability.52,120,173 For the Blatt type of capsule reconstruction, a long rectangular flap, about 1.5 cm wide, based on the dorsal aspect of the distal radius, is used. The distal edge of capsule is sutured to the distal pole of the scaphoid once the scaphoid is placed in a reduced position. A K-wire can be passed into the dorsum of the lunate to be used as a joystick to reduce any DISI. The scaphoid is reduced by pressure on the scaphoid tubercle and then transfixed to the capitate by another K-wire. The dorsal surface of the scaphoid is roughened with a fine rongeur just distal to the center of rotation. The dorsal flap of wrist capsule is sutured under tension with intraosseous anchors distal to the scaphoid center of rotation so that it tethers the proximal pole in the scaphoid fossa. The flap is sutured to reinforce the local tissue of the SL interval. For a distally based flap, one can raise a rectangular capsular flap, leaving the distal end of the flap attached to the scaphoid. After SL ligament reconstruction, immobilization in a below-elbow cast is recommended for 8 weeks. The K-wires are removed at 8 weeks. Splint immobilization for an additional 4 weeks is suggested to allow for tissue healing with gradual stress loading. Supporting splints are best worn intermittently for 6 months to prevent sudden stress to the wrist and to allow further collagen maturation.

Lunotriquetral Dissociation of Carpal Ligament Injuries

Lunotriquetral dissociation (LTD) includes sprains, partial or complete ligament tears, as well as part of the spectrum of perilunate dislocation, or in association with ulnocarpal impingement and TFCC injuries.173 Lunotriquetral ligament injuries are less common than scapholunate ligament injuries.243 Although LTD is not associated with the development of degenerative changes in the carpus, it can lead to potentially devastating changes to carpal kinematics, especially if it advances to a stage of a VISI deformity. Even without this progression, the patient with chronic ulnar-sided pain experiences significant ongoing disability.410 
The mechanism of an isolated LTD is relatively unknown when compared to LTD injury as part of a perilunate dislocation. The lunotriquetral joint is inherently stable, more so than the scapholunate joint, and it seems that associated ligament damage to the dorsal radiotriquetral ligament or palmar ulnocarpal ligaments must be present before severe fixed deformities occur.274 

Clinical Assessment and Diagnosis

Patients present with a history of injury associated with ulnar-sided wrist pain, worse on activity.384 Some patients describe a clunking sensation when the wrist moves from radial to ulnar deviation.384 Clinical signs are often diffuse, although tenderness is often present directly over the lunotriquetral joint, and ballottement of the unstable triquetrum may be possible.384 Stress provocation tests of the joint including compression, ballottement, or shear may be present, with the most sensitive test to diagnose LTD the LT shear test.384 
Imaging.
Primary assessment uses standard scaphoid radiographs; however, one of the major issues with diagnosing LTD is that many patients have a normal radiograph, with findings often subtle and dynamic, although stress-induced deformity is less frequent than with SLD.384 The following may be found with an LTD: 
  •  
    Disruption of Gilula lines on the PA view indicative of an altered intercarpal relationship
  •  
    A static VISI deformity on the lateral view (Fig. 31-41)
  •  
    Associated fractures; for example, a hamate fracture
Figure 31-41
A VISI deformity of the left wrist.
 
Subsequent MRI confirmed LTD.
Subsequent MRI confirmed LTD.
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Figure 31-41
A VISI deformity of the left wrist.
Subsequent MRI confirmed LTD.
Subsequent MRI confirmed LTD.
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Secondary imaging modalities may be required. Wrist arthrography is not a reliable diagnostic tool, but videofluoroscopy can be helpful.173 Arthroscopy has become the most important diagnostic tool for confirming the presence and degree of LTD, with views of the radiocarpal and midcarpal joints allowing visualization of the scaphoid-trapezoid-trapezium joint, midcarpal extrinsic ligaments, the capitohamate joint, and the articular surfaces of the carpal bones.180,223 Arthroscopic staging is applicable to all ligamentous dissociations.180 

Management

Acute LTD with little deformity is routinely managed with a below elbow cast.384 If conservative measures fail, surgical intervention should be considered. Closed reduction and percutaneous internal fixation of the lunate to the triquetrum is indicated when there is displacement.173 Arthroscopy can be helpful in acute injuries to guide closed reduction and percutaneous pinning,361,406 with some suggesting the arthroscope be placed in the radial midcarpal portal for this procedure because the alignment of the LT joint is much easier to evaluate. 
Indications for open surgery include if closed reduction ± arthroscopy fails, when the LTD is associated with an angular deformity, or following unsatisfactory results from previous treatment. An open repair should be attempted only when there are sufficiently strong ligament remnants present, when the ligament remnants have a reasonable healing potential, and when the LT relationship is easily reduced.173 
Open reduction, repair of lax or damaged ligaments, and temporary internal fixation with percutaneous wires across the triquetrum and lunate left in place for 6 to 8 weeks is recommended.173 All ligaments that seem to be concerned with LT stability should be reattached and it is mandatory to correct any VISI deformity. The interosseous ligament repair is usually done through a dorsal approach. Care should be taken to avoid injury to the dorsal sensory branch of the ulnar nerve. The fifth extensor compartment is opened and an ulnar-based retinacular flap is elevated. The ligament is more likely to be stripped from the triquetrum. Intraosseous bone anchors with attached sutures are used for reconstruction. Capsular flaps are useful for reinforcing the dorsal portion of such a repair or augmenting the dorsal radiotriquetral and dorsal scaphotriquetral ligaments. For late presentations with complete ligament disruption and no tissue for repair, ligament reconstruction using part of the extensor carpi ulnaris tendon is recommended.173,410 
In cases of recurrence and/or when soft tissue repair cannot control recurrent deformity, lunotriquetral joint fusion may be indicated, with or without accompanying denervation procedures. Concomitant ulnar shortening procedures should be considered (especially with ulnar plus variance) to tighten the palmar ulnocarpal ligaments in addition to fusion or ligament reconstruction. More aggressive treatments are proximal row carpectomy and total wrist arthrodesis in patients with radiologic signs of arthrosis.173 

Perilunate Dislocation and Fracture-dislocation

Etiology

A perilunate dislocation or fracture-dislocation is the most common form of wrist dislocation and encompasses a spectrum of injury, which can include both ligamentous and osseous disruption. In clinical practice, the prefix trans is commonly used to refer to associated fractures, whereas the prefix peri is used to describe a dislocation.173 Perilunate fracture-dislocations (greater-arc injuries) are more frequently seen than perilunate dislocations (lesser-arc injuries) with the ratio reported to be two to one, with displacement in a dorsal direction in 97% of cases.215 The injury is frequently seen in young males with strong bone as the distal radius and the scaphoid need to be strong enough to resist the amount of torque that results in a perilunate dislocation.215 
Prompt management improves the chance of a good long-term outcome; however, all patients should be advised regarding the severity of these injuries and the guarded prognosis. Late diagnosis delays treatment, which is difficult and frequently less successful. Approximately 20% of patients are misdiagnosed at presentation and that delay between injury and treatment worsens the prognosis with neglected cases resulting in pain, weakness, stiffness, carpal tunnel syndrome, and post-traumatic osteoarthritis.15,154,215,256 
Perilunate Dislocations.
Perilunate dislocations (lesser-arc injury) are characterized by a progressive disruption of capsular and ligamentous connections of the lunate to the adjacent carpal bones and radius, without associated fractures to the carpus and distal radius. Ligament disruption typically begins radially and propagates around or through the lunate to the ulnar side of the carpus (Fig. 31-42). Classically, the distal row dislocates in a dorsal or dorsoradial direction followed by the entire scaphoid and triquetrum in pure perilunate dislocations or just by the distal portion of these bones in perilunate fracture-dislocations. SLD or LTD often persists even after relocation, with recurrence of instability common whether the injury involves one or both of the lesser or greater arc. It is important to define any associated ligamentous injuries such as LTD or SLD to prevent late carpal collapse.173 For the detailed pathoanatomy of injury please see Page 1002. 
Figure 31-42
Different types of perilunate dislocations and fracture-dislocations.
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Perilunate Fracture-dislocations.
Perilunate fracture-dislocations (greater-arc injury) combine ligament ruptures, osseous avulsions and various types of fractures. The most common pattern of perilunate instability is the transscaphoid perilunate fracture-dislocation.87,101,215 Fractures of the capitate, hamate, lunate, triquetrum, and radial styloid can also occur. In a series of 166 perilunate dislocations and fracture-dislocations, fracture-dislocations were twice as frequent as a dislocation alone, with 61% being dorsal transscaphoid perilunate fracture-dislocations.215 Displaced transverse fractures of the neck of the capitate and sagittal fractures of the triquetrum are also quite frequent.24,25,82,215,273 The capitate fragment is frequently rotated through 180 degrees so that its articular surface faces the raw cancellous surface of the major capitate fragment.173 Both capitate and scaphoid fragments are devascularized by displacement and this is known as the scaphocapitate syndrome.24,510 

Clinical Assessment and Diagnosis

Patients are often young males who present following a high-energy (e.g., fall from height, motor vehicle accident, sports) hyperextension injury, with persistent wrist pain, swelling, and deformity.15,215,219 Approximately a quarter of presentations will be associated with a polytrauma, with one in ten sustaining an associated upper limb injury.215 In around 16% of cases the clinical presentation includes median nerve symptoms and signs,4 but an ulnar neuropathy, arterial injury, or tendon disruption may also be seen.4,15,101,215,323 
Some perilunate dislocations may be seen several months or years after the initial injury.473 The patient is more likely to present because of increasing nerve symptoms or tendon rupture than because of wrist deformity to which the patient has often become accustomed. 
Imaging.
Primary assessment uses standard scaphoid radiographs with the following appearances suggestive of a perilunate dislocation.192,217 
  •  
    Disruption of Gilula lines on the PA view indicative of an altered intercarpal relationship (Fig. 31-43)
  •  
    “Spilled teapot sign” on the lateral view due to palmar rotation of the lunate and disruption of the lunate-capitate articulation
  •  
    Triangular appearance of lunate secondary to rotation
  •  
    Increased ulnocarpal translation454,550
    •  
      Neutral PA and radial deviation radiographs recommended
    •  
      Defined as >50% of lunate uncovering
    •  
      Some suggest seen in 80% of perilunate injuries
Figure 31-43
Wrist radiographs demonstrating typical radiologic signs of perilunate fracture-dislocation.
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Subtle signs of disruption may include loss of carpal height and increased intercarpal spaces. It is essential to assess for associated fractures of the carpus and distal radius. The literature suggests that 16% to 25% of perilunate dislocations are missed initially,15,215,256 with lesser-arc injuries commonly missed because of the lack of an obvious osseous pathology and inexperience of the initial observer. Stress radiographs or an EUA may be necessary. Often secondary imaging modalities are necessary including CT and MRI, with arthrography and arthroscopy useful in determining the extent of the injury.20,113 
Classification.
The most frequent systems for describing perilunate injuries include the Mayfield classification (Fig. 31-10), and the greater- or lesser-arc injury patterns (Page 1002).239,301304 Injuries can also be classified as acute or chronic, and reducible or irreducible. The pattern of skeletal deformity is variable. The hand and distal carpal row usually remain intact, but the disruption pattern between distal and proximal carpal rows is quite variable. In the transscaphoid fracture-dislocation, the distal scaphoid dislocates with the distal row leaving the proximal scaphoid and lunate in near-normal relationship to the forearm. When the perilunate ligaments rupture, the lunate usually remains within the radiocarpal joint and the remainder of the carpus dislocates, usually dorsally but occasionally in a volar direction. Occasionally, the lunate is displaced and rotated palmarly and the remainder of the carpus settles into a seminormal alignment with the distal radius. Rarely, even the palmar attachment of lunate is torn, allowing extrusion into the forearm or through the skin.173 
An alternate classification system was put forward by Witvoet and Allieu.545 
  •  
    Grade I: Lunate appears normally aligned
  •  
    Grade II: Lunate rotated palmarly <90 degrees
  •  
    Grade III: Lunate rotated palmarly >90 degrees but still attached to the radius by its palmar ligaments
  •  
    Grade IV: Lunate totally enucleated without any connection to the radius
Herzberg et al. suggested a three-stage classification.531 
  •  
    Stage I: Dorsal dislocation of capitate, lunate remains in fossa
  •  
    Stage IIA: Dorsal dislocation of capitate, lunate dislocated from fossa, rotated <90 degrees
  •  
    Stage IIB: Dorsal dislocation of capitate, lunate dislocated from fossa, rotated >90 degrees

Management

Nonoperative management and delayed intervention of perilunate dislocations and fracture-dislocations has been shown to give poor results.25,189,215,531 Early reduction and operative stabilization is now recommended for the vast majority of cases. However, patients need to be warned regarding the severity of this injury, and prognosis must always be guarded. Poor prognostic indicators have been found to be manual workers, a poor initial reduction, or those patients managed with a combined volar–dorsal surgical approach.157,258 
Prompt reduction reduces swelling, as well as potential damage to the median nerve.241 The earlier a reduction of a perilunate dislocation is performed, the easier it is. Ideally, reduction should be undertaken in the emergency room. Complete relaxation under general or regional anesthesia is required, with local anesthesia usually not sufficient. The most commonly used method of closed reduction is the Tavernier maneuver.173 It consists of locking the capitate into the distal concavity of the lunate by combined axial traction and flexion of the distal row, followed by reduction of the capitate-lunate unit onto the radius by an extension movement, while externally applying a localized dorsally directed force to the lunate to help reposition it. When the injury cannot be reduced closed, urgent reduction in theatre is required.241 Post reduction radiographs are essential to assess the quality of the reduction and the presence of any concomitant fractures that may not have been apparent on initial radiographs. 
Immediate closed reduction reduces any potential pressure on the median nerve, with the majority of patients experiencing resolution of their symptoms after closed reduction.4,219 Immediate median nerve decompression is not usually required but should be performed where there is no resolution of symptoms or when late symptoms develop.129 Severe or increasing median or ulnar neuropathy is always an indication for surgical exploration. 
Surgery can be performed through either a dorsal or a volar approach, although a combined approach may be necessary especially if the dislocation is irreducible closed.219,288,501 Some authors use a combined approach in all cases in order to repair the palmar capsule. The dorsal midline approach allows good exposure of the proximal carpal row and midcarpal joint (Fig. 31-44).173 If there are neurovascular problems, an additional palmar approach allows access for median nerve decompression or repair, vascular repair if required, and repair of the damaged palmar carpal ligaments. This allows both intra-articular and extra-articular damage to be assessed and treated adequately. Some studies have suggested a combined approach can lead to complications (e.g., wound infection, flexor tendon adhesions) and inferior functional results; however, most authors acknowledge that a combined approach is routinely employed for more severe injuries that are associated with a difficult reduction and/or median nerve symptoms.258,455 Minimally invasive and arthroscopic-assisted techniques of fixation and repair have also been used with satisfactory results.237,531,552 
Figure 31-44
 
A: The dorsal capsule is exposed through a longitudinal incision that is centered on the Lister tubercle, dividing the extensor retinaculum between the second and third extensor compartments. The fourth compartment is opened by sectioning the septum between the third and fourth compartments. B: A ligament splitting capsulotomy is performed exposing the dorsal structures. C: Reduction and percutaneous pinning is performed under direct control. Additional K-wires can be inserted into scaphoid and lunate to help with the reduction. Ligaments are repaired using anchors and sutures.
A: The dorsal capsule is exposed through a longitudinal incision that is centered on the Lister tubercle, dividing the extensor retinaculum between the second and third extensor compartments. The fourth compartment is opened by sectioning the septum between the third and fourth compartments. B: A ligament splitting capsulotomy is performed exposing the dorsal structures. C: Reduction and percutaneous pinning is performed under direct control. Additional K-wires can be inserted into scaphoid and lunate to help with the reduction. Ligaments are repaired using anchors and sutures.
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Figure 31-44
A: The dorsal capsule is exposed through a longitudinal incision that is centered on the Lister tubercle, dividing the extensor retinaculum between the second and third extensor compartments. The fourth compartment is opened by sectioning the septum between the third and fourth compartments. B: A ligament splitting capsulotomy is performed exposing the dorsal structures. C: Reduction and percutaneous pinning is performed under direct control. Additional K-wires can be inserted into scaphoid and lunate to help with the reduction. Ligaments are repaired using anchors and sutures.
A: The dorsal capsule is exposed through a longitudinal incision that is centered on the Lister tubercle, dividing the extensor retinaculum between the second and third extensor compartments. The fourth compartment is opened by sectioning the septum between the third and fourth compartments. B: A ligament splitting capsulotomy is performed exposing the dorsal structures. C: Reduction and percutaneous pinning is performed under direct control. Additional K-wires can be inserted into scaphoid and lunate to help with the reduction. Ligaments are repaired using anchors and sutures.
View Original | Slide (.ppt)
X
 
Lesser-Arc Injuries.
There are reductions that are so stable that it is difficult to determine whether a full perilunate-type dislocation took place, and there are others that reduce and can be maintained in near-normal alignment with cast immobilization. Successful closed reduction requires adequate imaging with good standardized AP and lateral radiographs of the wrist. Inadequate reduction leads to a poor prognosis. It is important to confirm any ligamentous stability with stress-test radiographs, MRI, arthroscopy, or open exploration. The very rare injury that reduces to normal alignment by closed reduction and appears stable can be treated with a scaphoid cast with the wrist in a neutral position. Many would advocate daily review in the first week to ensure there is no redisplacement. Review should then take place every week up until 12 weeks when the cast can be removed.173 
However, the results of closed reduction and cast immobilization are unpredictable with loss of reduction common,4,25 with one study finding that despite 17 weeks in cast carpal instability persisted.101 It is now generally agreed that the risk of late deformity after successful reduction and cast management alone is unacceptably high and many advocate early operative intervention.4,25,173 The use of percutaneous K-wire fixation to stabilize the carpus after closed reduction is now recommended. This reduces the incidence of late loss of reduction and enhances the healing capability of the intrinsic ligaments. If possible, pin fixation can be performed using arthroscopy.237,531 Perilunate dislocations that are stable after reduction require only two pins for fixation. One transverse pin is placed from the scaphoid into the lunate (this can also be pinned through the radius into the lunate to neutralize the radiolunate alignment), and a second pin is placed from the scaphoid into the capitate. Pin stabilization of the lunotriquetral articulation is debated.157,173,253 The pins can routinely be taken out at 8 weeks, but immobilization in a scaphoid cast should be continued for a total of 12 weeks post reduction.173 
The vast majority of perilunate dislocations are irreducible or unstable. If reduction is not optimal or reduction cannot be achieved at all, then open exploration and repair is indicated.25,78,196 Significantly superior results have been reported following open reduction, ligament repair, and K-wire stabilization when compared to closed reduction and percutaneous pinning.25,216 Some authors advocate the use of temporary screw fixation as opposed to K-wires to facilitate early motion.456 
The prognosis for these injuries is guarded even with successful reduction and maintenance of intercarpal stability, with longer-term studies reporting good patient satisfaction, but with high rates of loss of reduction and arthrosis although this does not correlate with outcome.15,258 In a midterm study of 22 patients with perilunate dislocations treated with open reduction, cerclage wire fixation and ligament repair patient satisfaction was high for 15 patients, range of movement was 87% and grip strength 77% of the contralateral wrist, but only 10 patients returned to the same type of employment as before their injury.501 
Greater-Arc Injuries.
Management is with closed reduction followed by ORIF, as it is the best method of achieving anatomic reduction of the fracture. This also allows repair of associated ligament injuries, as well as primary bone grafting when there is comminution of the scaphoid.101 Cannulated screw fixation of the scaphoid is routinely recommended,253,258,456 although there are some reports of K-wire fixation alone.157,216 Again, stabilization of the lunotriquetral articulation is debated.157,253 
Most series report satisfactory radiologic results, although the majority of cases have arthritis at longer-term review that does not seem to correlate with outcome.157,215,216,253,258 Overall patient satisfaction is reported to be satisfactory with return to employment, although restoration of function is rarely complete with residual wrist stiffness and weakness of grip strength documented.215,216,253,258 
Chronic Perilunate Dislocations.
Those injuries seen within 3 months are still potentially treatable by open reduction as long as no cartilage degeneration has already occurred, although treatment at this stage is often more difficult because of articular changes and capsular contracture, leading to inferior outcomes.251,254 A good clue to the potential success of late reduction is gained by examining radiographs of the carpus under 25 to 30 pounds of traction.173 An attempt at open reduction (by palmar and dorsal approaches), repair, and internal fixation should be offered if carpal bone realignment is feasible, because even in late cases results can be surprisingly good.173,254,410,473 Late problems such as carpal bone ischemia and ligament contracture nearly always require some type of salvage operation; for example, a proximal row carpectomy or a total wrist arthrodesis.219 Proximal row carpectomy usually provides satisfactory results when the capitate head and lunate fossa are preserved.241,234,389 
Some patients undergo unsuccessful acute management. Depending on the time of presentation from injury and the extent and type of any surgery that has already been undertaken, the options for treatment are identical to those of acute treatment. When a bone or bone fragment has been removed such as a proximal scaphoid or capitate fragment, the alternatives are to rehabilitate the limb and assess the functional level or to consider a salvage procedure such as radiocarpal fusion or proximal row carpectomy.173 

Authors’ Preferred Management—Perilunate Dislocation and Fracture-Dislocations

 
 

All patients with an acute perilunate injury should undergo immediate closed reduction. For those patients with a lesser-arc injury that is reducible closed, we prefer K-wire fixation over conservative treatment in cast. The role of percutaneous reduction and fixation is unclear and still experimental.

 

We prefer a dorsal midline approach to expose and realign the bones (Fig. 31-44), with an additional palmar approach for neurovascular problems. The surgery is similar to that for treatment of SLD, except that an extended carpal tunnel release is performed when required. The palmar capsule should be examined either along its attachments to the radial rim or through the frequently damaged space of Poirier. The dorsal capsule is usually opened along its origin from the dorsal radial rim, as well as longitudinally in the space between the second and fourth extensor compartments, and the proximal carpal row is examined.173

 

If a scaphoid fracture is present (greater-arc injury), it can be reduced through the dorsal approach, temporarily stabilized with K-wires, and fixed with a cannulated screw. Autogenous cancellous bone graft from the distal radius is sometimes placed in comminuted scaphoid fractures. If there is not a scaphoid fracture, the scaphoid is aligned to the lunate and a screw is placed from radial to ulnar percutaneously. The dorsal scapholunate ligament is reattached with a small suture anchor. The screw is removed between 2 and 6 months after injury. Once the scaphoid is reduced, the lunotriquetral joint usually lines up. We sometimes stabilize it with K-wires or a temporary screw, but have left it unsecure more recently.

 

Reduction and K-wire fixation should be centered on the lunate. The lunate must be aligned and pinned first to the distal radius to neutralize the radiolunate alignment. The lunotriquetral joint is then reduced and fixed by a second K-wire. Ligaments are repaired as needed. The capitolunate joint alignment is then evaluated and correct colinear alignment is assessed. Lastly, the scapholunate joint is reduced and held with K-wires. Many of the patients have an associated radial styloid fracture, which should be reduced anatomically and stabilized with K-wires or a compression screw.173

Radiocarpal Instability

Etiology

The most common injuries at the radiocarpal joint are fracture-dislocations of the distal radius and carpus; for example, palmar and dorsal Barton fracture-dislocations, radial styloid fracture-dislocations, and die-punch fracture-dislocations. Less common are the pure ligamentous radiocarpal injuries that may result in a true ulnar, dorsal, or palmar dislocation of the wrist, with some missed as they may spontaneously reduce (Fig. 31-45). Ulnar translation is the most frequent radiocarpal instability. These injuries occur predominantly in young males and are often severe in nature.173 
Figure 31-45
Radiocarpal dislocation with torn radiocarpal ligaments.
 
This injury requires K-wire stabilization and direct repair of the radiocarpal ligaments.
This injury requires K-wire stabilization and direct repair of the radiocarpal ligaments.
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Figure 31-45
Radiocarpal dislocation with torn radiocarpal ligaments.
This injury requires K-wire stabilization and direct repair of the radiocarpal ligaments.
This injury requires K-wire stabilization and direct repair of the radiocarpal ligaments.
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X
 

Clinical Assessment and Diagnosis

Radiocarpal instability may occur acutely, develop gradually, or be observed as a late sequela of a perilunate dislocation. In the acute phase, patients present with a history of high-energy trauma; for example, fall from height. They complain frequently of wrist swelling, deformity, and pain. Dorsal wrist swelling and tenderness are most noticeable at the radiocarpal level and are aggravated by wrist motion. Deformity may be due an ulnar, dorsal, or palmar translation of the carpus. With ulnar translation, the wrist and hand are offset in an ulnar direction. The majority of patients sustain an associated injury, with disruption to the ipsilateral distal radioulnar joint common, and thorough assessment is recommended.138,333 
Imaging.
Primary assessment uses standard scaphoid radiographs to detect displacement and associated fractures. Provocative stress tests may be required to demonstrate dynamic radiocarpal instability.138,333 In those patients with an ulnar translation, the radiographic appearance is often dramatic with the lunate positioned just distal to the ulna and a large space between the radial styloid and the scaphoid. If a perilunate injury is also present the lunate and triquetrum slide ulnarly, opening a gap between scaphoid and lunate. In some cases, the ulnar shift is subtle, and a decrease in the ulnocarpal index may provide the only clue to diagnosis. Chronic causes for ulnar translation include rheumatoid arthritis and in developmental deformities; for example, Madelung deformity.173 
To better define associated bony injuries, CT may be required. To determine the extent of ligamentous disruption, MRI can be used. 
Classification.
Radiocarpal dislocation has been classified into two groups by Dumontier et al.138 
  •  
    Type I: Radiocarpal dislocation with no fracture, or a fracture of the tip of the radial styloid, when it is assumed that the radiocarpal ligaments are avulsed from the radius.
  •  
    Type II: Radiocarpal dislocation with a fracture of the radial styloid involving more than one-third of the scaphoid fossa, when it is assumed that the radiocarpal ligaments remain attached to the styloid process.
Moneim et al.322 also classified these injuries into two groups, but his classification is dependent on the presence or absence of intercarpal ligament injury. 
  •  
    Type I: Intact intercarpal ligaments
  •  
    Type II: A combination of radiocarpal and intercarpal dislocation
Dorsal translation of the carpus together with ulnar translation can be seen in two modes: one a true instability secondary to ligament damage, the other an apparent instability due to a carpal shift in response to a change in position of the distal radial articular surface. Pure dorsal translation usually occurs after a loss of the normal palmar slope of the distal radius from a flexion angle to an extension angle. The latter is a common problem after collapse of a distal radius fracture.173 

Management

Dislocations of the radiocarpal joint require immediate reduction because the associated deformity may compromise adjacent neurovascular structures. Although reduction is usually possible, maintaining it is often difficult. Open treatment should be considered in most carpal dislocations.173 
For type I injuries, the volar radiocarpal ligaments should be repaired using anchor sutures to prevent secondary ulnar or volar translation.138 Where there is a substantial fracture fragment, the volar ligaments are likely to be attached to it; therefore, ORIF of the fragment is necessary. Added stabilization of the radiocarpal joint is recommended using percutaneous K-wires or external fixation to prevent late carpal translation, especially in type I injuries.138,233 Concomitant intercarpal ligament injuries should also be repaired.322 Limitation of wrist movement of 30% to 40% of normal should be expected following radiocarpal dislocation.138,333 
For those with a delayed presentation or diagnosis, ligamentous repair does not usually provide a good result. The most certain method of controlling possible recurrence of deformity is to carry out a partial or total radiocarpal arthrodesis. Radiolunate fusion is an appropriate technique for this situation, although the variation of joint damage may indicate radioscaphoid fusion in some cases and RSL fusion in others. The latter is usually indicated in the combination of radiocarpal and perilunate instability.173 

Directions for Future Research in Radiocarpal Instability

More short-term and long-term outcome data is needed in relation to all the carpal instabilities. Recently, substantial progress has been made in the understanding and detection of carpal ligament injuries, predominantly due to the ever-improving imaging modalities available. Hopefully, improved imaging and surgery will allow better prediction of the evolution of individual carpal instabilities and therefore determine the requirement for operative treatment at an earlier stage. It is likely that improved surgical methods will be devised to treat these problems. The use of closed fluoroscopically or arthroscopically controlled techniques may increase and the results of treatment could improve. 
It is interesting to speculate whether an increasingly aging society will affect the diagnosis and management of both carpal fractures and instabilities. Currently, they mainly occur in younger patients, but with altering patient demographics, this may not continue and a new set of challenges may emerge. 

Carpal Ligament Injuries: Pearls and Pitfalls

  •  
    SLD is the most common pattern of carpal instability
  •  
    SLD without a dorsiflexed lunate is probably not traumatic
  •  
    For SLD the results of K-wire treatment are unpredictable and ligamentous repair should be undertaken if closed reduction is unsuccessful on serial radiographs
  •  
    For chronic scapholunate instability, partial or complete wrist fusion may be needed
  •  
    Perilunate dislocation patterns include a considerable spectrum of sprains, fracture-dislocations, and instabilities
  •  
    Up to a quarter of perilunate dislocations are initially missed
  •  
    Perilunate dislocation and fracture-dislocations routinely require immediate reduction and operative stabilization
  •  
    LTD may result in disruption of Gilula lines on radiograph
  •  
    Open repair of the lunotriquetral ligament is only possible in acute injury

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