Chapter 30: Intra-Articular Injuries of the Knee

Benton E. Heyworth, Mininder S. Kocher

Chapter Outline

Introduction to Fracture of the Tibial Spine (Intercondylar Eminence)

Fractures of the tibial eminence occur because of a chondroepiphyseal avulsion of the anterior cruciate ligament (ACL) insertion on the anteromedial tibial eminence.305,413 Tibial eminence fractures were once thought to be the pediatric equivalent of midsubstance ACL tears in adults,39,46,79,151,187,213,240,255,256,311,319,408,410 though recent evidence suggests that the relative incidence of ACL tears in children may be increasing,353 and that tibial spine fractures in some adult populations may be more common than previously appreciated.100,205 
Avulsion fracture of the tibial spine is a relatively uncommon injury in children: Skak et al.361 reported that it occurred in 3 per 100,000 children each year. The most common causes of these fractures are bicycle accidents and athletic activities.279 
Treatment has evolved from closed treatment of all fractures to operative treatment of certain fractures. Garcia and Neer133 reported successful closed management in half of the 42 fractures of the tibial spine seen in patients ranging in age from 7 to 60 years. Meyers and McKeever,280 however, recommended arthrotomy and open reduction for all displaced fractures, followed by cast immobilization with the knee in 20 degrees of flexion rather than hyperextension, believing that hyperextension could aggravate the injury. Gronkvist et al.151 reported late instability in 16 of 32 children with tibial spine fractures treated nonoperatively, and therefore recommended surgery for all displaced tibial spine fractures, especially in children older than 10 years, because “the older the patient the more the demand on the ACL–tibial spine complex.” Notably, Baxter and Wiley39 noted mild-to-moderate knee laxity at follow-up in 45 patients, even after anatomic reduction of the tibial spine, suggesting that a partial ligamentous stretch injury may occur concomitantly with the spine fracture in many cases. McLennan271 reported 10 patients with type III intercondylar eminence fractures treated with either closed reduction or arthroscopic reduction, with or without internal fixation. At second look arthroscopy 6 years after the initial injury, those treated with closed reduction had more knee laxity than those treated arthroscopically. 
Historically, a variety of treatment options have been reported, including cast immobilization,240,286 closed reduction with immobilization,311,410 open reduction with immobilization,286 open reduction with internal fixation,289,311 arthroscopic reduction with immobilization,271 arthroscopic reduction with suture fixation,171,196,240,255,256 and arthroscopic reduction with wire,36 screw fixation,46,240,271 anchor fixation,397 or bioabsorbable implant fixation.349 However, modern treatment is based specifically on fracture type. Nondisplaced fractures and hinged or displaced fractures which are able to be reduced can be treated closed. Significantly hinged and displaced fractures which are not able to be reduced require open or arthroscopic reduction with internal fixation. 
The prognosis for closed treatment of nondisplaced and reduced tibial spine fractures and for operative treatment of displaced fractures is good. Most series report healing with an excellent functional outcome despite some residual knee laxity.36,39,46,196,215,240,248,255,256,271,272,286,289,365,408,410 Potential complications include nonunion, malunion, arthrofibrosis, residual knee laxity, and growth disturbance.36,39,46,196,215,240,255,256,271,272,286,289,365,394,408,410 

Assessment of Fracture of the Tibial Spine (Intercondylar Eminence)

Mechanisms of Injury for Fracture of the Tibial Spine (Intercondylar Eminence)

Historically, the most common mechanism of tibial eminence fracture in children has been a fall from a bicycle.279,331 However, with increased participation in youth sports at earlier ages and at higher competitive levels, tibial spine fractures resulting from sporting activities are being seen with increased frequency. The most common biomechanical scenario leading to tibial eminence fracture is forced valgus and external rotation of the tibia, although tibial spine avulsion fractures can also occur from hyperflexion, hyperextension,288 or tibial internal rotation. As with ACL injury, tibial eminence fractures in sport may result from both contact and noncontact injuries. 
The actual tissue injury in a tibial eminence fracture is a chondroepiphyseal avulsion of a fragment of the anteromedial tibial eminence from the rest of the central proximal tibial epiphysis via the ACL insertion. In a cadaver study by Roberts and Lovell,330,331 fracture of the anterior intercondylar eminence was simulated by oblique osteotomy beneath the eminence and traction on the ACL. In each specimen, the displaced fragment could be reduced into its bed by extension of the knee. In adults, the same stress might cause an isolated tear of the ACL, but in children the incompletely ossified tibial spine is generally weaker to tensile stress than the ligament, so failure occurs through the cancellous bone beneath the subchondral bone of the tibial spine. In addition, loading conditions may result in differential injury patterns. In experimental models, midsubstance ACL injuries tend to occur under rapid loading rates, whereas tibial eminence avulsion fractures tend to occur under slower loading rates.305,413 
Intercondylar notch morphology may also influence injury patterns. In a retrospective case-control study of 25 skeletally immature patients with tibial spine fractures compared to 25 age- and sex-matched skeletally immature patients with midsubstance ACL injuries, Kocher et al.219 found narrower intercondylar notches in those patients sustaining midsubstance ACL injuries. 

Associated Injuries with Fracture of the Tibial Spine (Intercondylar Eminence)

Associated intra-articular injuries are relatively uncommon. Although Shea et al.352 identified bone bruises in 18 of 20 MRI studies in children with tibial spine fractures, in a series of 80 skeletally immature patients who underwent surgical fixation of tibial eminence fractures Kocher et al. found no intra-articular chondral injuries. Associated meniscal tears (Fig. 30-1) have been reported in 0183 to 40% of MRI studies, but only 4%220 of cases in a larger series based on arthroscopic assessment.220 Associated collateral ligament injury or proximal ACL avulsion are uncommon, but have been described in case reports.163,332 There is one published series of 21 tibial eminence fractures associated with tibial plateau fractures, but the mean age was 20.8 years, with no reporting of age range or inclusion of pediatric patients.100 
Figure 30-1
Longitudinal meniscus tear associated with tibial eminence fracture.
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Signs and Symptoms of Fracture of the Tibial Spine (Intercondylar Eminence)

Patients typically present with a painful, swollen knee after an acute traumatic event. They are usually unable to bear weight on their affected extremity. On physical examination, there is often a large hemarthrosis because of the intra-articular fracture and limited motion due to pain, swelling, and occasionally mechanical impingement of the fragment in the intercondylar notch. Sagittal plane laxity is often present, but the contralateral knee should be assessed for physiologic laxity. Gentle stress testing should be performed to detect any tear of the medial collateral ligament (MCL) or lateral collateral ligament (LCL) or physeal fracture of the distal femur or proximal tibia. 
Patients with late malunion of a displaced tibial spine fracture may lack full extension because of a mechanical bony block. Patients with late nonunion of a displaced tibial spine fracture may have increased knee laxity, with a positive Lachman examination and pivot-shift examination. 

Imaging and Other Diagnostic Studies for Fracture of the Tibial Spine (Intercondylar Eminence)

Radiographs typically demonstrate the fracture, seen best on the lateral and tunnel/notch views. The lateral radiograph is most useful in fracture classification. Radiographs should be carefully scrutinized, as the avulsed fragment may be mostly nonossified cartilage with only a small, thin ossified portion visible on the lateral view. 
To guide treatment, important information to ascertain from the radiographs includes the classification type, amount of displacement, size of the fracture fragment, comminution of the fracture fragment, and status of the physes. Bone age radiographs may be obtained for patients around the time of skeletal maturity, if transphyseal screw fixation is being considered. 
MRI is typically not required in the diagnosis and management of tibial eminence fractures in children, particularly because operative cases will undergo a thorough diagnostic arthroscopy to assess for possible concurrent intra-articular knee injuries, such as meniscal tears, but may be helpful to confirm the diagnosis in cases with a very thin ossified portion of the avulsed fragment or evaluate for suspected associated injuries.183,231,352 

Classification of Fracture of the Tibial Spine (Intercondylar Eminence)

The classification system of Meyers and McKeever,279 which is based on the degree of displacement of the tibial spine fragment, continues to be widely used to classify fractures and guide treatment (Fig. 30-2). 
Figure 30-2
Classification of tibial spine fractures.
 
A: Type I—minimal displacement. B: Type II—hinged posteriorly. C: Type III—complete separation.
A: Type I—minimal displacement. B: Type II—hinged posteriorly. C: Type III—complete separation.
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Figure 30-2
Classification of tibial spine fractures.
A: Type I—minimal displacement. B: Type II—hinged posteriorly. C: Type III—complete separation.
A: Type I—minimal displacement. B: Type II—hinged posteriorly. C: Type III—complete separation.
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  1.  
    Type I—minimal displacement of the fragment from the rest of the proximal tibial epiphysis.
  2.  
    Type II—displacement of the anterior 1/3 to 1/2 of the avulsed fragment, which is lifted upward but remains hinged on its posterior border in contact with the proximal tibial epiphysis.
  3.  
    Type III—complete separation of the avulsed fragment from the proximal tibial epiphysis, with upward displacement and rotation.
Radiographs of these fracture types are shown in Figure 30-3. The interobserver reliability between type I and type II/III fractures is good; however, differentiation between type II and III fractures may be difficult.219 
Figure 30-3
Stages of displacement of tibial spine fractures.
 
A: Type I fracture, minimal displacement (open arrow). B: Type II fracture, posterior hinge intact. C: Type III fracture, complete displacement and proximal migration.
A: Type I fracture, minimal displacement (open arrow). B: Type II fracture, posterior hinge intact. C: Type III fracture, complete displacement and proximal migration.
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A: Type I fracture, minimal displacement (open arrow). B: Type II fracture, posterior hinge intact. C: Type III fracture, complete displacement and proximal migration.
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Figure 30-3
Stages of displacement of tibial spine fractures.
A: Type I fracture, minimal displacement (open arrow). B: Type II fracture, posterior hinge intact. C: Type III fracture, complete displacement and proximal migration.
A: Type I fracture, minimal displacement (open arrow). B: Type II fracture, posterior hinge intact. C: Type III fracture, complete displacement and proximal migration.
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A: Type I fracture, minimal displacement (open arrow). B: Type II fracture, posterior hinge intact. C: Type III fracture, complete displacement and proximal migration.
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Zaricznyj421 further classified a type IV fracture to describe comminution of the tibial eminence fragment. An alternative classification scheme more broadly classifies tibial spine fractures as one of several different types of proximal tibial fractures, based on mechanism of injury, but has not gained wide acceptance or use.288 

Outcome Measures for Fracture of the Tibial Spine (Intercondylar Eminence)

Although healing of the fracture on radiographs is important for decisions on timing of return to activities, the most important long-term outcome measures used to assess the results of tibial spine fracture fixation include functional knee scores, such as the Pedi-IKDC225 and Lysholm364 knee scores, and a patient's ability to make a full return to activities of daily life and sports activities, which can be assessed using the Marx or Tegner activity scores.264 Asymmetry in the Lachman examination is not uncommon,39,408 even after anatomic fixation of fractures, but has not been shown to correlate with symptomatic instability or long-term clinic results. 

Pathoanatomy and Applied Anatomy Relating to Fracture of the Tibial Spine (Intercondylar Eminence)

The intercondylar eminence is that part of the tibial plateau lying between the anterior poles of the menisci. It is triangular, with the base of the triangle running along the anterior border of the proximal tibia. In the immature skeleton, the proximal surface of the eminence is covered entirely with cartilage. The ACL attaches in the interspinous region of the eminence and just anteriorly to the tibial spines, with separate slips anteriorly and laterally as well (Fig. 30-4). The ligament originates off the posterior margin of the lateral aspect of the intercondylar notch. The anterior horn of the lateral meniscus is typically attached in the region of the tibial intercondylar eminence just adjacent to the ACL insertion. In 12 patients with displaced tibial spine fractures which did not reduce closed, Lowe et al.249 reported that the anterior horn of the lateral meniscus consistently remained attached to the tibial eminence fracture fragment. The posterior cruciate ligament (PCL) originates off the medial aspect of the intercondylar notch and inserts on the posterior aspect of the proximal tibia, distal to the joint line. 
Figure 30-4
Anterior cruciate ligament insertion on the tibial eminence.
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Meniscal or intermeniscal ligament entrapment under the displaced tibial eminence fragment has been reported and may be a rationale for considering arthroscopic or open reduction in displaced tibial spine fractures (Fig. 30-5).67,75,119,220 Meniscal entrapment prevents anatomic reduction of the tibial spine fragment, which may result in increase of a block to extension and/or eventual anterior laxity.151,187,272,311,408 Furthermore, meniscal entrapment itself may cause knee pain after fracture healing.75 Falstie-Jensen and Sondergard Petersen, Burstein et al., and Chandler and Miller67,75,119 have all reported cases of meniscal incarceration blocking reduction of type II or III tibial spine fractures in children. The prevalence of meniscal entrapment in tibial spine fractures may be common for displaced fractures. Although the anterior horn of the lateral meniscus may remain attached to the tibial eminence fracture fragment, it may instead remain attached to the intermeniscal ligament, generating a soft tissue complex that may become incarcerated between the elevated bony or cartilaginous fracture fragment and its underlying bony bed. Mah et al.255 found medial meniscal entrapment preventing reduction in 8 of 10 children with type III fractures undergoing arthroscopic management. In a consecutive series of 80 skeletally immature patients who underwent surgical fixation of hinged or displaced tibial eminence fractures which did not reduce in extension, Kocher et al.220 found entrapment of the anterior horn medial meniscus (n = 36), intermeniscal ligament (n = 6), or anterior horn lateral meniscus (n = 1) in 26% (6/23) of hinged (type II) fractures and 65% (37/57) of displaced (type III) fractures. The entrapped meniscus can typically be extracted with an arthroscopic probe and retracted with a retaining suture (Fig. 30-6). 
Figure 30-5
Meniscal entrapment under a tibial eminence fracture.
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Figure 30-6
Retraction of an entrapped anterior horn medial meniscus using a retaining suture.
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Treatment Options of Fractures of the Tibial Spine (Intercondylar Eminence)

Treatment options include cast immobilization,240,286 closed reduction with immobilization,311,409,410 open reduction with immobilization,286 open reduction with internal fixation,289,311 arthroscopic reduction with immobilization,271 arthroscopic reduction with suture fixation,171,196,240,255,256 or suture mattress technique,259 and arthroscopic reduction with wire,36 screw fixation,46,240 percutaneous K-wire fixation,131,161,170 anchor fixation,397 or bioabsorbable fixation.349,416 Studies of the biomechanical strength of internal fixation suggest similar fixation strength between bioabsorbable and metallic internal fixation257 and increased fixation strength of suture fixation over internal fixation,61,111 with advocates of both bioabsorbable implant fixation and suture techniques emphasizing the advantage of avoiding subsequent hardware removal procedures.259,416 

Nonoperative Treatment of Fracture of the Tibial Spine (Intercondylar Eminence)

Indications/Contraindications

Closed treatment is typically utilized for Type I fractures and for Type II or III fractures that successfully reduce with closed maneuvers (Table 30-1). 
 
Table 30-1
Fracture of the Tibial Spine (Intercondylar Eminence)
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Table 30-1
Fracture of the Tibial Spine (Intercondylar Eminence)
Nonoperative Treatment
Indications Relative Contraindications
Type I (nondisplaced) fractures Type III fractures
Anatomic reduction of type II (hinged) fractures Persistent/recurrent displacement of type II fractures
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Techniques

Closed reduction is usually performed with placement of the knee in full extension or 20 to 30 degrees of flexion. Aspiration of the intra-articular fracture hematoma, with or without the intra-articular injection of a short-acting local anesthetic, has historically been common practice prior to reduction, but is not required for a successful reduction and is performed less commonly today. Radiographs, most importantly the lateral view, are utilized to assess adequacy of reduction. If the proximal fracture fragment includes bony segments of the medial or lateral tibial plateau, extension may affect a reduction through pressure applied by medial or lateral femoral condyle (LFC) congruence (Fig. 30-7). Fractures confined within the intercondylar notch, however, are unlikely to reduce in this manner. Portions of the ACL are tight in all knee flexion positions; therefore there may not be any one position that eliminates the traction effect of the ACL on the fragment. Interposition of the anterior horn medial meniscus or intermeniscal ligament may further block reduction. 
Figure 30-7
Reduction of type II tibial fracture with knee in 10 to 20 degrees of flexion.
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Outcomes

Closed reduction can be successful for some type II fractures, but is infrequently successful in type III fractures. While Bakalim and Wilppula33 reported successful closed reduction in 10 patients, and Meyers and McKeever280 recommended cast immobilization with the knee in 20 degrees of flexion for all type I and II fractures, Kocher et al.220 reported successful closed reduction in only 50% of type II fractures (26/49). However, no type III fractures were able to be close reduced (0/57), in their series, and Meyers and McKeever280 similarly recommended open reduction or arthroscopic treatment for all type III fractures. Smillie362 suggested that closed reduction by hyperextension can be accomplished only with a large fragment. 

Operative Treatment of Fracture of the Tibial Spine (Intercondylar Eminence)

Indications/Contraindications

Arthroscopic or open reduction with internal fixation of three tibial eminence fractures and type II which do not reduce has been advocated for a variety of reasons, including concern over meniscal entrapment under the fractured tibial eminence preventing anatomic closed reduction,67,75,119,255 the potential for instability and loss of extension associated with closed reduction and immobilization,151,187,272,311 the ability to evaluate and treat associated intra-articular meniscal or osteochondral injuries with surgery, and the opportunity for early mobilization following fixation. For displaced fractures, Wiley and Baxter408 found a correlation between fracture displacement at healing with knee laxity and functional outcome. 

Arthroscopic Reduction and Internal Fixation with Epiphyseal Cannulated Screws

Preoperative Planning (Table 30-2
 
Table 30-2
Fracture of the Tibial Spine (Intercondylar Eminence)
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Table 30-2
Fracture of the Tibial Spine (Intercondylar Eminence)
Preoperative Planning Checklist—Screw Fixation
  •  
    OR table: Standard table with lateral thigh post
  •  
    Position/positioning aids: Supine
  •  
    Fluoroscopy location: From operative side, perpendicular to table
  •  
    Equipment: Knee arthroscopy setup, 3.5 or 4 mm cannulated screw system (partially threaded)
  •  
    Tourniquet (sterile/nonsterile): Nonsterile
X

Technique

General anesthesia is typically used. The patient is positioned supine on the operating room table. A lateral breakaway post is used. Alternatively, a circumferential post can be utilized. A standard arthroscope is used in most patients. A small (2.7 mm) arthroscope is used in younger children. An arthroscopic fluid pump is used at 35 Torr. A tourniquet is routinely used. Standard anteromedial and anterolateral portals are used. Prior to insertion of the arthroscope through the arthroscopic cannula in the anterolateral portal, the large hematoma should be evacuated, and use of up to 2 to 3 L of fluid for repetitive flushing of the joint prior to initiation of the diagnostic arthroscopy should be considered to optimize arthroscopic visualization. An accessory superomedial or superolateral portal can be later developed for guidewire and screw insertion. 
A thorough diagnostic arthroscopic examination of the patellofemoral joint, medial compartment, and lateral compartment are essential to evaluate for concomitant injuries. Usually, some anterior fat pad must be excised with an arthroscopic shaver for complete visualization of the intercondylar eminence fragment. Entrapped medial meniscus or intermeniscal ligament is extracted with an arthroscopic probe and retracted with a retention suture (Fig. 30-5). The base of the tibial eminence fragment is elevated (Fig. 30-8A) and the fracture bed debrided with an arthroscopic shaver or hand curette (Fig. 30-8B). Anatomic reduction is obtained using an arthroscopic probe or microfracture pick with the knee in 30 to 90 degrees of flexion (Fig. 30-8C). Cannulated guidewires can be placed through portals just off the superomedial or superolateral border of the patella, using a spinal needle to determine the optimal inferiorly directed vector for fracture fixation and taking care to avoid injury to the chondral surfaces adjacent to the intercondylar notch. The guidewires are placed into the intercondylar eminence at the base of the ACL. Fluoroscopic assistance is utilized to confirm anatomic reduction, to guide correct wire orientation, and to avoid guidewire protrusion across the proximal tibial physis. A cannulated drill is used over the guidewires, taking care to drill the entire depth of the proximal fragment, but avoiding plunging through the proximal tibial physis. One or two screws are placed, based on the size of the tibial eminence fragment (Fig. 30-8D). Partially threaded 3.5-mm diameter screws (Fig. 30-8E) are used in children and either 4- or 4.5-mm diameter screws are used in adolescents. The knee is brought through a range of motion (ROM) to ensure rigid fixation without fracture displacement and to evaluate for impingement of the screw head(s) in extension (Table 30-3). 
Figure 30-8
Arthroscopic reduction and cannulated screw internal fixation of a displaced tibial spine fracture.
 
A: Elevation of the tibial eminence fragment. B: Debridement of the fracture bed. C: Reduction of the tibial eminence. D: Drilling over the cannulated screw guidewire. E: Cannulated screw fixation.
A: Elevation of the tibial eminence fragment. B: Debridement of the fracture bed. C: Reduction of the tibial eminence. D: Drilling over the cannulated screw guidewire. E: Cannulated screw fixation.
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Figure 30-8
Arthroscopic reduction and cannulated screw internal fixation of a displaced tibial spine fracture.
A: Elevation of the tibial eminence fragment. B: Debridement of the fracture bed. C: Reduction of the tibial eminence. D: Drilling over the cannulated screw guidewire. E: Cannulated screw fixation.
A: Elevation of the tibial eminence fragment. B: Debridement of the fracture bed. C: Reduction of the tibial eminence. D: Drilling over the cannulated screw guidewire. E: Cannulated screw fixation.
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Table 30-3
Fracture of the Tibial Spine (Intercondylar Eminence)
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Table 30-3
Fracture of the Tibial Spine (Intercondylar Eminence)
Surgical Steps—Screw Fixation
  •  
    Flush hemarthrosis from knee prior to diagnostic arthroscopy
  •  
    Diagnostic arthroscopy (assess menisci)
  •  
    Debride fracture edges (underside of eminence fragment and underlying fracture bed) with motorized shaver and/or currette
  •  
    Reduce eminence fragment (retract intermeniscal ligament and/or meniscal anterior horn[s] if interposed) with tagging suture or probe through accessory transpatellar portal
  •  
    Maintain reduction with cannulated screw guidewire (appropriate vector usually requires start point medial or lateral to patella, not distal)
  •  
    Assess reduction and measure optimal guidewire length with fluoroscopy
  •  
    Advance screw over guidewire to achieve fixation (screw tip should be proximal to physis)
  •  
    Repeat guidewire/screw steps for second screw if required
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Arthroscopic Reduction and Internal Fixation with Suture

Preoperative Planning (Table 30-4). 
 
Table 30-4
Fracture of the Tibial Spine (Intercondylar Eminence)
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Table 30-4
Fracture of the Tibial Spine (Intercondylar Eminence)
Preoperative Planning Checklist—Suture Fixation
  •  
    OR table: Standard table with lateral thigh post
  •  
    Position/positioning aids: Supine
  •  
    Fluoroscopy: Optional
  •  
    Equipment: Knee arthroscopy setup, ACL tibial guide with <3-mm guidewire (but not reamer), suture passing devices (to advance through ACL at level of footprint and to retrieve through <3-mm tibial tunnels), repair suture (no. 2 size or greater)
  •  
    Tourniquet (sterile/nonsterile): Nonsterile
X

Technique

Arthroscopic setup and examination is similar to the technique described for epiphyseal screw fixation. Accessory superomedial and superolateral portals are not used, though an accessory transpatellar working portal may be considered to facilitate fracture reduction and suture management. The fracture is elevated (Fig. 30-9A) and the fracture base debrided (Fig. 30-9B). The fracture is reduced, and an optimal reduction may be provisionally maintained with a small K-wire directed inferiorly, though reduction of a previously entrapped intermeniscal ligament or anterior meniscal horn over the anterior aspect of the fragment often maintains the reduction adequately. Two superiorly directed guidewires, approximately 2.7 mm in size, are then placed using the tibial ACL guide system from a small incision made just medial to the tibial tubercle and distal to the proximal tibial physis. Care is taken to create separate starting points for the two guidewires, to ensure a cortical bone bridge for later suture tying, and to place the intra-articular exit points through either side of the base of the intercondylar eminence fragment (Fig. 30-9D) right along the fracture line. Either suture passing devices or small wire loops (smaller than 2.7 mm in diameter) are then placed up the guidewire tracts, either concomitantly or sequentially, to retrieve a suture, which has been passed through the base of the ACL using a suture punch (Fig. 30-9C) or another suture passer. These transtibial suture passers or retrievers then feed the sutures out through the inferior incision (Fig. 30-9E), and the sutures are tied down onto the tibia over the bony bridge (Fig. 30-9F), using arthroscopic assessment to confirm maintenance of the optimal reduction. The procedure is generally repeated for 1 to 2 additional sutures, so as to space the position of the “suture bridge” over a large segment of the ACL footprint and improve rotational stability of the fragment. Resorbable monofilament suture may be used, though we favor heavier nonabsorbable braided sutures, and there are no published reports of complications associated with growth disturbance secondary to the bony bridging or prolonged nonabsorbable suture retention through the small transtibial guidewire tracts (Table 30-5). 
Figure 30-9
Arthroscopic reduction and suture fixation of a displaced tibial spine fracture.
 
A: Elevation of the tibial eminence. B: Debridement of the fracture bed. C: Suture passing through the base of the ACL using a suture punch. D: Drilling of a tibial tunnel into the tibial eminence fragment using the ACL tibial guide. E: Retrieval of sutures using a suture passer. F: Appearance after suture fixation.
A: Elevation of the tibial eminence. B: Debridement of the fracture bed. C: Suture passing through the base of the ACL using a suture punch. D: Drilling of a tibial tunnel into the tibial eminence fragment using the ACL tibial guide. E: Retrieval of sutures using a suture passer. F: Appearance after suture fixation.
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A: Elevation of the tibial eminence. B: Debridement of the fracture bed. C: Suture passing through the base of the ACL using a suture punch. D: Drilling of a tibial tunnel into the tibial eminence fragment using the ACL tibial guide. E: Retrieval of sutures using a suture passer. F: Appearance after suture fixation.
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Figure 30-9
Arthroscopic reduction and suture fixation of a displaced tibial spine fracture.
A: Elevation of the tibial eminence. B: Debridement of the fracture bed. C: Suture passing through the base of the ACL using a suture punch. D: Drilling of a tibial tunnel into the tibial eminence fragment using the ACL tibial guide. E: Retrieval of sutures using a suture passer. F: Appearance after suture fixation.
A: Elevation of the tibial eminence. B: Debridement of the fracture bed. C: Suture passing through the base of the ACL using a suture punch. D: Drilling of a tibial tunnel into the tibial eminence fragment using the ACL tibial guide. E: Retrieval of sutures using a suture passer. F: Appearance after suture fixation.
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A: Elevation of the tibial eminence. B: Debridement of the fracture bed. C: Suture passing through the base of the ACL using a suture punch. D: Drilling of a tibial tunnel into the tibial eminence fragment using the ACL tibial guide. E: Retrieval of sutures using a suture passer. F: Appearance after suture fixation.
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Table 30-5
Fracture of the Tibial Spine (Intercondylar Eminence)
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Table 30-5
Fracture of the Tibial Spine (Intercondylar Eminence)
Surgical Steps—Suture Fixation
  •  
    Flush hemarthrosis from knee prior to diagnostic arthroscopy
  •  
    Diagnostic arthroscopy (assess menisci)
  •  
    Debride fracture edges (underside of eminence fragment and underlying fracture bed) with motorized shaver and/or currette
  •  
    Reduce eminence fragment (retract intermeniscal ligament and/or meniscal anterior horn[s] if interposed) with tagging suture or probe through accessory transpatellar portal
  •  
    Pass repair sutures through ACL at level of tibial footprint (one anterior, one posterior to maximize fixation/repair stability)
  •  
    Through proximal tibial incision, create tibial tunnels (<3 mm) with ACL guide/guidewire on either side of fragment with cortical bone bridge between tunnel starting points
  •  
    Pass trans-ACL sutures through tunnels
  •  
    Optimize reduction, tie sutures over bone bridge on maximum tension
X

Author's Preferred Treatment of Fracture of the Tibial Spine (Intercondylar Eminence)

The author's algorithm to decision making is shown in Figure 30-10. Type I fractures are treated with a locked hinged knee brace in an older child or adolescent or long-leg cast immobilization in a younger child, applied in full extension (0 degrees), to prevent loss of reduction and a flexion contracture, which is generally harder to treat than loss of flexion. The patient and family are cautioned to elevate the leg to avoid swelling. Radiographs are repeated in 1 to 2 weeks to ensure that the fragment has not displaced. The cast is removed 4 to 6 weeks after injury. A hinged knee brace is then used and physical therapy initiated to regain motion and strength. Patients are typically allowed to return to sports 3 to 4 months after injury if they demonstrate fracture healing and adequate motion and strength. 
Figure 30-10
Algorithm for the management of tibial eminence fractures in children.
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Type II fractures are usually treated with attempted closed reduction. Aspiration of hematoma and injection of local anesthetic under sterile conditions may be considered if the patient is in severe pain, but is not required for a successful reduction. Reduction is usually attempted at full extension, with radiographs taken to assess reduction, though if dynamic fluoroscopy is being used, assessment of reduction should also be performed at 20 degrees of flexion and casted in the optimal position. Follow-up radiographs are performed at 1 and 2 weeks postreduction to ensure maintenance of reduction. Length of casting and postcasting management is similar to type I fractures. If the fracture does not reduce anatomically or if the fracture later displaces, operative treatment should be performed to optimize outcomes. 
Type III fractures may be treated with attempted closed reduction; however this is usually unsuccessful, and we favor primary operative treatment in the absence of significant medical comorbidities or surgical contraindications. The author's preferred operative treatment is arthroscopic reduction and internal fixation. However, open reduction through a medial parapatellar incision can also be performed per surgeon preference/experience, or if arthroscopic visualization is difficult. The author's preferred fixation is epiphyseal cannulated screws if the fragment is large or suture fixation if the fragment is small or comminuted. 

Postoperative Care of Fracture of the Tibial Spine (Intercondylar Eminence)

Postoperatively, patients are placed in a postoperative hinged knee brace and maintained touch-down weight bearing for 6 weeks postoperatively. Motion is restricted to 0 to 30 degrees for the first 2 weeks, 0 to 60 degrees for the next 2 weeks, and then 0 to 90 for weeks 4 to 6, with full ROM after 6 weeks, provided early radiographic healing is seen. The brace is kept locked in extension at night for the first 6 weeks to prevent a flexion contracture. Radiographs are obtained at each postoperative visit to evaluate maintenance of reduction and fracture healing (Fig. 30-11). Cast immobilization for 4 weeks postoperatively may be considered in younger children if there is concern for inability to comply with protected weight bearing and brace immobilization. Early initiation of physical therapy is routinely utilized to optimize motion, strength, and sport-specific training. Patients are typically allowed to return to sports at 12 to 16 weeks postoperatively, depending on knee function. Screws are not routinely removed. Functional ACL bracing is utilized if there is residual knee laxity. 
Figure 30-11
Type III tibial spine fracture in an 11-year-old male child treated with arthroscopic reduction and 3.5-mm cannulated screw fixation.
 
Preoperative AP (A) and lateral (B) radiographs. Postoperative AP (C) and lateral (D) radiographs.
Preoperative AP (A) and lateral (B) radiographs. Postoperative AP (C) and lateral (D) radiographs.
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Preoperative AP (A) and lateral (B) radiographs. Postoperative AP (C) and lateral (D) radiographs.
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Figure 30-11
Type III tibial spine fracture in an 11-year-old male child treated with arthroscopic reduction and 3.5-mm cannulated screw fixation.
Preoperative AP (A) and lateral (B) radiographs. Postoperative AP (C) and lateral (D) radiographs.
Preoperative AP (A) and lateral (B) radiographs. Postoperative AP (C) and lateral (D) radiographs.
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Preoperative AP (A) and lateral (B) radiographs. Postoperative AP (C) and lateral (D) radiographs.
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Potential Pitfalls and Preventative Measures of Fracture of the Tibial Spine (Intercondylar Eminence)

In the closed management of tibial eminence fractures, follow-up radiographs must be obtained at 1 and 2 weeks postinjury to verify maintenance of reduction. Late displacement and malunion can occur, particularly for type II fractures. Though generally not necessary, aspiration of hemarthrosis and injection of local anesthetic under sterile conditions can occasionally be helpful to minimize pain and allow for full knee extension at the time of closed reduction. 
During arthroscopic reduction and fixation of tibial spine fractures, arthroscopic visualization can be difficult unless the large hematoma is evacuated and flushed prior to introduction of the arthroscope. Adequate inflow and outflow is essential for proper visualization. Careful attention to preparation of the fracture bed is important to provide optimal conditions for bony healing. Attempted epiphyseal cannulated screw fixation of small or comminuted tibial eminence fragments can fail as the screw may further comminute the fragment. In these cases, suture fixation is generally a better method. If epiphyseal cannulated screw fixation is used, fluoroscopy is necessary to ensure that the drill or screw does not traverse the proximal tibial physis, which may result in a proximal tibial physeal growth arrest. 
Early mobilization is helpful to avoid arthrofibrosis which can occur with immobilization. However, in younger children (less than 7 years old), compliance with protected weight bearing and brace use can be problematic (Table 30-6). 
 
Table 30-6
Fracture of the Tibial Spine (Intercondylar Eminence)
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Table 30-6
Fracture of the Tibial Spine (Intercondylar Eminence)
Potential Pitfalls and Preventions
Pitfall Preventions
Pitfall #1: Failure/loss of reduction of type II Prevention 1a: Ensure cast is in full extension
Prevention 1b: Obtain MRI if meniscal/intermeniscal interposition is suspected
Prevention 1c: Follow XRs closely (5–7 days and 12–14 days postreduction)
Pitfall #2: Inadequate visualization during arthroscopy Prevention 2: Before starting arthroscopy, flush hemarthrosis until arthroscopy fluid clear
Pitfall #3: Comminution of eminence fragments during attempted screw fixation (or upon initial assessment) Prevention 3: Utilize suture fixation instead of screw fixation
Pitfall #4: Growth disturbance with screw fixation Prevention 4: Multiple fluoroscopic views to ensure no physeal penetration
Pitfall #5: Postoperative arthrofibrosis Prevention 5: Ensure adequate fixation to allow early ROM
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Treatment-Specific Outcomes for Fracture of the Tibial Spine (Intercondylar Eminence)

The prognosis for closed treatment of nondisplaced and reduced tibial spine fractures and for operative treatment of displaced fractures is good. Most series report healing with an excellent functional outcome despite some residual knee laxity.36,39,46,196,215,240,255,256,271,272,286,289,365,387,408,410 Potential complications include nonunion, malunion, arthrofibrosis, residual knee laxity, and growth disturbance.36,39,46,196,215,240,255,256,271,272,286,289,365,391,408,410 
Mild residual knee laxity is seen frequently, even after anatomic reduction and healing of tibial eminence fractures. Baxter and Wiley39,408 found excellent functional results without symptomatic instability in 17 pediatric knees with displaced tibial spine fractures, despite a positive Lachman examination in 51% of patients and increased mean instrumented knee laxity of 3.5 mm. After ORIF of type III fractures in 13 pediatric knees, Smith365 identified patient-reported instability in only two patients, despite a positive Lachman examination in 87% of patients. In a group of 50 children after closed or open treatment, Willis et al.410 found excellent clinical results despite a positive Lachman examination in 64% of patients and instrumented knee laxity of 3.5 mm for type II fractures and 4.5 mm for type III fractures. Similarly, Janarv et al.187 and Kocher et al.215 found excellent functional results despite persistent laxity even in anatomically healed fractures. More recent long-term follow-up studies have replicated these findings.72,387 Despite four patients demonstrating signs, but no symptoms, of instability, Tudisco et al.387 recently reported good results in 13 of 14 knees followed for a mean of 29 years postinjury, with the one suboptimal result reported in a type III fracture treated nonoperatively. 
Persistent laxity despite anatomic reduction and healing of tibial spine fractures in children is likely related to plastic deformation of the collagenous fibers of the ACL occurring in association with tibial spine fracture. At the time of tibial spine fixation, the ACL often appears hemorrhagic within its sheath, but grossly intact and in continuity. In a primate animal model, Noyes et al.305 found frequent elongation and disruption of ligament architecture despite gross ligament continuity in experimentally produced tibial spine fractures at both slow and fast loading rates. This persistent anteroposterior laxity despite anatomic reduction may be avoided by countersinking the tibial spine fragment within the epiphysis at the time of reduction and fixation. However, ACL injury after previous tibial spine fracture is rare. 

Management of Expected Adverse Outcomes and Unexpected Complications in Fracture of the Tibial Spine (Intercondylar Eminence)

Poor results may occur after eminence fractures associated with unrecognized injuries of the collateral ligaments or complications from associated physeal fracture.278,365,376 In addition, hardware across the proximal tibial physis may result in growth disturbance with recurvatum deformity or shortening.290 
Malunion of type II and III fractures may cause mechanical impingement of the knee during full extension (Fig. 30-12).132,255,256 For symptomatic patients, this can be corrected by either osteotomy of the fragment and fixation in a more recessed, anatomic position or excision of the manumitted fragment with anatomic suture repair of the ACL to its bony footprint. Alternatively, excision of the fragment and ACL reconstruction can be considered in adults and older adolescents. 
Figure 30-12
Lateral radiograph of a malunited displaced fracture of the intercondylar eminence of the tibia with an extension block.
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Nonunion of type II and III tibial spine fractures treated closed can usually be managed by arthroscopic or open reduction with internal fixation.204,247,394 Technically, debridement of the fracture bed and the fracture fragment to fresh, bleeding bone is essential to optimize bony healing. Bone graft may be required in cases of chronic nonunion. Similarly to management of malunions described above, excision of the fragment and ACL reconstruction can alternatively be considered in adults and older adolescents, and may be preferable, given the increasingly favorable reports of outcomes of pediatric ACL reconstruction techniques. 
Stiffness and arthrofibrosis can be a challenging problem after both nonoperative and operative management of tibial eminence fractures. The milieu of a major traumatic intra-articular injury, a large hemarthrosis, and immobilization can predispose to arthrofibrosis. Vander Have et al. reported on 20 cases of arthrofibrosis out of 205 patients (10%) from four institutions over a 10-year period who had undergone surgical intervention for tibial spine fracture, as well as 12 additional cases referred from other institutions. Of the 32 total cases, 25 (78%) had been immobilized for 4 to 6 weeks postoperatively without motion, and 24 (75%) required additional operative treatment within 6 months to address debilitating loss of knee motion.391 The authors concluded that for fractures that undergo fixation, early mobilization utilizing physical therapy can minimize the risk of arthrofibrosis, an approach supported by subsequent analyses.318 If stiffness is detected, dynamic splinting and aggressive physical therapy can be employed during the first 3 months from fracture. If significant stiffness remains after 3 months from fracture, patients should be managed with manipulation under anesthesia, but only in conjunction with arthroscopic lyses of adhesions, an approach shown to be successful in resolving the stiffness in majority of cases.391 Overly vigorous manipulation should be avoided to avert iatrogenic proximal tibial or distal femoral physeal fracture, which may lead to growth arrest or deformity requiring further treatment (Table 30-7).391 
 
Table 30-7
Fracture of the Tibial Spine (Intercondylar Eminence)
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Table 30-7
Fracture of the Tibial Spine (Intercondylar Eminence)
Common Adverse Outcomes and Complications
Arthrofibrosis
Nonunion
Malunion
ACL laxity
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Introduction to Osteochondral Fractures

Osteochondral fractures in skeletally immature patients are more common than once thought. They are typically associated with acute lateral patellar dislocations. The most common locations for these fractures are the inferior aspect of the patellar median ridge, the inferior medial patellar facet, or the lateral aspect of the LFC (Fig. 30-13). The osteochondral fracture fragments may range from small incidental loose bodies to large portions of the articular surface. The prevalence of osteochondral fractures associated with acute patella dislocation ranges from 19% to 50%.15,54,120,266,297,302,371 Matelic et al.266 found 67% of one series of children presenting with an acute hemarthrosis of the knee were found to have an osteochondral fracture. 
Figure 30-13
A: Medial facet. B: Lateral femoral condyle.
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Figure 30-13
Osteochondral fractures associated with dislocation of the right patella.
A: Medial facet. B: Lateral femoral condyle.
A: Medial facet. B: Lateral femoral condyle.
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The diagnosis can be difficult to make because even a large osteochondral fragment may contain only a small ossified portion that is visible on plain radiographs. MRI has therefore emerged as having a critical role in identifying associated osteochondral fractures or chondral-only fragments in cases of traumatic patellar dislocation. Acute osteochondral fractures must be differentiated from acute chondral injuries, which do not involve subchondral bone, and osteochondritis dissecans (OCD),124,221 which is most often a repetitive overuse lesion of the subchondral bone, which may result in a nonhealing stress fracture that can progress to fragment dissection. 
Treatment of osteochondral fractures includes removal of small loose bodies and fixation of larger osteochondral fragments. In cases associated with patellar dislocation, lateral retinacular release, medial retinacular repair, medial patellofemoral ligament (MPFL) repair, or primary reconstruction may be performed adjunctively. 

Assessment of Osteochondral Fractures

Mechanisms of Injury for Osteochondral Fractures

There are two primary mechanisms for production of an osteochondral fracture.15,54,81,120,122,201,266,273,297,371 First, a direct blow to the knee with a shearing force applied to either the medial or LFC can create an osteochondral fracture. The second mechanism involves a flexion-rotation injury of the knee in which an internal rotation force is placed on a fixed foot, usually coupled with a strong quadriceps contraction. The subsequent contact between the tibia and femur or patella and LFC causes the fracture. This latter contact mechanism occurs during an acute patellar dislocation. When the patella dislocates laterally, the medial retinaculum and the associated medial MPFL tears, while the extensor mechanism still applies significant compressive forces as the patella shears across the LFC. The medial border of the patella then temporarily becomes impacted on the prominent edge of the LFC before it slides back tangentially over the surface of the LFC because of pull of the quadriceps. Either the dislocation or the relocation phase of this injury can cause an osteochondral fracture to the LFC, the medial facet of the patella, or both (Fig. 30-14). Interestingly, osteochondral fractures are uncommon with chronic, recurrent subluxation, or dislocation of the patella. In this situation, the laxity of the medial knee tissues and decreased compressive forces between the patella and the LFC prevent development of excessive shear forces. With more acute or traumatic dislocations, even if a frank osteochondral fracture does not occur, bone bruising is generally seen on MRI on both the patella and LFC, and chondral injuries, such as fissuring of the articular surface of the medial facet and median ridge, are also common.116,203,300,302 
Figure 30-14
Osteochondral fractures associated with dislocation of the patella.
 
A: Medial facet of patella. B: Lateral femoral condyle.
A: Medial facet of patella. B: Lateral femoral condyle.
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Figure 30-14
Osteochondral fractures associated with dislocation of the patella.
A: Medial facet of patella. B: Lateral femoral condyle.
A: Medial facet of patella. B: Lateral femoral condyle.
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Ahstrom10 reported on a series of 18 osteochondral fractures, 14 of which occurred during sports-related activities. Most patients give a history of a twisting injury consistent with acute patellar dislocation, but a few report a direct blow to the lateral or medial femoral condyle, accounting for a shear injury. The prevalence of osteochondral fractures associated with acute patella dislocation ranges from 19% to 50% in the literature.15,54,120,266,297,302,371 Nietosvaara et al.297 reported that of 69 acute patellar dislocations in children and adolescents, 62 (90%) of which occurred during or as a result of a fall, 39% had osteochondral fractures. 

Associated Injuries with Osteochondral Fractures

As described above, common injuries associated with osteochondral fractures caused by patellar dislocation include MPFL tear and bone bruises or impaction injuries to the LFC and medial aspect of the patella. Other osteochondral fractures may occur in association with severe cruciate or collateral ligament tears, as well as knee dislocation. 

Signs and Symptoms of Osteochondral Fractures

Acutely, osteochondral fractures present with severe pain, swelling, and difficulty in weight bearing.2,10,11,32,38,45,81,82,109,142,166,176,177,189,201,242,273,297,308,334,335,348,362,368,411,412 On examination, tenderness to palpation is often most severe over the medial patella and lateral aspect of the LFC, though medial femoral condylar tenderness may also be exhibited, either from a femoral-sided tear of the MPFL from the adductor tubercle region or because of a partial MCL sprain, which is not uncommon in association with patellar dislocation. The patient will usually resist attempts to flex or extend the knee and may hold the knee in 15 to 20 degrees of flexion for comfort. The large hemarthrosis is due to an intra-articular fracture of the highly vascular subchondral bone. Joint aspiration may reveal fatty globules or a supernatant layer of fat if allowed to stand for 15 minutes indicating an intra-articular fracture. Similarly, fluid–fluid levels may be seen on MRI, from the separation of fat and blood. Late examination findings may be similar to those of a loose body with intermittent locking or catching of the knee. 

Imaging and Other Diagnostic Studies for Osteochondral Fractures

Radiographic assessment of a possible osteochondral fracture should begin with anteroposterior, lateral, and skyline plain radiographs. However, a roentgenographic diagnosis can be difficult because even a large osteochondral fragment may contain only a small ossified portion that is visible on plain radiographs. A tunnel view may help locate a fragment in the region of the intercondylar notch. Because the osteochondral fragment may be difficult to see on plain radiographs, radiographs should be carefully assessed for even the smallest ossified fragment (Fig. 30-15). 
Figure 30-15
Osteochondral fracture of lateral femoral condyle after patellar dislocation.
 
A: Fragment seen in lateral joint space. B: Lateral view.
A: Fragment seen in lateral joint space. B: Lateral view.
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Figure 30-15
Osteochondral fracture of lateral femoral condyle after patellar dislocation.
A: Fragment seen in lateral joint space. B: Lateral view.
A: Fragment seen in lateral joint space. B: Lateral view.
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Matelic et al.266 report that standard radiographs failed to identify the osteochondral fracture in 36% of children who had an osteochondral fracture found during arthroscopy. For this reason, MRI is recommended in most cases, due to the importance of identifying a possible osteochondral fracture despite negative radiographs60,214,406 or a large chondral fragment. Such cases usually occur in the setting of an acute traumatic patellar dislocation in a patient with a large hemarthrosis, whereas ligamentously lax patients with chronic, recurrent, atraumatic patellar instability are less likely to sustain osteochondral fractures. A high-riding patella may also have a protective effect against associated intra-articular osteochondral fractures. Patients with an Insall index > 1.3 have a decreased chance of sustaining an osteochondral fracture compared with patients who have an Insall index within normal limits.60 An arthrogram effect is usually present during MRI, given the large hemarthrosis. 

Classification of Osteochondral Fractures

The classification of osteochondral fractures of the knee is based on the site, the type, and the mechanism of injury. The classification outlined in Table 30-8 is based on the descriptions of osteochondral fractures by Kennedy201 and Smillie.362 
 
Table 30-8
Mechanism of Osteochondral Fractures
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Table 30-8
Mechanism of Osteochondral Fractures
Site Mechanism
Medial femoral condyle Direct blow (fall)
Compression and rotation (tibiofemoral)
Lateral condyle Direct blow (kick)
Compression and rotation (tibiofemoral)
Acute patellar dislocation
Patella (medial margin) Acute patellar dislocation
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Outcome Measures for Osteochondral Fractures

Healing of osteochondral fractures must be followed closely with radiographs, as healing is the most important predictor of outcome. Once healed, standard outcome measures, such as functional knee metrics (the Pedi-IKDC225 and Lysholm364 knee scores), can be used to assess the results and, paired with the Marx or Tegner activity scores,264 ascertain a patient's ability to make a full return to activities of daily life and sports activities. 

Pathoanatomy and Applied Anatomy Relating to Osteochondral Fractures

The patella tracks in the trochlear groove between the medial and LFCs during flexion and extension of the knee.142,177 With increasing knee flexion, the contact area on the articular surface of the patella moves from the distal to the proximal aspect of the articular surface of the patella. Between 90 and 135 degrees of flexion, the patella glides into the intercondylar notch between the femoral condyles. The two primary areas of contact are the medial patellar facet with the medial femoral condyle and the superolateral quadrant of the lateral patellar facet with the LFC. Soft tissue support for the patellofemoral joint includes the quadriceps muscle, the MPFL, the patellar tendon, and the vastus medialis and lateralis muscles. 
Dislocation of the patella may tear the medial retinaculum and MPFL, but the rest of the quadriceps muscle–patellar ligament complex continues to apply significant compression forces as the patella dislocates laterally. These forces are believed to cause fracture of the medial patellar facet, the LFC articular rim, or both (Fig. 30-13).200,201,305,306,308,332,333,335 Osteochondral fractures are uncommon with chronic recurrent subluxation or dislocation of the patella because of relative laxity of the medial retinaculum and lesser compressive forces on the patella and the LFC. 
A histopathologic study by Flachsmann et al.122 helps to explain the occurrence of osteochondral fractures in the skeletally immature at an ultrastructural level. They noted that in the joint of a juvenile, interdigitating fingers of uncalcified cartilage penetrate deep into the subchondral bone providing a relatively strong bond between the articular cartilage and the subchondral bone. In the adult, the articular cartilage is bonded to the subchondral bone by the well-defined calcified cartilage layer, the cement line. When shear stress is applied to the juvenile joint, the forces are transmitted into the subchondral bone by the interdigitating cartilage with the resultant bending forces causing the open pore structure of the trabecular bone to fail. In mature tissue, the plane of failure occurs between the deep and calcified layers of the cartilage, the tidemark, leaving the osteochondral junction undisturbed. Although the juvenile and adult tissue patterns are different, they both provide adequate fracture toughness to the osteochondral region. As the tissue transitions, however, from the juvenile to the adult pattern during adolescence, the fracture toughness is lost. The calcified cartilage layer is only partially formed and the interdigitating cartilage fingers are progressively replaced with calcified matrix. Consequently, the interface between the articular cartilage and the subchondral bone becomes a zone of potential weakness in the joint which may explain why osteochondral fractures are seen frequently in adolescents and young adults. 

Treatment Options for Osteochondral Fractures

Nonoperative Treatment of Osteochondral Fractures

Nonoperative treatment of osteochondral fractures is reserved for small fragments, 5 mm or less, that have failed to cause or are unlikely to cause symptoms associated with loose body fragments. Every osteochondral fracture and the injury through which it occurred are different, but treatment should be individualized, to some degree, based on a patient's age and activity level. However, as general principles, the larger the fragment, the more bone attached a given fragment, and the more central the weight-bearing zone from which the fragment was detached, the more consideration should be given to attempted refixation. 

Operative Treatment of Osteochondral Fractures

Indications/Contraindications and Surgical Procedure

The recommended management of acute osteochondral fractures of the knee is either surgical removal of the fragment or fixation of the fragment, depending on its size and the quality of the tissue.213,220 In patients with an osteochondral fracture after acute patellar dislocation, concomitant repair of the medial retinaculum and MPFL, either at the patellar or femoral insertion sites of the ligament, or through an intrasubstance imbrications, at the time of fragment excision or fixation, may decrease the risk of recurrent patellar instability,7,70,82,334 though there is conflicting evidence whether this repair improves the ultimate redislocation rate.78,298,299,314 

Fixation

If the lesion is large (≥5 mm), easily accessible, involves a weight-bearing area, and has adequate cortical bone attached to the chondral surface then fixation should be considered.45,201,362,368,411,412 
Preoperative Planning (Table 30-9
 
Table 30-9
Fixation of Osteochondral Fractures
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Table 30-9
Fixation of Osteochondral Fractures
Preoperative Planning Checklist
  •  
    OR table: If fluoroscopy planned, radiolucent table
  •  
    Position/positioning aids: Supine
  •  
    Fluoroscopy location: Nonoperative side, perpendicular to table
  •  
    Equipment: Small K-wires, bioabsorbable pins/tacks/screws, headless compression screws
  •  
    Tourniquet (sterile/nonsterile): Nonsterile
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Surgical Approach and Technique

Fixation can be performed via arthroscopy or arthrotomy. Fixation options include K-wires, Steinmann pins, cannulated or solid metal screws, variable pitch headless screws, or bioabsorbable pins,76,138,401 tacks, or screws, which have recently increased in popularity and have the advantage of not requiring implant removal.103 For nonbioabsorbable implants, hardware removal is typically performed after fracture healing, though headless compression screws may be buried beneath the superficial level of the cartilage and may be retained.242 Traditionally, fixation of chondral fragments with no bone attached was not considered amenable to refixation, because of concerns regarding poor healing capacity. However, new reports have suggested that large chondral-only fragments may be able to heal in children or adolescents if early refixation is pursued (Table 30-10).291,388 
 
Table 30-10
Fixation of Osteochondral Fractures
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Table 30-10
Fixation of Osteochondral Fractures
Surgical Steps
  •  
    Diagnostic arthroscopy to retrieve loose body, assess viability, and assess fracture bed and feasibility of fixation
  •  
    If optimal fixation is achievable through arthroscopic means (rare), skip below arthrotomy step
  •  
    Arthrotomy (medial parapatellar or lateral parapatellar) to optimize access to fracture bed; if patellar, make long enough to ensure adequate inversion of patella
  •  
    Debride/prepare fracture bed and fragment
  •  
    Reduce fragment, provisionally fix with small K-wire
  •  
    Fixation with bioabsorbable pins/tacks/screws or headless metal compression screws (reserved for larger fragments with adequate bone)
  •  
    Repair arthrotomy (taking care not to overtension to avoid increasing patellofemoral contact forces)
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Removal of Fragment(s)

If the fracture fragment is small (<5 mm), chronic, or has fractured from a non–weight-bearing region of the knee, then removal of loose bodies is recommended.11,176,189,238,335,348 The fragment's crater should be debrided to stable edges and the underlying subchondral bone should be perforated through marrow stimulation techniques to encourage fibrocartilage formation.238 

Author's Preferred Treatment of Osteochondral Fractures

The author's algorithm to decision making is shown in Figure 30-16. In patients with an acute, traumatic patellar dislocation with a large hemarthrosis, MRI is performed, even if initial radiographs do not clearly show any associated osteochondral fracture. If MRI does not reveal any associated osteochondral fracture or any large chondral fragments, these patients are treated with a brief (1 to 2 weeks) period with a hinged knee brace locked in extension for ambulation with crutches for comfort and weight bearing and ROM as tolerated, followed by use of a soft, lateral-stabilizing patellofemoral brace and physical therapy emphasizing patellar mobilization, straight leg raises, progressive resistance exercises, and vastus medialis obliquus (VMO) strengthening. Routine diagnostic arthroscopy and MPFL repair are not performed on initial patellofemoral dislocators. Patients are allowed to return to sports 6 to 12 weeks after dislocation depending on their progress with rehabilitation, with use of the lateral-stabilizing brace during sports recommended for those who feel it helps limit pain or apprehension. 
Figure 30-16
Algorithm for the management of osteochondral fracture in children.
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Patients with small (≤5 mm) osteochondral fractures or chondral shear fragments, chronic loose bodies, and fractures involving non–weight-bearing areas are treated with arthroscopic removal of loose bodies. Occasionally, a patient may be seen more than 4 weeks following the initial injury with radiologic evidence of a small loose body but no symptoms; in such instances, arthroscopy may be deferred unless the patient develops any mechanical symptoms. If arthroscopy is pursued for a small osteochondral fracture, the fragment's crater is debrided to stable edges to prevent further loose bodies and the underlying subchondral bone should be perforated with marrow stimulation techniques, such as microfracture, to encourage fibrocartilage formation. Lateral retinacular release with medial retinacular/patellofemoral ligament repair is performed adjunctively in cases of traumatic patellofemoral dislocation to decrease the risk of recurrent patellofemoral instability. 
Repair may be performed with one or two suture anchors on either the patellar or femoral insertion sites if the site of the tear is clearly appreciated on MRI or intraoperatively. Alternatively, imbrication, a pants-over-vest advancement, or removal of a small elliptical segment of retinacular tissue followed by side-to-side repair are all effective options for an intrasubstance MPFL tear or diffuse attenuation of the retinacular tissue. 
Patients with large (>5 mm) osteochondral fractures, and chondral fragments which involve weight-bearing areas in good condition in skeletally immature patients, are treated with fragment fixation. At times, the fragments can be very large, involving nearly the entire weight-bearing surface of the medial patellar facet (Fig. 30-17) or LFC (Fig. 30-18). Medial patellar facet osteochondral fractures can be fixed through an open lateral retinacular release by manually tilting the patella (Fig. 30-17) or a medial parapatellar arthrotomy, which allows for tensioning of the medial retinacular repair during closure. LFC osteochondral fractures typically require a lateral parapatellar arthrotomy for fragment fixation (Fig. 30-18). Z-knee retractors are helpful for exposure and the knee is flexed or extended to optimize visualization of the fracture bed. The osteochondral fracture fragment and the fracture bed are debrided of fibrous tissue to healthy bone. The fragment is replaced anatomically. Countersunk cannulated screws (3, 3.5, or 4.5 mm) or Herbert screws are often preferable for fixation, compared to bioabsorbable tacks, because of the strength of fixation which allows for fragment compression and early mobilization. Because chondral-only fragments will have no subchondral bone upon which to compress metal screws, bioabsorbable tacks are favored. Lateral retinacular release with medial retinacular/patellofemoral ligament repair is often performed adjunctively in cases of traumatic patellofemoral dislocation to decrease the risk of recurrent patellofemoral instability. 
Figure 30-17
Fixation of a medial patellar facet osteochondral fracture in an adolescent male athlete.
 
A: Skyline radiograph demonstrating a fracture of the medial patellar facet with the fragment in the lateral recess. B: Axial MRI demonstrating medial facet fracture and loose fragment. C: Arthroscopic view of osteochondral fragment in the lateral recess. D: Open view of patella. E: Open view of osteochondral fragment. F: Open view of reduction and cannulated screw fixation of medial patellar facet. G: Intraoperative lateral radiograph after fracture fixation. H: Lateral radiograph 3 months after fracture fixation and 6 weeks after screw removal demonstrating healing.
A: Skyline radiograph demonstrating a fracture of the medial patellar facet with the fragment in the lateral recess. B: Axial MRI demonstrating medial facet fracture and loose fragment. C: Arthroscopic view of osteochondral fragment in the lateral recess. D: Open view of patella. E: Open view of osteochondral fragment. F: Open view of reduction and cannulated screw fixation of medial patellar facet. G: Intraoperative lateral radiograph after fracture fixation. H: Lateral radiograph 3 months after fracture fixation and 6 weeks after screw removal demonstrating healing.
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A: Skyline radiograph demonstrating a fracture of the medial patellar facet with the fragment in the lateral recess. B: Axial MRI demonstrating medial facet fracture and loose fragment. C: Arthroscopic view of osteochondral fragment in the lateral recess. D: Open view of patella. E: Open view of osteochondral fragment. F: Open view of reduction and cannulated screw fixation of medial patellar facet. G: Intraoperative lateral radiograph after fracture fixation. H: Lateral radiograph 3 months after fracture fixation and 6 weeks after screw removal demonstrating healing.
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Figure 30-17
Fixation of a medial patellar facet osteochondral fracture in an adolescent male athlete.
A: Skyline radiograph demonstrating a fracture of the medial patellar facet with the fragment in the lateral recess. B: Axial MRI demonstrating medial facet fracture and loose fragment. C: Arthroscopic view of osteochondral fragment in the lateral recess. D: Open view of patella. E: Open view of osteochondral fragment. F: Open view of reduction and cannulated screw fixation of medial patellar facet. G: Intraoperative lateral radiograph after fracture fixation. H: Lateral radiograph 3 months after fracture fixation and 6 weeks after screw removal demonstrating healing.
A: Skyline radiograph demonstrating a fracture of the medial patellar facet with the fragment in the lateral recess. B: Axial MRI demonstrating medial facet fracture and loose fragment. C: Arthroscopic view of osteochondral fragment in the lateral recess. D: Open view of patella. E: Open view of osteochondral fragment. F: Open view of reduction and cannulated screw fixation of medial patellar facet. G: Intraoperative lateral radiograph after fracture fixation. H: Lateral radiograph 3 months after fracture fixation and 6 weeks after screw removal demonstrating healing.
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A: Skyline radiograph demonstrating a fracture of the medial patellar facet with the fragment in the lateral recess. B: Axial MRI demonstrating medial facet fracture and loose fragment. C: Arthroscopic view of osteochondral fragment in the lateral recess. D: Open view of patella. E: Open view of osteochondral fragment. F: Open view of reduction and cannulated screw fixation of medial patellar facet. G: Intraoperative lateral radiograph after fracture fixation. H: Lateral radiograph 3 months after fracture fixation and 6 weeks after screw removal demonstrating healing.
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Figure 30-18
Fixation of a lateral femoral condyle osteochondral fracture in an adolescent female athlete.
 
A: Arthroscopic view of the lateral femoral condyle. B: Open view of the fracture fragment. C: Open view of fracture fixation using cannulated screws through a limited lateral arthrotomy. D: Six weeks postoperative lateral radiograph demonstrating fracture healing. E: Arthroscopic appearance at the time of screw removal 6 weeks postoperatively.
A: Arthroscopic view of the lateral femoral condyle. B: Open view of the fracture fragment. C: Open view of fracture fixation using cannulated screws through a limited lateral arthrotomy. D: Six weeks postoperative lateral radiograph demonstrating fracture healing. E: Arthroscopic appearance at the time of screw removal 6 weeks postoperatively.
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Figure 30-18
Fixation of a lateral femoral condyle osteochondral fracture in an adolescent female athlete.
A: Arthroscopic view of the lateral femoral condyle. B: Open view of the fracture fragment. C: Open view of fracture fixation using cannulated screws through a limited lateral arthrotomy. D: Six weeks postoperative lateral radiograph demonstrating fracture healing. E: Arthroscopic appearance at the time of screw removal 6 weeks postoperatively.
A: Arthroscopic view of the lateral femoral condyle. B: Open view of the fracture fragment. C: Open view of fracture fixation using cannulated screws through a limited lateral arthrotomy. D: Six weeks postoperative lateral radiograph demonstrating fracture healing. E: Arthroscopic appearance at the time of screw removal 6 weeks postoperatively.
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Postoperative Care for Osteochondral Fractures

Postoperatively, patients treated by excision of the fragment can begin ROM exercises immediately. Crutches may be necessary in the immediate postoperative period but patients can progress to weight bearing as tolerated. 
After osteochondral or chondral fragment fixation, patients are treated with touch-down weight bearing in a postoperative brace until fracture healing. ROM when not weight bearing is allowed from 0 to 30 degrees for the first 2 weeks, followed by 0 to 90 degrees until fracture healing. The fracture is typically healed between 6 and 12 weeks postoperatively, and confirmation with follow-up MRI may be utilized. If metal screw fixation was utilized, arthroscopy is performed to confirm fragment healing, remove hardware, and assess the integrity of the articular surface. Return to athletic activities is permitted when full ROM is recovered and strength is symmetric. 

Potential Pitfalls and Preventative Measures of Osteochondral Fractures

An important pitfall to avoid is the failure to diagnose osteochondral fractures associated with acute, traumatic patellar dislocations. Radiographs should be scrutinized for small osseous fragments, and MRI should be obtained in cases despite negative radiographs with a clinical suspicion for possible osteochondral fracture. 
In cases of arthroscopic removal of loose bodies associated with acute, traumatic patellar dislocation, consideration should be given to repair of the medial structures (medial retinaculum and MPFL) to decrease the risk of recurrent patellar instability, but with care taken not to overtension the medial tissues, so as not to excessively increase patellofemoral contact forces.384 
In cases of osteochondral fracture fixation, adequate internal fixation must be obtained to allow for early motion. Screw heads must be countersunk or headless, variable pitch screws may be used to avoid scuffing of articular surfaces. When chondral-only fixation is pursued with bioabsorbable tacks, care must be taken to partially countersink the smooth heads below the articular surface without fissuring through the cartilage completely. Moreover, close postoperative clinical monitoring of crepitus, swelling, or new pain must be maintained, with consideration of serial MR imaging if necessary, because of risk of potential back out of the implants not seen on radiographs. In children or adolescents with growth remaining, care must also be taken to prevent crossing the distal femoral physis with hardware (Table 30-11). 
 
Table 30-11
Osteochondral Fractures
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Table 30-11
Osteochondral Fractures
Potential Pitfalls and Preventions
Pitfall Preventions
Pitfall no. 1: Further fragmentation of fracture fragment Prevention 1a: Extend portal incisions adequately for removal
Prevention 1b: Arthroscopically position fragment in gutter/anterior recess near arthrotomy site; retrieve only after full arthrotomy
Pitfall no. 2: Fragment does not fit in bed Prevention 2a: Plan surgery for <7 days postinjury to prevent swelling of fragment
Prevention 2b: Trim fragment cartilage to fit bed
Pitfall no. 3: Inadequate fixation Prevention 3: Achieve at least two points of fixation for rotational stability
Pitfall no. 4: Growth disruption Prevention 4: In skeletally immature patients, implants should be short enough to avoid physeal trauma during fixation
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Treatment-specific Outcomes of Osteochondral Fractures

Osteochondral fractures with small fragments not involving the weight-bearing portion of the joint usually has a good prognosis after removal of loose bodies. The prognosis for larger osteochondral fractures involving the weight-bearing surfaces is more variable.138,345 Excision of large fragments involving the weight-bearing articular surfaces predictably leads to the development of degenerative changes.20 Fracture fixation resulting in fragment healing with a congruous articular surface offers the best long-term prognosis; however even these cases may develop crepitus, stiffness, and degenerative changes.10 Recently reported results of chondral-only fragment fixation have been favorable, but only small series or case reports with short-term follow-up have emerged.291,388 

Management of Expected Adverse Outcomes and Unexpected Complications in Osteochondral Fractures

Among the most common and concerning complications after both excision of loose bodies and fracture fixation is recurrent patellar instability with the possibility of further osteochondral injury. Although studies have suggested that concomitant MPFL repair decreases the risk of recurrent instability,38,334 this concept remains controversial.70,78,298,299,314 Stiffness is also a common complication following patellofemoral dislocation, particularly after fracture fixation. Adequate internal fixation is necessary to allow for early motion, which decreases the risk of arthrofibrosis. Stiffness may be treated with aggressive therapy and dynamic splinting during the first 3 to 4 months after injury. Beyond this time frame, arthroscopic lysis of adhesions and manipulation under anesthesia is typically required, with care taken to avoid distal femoral physeal injury through excessive manipulation in skeletally immature patients. Nonunion after fragment fixation may also occur, necessitating further attempts at fracture fixation or fracture excision. Excision of larger osteochondral fractures involving the weight-bearing articular surfaces requires associated chondral resurfacing, such as marrow stimulation procedures (microfracture), osteochondral grafting (mosaicplasty), or autologous chondrocyte implantation,44,48,321,372 all of which may be more technically challenging, with somewhat less optimal outcomes, when performed for the patellofemoral joint, compared with the tibiofemoral articular surfaces.121,139,165,258,382 Complications related to hardware for fracture fixation may also occur. Proud screw heads may scuff articular surfaces. Prior to reabsorption, bioabsorbable implants may also scuff the cartilage, and over time may be associated with reactive synovitis, sterile effusions, or fragmentation (Table 30-12). 
 
Table 30-12
Osteochondral Fractures
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Table 30-12
Osteochondral Fractures
Common Adverse Outcomes and Complications
Arthrofibrosis
Loss of fixation/nonunion
Osteoarthritis/focal chondral degeneration
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Introduction to Patellar Dislocation

Compared with other dislocation and subluxation injuries that occur in children, patellar instability is relatively common. Patellar instability involves cases ranging from acute, traumatic patellar dislocation to chronic, recurrent patellar subluxation in a patient with ligamentous laxity. 
Acute, traumatic patellar dislocation occurs more commonly in adolescents than other age groups, with the peak age being 15 to 19 years old.404 Acute patellar dislocations in younger children usually occur in the context of underlying patellofemoral dysplasia.273 Chronic, atraumatic, recurrent patellofemoral instability occurs most frequently in adolescent females, often with underlying laxity and risk factors related to abnormal coronal and rotational lower extremity alignment, such as genu valgum, femoral anteversion, and external tibial torsion. Despite this subpopulation, in terms of the overall epidemiology of patellar dislocation, sex has recently been shown not to be a risk factor.404 Approximately half of all dislocations occur during athletic activity, with basketball, soccer, and football as the most common sports involved.404 
Acute, traumatic patellar dislocations without associated osteochondral fracture are primarily treated with a short period of immobilization followed by patellofemoral bracing and rehabilitation. Acute, traumatic patellar dislocations with osteochondral fractures are treated as discussed in the previous section, with removal of loose bodies or fracture fixation. Chronic, recurrent, atraumatic patellofemoral instability is typically treated with patellofemoral bracing, rehabilitation, and orthotics if needed. Recurrent patellofemoral instability which has been recalcitrant to nonoperative treatment can be managed with a variety of proximal and distal realignment procedures. 

Assessment of Patellar Dislocation

Mechanisms of Injury for Patellar Dislocation

Patellar dislocations usually occur because of a flexion-rotation injury of the knee in which an internal rotation force is placed on a fixed foot, usually coupled with a strong quadriceps contraction. As the patella dislocates, the medial retinaculum and MPFL tear but the remaining quadriceps muscle–patellar ligament complex still applies significant compressive forces as the patella dislocates laterally and slides across the LFC. This primary injury mechanism, or the subsequent reduction of the patella medially back over the lateral edge of the lateral condyle, may result in associated osteochondral fracture. Recent MRI evidence suggests a predictable constellation of findings in conjunction with patellar dislocation: MPFL injury either at the femoral attachment site, patellar site, or both; VMO edema in most patients; and osteochondral fracture in about one-third of patients, most of which shear off of the medial patellar facet, but more rarely may be from the LFC.346 Reduction of the patella may occur spontaneously as the patient simply extends the knee after a fall or may require forced manual reduction, often with the need for sedation to allow for quadriceps muscle relaxation. 
Less commonly, patellar dislocation can be caused by a direct blow to the medial aspect of the patella. Larsen and Lauridsen233 found that a direct blow accounted for only 10% of the acute patellar dislocations in one series. Patellar dislocations are more likely to be caused by falls, or during the course of gymnastics, dancing, cheerleading, cutting, and pivoting sports. Along with cruciate or collateral ligament tear and meniscal injury, acute patellar dislocation should be considered in the evaluation of all knee injuries in adolescents and young adults. 

Associated Injuries with Patellar Dislocation

Common injuries associated with patellar dislocation include MPFL tear and bone bruises, impaction injuries, or osteochondral fractures to the lateral aspect of the LFC and medial facet or median ridge of the patella. 

Signs and Symptoms of Patellar Dislocation

Patients with an acute, traumatic patellar dislocation often give a history of a twisting injury. Patients may remember feeling or seeing the patella in a laterally displaced position. Most acute patellar dislocations spontaneously reduce or reduce with incidental knee extension. It is more unusual to see a patient with a patellar dislocation which is unreduced (Fig. 30-19). Patients may report a “pop” associated with dislocation and a second “pop” associated with spontaneous reduction. 
Figure 30-19
Acute dislocation of the left patella in a 6-year-old boy.
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Symptoms include diffuse parapatellar tenderness and pain with any attempt passively to displace the patella. Patients may have a positive lateral apprehension test with lateral translation of the patella. A defect may be palpable in the medial attachment of the VMO to the patella if the medial retinaculum is completely avulsed. Although often difficult to differentiate from diffuse tenderness throughout a swollen knee joint, the sites of greatest focal tenderness usually include the medial aspect of the patella (either from a chondral or bony contusion), the medial epicondyle (due to tearing of the femoral attachment of the MPFL), and lateral aspect of the LFC just proximal to the joint line (due to bony contusion). Hemorrhage into the joint may cause hemarthrosis, and severe hemarthrosis should suggest the possibility of an osteochondral fracture.334 Nietosvaara et al.297 reported that of 72 patients with acute patellar dislocations, 28 (39%) had associated osteochondral fractures. These fractures included 15 capsular avulsions of the medial patellar margin and 15 loose intra-articular fragments detached from the patella, the LFC, or both. All knee ligaments should be carefully evaluated because the mechanism of patellar dislocation may cause associated ligamentous injuries, such as ACL or MCL tear. 

Imaging and Other Diagnostic Studies for Patellar Dislocation

Radiographs after acute dislocation are obtained primarily to detect any associated osteochondral fracture. Occasionally, an osteochondral fragment from the medial aspect of the patella or the LFC is visible on the anteroposterior or lateral view. A “patellar,” “skyline,” or “sunrise” view is difficult to obtain in a child after acute dislocation because the required flexed positioning of the knee causes pain, but should be attempted if possible. In a recent report, the “sliver sign,” an intra-articular linear or curvilinear ossific density representing an osteochondral fragment, was seen on 19% of 219 cases of patellar dislocation, eight of which were visible on a patellar view only.155 Rarely, stress radiographs may be obtained for evaluation of suspected physeal fracture or ligamentous injury. In the setting of an acute patellar dislocation or recurrent dislocation with severe knee swelling, MRI has emerged as the gold standard of radiologic evaluation, because of its ability to detect the constellation of injuries associated with patellar dislocations, such as chondral shear injuries, cruciate or collateral ligament tears, and severe disruption of the medial retinaculum and MPFL. Moreover, the three-dimensional axial imaging of MRI allows for optimal assessment and quantification of the severity of potential risk factors for recurrence, such as patellar dysplasia (e.g., Wiberg classification),293 trochlear dysplasia (e.g., Dejour classification),26,95,322,386 patella alta (e.g., Salvatti–Insall ratio or Blackburne–Peel ratio),181,182 lateral patellar displacement (e.g., congruence angle),277 patellar tilt (e.g., lateral patellofemoral angle),235 and femorotibial alignment at the level of the knee joint (e.g., tibial tubercle-trochlear groove distance [TT-TG]).34,35,144 In patients assessed to have significant femoral anteversion or abnormal tibial torsion, use of newer MRI-sequencing protocols which additionally incorporate several slices of both the femoral neck and distal tibia in the scout views may be helpful for a formal version analysis to understand if an abnormal femoral and/or tibial rotational profile represents a contributing etiologic factor in the dislocation that may benefit from specific surgical procedures, such as derotational osteotomy. 

Classification of Patellar Dislocation

Although there is no specific classification of patellar dislocations in children, acute dislocation should be distinguished clinically from chronic patellar subluxation or dislocation63,104,127,140 and from congenital patellar dislocation, which is generally not a cause of intra-articular fractures. Whereas acute patellar dislocation is more commonly associated with trauma or severe twisting injuries of the knee, chronic patellar subluxation is associated with lower energy mechanisms, is more common in children with ligamentous laxity or hypermobility syndromes, and has a lower frequency of significant intra-articular knee injuries. Although medial patellar dislocation or subluxation is exceedingly rare, it has been described in association with a medially directed direct blow or following overzealous lateral release.175 

Outcome Measures for Patellar Dislocation

The rate or occurrence of redislocation after operative or nonoperative treatment of patellar dislocation is the most basic assessment of treatment success. However, standard outcome measures, such as functional knee metrics (the Pedi-IKDC225 and Lysholm364 knee scores), should also be used to assess the results and, paired with the Marx or Tegner activity scores,264 ascertain a patient's ability to make a full return to activities of daily life and sports activities. 

Pathoanatomy and Applied Anatomy Relating to Patellar Dislocations

The patella is a sesamoid bone in the quadriceps mechanism. As the insertion site of all muscle components of the quadriceps complex, it serves biomechanically to provide an extension moment during ROM of the knee joint. The trochlear shape of the distal femur stabilizes the patella as it tracks through a ROM. The hyaline cartilage of the patella is the thickest in the body. 
At 20 degrees of knee flexion, the inferior pole of the patella contacts a relatively small area of the femoral groove. With further flexion, the contact area moves superiorly and increases in size. The medial facet of the patella comes in contact with the femoral groove only when flexion reaches 90 to 130 degrees. 
The average adult trochlear femoral groove height is 5.2 mm and LFC height is 3.4 mm. The patellar articular cartilage is 6 to 7 mm in its thickest region, the thickest articular cartilage in the body, and is a reflection of the joint's inherent incongruity. The normal lateral alignment of the patella is checked by the medial quadriceps expansion and focal thickening of the capsule in the areas of the MPFL and medial meniscopatellar ligament.99 Dynamic stability depends on muscle forces, primarily the quadriceps and hamstrings acting through an elegant lower extremity articulated lever system that creates and modulates forces during gait. The quadriceps blends with the joint capsule to provide a combination of dynamic and static balance. Tightness or laxity of any of the factors involved with maintenance of the balance leads to varying levels of instability. Sallay et al.340 demonstrated avulsions of the MPFL from the femur in 94% (15 of 16) of patients during surgical exploration after acute patellar dislocation. Desio et al.99 using a cadaveric serial cutting model, found that the MPFL provided 60% of the resistance to lateral patellar translation at 20 degrees of knee flexion. The medial patellomeniscal ligament accounted for an additional 13% of the medial quadrant restraining force. If the deficit produced by attenuation of the medial vectors after acute dislocation is not eliminated, patellofemoral balance is lost, resulting in feelings of giving way and recurrent dislocation. 
The patella is under significant biomechanical compressive load during activity. It has been estimated that at 60 degrees of knee flexion, the forces across the patellofemoral articulation are three times the body weight and increase to over seven times the body weight during full knee flexion. 
The quadriceps mechanism is aligned in a slightly valgus position in relation to the patellar tendon. This alignment can be approximated by a line drawn from the anterosuperior iliac spine to the center of the patella. The force of the patellar tendon is indicated by a line drawn from the center of the patella to the tibial tubercle. The angle formed by these two lines is called the quadriceps angle or Q angle (Fig. 30-20). As this angle increases, the pull of the extensor mechanism tends to sublux the patella laterally. Recurrent patellar dislocation is most likely associated with some congenital or developmental deficiency of the extensor mechanism, such as patellofemoral dysplasia, deficiency of the VMO, or an increased Q angle with malalignment of the quadriceps–patellar tendon complex. However, although the Q angle can be difficult to measure clinically, the increasing use of MRI in patients with patellar dislocation has generated heightened interest in, and application of, the TT-TG distance, which many consider an imaging equivalent of the Q angle. When significantly elevated above the normal value of approximately 13 mm – a common threshold for “abnormal” is 20 mm – the TT-TG has been shown to be a risk factor for both primary and recurrent patellar dislocation in adults, adolescents, and children. Interestingly, despite the different technical approach to patellar instability, different authors have used it as an indication for MPFL reconstruction or tibial tubercle osteotomy (TTO).6,373 
Figure 30-20
The Q angle.
 
Normal valgus alignment of the quadriceps mechanism: Line drawn from the anterosuperior iliac spine to center of the patella, line drawn from center of the patella to tibial spine.
Normal valgus alignment of the quadriceps mechanism: Line drawn from the anterosuperior iliac spine to center of the patella, line drawn from center of the patella to tibial spine.
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Figure 30-20
The Q angle.
Normal valgus alignment of the quadriceps mechanism: Line drawn from the anterosuperior iliac spine to center of the patella, line drawn from center of the patella to tibial spine.
Normal valgus alignment of the quadriceps mechanism: Line drawn from the anterosuperior iliac spine to center of the patella, line drawn from center of the patella to tibial spine.
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Treatment Options for Patellar Dislocation

Nonoperative Treatment of Patellar Dislocation

Indications/Contraindications

Most acute patellar dislocations in children reduce spontaneously; if they do not, reduction usually can be easily performed. Surgery is usually not indicated for primary acute patellar dislocations in children.38,81,233 Most patellar dislocations are treated nonoperatively with immobilization in extension, followed by patellofemoral bracing and rehabilitation focused on regaining normal ROM and strengthening of the quadriceps, particularly the VMO (Table 30-13). 
 
Table 30-13
Patellar Dislocations
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Table 30-13
Patellar Dislocations
Nonoperative Treatment
Indications Relative Contraindications
Primary patellar dislocation Osteochondral fracture/loose body >5 mm seen on XR/MRI
Repeat patellar dislocation with few/no risk factors for recurrence Recurrent patellar dislocation with underlying/anatomic risk factors for recurrence
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Techniques

After appropriate sedation, reduction is achieved by flexing the hip to relax the quadriceps muscle, gradually extending the knee, and gently pushing the patella medially back into its normal position. Gentle reduction should be emphasized to avoid the risk of osteochondral fracture associated with patellar relocation. 

Outcomes

The prognosis of patellar dislocations in children, when not associated with osteochondral injury, is generally good. Patients with a younger age at first dislocation are at higher risk for recurrent instability. Cash and Hughston73 noted 75% satisfactory results after nonoperative treatment in carefully selected patients. 
Recurrent patellar dislocations with associated osteochondral injuries can lead to osteoarthritis of the patellofemoral joint. Given that some studies cite rates of chondral injury, which may include not only frank displacement of chondral fragments, but also fissuring, fraying, and impaction injuries, as high as 95%,302 longer-term studies are needed to better assess functional outcomes in patients who have dislocated. 

Operative Treatment of Patellar Dislocation

Indications/Contraindications

Surgical repair may be considered if the VMO and/or MPFL is completely avulsed from the medial aspect of the patella, leaving a large, palpable soft tissue gap and severely lateralized patella. If osteochondral fracture has occurred, arthroscopy/arthrotomy is indicated for removal or repair of an osteochondral loose body, as discussed in the previous section. The importance of performing a concurrent MPFL “repair” is controversial, but an MPFL tightening procedure, sometimes referred to as a “reefing,” “imbrication,” or “medial retinaculum plasty” procedure, with or without a lateral retinacular “release,” which generally involves a longitudinal division of the tissue over the length of the patella, or lateral retinacular lengthening procedure, is still favored by many authors.70,78,252,298,299,314 
Recurrent instability of the patella which has been recalcitrant to nonoperative treatment is typically managed through one of various proximal and/or distal patellofemoral realignment procedures. Proximal realignment options include isolated or combination procedures including lateral retinacular release or lateral retinacular z-lengthening74 medial retinacular plication, reefing, or MPFL reconstruction using semitendinosus autograft or, more commonly, allograft.6,40,53,65,66,77,87,93,105,275,301,333,373 

Surgical Procedure

Preoperative Planning (Table 30-14
 
Table 30-14
Patellar Dislocation
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Table 30-14
Patellar Dislocation
Preoperative Planning Checklist
  •  
    OR table: If fluoroscopy planned, radiolucent table
  •  
    Position/positioning aids: Supine
  •  
    Fluoroscopy location: Nonoperative side, perpendicular to table
  •  
    Equipment: (If osteochondral fragment fixation planned), small K-wires, bioabsorbable pins/tacks/screws, headless compression screws
  •  
    Tourniquet (sterile/nonsterile): Nonsterile
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Positioning

Arthroscopy is generally pursued prior to any open treatment related to patellar dislocation, so a standard arthroscopy setup should be utilized. However, for both arthroscopic and open techniques, most of the surgery is performed with the knee in full extension. If osteochondral fragment fixation is planned, a bump for both the knee and ankle are helpful to elevate the entire leg and facilitate true lateral XRs, if necessary. 

Surgical Approach and Technique

The most common distal realignment approach in skeletally mature patients is the TTO, which may involve straight medialization of the tubercle (the Elmslie–Trillat procedure),386 straight anteriorization (the Maquet procedure),261 or a combination anteromedialization (an “AMZ,” or the Fulkerson osteotomy).130 However, these are contraindicated in patients with an open tibial tubercle apophysis because of the risk of a growth arrest, which can result in recurvatum deformity. In cases of significant patella alta, some authors have additionally proposed distalization of the tibial tubercle, with and without patellar tendon tenodesis, designed to shorten the tendon.96,268 In skeletally immature patients, Galeazzi semitendinosus tenodesis30,146 or the Roux–Goldthwait reconstruction262,295 are distal realignment soft tissue procedures that have been traditionally utilized, though more recent studies have suggested that outcomes of these procedures may be less favorable than historically reported.30,146,295 These perspectives have further stimulated interest in MPFL reconstruction techniques in skeletally immature children. However, there remains controversy about the appropriate technique and location of fixation of the graft on the femoral side, in part because of conflicting data on the true anatomic MPFL attachment relative to the distal femoral physis.203,351 Literature detailing significant complications associated with MPFL reconstruction have emerged,275,295,383,384 including inaccurate or inappropriate femoral fixation, making this an evolving topic with imprecise indications (Table 30-15).31 
 
Table 30-15
Patellar Dislocation
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Table 30-15
Patellar Dislocation
Operative Treatment
Surgical Steps
  •  
    (If any questionable findings on MRI) perform diagnostic arthroscopy to assess status of patellar and lateral condylar cartilage, assess patellofemoral alignment/tracking, rule out presence of any intra-articular loose bodies, consider performing arthroscopic lateral release, if indicated by lateral patellar tilt or severe patellar lateralization
  •  
    Distal patellar realignment (TTO), if skeletally mature and indicated by elevated TT-TG
  •  
    Proximal patellar realignment (proximal medial reefing) versus MPFL reconstruction
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Author's Preferred Treatment of Patellar Dislocation

The author's algorithm to decision making is shown in Figure 30-21
Figure 30-21
Algorithm for the management of patellar dislocations in children and adolescents.
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Most acute patellar dislocations in children without osteochondral fracture are treated by closed methods with satisfactory results. A knee immobilizer is generally used for approximately 2 weeks. Patients are allowed full weight bearing as tolerated. After immobilization, the patient is placed in a patellofemoral brace with a lateral bolster. Physical therapy is begun, emphasizing straight leg raises, progressive resistance exercises, patellar mobilization, and vastus medialis strengthening. Patients are allowed to return to sports 6 to 12 weeks after injury, depending on their patellofemoral mechanics and progress with rehabilitation. 
Acute surgical intervention is indicated most commonly for an associated osteochondral fracture. Removal of loose bodies for fragments ≤5 mm or fracture fixation for larger fragments is performed. Adjunctive medial retinacular/MPFL reefing, either through excision of an elliptical segment (usually 1 cm wide, 2 cm long) of attenuated medial parapatellar retinacular tissue, or through a pants-over-vest advancement, is usually also performed to reduce the risk of recurrent patellar instability, with or without lateral retinacular release or lengthening, depending on the tightness of the lateral patellar restraints. 
Chronic patellar subluxation or dislocation is most common in adolescents, especially females. Several risk factors have been identified in children likely to have chronic subluxation or dislocation, including age younger than 16 years, abnormal Q angle, significant genu valgum, radiographic evidence of dysplasia of the patella or trochlea, LFC hypoplasia, femoral anteversion or external tibial torsion, significant atrophy of the VMO, connective tissue disorders predisposing to hypermobility of the patella (e.g., Ehlers–Danlos syndrome), elevated TT-TG distance, and multiple previous dislocations (Fig. 30-22).17,57 Initial treatment of chronic patellar subluxation or dislocation in adolescents is immobilization followed by aggressive physical therapy for rehabilitation of the VMO and quadriceps muscles. Surgical intervention is warranted in children who do not respond to this treatment regimen and continue to have subluxation or dislocation.50,164,234,254 For the rare patient with minimal risk factors for recurrence or only minor, but recurrent symptomatic subluxation episodes, an isolated proximal soft tissue realignment procedure, consisting of medial retinaculum/MPFL reefing with lateral retinacular release or lengthening, may be considered (Fig. 30-23A). 
Figure 30-22
Chronic lateral patellar subluxation in a 13-year-old girl.
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Figure 30-23
Surgical technique for treatment of chronic patellar subluxation or dislocation.
 
A: Lateral retinacular release and medial imbrication. B: Semitendinosus tenodesis. C: Elmslie–Trillat procedure.
A: Lateral retinacular release and medial imbrication. B: Semitendinosus tenodesis. C: Elmslie–Trillat procedure.
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Figure 30-23
Surgical technique for treatment of chronic patellar subluxation or dislocation.
A: Lateral retinacular release and medial imbrication. B: Semitendinosus tenodesis. C: Elmslie–Trillat procedure.
A: Lateral retinacular release and medial imbrication. B: Semitendinosus tenodesis. C: Elmslie–Trillat procedure.
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If subluxation or dislocation persists despite this less invasive approach, or in patients with recurrent instability and multiple underlying risk factors, a more significant proximal realignment procedure or more complex combinations of proximal and distal realignment procedures are indicated. MPFL reconstruction allows for reconstitution of a robust medial patellar checkrein40,65,93 and is indicated in patients with attenuation of medial retinacular tissues. Semitendinosus allograft is generally used, with either suture fixation of an appropriately tensioned graft to the femoral and patellar periosteum in younger children, or suture anchor fixation in adolescents, utilizing intraoperative fluoroscopy to place the femoral anchor just distal to the distal femoral physis. Small (≤5 mm), short (≤20 mm), transverse bone tunnels may also be drilled under fluoroscopic guidance at the patellar and femoral MPFL attachment sites, using small biocomposite interference screws for graft fixation. 
In skeletally mature patients with a significantly abnormal Q angle or TT-TG distance over 20 mm, TTO in conjunction with proximal realignment procedures is preferred. Tubercle medialization with the Elmslie–Trillat procedure (Fig. 30-23C) is effective in improving patellofemoral kinematics in the coronal plane, though a Fulkerson osteotomy incorporating anteriorization of the patella is preferred in cases with pre-existing patellar chondrosis or significant osteochondral injury which has undergone fixation or microfracture. Combined TTO/MPFL reconstruction procedures may give the greatest reduction in risk of redislocation, but represents a maximally invasive approach with significant operative times, increasing risk of stiffness and other complications. More research is needed to justify the benefits of MPFL reconstruction over simpler medial retinacular tightening procedures in conjunction with TTO. 

Postoperative Care for Patellar Dislocation

After patellar realignment procedures, patients are treated with touch-down weight bearing in a postoperative brace for 2 weeks. ROM when not weight bearing is limited to 0 to 30 degrees for the first 2 weeks. Patients may begin weight bearing as tolerated after 2 weeks, but only with the hinged knee brace locked in extension. When not ambulating, ROM is advanced to 0 to 60 from post-op weeks 2 to 4 and from 0 to 90 from post-op weeks 4 to 6. At 6 weeks, the brace is unlocked when ambulating and discontinued by week 8, with weight-bearing strengthening exercises initiated. Straight ahead running is allowed around 3 months post-op, with advancement to agility and sport-specific exercises as indicated. Return to athletic activities is permitted when full ROM is recovered, strength is symmetric, and the knee feels stable with agility exercises. 

Potential Pitfalls and Preventative Measures of Patellar Dislocation

Unrecognized associated osteochondral fractures may present later as loose bodies. Unrecognized associated ligamentous injury can present later as knee instability. Aggressive nonoperative treatment should be pursued for cases of patellofemoral instability before considering surgical management, and MRI should be obtained for all patellar dislocation patients, particularly primary episodes, to evaluate for associated injuries and underlying anatomic risk factors, such as patellofemoral dysplasia. Overzealous and injudicious use of lateral retinacular release may result in iatrogenic medial patellar instability. For MPFL reconstruction procedures, while there are conflicting reports about the appropriate degrees of knee flexion at which MPFL tensioning and fixation should be pursued, ranging from 30 to 90 degrees,6,7,16,41,66,77,87,244,275,294,333,373,422 graft isometry and assessment of tension through a wide ROM is indicated to avoid increasing patellar contact forces.41,275 Fluoroscopy is indicated if short patellar and/or femoral bone tunnels are drilled for graft placement, with bioabsorbable or biocomposite interference screw fixation. We recommend against long tunnels (>20 mm), large diameter tunnels (>5 mm), oblique tunnels, complete transpatellar tunnels, or multiple tunnels, to avoid subsequent patellar fracture in this young, active, athletic patient population. 

Treatment-Specific Outcomes for Patellar Dislocation

A variety of surgical approaches are associated with relatively low rates of redislocation and good short-term knee scores in both adults and children.6,31,70,310,422 However, one recent study suggests that longer-term knee scores and satisfaction in children may be slightly lower than presumed from the low redislocation rates.251 

Management of Expected Adverse Outcomes and Unexpected Complication in Patellar Dislocation

Complications may occur after surgery for patellar instability. Lateral release alone without medial retinaculum/MPFL repair may not adequately prevent recurrent dislocation. Stiffness, with lack of knee flexion, may occur after MPFL reconstruction or Galeazzi tenodesis, if the graft is overly tensioned. After TTO, nonunion, hardware failure, neurovascular injury, and compartment syndrome have been reported (Table 30-16). 
 
Table 30-16
Patellar Dislocation
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Table 30-16
Patellar Dislocation
Common Adverse Outcomes and Complications
Arthrofibrosis
Patellar subluxation/instability
Patellar redislocation
X

Introduction to Meniscal Injuries

Meniscal injuries in the pediatric athlete are being seen with increased frequency.1,2,22,52,68,80,125,159,195,208,213,218,260,274,284,287,303,339,390,398,417,420 Meniscal disorders include meniscal tears, discoid meniscus, and meniscal cysts. The exact incidence of meniscal injuries in children and adolescents is unknown, but is known to increase with age within this subpopulation.92 With adolescence, increased size and speed, and increased athletic demands, come higher energy injuries and an increase of intra-articular lesions. Meniscal injuries under the age of 10 are rare, unless associated with a discoid meniscus.5,12,14,43,86,101,102,123,129,157,162,179,191,192,193,199,211,220,292,296,307,316,320,326,336,344,363,374,375,393,402,415 
Meniscal injury patterns differ in children compared to adults. It is estimated that longitudinal tears comprise 50% to 90% of meniscal tears in children and adolescents.213 Bucket-handle displaced tears are not uncommon (Fig. 30-1). Also in these age groups, meniscal injuries are commonly associated with ACL injuries.71,112,220,260 Cannon and Vittori 71 estimated that repairable meniscal tears occur in 30% of all knees with acute ACL rupture and in 30% of patients under 20 years old. However, a more recent series341 of 124 ACL tears in skeletally immature patients demonstrated an incidence of associated meniscus tears of 69%. Overall, approximately two-thirds of repairable meniscal tears are associated with ACL rupture, with the majority of these tears involving the posterior horn. 
Although there is limited data on the subject, one report suggests that the incidence of medial meniscal tears is greater than lateral meniscal tears in the adolescent age group.370 The previously mentioned series341 involving a high rate of meniscus repairs performed with ACL reconstruction (ACL-R) in children with open physes conversely showed a significantly higher rate of lateral meniscal tears compared with medial meniscus tears. There also appears to be a relatively increased incidence of lateral tears in the preadolescent age group, which may in part be because of the existence of lateral discoid menisci.213 

Assessment of Meniscal Injuries

Mechanisms of Injury for Meniscal Injuries

Injury to the nondiscoid meniscus is virtually always traumatic in nature in children and adolescents. Multiple studies have shown that between 80% and 90% of meniscal injuries in children and adolescents are sustained during sports activities.5,148,149,260,370 These numbers may be lower in the preadolescent age group. Meniscal tears most commonly occur with cutting, pivoting and twisting motions, such as those performed frequently during football, soccer, and basketball. The mechanism involves rotation of the condyles relative to the tibial plateau, as the flexed knee moves toward extension. This rotational force with the knee partially flexed causes the condyle to force the menisci toward the center of the joint, leading to injury. 

Associated Injuries with Meniscal Injuries

Twisting mechanisms may also cause associated ligamentous injuries, and ACL injuries are commonly associated with both medial and lateral meniscal tears in adolescents. More chronically, meniscal injuries also may be associated with degenerative changes, cyst formation, or congenital anomalies.125 

Signs and Symptoms of Meniscal Injuries

Pain and swelling are the most common chief complaints of a meniscal tear. Other complaints include mechanical symptoms such as snapping, popping, clicking, catching, or locking. A bucket-handle tear that is displaced into the intercondylar notch may present with a locked knee or a knee unable to fully extend. 
The differential diagnosis of acute meniscal tear in the pediatric patient includes other conditions that may result in a traumatic effusion, such as a ligamentous injury, osteochondral fracture, chondral injury, or patellofemoral dislocation. In addition, conditions causing pain at or adjacent to the joint line must be distinguished from meniscal tears, such as plica syndrome, iliotibial friction band syndrome, OCD, and bone bruises.213 
The diagnosis of meniscal tear in children and adolescents can be difficult to make. Because of the diversity of pathology and the difficulty of examination in children, diagnostic accuracy of clinical examination for meniscus tear has been shown to be as low as 29% to 59%.213,214 An accurate history may be difficult to obtain in a very young child. The older the patient, the more likely a history of specific injury. Pain is reported by approximately 85% of patients, predominantly in the area of the affected joint line. More than half of patients report giving way and effusion of the knee joint. 
The most common physical examination signs, similar to adults, are joint line tenderness, pain with hyperflexion and/or hyperextension, and effusion.22,274 However, some patients may have minimal findings on physical examination. McMurray test may be helpful in the diagnosis of a subacute or chronic lesion, but with acute injury the knee may be too painful to allow these maneuvers.88 In Vahvanen and Aalto's series of patients with documented meniscal tears,390 almost one-third of the patients had no significant findings on physical examination. The classic McMurray test may be of little value in this age group whose tears are peripheral and not degenerative posterior horn lesions.213 Two recent studies, by examiners with pediatric sports medicine experience have shown the diagnostic accuracy of clinical examination to be 86.3% and 93.5% overall.214,369 When medial meniscus tears were looked at alone, the sensitivity and specificity of clinical examination were 62.1% and 80.7% respectively.214 The sensitivity and specificity for lateral meniscal tears were 50% and 89.2% respectively.214 

Imaging and Other Diagnostic Studies for Meniscal Injuries

Routine radiographs are obtained primarily to rule out a fracture, OCD lesion, or other bony sources of knee pain. Arthrography84 has been described historically to help identify a meniscal tear, but has been used minimally since the advent of arthroscopy and MRI.287,304 
MRI is the gold standard method for evaluating meniscal injuries in children. MRI accuracy rates reportedly range from 45% to 90% in the diagnosis of meniscal tears.59,184,323,357 Sensitivity and specificity of 83% and 95% respectively has been shown in skeletally immature patients.214,369 Kocher et al.214 showed that for medial meniscal tears the sensitivity and specificity for MRI diagnosis were 79% and 92% respectively.214 For lateral meniscal tears, these numbers were 67% and 83% respectively. 
However, MRI should not be used indiscriminately as a screening procedure, because of significant limitations of the technique in this age group.58,232,323,380 Only the specificity for medial meniscal tears was significantly higher with MRI as compared to clinical examination.214 The sensitivity and specificity of MRI decrease in younger children compared to older adolescents.214,369 In recent studies that compared the diagnostic accuracy of physical examination versus MRI, clinical examination rates were equivalent or superior to MRI.214,369 These authors recommended judicious use of MRI in evaluating intra-articular knee disorders. 
Normal MRI signal changes exist in the posterior horn of the medial and lateral meniscus in children and adolescents.210,214,369,423 These signal changes do not extend to the superior or inferior articular surfaces of the meniscus and likely represent vascular developmental changes.213 Takeda et al.378 reviewed the MRI signal intensity and pattern in the menisci of 108 knees in 80 normal children 8 to 15 (average 12.2) years of age using the classification of Zobal et al.,423 which allows for equivocation for type III signals. Using tibial tubercle maturity as a definition of skeletal maturity, Takeda et al.378 found signal intensity to be proportional to age, with high signal (grades II and III) evident in 80% of patients 10 years of age or younger, 65% by 13 years of age, and 33% at 15 years of age, which is similar to the false-positive rate of 29% reported in asymptomatic adults.137,232 Overall, two-thirds of the patients had positive findings (grades II or III), often grade IIIA, which is equivocal extension through the surface of the meniscus. Takeda et al.378 suggested that the decrease in signal intensity was proportional to diminution of peripheral vascularity, especially in the posterior horn of the meniscus. These investigators cautioned against misinterpretation of pediatric knee MRIs and emphasized the necessity for correlation of the clinical findings with any imaging study results. When interpreting an MRI of the developing knee, care must be taken to identify a meniscal tear only when linear signal changes extend to the articular surface. As with any test, clinical correlation is mandatory before treatment decisions are made. 

Classification of Meniscal Injuries

Classification is generally descriptive in nature, and is based on the meniscus involved (medial vs. lateral), the location of the tear (posterior horn, body/pars intermedia, anterior horn), the chronicity of the tear (acute [<6 weeks], chronic [>6 weeks]), and the tear pattern (vertical/longitudinal, bucket-handle, horizontal cleavage, transverse/radial, or complex) (Fig. 30-24). Other important factors include site of the tear (outer/peripheral 1/3, middle 1/3, inner/central 1/3), stability of the horns or overall meniscus, and associated ligamentous and chondral injuries. 
Figure 30-24
Meniscal tears in adolescents.
 
A: Peripheral. B: Bucket handle. C: Horizontal cleavage. D: Transverse. E: Complex.
A: Peripheral. B: Bucket handle. C: Horizontal cleavage. D: Transverse. E: Complex.
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Figure 30-24
Meniscal tears in adolescents.
A: Peripheral. B: Bucket handle. C: Horizontal cleavage. D: Transverse. E: Complex.
A: Peripheral. B: Bucket handle. C: Horizontal cleavage. D: Transverse. E: Complex.
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X

Outcome Measures for Meniscal Injuries

Recurrence or failure to heal a meniscus tear following repair is the most significant predictor of treatment success. Symptoms from retear generally warrant revision repair or, if the recurrent tear is not repairable, partial meniscectomy. On a longer-term basis, standard outcome measures, such as functional knee metrics (the Pedi-IKDC225 and Lysholm364 knee scores), should be used to assess results and paired with the Marx or Tegner activity scores264 to ascertain a patient's ability to make a full return to activities of daily life and sports activities, which are the dual goals of surgery. 

Pathoanatomy and Applied Anatomy Relating to Meniscal Injuries

The menisci become clearly defined by as early as 8 weeks of embryologic development.199 By week 14, they assume the normal mature anatomic relationships. At no point during their embryology are the menisci discoid in morphology.199 Thus, the discoid meniscus represents an anatomic variant, not a vestigial remnant. The developmental vasculature of the menisci has been studied extensively by Clark and Ogden.80 The blood supply arises from the periphery and supplies the entire meniscus. This vascular pattern persists through birth. During postpartum development, the vasculature begins to recede and by as early as the ninth month, the central 1/3 is avascular. This decrease in vasculature continues until approximately age 10, when the menisci attain their adult vascular pattern. Injection dye studies by Arnoczky and Warren27 have shown that only the peripheral 10% to 30% of the medial and 10% to 25% of the lateral meniscus receive vascular nourishment.Importantly, the anterior and posterior horns have improved vascularity, compared with the body, or pars intermedia, of both the medial and lateral meniscus.27 
The medial meniscus is C shaped. The posterior horn is larger in anterior–posterior width than the anterior horn. The medial meniscus covers approximately 50% of the medial tibial plateau. The medial meniscus is attached firmly to the medial joint capsule through the meniscotibial or coronary ligaments. There is a discrete capsular thickening at the level of the meniscal body which constitutes the deep MCL. The inferior surface is flat and the superior surface concave so that the meniscus conforms to its respective tibial and femoral articulations. To maintain this conforming relationship, the medial meniscus translates 2.5 mm posteriorly on the tibia as the femoral condyle rolls backward during knee flexion.148,149 
The lateral meniscus is more circular in shape and covers a larger portion, approximately 70%, of the lateral tibial plateau. The lateral meniscus is more loosely connected to the lateral joint capsule. There are no attachments in the area of the popliteal hiatus and the fibular collateral ligament does not attach to the lateral meniscus. Accessory meniscofemoral ligaments exist in up to 1/3 of cases. These arise from the posterior meniscus. If a discrete meniscofemoral ligament inserts anterior to the PCL it is known as the ligament of Humphrey, and if it inserts posterior to the PCL, the ligament of Wrisberg. Because of the lack of restraining forces, the lateral meniscus is able to translate four times as much as the medial meniscus, approximately 9 to 11 mm on the tibia with knee flexion. Both menisci are attached anteriorly via the anterior transverse meniscal ligament.148,149 
The blood supply arises from the superior, inferior, medial, and lateral geniculate arteries. These vessels form a perimeniscal synovial plexus. There may be some contribution from the middle geniculate artery as well. King, in the 1930s, published classic research indicating that the peripheral meniscus did communicate with the vascular supply and therefore was capable of healing.209 It is believed that the central two-thirds of the meniscus receives its nutrition through diffusion and mechanical pumping. 
The menisci are composed primarily of type I collagen, accounting for 60% to 70% of its dry weight. Lesser amounts of types II, III, and VI collagen are also present. The collagen fibers are oriented primarily in a circumferential pattern, parallel with the long access of the meniscus.148,149 There are also radial, oblique, and vertically oriented fibers in organized layers. Proteoglycans and glycoproteins are present, but in smaller concentrations than in articular cartilage. The menisci also contain neural elements including mechanoreceptors and type I and II sensory fibers. In a sensory mapping study, Dye et al.107 demonstrated that the probing of the peripheral meniscus led to pain whereas stimulation of the central meniscus elicited little or no discomfort. 
Our understanding of the functional importance of the meniscus has evolved. In 1897, Bland-Sutton56 characterized the menisci as “functionless remnants of intra-articular leg muscles.” The sentiment was largely embraced through the 1970s, when menisci were routinely excised. However, Fairbank, in 1948, published the first long-term follow-up study of patients after total meniscectomy.118 His article demonstrated that degenerative changes followed meniscectomy in a substantial proportion of patients. Now, myriad investigations have established the deleterious consequences of total and even partial meniscectomy on the chronic health of the articular cartilage.5,112,213,260,274,326,328,390,393,402,417 Nowhere are these principles more important than in children and adolescents, in whom the long-term effects of meniscectomy will be magnified by higher activity levels and simple longevity. 
It is now realized that the menisci actually have a number of different functions. The menisci serve to increase contact area and congruency of the femoral tibial articulation. This allows the menisci to participate in load sharing and reduces the contact stresses across the knee joint. It is estimated that the menisci transmit up to 50% to 70% of the load in extension and 85% of the load in 90 degrees of flexion.8 Baratz et al.37 showed that after total meniscectomy articular contact areas at a point in time may decrease by 75% and contact stresses on the involved areas increase by 235%. They also documented the deleterious effects of partial meniscectomy, demonstrating that contact stresses increase in proportion to the amount of meniscus removed. Excision of small bucket-handle tears of the medial meniscus increased contact stress by 65%, and resection of 75% of the posterior horn increased contact stresses equivalent to that after total meniscectomy.37 Repair of meniscal tears, by either arthroscopic or open techniques, reduced the contact stresses to normal. Multiple other studies have corroborated these findings, illustrating the mechanical importance of the meniscus.148,149 
Meniscal tissue is about ½ as stiff as articular cartilage, allowing it to participate in shock absorption as well. Shock absorption capacity in the normal knee is 20% higher than in the meniscectomized knee.241,274 The menisci also have a role in joint stability. In the ACL-deficient knee the posterior horn of the medial meniscus plays a very important passive stabilizing role. In the ACL-deficient knee, medial meniscectomy leads to a 58% increase in anterior translation at 90 degrees of flexion.241,355 Given the presence of neural elements within their substance, it is also theorized that the menisci may have a role in proprioception. 

Discoid Lateral Meniscus

Lateral meniscal tears may be seen in association with an underlying discoid lateral meniscus, particularly in younger children. The discoid lateral meniscus represents an anatomical variant of meniscal morphology. The incidence is thought to be 3% to 5% in the general population102,192,193,213 and slightly higher in Asian populations.102,192,193,213 Interestingly, OCD has been described associated with discoid lateral meniscus, both before and after saucerization.51,94,160 Discoid morphology almost exclusively occurs within the lateral meniscus, but medial discoid menisci have been described in various case reports.102,192,193,213 Although the incidence of bilateral abnormality has been reported to be as high as 20%,12,43,320,363 routine screening on the contralateral knee is not indicated as part of treatment of a discoid lateral meniscus, because of the high rates of asymptomatic cases not requiring intervention. A recent study317 comparing cases of bilateral discoid menisci to those with unilateral discoid demonstrated that the bilateral cases required treatment at an average age 2 years younger than the unilateral cases, but that unilateral cases were more likely to have tearing than bilateral cases.317 Discoid menisci are classified based on the system of Watanabe et al.403: Complete morphology (type I), incomplete morphology (type II), and any morphology that lacks peripheral attachments (type III). One recent study proposed a more complex classification scheme that incorporates description of the presence and location of instability, paired with morphology.141 Although often synonymous with so-called “snapping knee syndrome,” discoid lateral menisci may manifest in a variety of ways. Symptoms are often related to the type of discoid present, peripheral stability of the meniscus, and the presence or absence of an associated meniscal tear.14,102,123,193,296,336,415 Stable discoid menisci without associated tears will often remain asymptomatic, identified only as incidental findings during MRI or arthroscopy.207 Unstable discoid menisci are more commonly present in younger children and often produce the so-called “snapping knee syndrome.” In such instances, a painless and palpable, audible or visible snap is produced with knee ROM, especially near terminal extension. Discoid menisci with posterior instability and a redundant anterior segment may limit knee extension.418 In children with stable discoid lateral menisci, symptoms often present when an associated tear is present. Unlike acute meniscal tears, such symptoms may present insidiously without significant previous trauma. Signs and symptoms of a meniscal tear may exist, including pain, swelling, catching, locking, and limited motion. On physical examination, there may be joint line tenderness, popping, limited motion, effusion, terminal motion pain, and positive provocative tests (McMurray test). Degenerative horizontal cleavage tears are the most common type of tear seen in this condition, reported in the largest series to occur in 58% to 98% of symptomatic discoid menisci.12,43,320 One study showed that Wrisberg types were more likely to require treatment complete discoids, which in turn were more likely to require treatment than incomplete discoids.317 Instability of a discoid meniscus may be more common than previously thought, with rates as high as 77% in a recent series141 demonstrating anterior instability to be the most common form (53%), followed by posterior instability (16%) and combined anterior/posterior instability (6%). 

Treatment Options for Meniscal Injuries

Nonoperative Treatment of Meniscal Injuries

Indications/Contraindications

Some small (<1 cm), nondisplaced meniscal tears in the peripheral vascular region of the meniscus may heal nonoperatively or may become asymptomatic (Table 30-17).148,149,213 
 
Table 30-17
Meniscal Injuries
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Table 30-17
Meniscal Injuries
Nonoperative Treatment
Indications Relative Contraindications
Small, nondisplaced, asymptomatic peripheral, vertical/longitudinal tears Symptomatic tears
Large tears ≥1 cm
Radial/flap tears, complex patterns
X

Techniques

Nonoperative treatment usually consists of rehabilitation of the injured knee with the avoidance of pivoting and sports for 12 weeks, with protection of weight bearing for 4 to 6 weeks to minimize shear forces across the healing meniscus. 

Outcomes

As there has been a general evolution to more proactive treatment of meniscus tears, particularly in younger populations, there is sparse literature related to successful nonoperative treatment of meniscus tears. However, Weiss et al.405 showed that few patients in a series of 80 with “stable” longitudinal, vertical meniscus tears required surgery or were symptomatic at a minimum of 2-year follow-up. The authors concluded that radial tears do not heal with nonoperative treatment and empirically warrant surgery. 

Operative Treatment of Meniscal Injuries

Indications/Contraindications

The majority of meniscal tears in pediatric patients is larger and requires surgical treatment.148,149,213 Arthroscopic management is standard, with either partial meniscectomy using motorized shavers and baskets or meniscal repairs using outside-in, all-inside, or inside-out techniques.90,148,149 

Arthroscopic Management

Preoperative Planning (Table 30-18
 
Table 30-18
Operative Treatment of Meniscal Injuries
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Table 30-18
Operative Treatment of Meniscal Injuries
Operative Treatment
Preoperative Planning Checklist
  •  
    OR table: Standard
  •  
    Position/positioning aids: Supine, lateral thigh post (especially for medial meniscal tears)
  •  
    Fluoroscopy location: N/A
  •  
    Equipment: Arthroscopy setup, inside-out meniscus repair cannulas, 2 meniscus repair suture, all-inside meniscus repair implants
  •  
    Tourniquet (sterile/nonsterile): Nonsterile, thigh
X

Positioning

Supine positioning is used, with a nonsterile tourniquet placed on the operative thigh, and a lateral thigh post, which is particularly useful for application of valgus knee stress to access the posterior horn of the medial meniscus in select tears. 

Surgical Approach and Technique

The historical treatment of a torn meniscus had been meniscectomy, but numerous reports5,25,52,112,172,208,213,229,260,274,326,328,380,390,393,402,417 indicating the poor long-term results of meniscectomy in children have made this less common. Up to 60% to 75% of patients may have degenerative changes after meniscectomy. Manzione et al.260 reported 60% poor results in 20 children and adolescents after meniscectomy. In cadaver studies, Baratz et al.37 showed that the contact stresses on the tibiofemoral articulation increase in proportion to the amount of the meniscus removed and the degree of disruption of the meniscal structure. As a clear principle, as much of the meniscus should be preserved as possible. 
The exact meniscal injury and potential for repair can be determined arthroscopically to help formulate treatment plans. Zaman and Leonard420 recommended observation of small peripheral tears, repair of larger peripheral tears, and, when necessary, partial meniscectomy, leaving as much of the meniscus as possible. They concluded that total meniscectomy is contraindicated in young patients. In general, peripheral tears, which are most common in children, and longitudinal/vertical tears are good candidates for repair, with success rates of up to 90% reported.89,158,167,263,287 
Although it was believed that longitudinal meniscal tears could heal if communication with peripheral blood supply existed, it was not until the work of Arnoczky et al.28 in the 1980s that meniscal repairs were popularized, based on documentation of the meniscal blood supply. They believed that tears within 3 mm of the meniscosynovial junction were vascularized, and ones more than 5 mm away were avascular unless bleeding was seen at surgery. Tears in the 3- to 5-mm range had inconsistent vascularity. Children and adolescents may have greater healing potential for meniscal repair. In adults, meniscal repair is indicated for tears involving the outer 1/3. In children and adolescents, repair of tears in the middle 1/3 zone typically heal as well,89,158,167,263,287 making repair of both red–red and red–white zone tears the standard of care for vertical tears in this young population. Horizontal cleavage tears, transverse/radial tears, flap tears extending from the central 1/3, and complex or degenerative tears most often should undergo partial meniscectomy, taking care to preserve as much meniscal tissue as possible, and establish smooth, stable edges to the trimmed meniscus. Occasionally, a complete radial tear will occur in a child, which would require a total or subtotal meniscectomy if treated with debridement. In these instances, side-to-side repair of the peripheral two-thirds of the torn meniscus with multiple nonabsorbable sutures should be trialed, at times in conjunction with partial debridement of the most central edges (white-white zone) of the tear, which may not heal due to diminished vascularity. The stability of the peripheral attachments should always be assessed meticulously with a probe, both before and after any meniscal interventions, to ensure there are no concomitant peripheral tears or underlying instability warranting repair. Familiarity with the arthroscopic appearance of normal meniscal mobility, and the differences between the medial and lateral side, is critical to the success of this assessment (Table 30-19). 
 
Table 30-19
Operative Treatment of Meniscal Injuries
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Table 30-19
Operative Treatment of Meniscal Injuries
Operative Treatment
Surgical Steps
  •  
    Diagnostic arthroscopy, assess position/pattern/size of tear
  •  
    For unrepairable tears (radial/flap/complex/degenerative), perform partial meniscectomy
    •  
      Use basket/punch instruments to trim torn portion, preserving as much of intact meniscus as possible
    •  
      Smooth transition zones between native/meniscectomized tissue
  •  
    For repairable tears, reduce any displaced portions to anatomic position
    •  
      Use meniscal rasp, shaver to freshen edges of meniscal tissue and/or peripheral capsular to stimulate healed
    •  
      Place meniscus repair sutures (preferably in vertical mattress pattern, inside-out)
    •  
      For posterior horn, select all-inside approach versus inside-out with mini-open protection of posterior structures
  •  
    Assess stability of repaired meniscus
X

Treatment of Discoid Lateral Meniscus in Meniscal Injuries

Several treatment options exist if the diagnosis of a discoid lateral meniscus is confirmed. For asymptomatic discoid lateral menisci, even if found incidentally on arthroscopy, no treatment is indicated. For stable, complete, or incomplete discoid menisci, partial meniscectomy, “saucerization,” is the treatment of choice (Fig. 30-25). If meniscal instability with detachment is also identified during the arthroscopic examination, meniscal repair should be performed. Historically, complete meniscectomy via open or arthroscopic means was suggested for such lesions, but has been clearly associated with poor long-term results and early degenerative changes,5,9,112,156,213,239,260,274,309,326,328,390,393,417 so is contraindicated. Although there may be a rare instance where salvage of a degenerative or torn discoid meniscus may seem unobtainable, better arthroscopic technology and techniques have made meniscal preservation the ideal treatment through saucerization and repair.4 
Figure 30-25
Discoid lateral meniscus saucerization.
 
A: Complete type discoid lateral meniscus extending into the intercondylar notch. B: Excision of the central portion of the discoid meniscus. C: Excision of the anterior portion of the discoid meniscus. D: Appearance after saucerization.
A: Complete type discoid lateral meniscus extending into the intercondylar notch. B: Excision of the central portion of the discoid meniscus. C: Excision of the anterior portion of the discoid meniscus. D: Appearance after saucerization.
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Figure 30-25
Discoid lateral meniscus saucerization.
A: Complete type discoid lateral meniscus extending into the intercondylar notch. B: Excision of the central portion of the discoid meniscus. C: Excision of the anterior portion of the discoid meniscus. D: Appearance after saucerization.
A: Complete type discoid lateral meniscus extending into the intercondylar notch. B: Excision of the central portion of the discoid meniscus. C: Excision of the anterior portion of the discoid meniscus. D: Appearance after saucerization.
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Author's Preferred Treatment of Meniscal Injuries

The author's treatment algorithm for meniscal tears in children and adolescents is shown in Figure 30-26. Treatment is based on size, site, shape and stability of the tear, acuity of the lesion, and knee stability. In a stable knee with an acute, arthroscopically documented outer third peripheral tear that is less than 1 cm long and cannot be displaced more than 3 mm, the tear may be allowed to heal. For a similarly sized tear in a chronic setting, we arthroscopically rasp or trephinate the interface between the meniscal edges and perform a repair. Protected weight bearing and limitation of flexion beyond 90 degrees is prescribed for 4 to 6 weeks. Healing can be assessed based on physical examination. Return to sports and activities is based on the absence of physical examination findings and adequate rehabilitation, usually at 3 to 4 months postoperatively with a small tear. 
Figure 30-26
Algorithm for the management of meniscal tears in children and adolescents.
Flynn-ch030-image026.png
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For larger tears involving the outer 1/3 or middle 1/3, which are longitudinal with an intact inner segment that can be reduced anatomically, meniscal repair is performed. In the chronic setting, rasping of the fragment edge, trephination, and use of a fibrin clot may enhance healing. Patients are protected postoperatively to allow for meniscal healing. Our postoperative protocol for isolated meniscal repair involves touch-down weight bearing for 6 weeks postoperatively. ROM is restricted from 0 to 30 degrees for the first 2 weeks followed by 0 to 90 degrees for the next 6 weeks. Progressive mobilization and strengthening are pursued from 6 to 12 weeks, and sports-specific therapy and agility exercises are initiated at 3 months under the direction of a physical therapist, provided sufficient strength has been achieved for dynamic knee stability. Return to sports is allowed at 4 to 5 months postoperatively, if there is full ROM, near-symmetric strength, no symptoms (pain, swelling, locking), and resolution of physical examination findings (joint line tenderness, McMurray maneuvers, terminal range joint line pain). Follow-up MRI is performed only in patients with persistent symptoms or concerning physical examination findings. Partial meniscectomy is performed for tears involving the inner 1/3 or middle 1/3 tears that are macerated, horizontal, degenerative, or complex. Care should be taken to preserve as much tissue as possible (Fig. 30-27). With horizontal tears, the smaller of the two leaves is resected. Rehabilitation after partial meniscectomy includes weight bearing as tolerated with crutches for comfort, ROM and strengthening. Return to sports and activities is based on the absence of physical examination findings and adequate rehabilitation, usually at 2 to 3 months postoperatively. Patients who have undergone complete or near-total meniscectomy, should be followed long-term and periodically into young adulthood, to assess the possible development of degenerative changes. Weight-bearing radiographs in slight flexion to measure any compromise in the joint space represent a standard monitoring approach. In symptomatic patients or those with loss of joint space or degenerative changes, such as early osteophytes, replacement with an allograft meniscus or synthetic scaffold transplant procedure may be considered. 
Figure 30-27
 
Complex inner 1/3 tear of the meniscus (A) treated with partial meniscectomy (B).
Complex inner 1/3 tear of the meniscus (A) treated with partial meniscectomy (B).
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Figure 30-27
Complex inner 1/3 tear of the meniscus (A) treated with partial meniscectomy (B).
Complex inner 1/3 tear of the meniscus (A) treated with partial meniscectomy (B).
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In children and adolescents, the emphasis should be on meniscal repair over meniscectomy whenever possible because of greater healing potential in this age group, the long life span of these patients, the poor results of total and near-total meniscectomy, and the lack of reassuring longer-term results of partial meniscectomy. Meniscal repair techniques include inside-out techniques, outside-in techniques, and all-inside techniques. Outside-in techniques can be useful for anterior horn medial or lateral meniscal tears. For body and posterior horn tears, the traditional technique of meniscal repair has been inside-out repair with vertical or horizontal sutures (Fig. 30-28). Zone-specific cannulae are helpful to direct the small caliber, flexible suture needles to the appropriate position to avoid neurovascular structures. In addition, we frequently make an incision posteromedially or posterolaterally to retrieve the suture needles and tie the sutures onto the joint capsule, thus protecting the saphenous nerve and vein medially and the peroneal nerve laterally. Newer all-inside devices have made the technique of meniscal repair more efficient, but a lack of longer-term studies makes the relative effectiveness unknown (Fig. 30-29). In addition, reports of articular cartilage damage from the heads of bioabsorbable arrows and darts exist,148,149 and these devices may cause slightly more trauma to the meniscal tissue than repair needles upon entry. Finally, many of the available devices extend too far through the capsule in the small pediatric knee, with potential for neurovascular injury. We prefer more recent all-inside suture devices with a low profile in the joint, and at times will utilize these for posterior horn tears in adolescent knees or the posterior horn portion of larger tears, with repair of the body through inside-out techniques. In place of a larger posterior incision, a smaller, portal-sized lateral or medial incision may be made, with retrieval of the percutaneous suture ends at the level of the capsule with a small curved clamp or arthroscopic probe. An arthroscopic knot pusher may be helpful to position the knots deep to these incisions, directly at their exit point through the capsule, to maintain optimal tightness of the repair suture. For smaller tears without substantial displacement, all-inside techniques are often used alone, whereas larger tears with displacement such as displaced bucket-handle tears will be addressed with an incision to safely accommodate all-inside technique throughout or in the above described “hybrid” manner with both all-inside (posterior horn) and inside-out (meniscal body) sutures. 
Figure 30-28
 
Longitudinal middle 1/3 tear of the meniscus (A) treated with inside-out meniscal repair (B).
Longitudinal middle 1/3 tear of the meniscus (A) treated with inside-out meniscal repair (B).
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Figure 30-28
Longitudinal middle 1/3 tear of the meniscus (A) treated with inside-out meniscal repair (B).
Longitudinal middle 1/3 tear of the meniscus (A) treated with inside-out meniscal repair (B).
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Figure 30-29
Longitudinal tear of the outer 1/3 of the posterior horn meniscus treated with all-inside fixation devices.
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Bucket-handle displaced tears with a locked knee are treated urgently to allow for reduction and meniscal repair, and to avoid further injury to the meniscus. Meniscal tears in association with ACL injuries are usually treated concurrently with ACL reconstruction. ACL reconstruction is essential to provide a stable environment for meniscal healing and prevention of further meniscal tears. Moreover, healing rates are higher with concurrent ACL reconstruction than with isolated meniscal repair, perhaps because of the healing environment of the associated postoperative hemarthrosis from the bone tunnels. For meniscal repair in association with ACL reconstruction, return to sports is dictated by the ACL reconstruction, usually at 6 months postoperatively. 

Postoperative Care for Meniscal Injuries

A variety of rehabilitation approaches may be employed in association with meniscus repair, with individualization of the regimen, depending on the severity of the tear and nature of the repair. Smaller tears that are discovered incidentally or well approximated by one or two repair sutures in association with ACL reconstruction may allow for normal weight bearing and advancement of ROM as those protocols not involving meniscus repair. However, given that most tears in children are larger and involve a number of inside-out repair sutures, the standard protocol involves protection of weight bearing for 6 weeks with crutches and limiting ROM to 0 to 90 degrees. 

Potential Pitfalls and Preventative Measures of Meniscal Injuries

Making the diagnosis of a meniscal tear can sometimes be difficult in the child or adolescent. The differential diagnosis is varied and includes other injuries and disorders that cause pain and swelling or that cause joint line pain. Physical examination findings can be variable. MRI scans must be carefully scrutinized by the orthopedist because of the relatively high prevalence of normal signal change in the posterior horns from the improved vascularity of the peripheral meniscal tissue, relative to adults. Extension of the meniscal signal to the superior or inferior edge of the meniscus must be confirmed before considering the MRI diagnostic of a meniscal tear. 
Total or near-total meniscectomy should be avoided in children and adolescents if at all possible to avoid the development of degenerative changes. Patients who have had near-total or total meniscectomy should be counseled regarding the risk of arthritis and the potential for meniscus replacement with allograft or synthetic scaffolds. 
Several technical pitfalls exist during meniscal repair. During inside-out meniscal repair of the posterior horn, a posterolateral incision should be made for lateral meniscus repair to avoid iatrogenic injury to the peroneal nerve and a posteromedial incision should be made for medial meniscus repair to avoid iatrogenic injury to the saphenous vein or nerve. During all-inside repair with meniscal repair devices, consideration must be given to the size of the implant relative to the pediatric knee. Implants that protrude too far may injure neurovascular structures or cause local irritation or cysts. Implants that are high-profile or protrude, may damage the articular surface of the femoral condyle. Sterile effusions and synovitis may occur with bioabsorbable implants (Table 30-20). 
 
Table 30-20
Meniscal Injuries
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Table 30-20
Meniscal Injuries
Potential Pitfalls and Preventions
Pitfall Preventions
Pitfall no. 1: Posteromedial (saphenous nerve) or posterolateral (peroneal) nerve injury with inside-out repair of posterior horn Prevention 1a: Incision to achieve adequate retraction/protection of structures (assistant must see posterior capsule)
Pitfall no. 2: Popliteal artery injury with all-inside repair of posterior horn Prevention 2a: Cut protective cannula to appropriate length for size of patient (especially in pediatric knee)
Prevention 2b: Direct cannula/device in appropriate vector to avoid central third of posterior knee
Pitfall no. 3: Chondral injury to medial femoral condyle or lateral femoral condyle Prevention 3a: For tight medial compartment, consider trephination of MCL to open joint space, with post-op bracing
Prevention 3b: For tight lateral compartment, elevation of foot in figure-four position
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Treatment-Specific Outcomes for Meniscal Injuries

The prognosis after complete or near-total meniscectomy is poor with numerous reports5,25,52,112,172,208,213,229,260,274,326,328,380,390,393,396,417 indicating poor long-term results with degenerative changes. The prognosis of meniscus repair in appropriately selected cases is good. Mintzer and Richmond reported on meniscal repair in 29 patients under the age of 18 (25 had closed physes and 17 underwent concomitant ACL reconstruction). They reported 100% clinical healing at an average follow-up of 5 years.284 Noyes and Barber-Westin looked at meniscal tears extending into the avascular zone in patients younger than 20 years old.303,338 Skeletal maturity had been reached in 88%. Their success rate in this group was 75%. This study showed a higher rate of healing with concomitant ACL reconstruction. Despite these historical improved results with concomitant ACL-R, a recent study in children230 reported a 26% failure rate in meniscal repair with ACL-R, with risk factors for failure being complex or bucket-handle tears. Other studies of pediatric populations392 have suggested that the time to return to sports is longer (8.2 months) in patients with meniscus repair performed with ACL-R, compared with those with isolated meniscus repairs (5.6 months). Eggli et al.112 found an overall healing rate for repair of isolated meniscal tears of 88% in patients younger than 30, compared to 67% in patients over age 30. Johnson et al.190 showed a 76% healing rate at an average follow-up of greater than 10 years in a population that averaged 20 years old at the time of surgery. Factors that have been shown to correlate with increased healing of meniscal repairs include: Younger age, peripheral tears, repairs of the lateral meniscus, concomitant ACL reconstruction, time from injury to surgery of less than 8 weeks, and tear length of less than 2.5 cm.3,69,71,112,148,149,190,381 One recent series of 25 meniscal tears in children228 demonstrated that healing rates of lateral and meniscal repairs were comparably high, with a mean Lysholm score of 95, regardless of zone or pattern, but that recurrent tears are more likely to occur in the body of the meniscus than the anterior or posterior horn. 

Management of Expected Adverse Outcomes and Unexpected Complications in Meniscal Injuries

Complications after either arthroscopic or open repair may include hemorrhage, infection, persistent effusion, stiffness, and nerve injury. Both the popliteal artery and inferior geniculate branches are close to the posterior capsule and are easily lacerated. Postoperative infection should be suspected if swelling or pain persists with an elevated temperature. Swelling is best treated with external compression dressings, and stiffness is best prevented by appropriate postoperative rehabilitation (Table 30-21). 
 
Table 30-21
Meniscal Injuries
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Table 30-21
Meniscal Injuries
Common Adverse Outcomes and Complications
Failure to heal/retear of meniscus repair
Neurovascular injury (saphenous nerve, peroneal nerve, popliteal artery)
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Introduction to Ligament Injuries

Ligamentous injuries of the knee in children and adolescents were once considered rare.83,327 Tibial eminence avulsion fractures were considered the pediatric ACL injury equivalent.215,219,220,327 However, major ligamentous injuries are being seen with increased frequency and have received increased attention.13,18,21,23,29,42,47,49,55,62,64,79,98,109,113,114,115,117,128,145,152,154,169,178,186,193,194,198,206,212,222,223,227,245,246,250,265,267,269,270,281,282,285,287,315,324,329,343,354,356,358,359,366,367,370,377,389,399,400,407 The increased frequency of diagnosis of knee ligament injuries in children is likely related to increased participation in youth sports at higher competitive levels, the advent of arthroscopy and MRI, and an increased awareness of injuries in this age group. 
ACL injury has been reported in 10% to 65% of pediatric knees with acute traumatic hemarthroses in series ranging from 35 to 138 patients.115,212,214,250,370,389 Stanitski et al.369 reported 70 children and adolescents with acute traumatic knee hemarthroses; arthroscopic examination revealed ACL injuries in 47% of those 7 to 12 years of age and in 65% of those 13 to 18 years of age. They determined that boys 16 to 18 years of age engaged in organized sports and girls 13 to 15 years of age engaged in unorganized sports had the highest risk for complete ACL tears; 60% of these patients had isolated ACL tears. 
Injury patterns in the skeletally immature knee are dependent on the loading conditions and the developmental anatomy. Fractures of the epiphyses or physes about the knee are more common than ligamentous injuries alone. Historical literature suggested that isolated knee ligament injury in children younger than 14 years of age was rare because of the relative strength of the ligaments compared to the physes.108,194,269,400 However, a recent report investigating rates of pediatric knee injuries presenting to a large children's hospital emergency room suggested that over a 12-year period, the rate of tibial spine fractures increased by 1%, whereas cases of ACL tears had increased by 11%.342 The inherent ligamentous laxity in children also may offer some protection against ligament injury, but this decreases as the adolescent approaches skeletal maturity. Faster loading conditions favor ligamentous injuries, whereas slower loading conditions favor fracture. Narrowing of the intercondylar notch during skeletal development may also predispose to ligamentous injury.219 Fractures and ligamentous injuries may also occur concurrently. Bertin and Goble,49 after reviewing 29 fractures, concluded that physeal fractures about the knee are associated with a higher incidence of ligamentous injury. In addition, tibial eminence fractures, even after anatomic fixation and healing, tend to demonstrate persistent ACL laxity.215 
Before the 1990s, reports of ligamentous injuries in children were isolated case reports, and most recommendations were for conservative treatment. More recent reports have indicated an increased awareness of ligament injury in association with physeal fractures,83 as well as isolated ligament injuries, and a more aggressive approach, especially in adolescents approaching skeletal maturity.47,113,114,287,356,377 Management of some of these injuries, particularly ACL injuries in skeletally immature patients, is controversial. Nonreconstructive treatment of complete tears typically results in recurrent functional instability with risk of injury to meniscal and articular cartilage. A variety of reconstructive techniques have been utilized, including physeal-sparing, partial transphyseal, and transphyseal methods using various grafts. Conventional adult ACL reconstruction techniques risk potential iatrogenic growth disturbance due to physeal violation. Growth disturbances after ACL reconstruction in skeletally immature patients have been reported. 

Assessment of Ligament Injuries

Mechanism of Injury for Ligament Injuries

The mechanism of ligamentous injury varies with the child's age. In younger children, ligamentous injury is often associated with significant polytrauma. Clanton et al.79 reported that five of nine children with acute knee ligament injuries were struck by automobiles. In contrast, adolescents are more likely to sustain ligamentous injury during contact sports or sports that require “cutting” maneuvers while running.361 As exact a description as possible of the mechanism of injury should be obtained, including the position of the knee at the time of injury, the weight-supporting status of the injured knee, whether the force applied was direct or indirect (generated by the patient's own momentum), and the position of the extremity after injury. Older adolescents may describe the knee as buckling or moving or jumping out of place and can usually relate the location and severity of their pain as well as the time between injury and onset of pain and swelling. Rapid intra-articular effusion within 2 hours of injury suggests hemarthrosis, most commonly from injury to the ACL. 
Palmer313 described four mechanisms capable of producing disruption of the ligamentous structures about the knee: Abduction, flexion, and internal rotation of the femur on the tibia; adduction, flexion, and external rotation of the femur on the tibia; hyperextension; and anterior–posterior displacement. The most common mechanism in adolescents is abduction, flexion, and internal rotation of the femur on the tibia occurring during athletic competition when the weight-bearing extremity is struck from the lateral side. The classic abduction, flexion, and internal rotation injury in the adolescent may cause the “unhappy triad” of O'Donoghue: Tears of the MCL and ACL and injury to the medial meniscus. 
Isolated injury of the LCL is rare in children, but a direct blow to the medial aspect of the knee may tear the LCL, usually with avulsion from the fibula or a physeal injury through the distal femur.180 Isolated injuries of the ACL and PCL are more common174,180,269 Disruption of the ACL with minimal injury to other supporting structures may be caused by hyperextension, marked internal rotation of the tibia on the femur, and pure deceleration. In contrast, isolated injury of the PCL most often is caused by a direct blow to the front of the tibia with the knee in flexion. The most extensive description of PCL injuries in children to date recently demonstrated that the majority of these injuries are sustained during sports, with less common causes including falls from height, trampoline injuries, and motor vehicle accidents.224 

Associated Injuries with Ligament Injuries

Common injuries associated with ACL tear include meniscus injuries (lateral more commonly than medial, in the acute setting), and MCL tears. Posterolateral corner and PCL injuries frequently occur in conjunction with each other. Complete and partial knee dislocations may have a variety of patterns of associated injuries, as described above. 

Signs and Symptoms of Ligament Injuries

Both lower extremities are examined for comparison. Large areas of ecchymosis and extensive effusion are easily identified, but smaller areas may require careful palpation. In general, acute hemarthrosis suggests rupture of a cruciate ligament, an osteochondral fracture, a peripheral tear in the vascular portion of a meniscus, or a tear in the deep portion of the joint capsule.88,91 The absence of hemarthrosis is not, however, an indication of a less severe ligament injury, because with complete disruption, the blood in the knee joint may escape into the soft tissues rather than distend the joint. Palpation of the collateral ligaments and their bony origins and insertions should locate tenderness at the site of the ligament injury. A defect in the collateral ligaments often can be felt if the MCL is avulsed from its insertion on the tibia or if the LCL is avulsed from the fibular head. If the neurovascular status is normal, stability should be evaluated by varus/valgus stress testing, which may be done immediately after injury in cooperative adolescents but can be more difficult in younger ages or those with significant pain. Beginning the examination by testing the uninjured knee often calms patients and makes them more cooperative; it also establishes a baseline for assessing the ligamentous stability of the injured knee as knee laxity varies during childhood.168 Valgus and varus stress testing of the MCL and LCL should be done at both 20 degrees of flexion and full extension, which may demonstrate gross instability if there is cruciate ligament rupture as well (Fig. 30-30). 
Figure 30-30
Valgus stress test of medial collateral ligament.
 
Extremity is abducted off table, knee is flexed to 20 degrees, and valgus stress is applied. A: Frontal view. B: Lateral view.
Extremity is abducted off table, knee is flexed to 20 degrees, and valgus stress is applied. A: Frontal view. B: Lateral view.
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Figure 30-30
Valgus stress test of medial collateral ligament.
Extremity is abducted off table, knee is flexed to 20 degrees, and valgus stress is applied. A: Frontal view. B: Lateral view.
Extremity is abducted off table, knee is flexed to 20 degrees, and valgus stress is applied. A: Frontal view. B: Lateral view.
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The anterior drawer test, as described by Slocum, is the classic maneuver for testing the stability of the ACL (Fig. 30-31). The Lachman and pivot-shift tests, however, are considered more sensitive for evaluating ACL injury when the examination can be done in a relaxed, cooperative adolescent, but may be confounded if there is significant guarding. The posterior drawer test (Fig. 30-32), quad active test, and assessment of the posterior sag sign are the key maneuvers for evaluation of the integrity of the PCL. 
Figure 30-31
Anterior drawer test of anterior cruciate ligament.
 
Foot is positioned in internal, external, and neutral rotation during examination. With anterior cruciate insufficiency, an anterior force (A) displaces the tibia forward (B).
Foot is positioned in internal, external, and neutral rotation during examination. With anterior cruciate insufficiency, an anterior force (A) displaces the tibia forward (B).
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Figure 30-31
Anterior drawer test of anterior cruciate ligament.
Foot is positioned in internal, external, and neutral rotation during examination. With anterior cruciate insufficiency, an anterior force (A) displaces the tibia forward (B).
Foot is positioned in internal, external, and neutral rotation during examination. With anterior cruciate insufficiency, an anterior force (A) displaces the tibia forward (B).
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Figure 30-32
Posterior cruciate ligament injury.
 
Note posterior sagging of the tibia with posterior cruciate injury.
Note posterior sagging of the tibia with posterior cruciate injury.
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Figure 30-32
Posterior cruciate ligament injury.
Note posterior sagging of the tibia with posterior cruciate injury.
Note posterior sagging of the tibia with posterior cruciate injury.
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Imaging and Other Diagnostic Studies for Ligament Injuries

Anteroposterior and lateral radiographs are obtained when any ligament injury of the knee is suspected in children. The radiographs are carefully inspected for evidence of occult epiphyseal or physeal fractures or bony avulsions. The intercondylar notch, especially, is inspected to detect a tibial spine fracture, which is confirmed by anterior or posterior instability on physical examination. Occasionally, a small fragment of bone avulsed from the medial femur or proximal tibia indicates injury to the MCL. Similarly, avulsion of a small fragment of bone from the proximal fibular epiphysis or the lateral aspect of the distal femur may indicate LCL injury. 
In children with open physes, stress radiographs may be considered to evaluate medial and lateral instabilities associated with physeal fractures. MRI is frequently used to further delineate ligamentous injuries in the knee. MRI should be used to confirm an uncertain diagnosis or to gain further information that may affect treatment. Conventional MRI can give information regarding MCL injury, LCL injury, ACL injury, PCL injury, posterolateral corner injury, bone bruising, chondral injury, and meniscal injury. 

Classification of Ligament Injuries

Classification of knee ligament injuries is based on the severity of the injury, the specific anatomic location of the injury, and the direction of the subsequent instability caused by an isolated ligament injury or combination of ligament injuries. 
A first-degree ligament sprain is a tear of a minimal number of fibers of the ligament with localized tenderness but no instability. A second-degree sprain is disruption of more ligamentous fibers, causing asymmetry with stress testing, compared with the contralateral knee, but minimal or minor instability. A third-degree sprain is complete disruption of the ligament, resulting in gross instability. Although difficult to assess clinically, the degree of sprain also is determined with collateral ligaments during stress testing by the amount of separation of the joint surfaces: First-degree sprain, 5 mm or less (normal/baseline); second-degree sprain, 5 to 10 mm; and third-degree sprain, more than 10 mm. 
The anatomic classification of knee ligament injuries (femoral attachment avulsion, midsubstance/interstitial tear, or tibial attachment avulsion) describes the exact location of the disruption,126 whether in the MCL (Fig. 30-33), ACL, LCL (Fig. 30-34), or PCL. Finally, the instability of the knee joint caused by the ligament disruption may be classified as having one-plane instability (simple or straight), rotary instability (anteromedial, anterolateral, posterolateral, or posteromedial), or combined instability (anterolateral–posterolateral, anterolateral–anteromedial, or anteromedial–posteromedial),173,360 which may be helpful in planning treatment. 
Figure 30-33
Medial collateral ligament injury.
 
A: Femoral origin. B: Middle portion. C: Tibial insertion.
A: Femoral origin. B: Middle portion. C: Tibial insertion.
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Figure 30-33
Medial collateral ligament injury.
A: Femoral origin. B: Middle portion. C: Tibial insertion.
A: Femoral origin. B: Middle portion. C: Tibial insertion.
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Figure 30-34
Lateral collateral ligament injury.
 
A: Femoral origin. B: Middle portion. C: Fibular insertion.
A: Femoral origin. B: Middle portion. C: Fibular insertion.
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Figure 30-34
Lateral collateral ligament injury.
A: Femoral origin. B: Middle portion. C: Fibular insertion.
A: Femoral origin. B: Middle portion. C: Fibular insertion.
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Outcome Measures for Ligament Injuries

Even though retear of a reconstructed ligament, particularly the ACL, is a well-described phenomenon that can occur even without any technical error or oversight in rehabilitation, it remains the most important assessment of outcome. However, for athletes, particularly elite athletes, return to sports and the ability to play at the previous level of competition may be important metrics as well. On a longer-term basis, standard outcome measures, such as functional knee measures (the Pedi-IKDC225 and Lysholm364 knee scores), should be used to assess results and paired with the Marx or Tegner activity scores264 to assess surgical outcomes. 

Pathoanatomy and Applied Anatomy Relating to Ligament Injuries

The MCL and LCL of the knee originate from the distal femoral epiphysis and insert into the proximal tibial and fibular epiphyses, respectively, except for the superficial portion of the MCL, which inserts into the proximal tibial metaphysis distal to the physis (Fig. 30-35). In children, these ligaments are generally stronger than the physes, and significant tensile stresses usually produce epiphyseal or physeal fractures rather than ligamentous injury. The ACL originates from the posterolateral intercondylar notch and inserts into the tibia slightly anterior to the intercondylar eminence. The ACL in children has collagen fibers continuous with the perichondrium of the tibial epiphyseal cartilage; in adults, the ligament inserts directly into the proximal tibia by way of Sharpey fibers. This anatomic difference probably accounts for the fact that fracture of the anterior tibial spine occurs more frequently in children than does ACL injury. The PCL originates from the anteromedial aspect of the intercondylar notch and attaches on the posterior aspect of the proximal tibial epiphysis. 
Figure 30-35
Anatomy of medial and collateral ligaments of the knee in the adolescent.
 
A: Superficial origins and insertions. B: Capsular and meniscal attachments.
A: Superficial origins and insertions. B: Capsular and meniscal attachments.
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Figure 30-35
Anatomy of medial and collateral ligaments of the knee in the adolescent.
A: Superficial origins and insertions. B: Capsular and meniscal attachments.
A: Superficial origins and insertions. B: Capsular and meniscal attachments.
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Treatment Options for Ligament Injuries

Nonoperative Treatment of Ligament Injuries

Indications/Contraindications

Isolated collateral ligament injuries are usually successfully treated with bracing and rehabilitation (Table 30-22). 
 
Table 30-22
Ligament Injuries
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Table 30-22
Ligament Injuries
Nonoperative Treatment
Indications Relative Contraindications
Partial ACL tear (<50% fibers, negative pivot-shift test, younger child) >50% tear, positive pivot shift, older adolescent
Symptomatic instability
Associated injury requiring operative treatment with prolonged rehabilitation regimen and maximum knee stability (e.g., meniscus repair)
Primary (midsubstance) PCL tear Complete bony avulsion injury of footprint
Partial/incomplete LCL/PCL injury Symptomatic instability despite prolonged PT regimen (quad strengthening)
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Outcomes

Nonoperative management of partial tears may be successful in some patients, with better results expected for younger children, those with a negative pivot-shift test, and those with less than 50% of the ACL fibers ruptured.222 The prognosis of nonoperative management of complete tears in skeletally immature patients is generally poor, with recurrent instability leading to further meniscal and chondral injuries, which has implications in terms of development of degenerative joint disease.13,145,186,236,270,282,285,324 

Operative Treatment of Ligament Injuries

Indications/Contraindications

Complete collateral ligament tears or avulsions of the bony attachments that are severely displaced or associated with chronic instability warrant consideration of acute repair or chronic reconstruction, respectively. 

Surgical Procedure—ACL

Preoperative Planning (Table 30-23
 
Table 30-23
Operative Treatment of Ligament Injuries-ACL
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Table 30-23
Operative Treatment of Ligament Injuries-ACL
Preoperative Planning Checklist
  •  
    OR table: Standard
  •  
    Position/positioning aids: Lateral thigh post
  •  
    Fluoroscopy location: N/A
  •  
    Equipment: ACL drilling guide system, interference screws
  •  
    Tourniquet (sterile/nonsterile): Nonsterile, thigh
X

Positioning

Standard positioning for arthroscopy is utilized, though some surgeons prefer a circumferential knee holder or standard table placed in “the ACL position,” which involves a small amount of Trendelenburg angulation to the table, with the foot of the table dropped to the floor, with the contralateral knee in a well-leg holder or hanging free as well. 

Surgical Approaches and Technique

The general approach to complete ACL ruptures in skeletally immature children has evolved over the last two to three decades, and has been the source of considerable controversy. Nonoperative management of partial tears may be successful in some patients.222 However, nonoperative management of complete tears in skeletally immature patients, which may include functional bracing, physical therapy, and activity modification, generally has a poor prognosis, with recurrent instability leading to further meniscal and chondral injuries which has implications in terms of development of degenerative joint disease.13,145,186,270,282,285,324 Graf et al., Mizuta et al., and Janarv et al.145,186,285 have reported instability symptoms, subsequent meniscal tears, decreased activity level, and need for ACL reconstruction in the majority of skeletally immature patients treated nonoperatively in a series of 8, 18, and 23 patients, respectively. Similarly, when comparing the results of operative versus nonoperative management of complete ACL injuries in adolescents, McCarroll et al.270 and Pressman et al.324 found that those managed by ACL reconstruction had less instability, higher activity and return to sport levels, and lower rates of subsequent reinjury and meniscal tears. Additional studies have found that a longer duration between the time of ACL injury and that of reconstructive surgery is associated with higher rates of meniscal and chondral injury in both children106,236,282 and the general athletic population.24 
Conventional surgical reconstruction techniques risk potential iatrogenic growth disturbance due to physeal violation. Cases of growth disturbance have been reported in animal models109,152,169 and clinical series.223,227,245 Animal models have demonstrated mixed results regarding growth disturbances from soft tissue grafts across the physes. In a canine model with iliotibial band grafts through 5/32-in tunnels, Stadelmaier et al.366 found no evidence of growth arrest in the four animals with soft tissue graft across the physis, whereas the four animals with drill holes and no graft demonstrated physeal arrest. In a sheep model of transphyseal reconstruction, Seil et al.347 did not find clinically relevant growth disturbances despite consistent physeal damage. In a rabbit model using a semitendinosus graft through 2-mm tunnels, Guzzanti et al.152 did have cases of growth disturbance, however these were not common: 5% relative extremity shortening (1/21) and 10% distal femoral valgus deformity (2/21). Janarv et al.188 quantified the size of various transphyseal tunnels as a percentage of the total cross-sectional area of the physis, and reported that 7% to 9% as was the lower threshold at which growth disturbances could be expected in a rabbit model. Examining the effect of a tensioned soft tissue graft across the physis, Edwards et al.110 found a substantial rate of deformity. In a canine model with iliotibial band graft tensioned to 80 N, these investigators found significant increases, compared to the nonoperated control limb, in distal femoral valgus deformity and proximal tibial varus deformity despite no evidence of a bony bar. Similarly, Houle et al.169 reported growth disturbance after a tensioned tendon graft in a bone tunnel across the rabbit physis. A recent radiologic study419 investigated 43 pubertal skeletally immature patients who underwent transphyseal ACL reconstruction with metaphyseal fixation of quadruple hamstring autograft. The authors identified MRI evidence of focal bone bridges within or adjacent to the femoral or tibial tunnels in 12% of patients. Although no gross growth disturbances were perceived clinically, premature physeal closure was identified radiologically in two of the patients, all of whom had less than 3 years of growth remaining, by bone age assessment. These data, derived from bone tunnels with cross-sectional areas all under 3% of that of the physes (significantly lower than the threshold previously identified by Janarv et al.188), underscore the potential adverse sequelae of transphyseal techniques in younger patients with more significant growth remaining. 
Despite these published basic science and radiologic data, clinical reports of growth deformity after ACL reconstruction remain relatively sparse, in part because most authors, secondary to early reports of growth-related complications, have exercised caution in surgeries compromising physeal integrity. Lipscomb and Anderson245 reported one case of 20-mm shortening in a series of 24 skeletally immature patients reconstructed with transphyseal semitendinosus and gracilis grafts. This was associated with staple graft fixation across the physis itself. Koman and Sanders227 reported a case of distal femoral valgus deformity requiring osteotomy and contralateral epiphysiodesis after transphyseal reconstruction with a doubled semitendinosus graft. This case was also associated with fixation across the distal femoral physis. Kocher et al.223 reported an additional 15 cases of growth disturbances gleaned from a questionnaire of expert experience, including eight cases of distal femoral valgus deformity with an arrest of the lateral distal femoral physis, three cases of tibial recurvatum with an arrest of the tibial tubercle apophysis, two cases of genu valgum without arrest because of a lateral extra-articular tether, and two cases of leg length discrepancy (one shortening and one overgrowth). Associated risk factors for disturbance or deformity included fixation hardware placed across the lateral distal femoral physis in three cases, bone plugs of a patellar tendon graft across the distal femoral physis in three cases, large (12 mm) tunnels in two cases, lateral extra-articular tenodesis in two cases, fixation hardware across the tibial tubercle apophysis in two cases, of the over-the-top femoral position in one case, and suturing near the tibial tubercle apophysis in one case. 
Surgical techniques to address ACL insufficiency in skeletally immature patients include primary repair, extra-articular tenodesis, transphyseal reconstruction, partial transphyseal reconstruction, and physeal-sparing reconstruction. Primary ligament repair79,117 and extra-articular tenodesis alone145,270 have had poor results in children and adolescents, similar to adults. Transphyseal reconstructions with tunnels that violate both the distal femoral and proximal tibial physes have been performed with hamstrings autograft, patellar tendon autograft, and allograft tissue.13,23,29,109,128,226,243,265,270,354,358,367,399 Partial transphyseal reconstructions violate only one physis with a tunnel through the proximal tibial physis and over-the-top positioning on the femur or a tunnel through the distal femoral physis with an epiphyseal tunnel in the tibia.21,55,154 A variety of physeal-sparing reconstructions have been described to avoid tunnels across either the distal femoral or proximal tibial physis.18,64,98,153,206,216,217,237,281,315,389 
In prepubescent patients, physeal-sparing techniques have been described that utilize hamstrings tendons under the intermeniscal ligament and over-the-top on the femur, through all-epiphyseal femoral and tibial tunnels, and with a femoral epiphyseal staple.18,64,98,153,206,216,217,281,315,389 In adolescent patients with growth remaining, transphyseal reconstructions have been performed with hamstrings autograft, patellar tendon autograft, quadriceps tendon autograft, and allograft tissue.13,23,29,109,128,135,136,226,265,270,354,358,367,399 In addition, partial transphyseal reconstructions have been described with a tunnel through the proximal tibial physis and over-the-top positioning on the femur or a tunnel through the distal femoral physis with an epiphyseal tunnel in the tibia (Table 30-24).21,55,154,246 
Table 30-24
Operative Treatment of Ligament Injuries—IT Band Physeal-sparing ACL Reconstruction
Surgical Steps
  •  
    (If positive Lachman/pivot-shift tests on examination under anesthesia), expose distal ITB
  •  
    Leave distal attachment to ITB intact, detach 1-cm band of ITB proximally with meniscotome/closed tendon stripper, tubularize/tag free end with no. 2 braided suture
  •  
    Perform diagnostic arthroscopy, debride ACL tissue/stump
  •  
    Retrieve free end of ITB autograft with extralong curved snap through posterolateral capsular aperture (over-the-top position)
  •  
    Create 2-cm trough in proximal medial tibial cortex (distal to physis, medial to tibial tubercle apophysis) with adjacent periosteal flaps
  •  
    Use curved snap to create space for graft passage supraperiosteally on proximal tibial, under intermeniscal ligament intra-articularly
  •  
    Create trough (with curved, rat-toothed rasp)in proximal tibial epiphysis at site of ACL footprint via tibial
  •  
    Use curved snap to pass free limb of graft from inside joint to proximal tibial incision
  •  
    With knee in 70–90 degrees flexion, suture proximal ITB to lateral capsule and periosteum adjacent to capsular aperture
  •  
    With knee in 20–30 degrees flexion, suture free end of ITB to proximal tibial periosteum on maximum tension
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Author's Preferred Treatment of Ligament Injuries

Medial Collateral Ligament

Isolated grade I or II sprains of the MCL are treated with a hinged knee brace for 1 to 3 weeks, with a shorter course of crutches for comfort. Return to athletic activities is allowed when a full, painless ROM is achieved and the patient can run and cut without pain. Isolated complete (grade III) disruption of the MCL can be treated with 6 weeks of immobilization in a hinged knee brace followed by formal physical therapy focused on rehabilitation of the quadriceps muscles and knee motion, provided this is an isolated injury. The physician must ensure that there is no associated injury to the ACL before pursuing nonoperative treatment for a grade III MCL injury. Grade III disruptions of the MCL in adolescents associated with injury of the ACL are usually treated with ACL reconstruction (ACL-R) without formal MCL repair, but medial stability must be gently assessed during the examination under anesthesia prior to the ACL-R procedure, which should be delayed at least 4 to 6 weeks following injury to ensure resolution of the inflammatory phase of injury, resolution of full ROM, and adequate time for early MCL healing. While some authors do not routinely employ hinged knee bracing following ACL-R, in the presence of an MCL tear, we recommend protecting the MCL with a hinged knee brace to complete the collateral ligament's healing process in the early postoperative period. 

Anterior Cruciate Ligament

The overall goal of treatment of ACL rupture is reestablishment of a functional knee without progressive intra-articular damage or predisposition to premature osteoarthrosis. All skeletally immature patients (i.e., those with open physes) are not the same. Some have a tremendous amount of growth remaining, whereas others are essentially done growing. The consequences of growth disturbance in the former group would be severe, requiring osteotomy and/or limb lengthening. However, the consequences of growth disturbance in the latter group would be minimal. When treating a skeletally immature athlete with an ACL injury, it is important to know their chronologic age, their skeletal age, and their physiologic age. Skeletal age can be determined from an anteroposterior radiograph of the left hand and wrist as per the atlas of Greulich and Pyle.150 Alternatively, skeletal age can be estimated from knee radiographs as per the atlas of Pyle and Hoerr.325 Physiologic age is established using the Tanner staging system (Table 30-25).379 In the office, the patient can be informally staged by questioning. In the operating room, after the induction of anesthesia, Tanner staging can be confirmed. The vast majority of ACL injuries in skeletally immature patients occur in adolescents. The management of these injuries in preadolescent children can be more challenging, given the poor prognosis with nonoperative management, the substantial growth remaining, and the consequences of potential growth disturbance. 
Table 30-25
Tanner Staging Classification of Secondary Sexual Characteristics
Tanner Stage Male Female
Stage 1 (Prepubertal) Growth
Development
5–6 cm/y
Testes <4 mL or <2.5 cm
No pubic hair
5–6 cm/y
No breast development
No pubic hair
Stage 2 Growth 5–6 cm/y 7–8 cm/y
Development Testes 4 mL or 2.5–3.2 cm
Minimal pubic hair at base of penis
Breast buds
Minimal pubic hair on labia
Stage 3 Growth 7–8 cm/y 8 cm/y
Development Testes 12 mL or 3.6 cm
Pubic hair over pubis
Voice changes
Muscle mass increases
Elevation of breast; areolae enlarge
Pubic hair of mons pubis
Axillary hair
Acne
Stage 4 Growth 10 cm/y 7 cm/y
Development Testes 4.1–4.5 cm
Pubic hair as adult
Axillary hair
Acne
Areolae enlarge
Pubic hair as adult
Stage 5 Growth No growth No growth
Development Testes as adult
Pubic hair as adult
Facial hair as adult
Mature physique
Adult breast contour
Pubic hair as adult
Other Peak height velocity: 13.5 y Adrenarche: 6–8 y
Menarche 12.7 y
Peak height velocity: 11.5 y
X
Our algorithm to ACL-R in the skeletally immature patient is based on physiologic age (Fig. 30-36). However, regardless of age, because of growing evidence that prolonged delays in timing of ACL-R is associated with great risk of meniscal and chondral injuries in children and adolescents,106,236 we advise that the surgery be performed relatively soon after preoperative rehabilitation to restore ROM and allow resolution of swelling. In prepubescent patients, we perform a physeal-sparing, combined intra-articular and extra-articular reconstruction utilizing autogenous iliotibial band.216,217 In adolescent patients with significant growth remaining, we perform transphyseal ACL reconstruction with autogenous hamstrings tendons with fixation away from the physes.226 In older adolescent patients approaching skeletal maturity, we perform conventional adult ACL reconstruction with interference screw fixation using either autogenous central third patellar tendon or autogenous hamstrings. 
Figure 30-36
Algorithm for ACL reconstruction in skeletally immature patients.
Flynn-ch030-image036.png
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In skeletally immature patients as in adult patients, acute ACL reconstruction is not performed within the first 3 weeks after injury to minimize the risk of arthrofibrosis. Prereconstructive rehabilitation is performed to regain ROM, decrease swelling, and resolve the reflex inhibition of the quadriceps. Rarely, consideration of staged ACL reconstruction may be given in some cases if there is a displaced, bucket-handle tear of the meniscus that requires extensive repair to protect the meniscal repair from the early mobilization prescribed by ACL reconstruction. Skeletally immature patients must be emotionally mature enough to actively participate in the extensive rehabilitation required after ACL reconstruction. 

Prepubescent Patient: Physeal-sparing ACL Reconstruction

In the prepubescent patient with a complete ACL tear, we perform a physeal-sparing, combined intra-articular and extra-articular reconstruction utilizing autogenous iliotibial band (Fig. 30-37).216,217 This procedure is a modification of the combined intra-articular and extra-articular reconstruction described by MacIntosh and Darby.253 Our rationale for utilization of this technique is to provide knee stability and improve function in prepubescent skeletally immature patients with complete intrasubstance ACL injuries while avoiding the risk of iatrogenic growth disturbance by violating the distal femoral and/or proximal tibial physes. In our opinion, the consequences of potential iatrogenic growth disturbance caused by transphyseal reconstruction in these young patients is prohibitive, and the outcomes of this physeal-sparing technique216 are comparable or superior to many series of adult-type reconstructions. Moreover, in a recent cadaveric kinematics study, Kennedy et al.200 demonstrated that the iliotibial band physeal-sparing construct better restored both anterior–posterior and rotational stability than the all-epiphyseal and transphyseal over-the-top reconstruction techniques. 
Figure 30-37
Physeal-sparing, combined intra-articular and extra-articular reconstruction utilizing autogenous iliotibial band for prepubescents.
 
A: The iliotibial band graft is harvested free proximally and left attached to Gerdy tubercle distally. B: The graft is brought through the knee in the over-the-top position posteriorly. C: The graft is brought through the knee and under the intermeniscal ligament anteriorly. D: Resulting intra-articular and extra-articular reconstruction.
A: The iliotibial band graft is harvested free proximally and left attached to Gerdy tubercle distally. B: The graft is brought through the knee in the over-the-top position posteriorly. C: The graft is brought through the knee and under the intermeniscal ligament anteriorly. D: Resulting intra-articular and extra-articular reconstruction.
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Figure 30-37
Physeal-sparing, combined intra-articular and extra-articular reconstruction utilizing autogenous iliotibial band for prepubescents.
A: The iliotibial band graft is harvested free proximally and left attached to Gerdy tubercle distally. B: The graft is brought through the knee in the over-the-top position posteriorly. C: The graft is brought through the knee and under the intermeniscal ligament anteriorly. D: Resulting intra-articular and extra-articular reconstruction.
A: The iliotibial band graft is harvested free proximally and left attached to Gerdy tubercle distally. B: The graft is brought through the knee in the over-the-top position posteriorly. C: The graft is brought through the knee and under the intermeniscal ligament anteriorly. D: Resulting intra-articular and extra-articular reconstruction.
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The procedure is performed under general anesthesia, with or without a femoral nerve block for regional anesthesia, as an overnight observation procedure to ensure good pain control and understanding and compliance with rehabilitation protocols. The child is positioned supine on the operating table with a pneumatic tourniquet about the upper thigh which is used routinely. Examination under anesthesia is performed to confirm ACL insufficiency. 
First, the iliotibial band graft is obtained. An incision of approximately 6 cm is made obliquely from the lateral joint line to the superior border of the iliotibial band (Fig. 30-38A). Proximally, the iliotibial band is separated from subcutaneous tissue using a periosteal elevator under the skin of the lateral thigh. The anterior and posterior borders of the iliotibial band are incised and the incisions carried proximally under the skin using curved meniscotomes (Fig. 30-38A). The iliotibial band is detached proximally under the skin using a curved meniscotome or an open tendon stripper. Alternatively, a counterincision can be made at the upper thigh to release the tendon. The iliotibial band is left attached distally at Gerdy tubercle. Dissection is performed distally to separate the iliotibial band from the joint capsule and from the lateral patellar retinaculum (Fig. 30-38B). The free proximal end of the iliotibial band is then tubularized with a no. 2 high-tensile strength braided suture with a whip stitch construct. 
Figure 30-38
Technique of physeal-sparing combined intra-articular and extra-articular anterior cruciate ligament reconstruction using iliotibial band.
 
A: The iliotibial band is harvested through an oblique lateral knee incision. B: The iliotibial band graft is detached proximally, left attached distally, and dissected free from the lateral patellar retinaculum. C: The iliotibial band graft is brought through the knee using a full-length clamp placed from the anteromedial portal through the over-the-top position into the lateral incision. D: The graft is then brought through the over-the-top position. E: A clamp is placed from a proximal medial leg incision under the intermeniscal ligament. A groove is made in the anteromedial tibial epiphysis using a rasp. F: The graft is brought through the knee in the over-the-top position and under the intermeniscal ligament. G: The graft is brought out the proximal medial leg incision. H: It is sutured to the intermuscular septum and periosteum of the lateral femoral condyle through the lateral knee incision and it is sutured in a trough to the periosteum of the proximal medial tibial metaphysis.
A: The iliotibial band is harvested through an oblique lateral knee incision. B: The iliotibial band graft is detached proximally, left attached distally, and dissected free from the lateral patellar retinaculum. C: The iliotibial band graft is brought through the knee using a full-length clamp placed from the anteromedial portal through the over-the-top position into the lateral incision. D: The graft is then brought through the over-the-top position. E: A clamp is placed from a proximal medial leg incision under the intermeniscal ligament. A groove is made in the anteromedial tibial epiphysis using a rasp. F: The graft is brought through the knee in the over-the-top position and under the intermeniscal ligament. G: The graft is brought out the proximal medial leg incision. H: It is sutured to the intermuscular septum and periosteum of the lateral femoral condyle through the lateral knee incision and it is sutured in a trough to the periosteum of the proximal medial tibial metaphysis.
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A: The iliotibial band is harvested through an oblique lateral knee incision. B: The iliotibial band graft is detached proximally, left attached distally, and dissected free from the lateral patellar retinaculum. C: The iliotibial band graft is brought through the knee using a full-length clamp placed from the anteromedial portal through the over-the-top position into the lateral incision. D: The graft is then brought through the over-the-top position. E: A clamp is placed from a proximal medial leg incision under the intermeniscal ligament. A groove is made in the anteromedial tibial epiphysis using a rasp. F: The graft is brought through the knee in the over-the-top position and under the intermeniscal ligament. G: The graft is brought out the proximal medial leg incision. H: It is sutured to the intermuscular septum and periosteum of the lateral femoral condyle through the lateral knee incision and it is sutured in a trough to the periosteum of the proximal medial tibial metaphysis.
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Figure 30-38
Technique of physeal-sparing combined intra-articular and extra-articular anterior cruciate ligament reconstruction using iliotibial band.
A: The iliotibial band is harvested through an oblique lateral knee incision. B: The iliotibial band graft is detached proximally, left attached distally, and dissected free from the lateral patellar retinaculum. C: The iliotibial band graft is brought through the knee using a full-length clamp placed from the anteromedial portal through the over-the-top position into the lateral incision. D: The graft is then brought through the over-the-top position. E: A clamp is placed from a proximal medial leg incision under the intermeniscal ligament. A groove is made in the anteromedial tibial epiphysis using a rasp. F: The graft is brought through the knee in the over-the-top position and under the intermeniscal ligament. G: The graft is brought out the proximal medial leg incision. H: It is sutured to the intermuscular septum and periosteum of the lateral femoral condyle through the lateral knee incision and it is sutured in a trough to the periosteum of the proximal medial tibial metaphysis.
A: The iliotibial band is harvested through an oblique lateral knee incision. B: The iliotibial band graft is detached proximally, left attached distally, and dissected free from the lateral patellar retinaculum. C: The iliotibial band graft is brought through the knee using a full-length clamp placed from the anteromedial portal through the over-the-top position into the lateral incision. D: The graft is then brought through the over-the-top position. E: A clamp is placed from a proximal medial leg incision under the intermeniscal ligament. A groove is made in the anteromedial tibial epiphysis using a rasp. F: The graft is brought through the knee in the over-the-top position and under the intermeniscal ligament. G: The graft is brought out the proximal medial leg incision. H: It is sutured to the intermuscular septum and periosteum of the lateral femoral condyle through the lateral knee incision and it is sutured in a trough to the periosteum of the proximal medial tibial metaphysis.
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A: The iliotibial band is harvested through an oblique lateral knee incision. B: The iliotibial band graft is detached proximally, left attached distally, and dissected free from the lateral patellar retinaculum. C: The iliotibial band graft is brought through the knee using a full-length clamp placed from the anteromedial portal through the over-the-top position into the lateral incision. D: The graft is then brought through the over-the-top position. E: A clamp is placed from a proximal medial leg incision under the intermeniscal ligament. A groove is made in the anteromedial tibial epiphysis using a rasp. F: The graft is brought through the knee in the over-the-top position and under the intermeniscal ligament. G: The graft is brought out the proximal medial leg incision. H: It is sutured to the intermuscular septum and periosteum of the lateral femoral condyle through the lateral knee incision and it is sutured in a trough to the periosteum of the proximal medial tibial metaphysis.
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Arthroscopy of the knee is then performed through standard anterolateral viewing and anteromedial working portals. Management of meniscal injury or chondral injury is performed if present. The ACL remnant is excised. The over-the-top position on the femur and the over-the-front position under the intermeniscal ligament are identified. Minimal notchplasty is performed to avoid iatrogenic injury to the perichondrial ring of the distal femoral physis which is in very close proximity to the over-the-top position.42 The free end of the iliotibial band graft is brought through the over-the-top position using a full-length clamp (Fig. 30-38C) or a two-incision rear-entry guide (Fig. 30-37) and out the anteromedial portal (Fig. 30-38D). 
A second incision of approximately 4.5 cm is made over the proximal medial tibia in the region of the pes anserinus insertion. Dissection is carried through the subcutaneous tissue to the periosteum. A curved clamp is advanced extraperiosteally from this incision proximally along the anterior proximal tibial cortex into the joint under the intermeniscal ligament (Fig. 30-38E). A small groove is made in the anteromedial proximal tibial epiphysis under the intermeniscal ligament using a curved rat-tail rasp to bring the tibial graft placement more posterior and allow for future intra-articular biologic tendon-to-bone healing. The free end of the graft is then brought through the joint (Fig. 30-38F), under the intermeniscal ligament in the anteromedial epiphyseal groove, and out the medial tibial incision (Fig. 30-38G). The graft is fixed on the femoral side through the lateral incision with the knee at 70 to 90 degrees flexion using figure-of-eight sutures to the periosteum of the LFC to effect an extra-articular reconstruction (Fig. 30-38H). The tibial side is then fixed through the medial incision with the knee flexed 30 degrees and tension applied to the graft. Within the medial tibial incision, the periosteum is divided and a trough is made in the proximal tibial medial metaphyseal cortex. The graft is sutured to the periosteum on either side of the trough with figure-of-eight sutures (Fig. 30-37). 
Postoperatively, the patient is maintained touch-down weight bearing for 6 weeks. ROM may be progressed slowly in 2-week intervals but generally is limited from 0 to 90 degrees for the first 6 weeks, followed by progressive full ROM. A continuous passive motion (CPM) and cryotherapy are used for 2 weeks postoperatively. A protective postoperative brace is used for 6 weeks postoperatively, after which the rehabilitation regimen progresses to more advanced strengthening exercises from 6 to 12 weeks postoperatively, straight ahead running in the brace at around 3 months postoperatively, agility exercises around 4 to 5 months postoperatively, and return to sports around 6 months postoperatively, provided sufficient quad and hamstring strength have been achieved. 

Skeletally Immature Adolescent Patient: Transphyseal ACL Reconstruction

For adolescent patients with growth remaining who have a complete ACL tear, we perform transphyseal ACL reconstruction with autogenous hamstrings tendons with fixation away from the physes.226 The procedure is performed under general anesthesia as an ambulatory outpatient procedure, unless there are specific concerns about pain control or underlying medical conditions, in which case overnight observation can be pursued. Given our access to anesthesiologists skilled in regional anesthesia techniques, we favor use of a femoral nerve block for most patients to facilitate early pain control and initiation of range-of-motion exercises in the CPM. The patient is positioned supine on the operating table with a pneumatic tourniquet about the upper thigh which is not used routinely. Examination under anesthesia is performed to confirm ACL insufficiency. 
First, the hamstrings tendons are harvested. If the diagnosis is in doubt, arthroscopy can be performed first to confirm ACL tear. A 3-cm incision is made over the palpable pes anserinus tendons on the medial side of the upper tibia (Fig. 30-39A). Dissection is carried through skin to the sartorius fascia. Care is taken to protect superficial sensory nerves. The sartorius tendon is incised longitudinally and the gracilis and semitendinosus tendons are identified. The tendons are dissected free distally and their free ends whip-stitched with a no. 2 braided suture. They are dissected proximally using sharp and blunt dissection. Fibrous bands to the medial head of gastrocnemius should be identified and released. A closed tendon stripper is used to dissect the tendons free proximally. Alternatively, the tendons can be left attached distally, and an open tendon stripper used to release the tendons proximally. The tendons are taken to the back table, where excess muscle is removed and the remaining ends are whip-stitched with additional no. 2 sutures. The tendons are folded over a suspensory fixation button. The graft diameter is sized and the graft is placed under tension. 
Figure 30-39
Transphyseal reconstruction with autogenous hamstrings for adolescents with growth remaining.
 
A: The gracilis and semitendinosus tendons are harvested through an incision over the proximal medial tibia. B: The tibial guide is used to drill the tibial tunnel. C: The transtibial over-the-top offset guide is used to drill the femoral tunnel.
A: The gracilis and semitendinosus tendons are harvested through an incision over the proximal medial tibia. B: The tibial guide is used to drill the tibial tunnel. C: The transtibial over-the-top offset guide is used to drill the femoral tunnel.
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Figure 30-39
Transphyseal reconstruction with autogenous hamstrings for adolescents with growth remaining.
A: The gracilis and semitendinosus tendons are harvested through an incision over the proximal medial tibia. B: The tibial guide is used to drill the tibial tunnel. C: The transtibial over-the-top offset guide is used to drill the femoral tunnel.
A: The gracilis and semitendinosus tendons are harvested through an incision over the proximal medial tibia. B: The tibial guide is used to drill the tibial tunnel. C: The transtibial over-the-top offset guide is used to drill the femoral tunnel.
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Arthroscopy of the knee is then performed through standard anterolateral viewing and anteromedial working portals. Management of meniscal injury or chondral injury is performed if present. The ACL remnant is excised. The over-the-top position on the femur is identified. Minimal notchplasty may be performed if notably stenotic. A tibial tunnel guide (set at 55 degrees) is used through the anteromedial portal (Fig. 30-39B). A guidewire is drilled through the hamstrings harvest incision into the posterior aspect of the ACL tibial footprint. The guidewire entry point on the tibia should be kept medial to avoid injury to the tibial tubercle apophysis. The guidewire is reamed with the appropriate diameter reamer. Excess soft tissue at the tibial tunnel is excised to avoid arthrofibrosis or a “cyclops lesion.”185 The transtibial over-the-top guide of the appropriate offset to ensure a 1- or 2-mm back wall is used to pass the femoral guide pin (Fig. 30-39C). Slight overdrilling to accommodate the diameter of the suspensory fixation button is completed, then full diameter reaming up to the lateral femoral cortex to accommodate the graft. The graft is then pulled into the joint using the tagging sutures placed on the slotted end of the guidewire, and graft is advanced into optimal position via the suspensory fixation system of choice. The knee is then extended to ensure no graft impingement. The knee is then cycled approximately 10 times with tension applied to the graft. The graft is fixed on the tibial side with the knee in 20 to 30 degrees of flexion, tension applied to the graft, and a posterior force placed on the tibia. On the tibial side, the graft is either fixed with a soft tissue interference screw if there is adequate tunnel distance below the physis to ensure metaphyseal placement of the screw or with a post and spiked washer. Fluoroscopy can be used to ensure that the fixation is away from the physes. Postoperative radiographs are shown in Figure 30-40
Figure 30-40
Postoperative anteroposterior (A) and lateral (B) radiographs.
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Figure 30-40
Transphyseal reconstruction with autogenous hamstrings for adolescents with growth remaining.
Postoperative anteroposterior (A) and lateral (B) radiographs.
Postoperative anteroposterior (A) and lateral (B) radiographs.
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Postoperative Care

Postoperatively, the patient is maintained partial weight bearing for 2 weeks. ROM is limited from 0 to 90 degrees for the first 2 weeks, followed by progressive full ROM. A CPM from 0 to 90 degrees and cryotherapy are used for 2 weeks postoperatively. A protective postoperative brace is used for 6 weeks postoperatively. 

Lateral Collateral Ligament

Grade III injuries of the LCL are extremely rare in children. Occasionally, the lateral capsular sign414 is seen on radiographs obtained for evaluation of knee injury. Most often, the LCL is avulsed from the proximal fibular epiphysis, with or without a cortical fleck fragment, as proximal and midsubstance tears are uncommon. This injury is treated in the same manner as injury to the MCL. For isolated grade III injuries, a 6-week period of immobilization in a hinged knee brace is recommended. If ACL injury is associated with minor LCL injury, treatment is as described above for combined injuries of the MCL and ACL. In the setting of a complete LCL avulsion with complete ACL tear, repair of the LCL, in conjunction with ACL reconstruction is pursued, usually between 2 and 4 weeks, so as to optimize the healing potential of the collateral ligament without undue risk of arthrofibrosis. 

Posterior Cruciate Ligament

In general, PCL injuries have traditionally been considered quite rare in children, with most case reports describing a bony avulsion injury.143,337,385 Kocher et al.224 recently described a series of 26 knees in patients 18 or younger with PCL injuries, 15 of which underwent surgery for gross instability secondary to either a partial tear (n = 1, 7%), a complete ligamentous tear (n = 4, 27%), or an osteochondral avulsion fragment from either the tibial or femoral footprint (n = 10, 67%). Of note, 53% of the operative cohort had a concomitant ligamentous injury, and 60% had concomitant meniscal tear. For skeletally immature patients, we prefer to perform arthroscopic-assisted suture repair of avulsions that occur directly from either footprint through small bony tunnels, with the limbs of suture tied over a cortical bone bridge, similar to the technique described above for tibial spine fractures. For skeletally mature adolescents, we will perform a PCL reconstruction with adult-based techniques, generally with an Achilles allograft. 

Knee Dislocation

Acute dislocations of the knee are uncommon in children because the forces required to produce dislocation are more likely to fracture the distal femoral or proximal tibial epiphysis.134 Acute knee dislocation usually involves major injuries of associated soft tissues and ligaments and often neurovascular injuries. Injuries typically occur in older skeletally mature adolescents from high-energy trauma, such as motor vehicle injuries, pedestrian versus motor vehicle injury, bicycle versus motor vehicle injury, trampoline injuries, and high-energy contact sports. 
Adequate follow-up studies of acute knee dislocations in children younger than 10 years of age are few,97 and most information has been obtained from reports of knee dislocations in adults. Because of the potential for associated vascular injury, acute knee dislocations in children may be emergent situations. The dislocation causes obvious deformity about the knee. With anterior dislocation, the tibia is prominent in an abnormal anterior position (Fig. 30-41). With posterior dislocation, the femoral condyles are abnormally prominent anteriorly. 
Figure 30-41
Dislocation of the knee.
 
A, B: Anteromedial dislocation of the knee in a 14-year-old girl.
A, B: Anteromedial dislocation of the knee in a 14-year-old girl.
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Figure 30-41
Dislocation of the knee.
A, B: Anteromedial dislocation of the knee in a 14-year-old girl.
A, B: Anteromedial dislocation of the knee in a 14-year-old girl.
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X
After the dislocation is reduced, the stability of the knee should be evaluated with gentle stress testing. For isolated anterior or posterior dislocations, the integrity of the collateral ligaments should be carefully evaluated. Some knees may spontaneously reduce after dislocation or reduce with manipulation of the leg for transport. 
The neurovascular status of the extremity should be carefully evaluated both before and after reduction, especially the dorsalis pedis and posterior tibial pulses and peroneal nerve function. There is increasing evidence283 supporting the diagnostic and prognostic value of the ankle-brachial index, which may be positive (<0.9) because of significant vascular injury, despite normal pulses and Doppler. Any abnormal vascular findings, either before or after reduction, require arteriography, which may be done in the operating room to facilitate rapid transition to repair. Popliteal artery laceration or intimal tear may occur in 20% to 35% of cases.85,97,134,147,202 Abnormalities in the sensory or motor function of the foot and distribution of the peroneal nerve function should be noted. Peroneal nerve injury has been reported in 16% to 40% of cases.85,97,134,147,202 MRI is usually performed to assess the integrity of the cruciate and collateral ligaments, the posterolateral and posteromedial corners, the menisci, and the articular surfaces. 
Knee dislocation usually occurs with disruption of both cruciate ligaments. With direct anterior or posterior dislocation, the collateral ligaments and the soft tissues may be retained because the femoral condyles are stripped out of their capsular and collateral ligament attachments, and when reduced slip back inside them. Associated medial displacement is often accompanied by LCL disruption. Associated lateral displacement is often accompanied by MCL disruption. Knee dislocations in adolescents have been associated with tibial spine fractures, osteochondral fractures of the femur or tibia, meniscal injuries, and peroneal nerve injuries.85 
Treatment of knee dislocations includes both acute and delayed reconstructive management. Acutely, the knee is reduced under anesthesia. If emergent vascular surgery is performed, fasciotomies are usually also performed. However, ligamentous reconstruction is typically delayed. The knee is braced with protected weight bearing and limited motion, or occasionally application of external fixation is warranted to protect the vascular repair. 
Reconstruction may be delayed approximately 2 to 4 weeks after injury, depending on the pattern. Primary ligament repairs become more difficult after this period of time because of scarring and lack of definition of tissues. Reconstructions may be staged or performed in a single multi-ligamentous knee procedure. Surgery often combines arthroscopic and open techniques. General principles include ligament repair for collateral ligament injuries, ligament reconstruction for midsubstance cruciate ligament injuries, and meniscal repair. Allograft tissue is often used because of the multiligamentous nature of the injury and the need to minimize tourniquet time and any additional knee trauma that would come from graft harvesting. Postoperatively, prolonged immobilization should be avoided because of the substantial risk of stiffness after knee dislocation surgery. Limited motion in a hinged knee brace and protected weight bearing are utilized, followed by mobilization and strengthening. 

Potential Pitfalls and Preventative Measures of Ligament Injuries

If a family wishes to pursue nonoperative treatment of complete ACL tears in children and adolescents, sufficient counseling must be performed so that the patient and the family understand the relative risks and benefits of nonoperative treatment versus ACL reconstruction. In such instances, compliance with bracing and activity restriction must be monitored. Careful regular follow-up is necessary to evaluate for instability episodes and further meniscal/chondral injury. Should further meniscal or chondral injury occurs, ACL reconstruction should be reemphasized, because of the risk of degenerative joint disease associated with injury episodes. 
Pitfalls to avoid with the physeal-sparing iliotibial band reconstruction in prepubescents include harvesting a short graft insufficient to reach the medial tibial incision, difficulty passing the graft through the posterior joint capsule, and difficulty passing the graft under the intermeniscal ligament. Pitfalls to avoid with the transphyseal hamstrings reconstruction in adolescents with growth remaining include amputation of the hamstring grafts, poor tunnel placement, and graft impingement. 
Based on the 15 cases of growth disturbance after ACL reconstruction in skeletally immature patients that we reported, we recommend careful attention to technical details during ACL reconstruction in skeletally immature patients, particularly the avoidance of fixation hardware across the lateral distal femoral epiphyseal plate.223 Care should also be taken to avoid injury to the vulnerable tibial tubercle apophysis.219,350 Given the cases of growth disturbances associated with transphyseal placement of patellar tendon graft bone blocks, we recommend the use of soft tissue grafts. Large tunnels should likely be avoided as likelihood of arrest is associated with greater violation of epiphyseal plate cross-sectional area. The reported cases and growing anecdotal evidence of genu valgum without arrest associated with lateral extra-articular tenodesis raise additional concerns about the effect of tension on physeal growth. Finally, care should be taken to avoid dissection or notching around the posterolateral aspect of the physis during over-the-top nonphyseal femoral placement to avoid potential injury to the very close perichondrial ring and subsequent deformity (Table 30-26).219 
 
Table 30-26
Ligament Injuries
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Table 30-26
Ligament Injuries
Potential Pitfalls and Preventions
Pitfall Preventions
Pitfall #1: Growth disturbance Prevention 1a: Failure to assess accurate bone age
Prevention 1b: Use soft tissue graft
Prevention 1c: Avoid transphyseal fixation/screw placement
Pitfall #2: ACL Retear Prevention 2a: Ensure adequate postoperative rehab, optimization of dynamic knee stability
Prevention 2b: Avoid allograft tissue
X

Treatment-Specific Outcomes for Ligament Injuries

The prognosis of ACL reconstruction depends on the surgical procedure. Several case series exist regarding ACL reconstruction in skeletally immature patients. However, most series are small and variably report the patients' skeletal age and growth remaining. Primary ligament repair79,117 and extra-articular tenodesis alone145,270 have had poor results in children and adolescents, similar to adults. Transphyseal reconstructions with tunnels that violate both the distal femoral and proximal tibial physes have been performed with hamstrings autograft, patellar tendon autograft, and allograft tissue.13,23,29,109,128,265,270,354,358,367,399 These anatomic ACL reconstruction procedures have high success rates as in adult patients, however risk injury to the physis, particularly in prepubescent patients. However, those adolescents in the intermediate group – pubescent patients with still open growth plates – in whom transphyseal tunnels are used with “physeal-respecting” principles, are unlikely to have any risk of growth disturbance. In one follow-up outcome study of 61 knees in 59 skeletally immature Tanner stage 3 adolescents with growth remaining (mean chronologic age: 14.7 years old, range: 11.6 to 16.9 years old) who underwent transphyseal reconstruction with autogenous hamstrings graft and metaphyseal fixation, we found a revision rate of 3% with excellent functional outcome, return to competitive sports, and no cases of growth disturbance.226 Partial transphyseal reconstructions violate only one physis with a tunnel through the proximal tibial physis and over-the-top positioning on the femur or a tunnel through the distal femoral physis with an epiphyseal tunnel in the tibia.21,55,154 These procedures are also near anatomic with good clinical results, however the potential for growth disturbance exists. 
A variety of physeal-sparing reconstructions have been described to avoid tunnels across either the distal femoral or proximal tibial physis.18,64,98,153,206,281,315,389 In general these procedures are nonanatomic and may have some persistent knee laxity. However they avoid physeal violation, and rates of graft rupture, persistent or recurrent instability have generally been low. In a follow-up outcome study of 44 skeletally immature prepubescent children who were Tanner stage 1 or 2 (mean chronologic age: 10.3 years old; range: 3.6 to 14 years old) who underwent the physeal-sparing combined intra-articular and extra-articular ACL reconstruction technique using autogenous iliotibial band that we describe above, we found a revision ACL reconstruction rate of 4.5% with excellent functional outcome, return to competitive sports, and no cases of growth disturbance.216,217 Anderson18,19 described a more anatomic physeal-sparing reconstruction in prepubescent children by utilizing carefully placed epiphyseal femoral and tibial tunnels with an autogenous hamstrings graft and epiphyseal fixation (Fig. 30-42). In 12 skeletally immature patients with mean age 13.3 years old (SD: 1.4), he found excellent functional outcome without growth disturbance. 
Figure 30-42
Physeal-sparing epiphyseal ACL reconstruction with autogenous hamstrings for prepubescents with growth remaining.
 
A: Femoral tunnel placement within the epiphysis. B: Tibial tunnel placement within the epiphysis. C: Appearance after epiphyseal graft fixation.
A: Femoral tunnel placement within the epiphysis. B: Tibial tunnel placement within the epiphysis. C: Appearance after epiphyseal graft fixation.
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Figure 30-42
Physeal-sparing epiphyseal ACL reconstruction with autogenous hamstrings for prepubescents with growth remaining.
A: Femoral tunnel placement within the epiphysis. B: Tibial tunnel placement within the epiphysis. C: Appearance after epiphyseal graft fixation.
A: Femoral tunnel placement within the epiphysis. B: Tibial tunnel placement within the epiphysis. C: Appearance after epiphyseal graft fixation.
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X
As interest in ACL-R techniques in skeletally immature patients has increased, however, the concept of transphyseal tunnel creation across open physes has remained controversial, as some authors contend that soft tissue graft placement without hardware across tunnels eliminates the risk of growth disturbance,136,197,312,395 a notion supported by some animal models.276 A recent European multicenter study compared 68 adolescent patients with a mean age of 12.5 years, 40 of whom were skeletally immature and underwent one of three different reconstruction techniques involving transphyseal tunnels. One of three different graft choices was used: 16 hamstring autografts, 12 quadriceps, and 12 fascia lata. No growth disturbances were seen at a mean follow-up of 33 months. One meta-analysis of 55 original studies assessed results in 935 patients with a median age of 13 at mean follow-up of 40 months, concluding that risk of angular deformity or leg length discrepancy was 1.8%, and was actually lower in transphyseal transosseous reconstruction than physeal-sparing transosseous reconstruction, perhaps because of the more parallel orientation of the tunnels relative to the physis in the latter technique. 

Management of Expected Adverse Outcomes and Unexpected Complications in Ligament Injuries

Complications after ligament injury in children are similar to adults: Arthrofibrosis,306 persistent instability, unrecognized concomitant injury, infection, graft failure, neurovascular injury, and donor site morbidity. A recent study of 933 ACL-R cases in children and adolescents with a mean age of 15 showed an arthrofibrosis rate of 8.3%, with older age (16 to 18 years), female age, concurrent meniscal repair, and patellar tendon autograft representing risk factors for arthrofibrosis requiring treatment. Although arthroscopic lysis of adhesions and manipulation under anesthesia were effective in improving ROM in this series of patients, 20% complained of some persistent pain at 6.3 years of mean follow-up. 
In skeletally immature patients, despite continued controversy, growth disturbance can occur from iatrogenic physeal injury and remains important area of continued research (Table 30-27). 
 
Table 30-27
Ligament Injuries
View Large
Table 30-27
Ligament Injuries
Common Adverse Outcomes and Complications
Ligament retear
Arthrofibrosis
Anterior knee/kneeling pain (patellar tendon/BTB autograft more commonly than hamstring)
X

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