Chapter 7: Principles of Internal Fixation

Michael Schütz, Thomas P. Rüedi

Chapter Outline

Historical Background and the Goals of Internal Fixation

Already the ancient Egyptians of 3,000 bc knew that splinting of a fractured limb not only reduces pain but also supports the healing process. The first reports on modern techniques of internal fixation are however only about 100 years old. The brothers Elie and Albin Lambotte from Belgium have described in detail the essentials of what they called “osteosynthesis” of fractures with plates and screws, wire loops and external fixators. Albin Lambotte (1866 to 1955) highlighted the importance of anatomical reduction and stable fixation of articular fractures as the only way to regain good joint function. While he planned and drew every fracture in detail, he also emphasized the importance of careful soft tissue handling to preserve vascularity and prevent infection. His pupil Robert Danis (1880 to 1962) introduced the term of “soudure autogéne” or primary bone healing without visible callus, which he observed when the fracture was anatomically reduced and fixed with his compression plate. In 1950 the 32-year-old Swiss orthopedic surgeon Maurice Müller spent 1 day only in the clinic of Danis and was deeply impressed by the patients he saw and the results of compression plating. Back in Fribourg, Switzerland Müller, got permission from his chief to treat a patient with the new technique and compression plates, which he soon modified and technically improved. Together with 13 other young Swiss surgeons he founded in 1958 the Arbeitsgemeinschaft für Osteosynthesefragen (AO) the main representatives being Martin Allgöwer, Walter Bandi, Robert Schneider, and Hans Willenegger.55 The AO set as their goal to improve the outcome of the injured patient by defining guidelines of the surgical management of fractures. They agreed on and adhered to strict rules and principles of fracture surgery and thanks to a meticulous follow-up of every single fracture, they were able to document their results and learn from the mistakes and complications. In parallel to the Swiss AO, Gerhard Küntscher (1900 to 1972) in Germany had developed the technique of IM nailing, which soon revolutionized the treatment of diaphyseal fractures especially of the femur and tibia.45 In contrast to the rigid fixation by interfragmentary compression, IM nailing was an internal splinting technique, which allowed for some motion at the fracture site and therefore healing by callus formation. Rigid fixation on one hand and the more elastic internal splinting on the other, have often been considered as competing techniques, while they are actually complementary, each having its pros and cons and specific indications. 
The ultimate goal of operative fracture fixation is to obtain full restoration of function of the injured limb and the patient to return to his preinjury status of activities, as well as to minimize the risk and incidence of complications. The purpose of the use of implants is to provide a temporary support, to maintain alignment during the fracture healing, and to allow for a functional rehabilitation. 

Influence of Biology and Biomechanics on Fracture Healing

The biologic and biomechanical influences on fracture treatment will be considered in this chapter. Any procedure will alter the biologic and biomechanical environment for fracture healing, which every surgeon treating fractures should be familiar with. From mechanical and biologic points of view, a fractured bone needs a certain degree of immobilization, an optimally preserved blood supply and biologic or hormonal stimuli in order to unite. All three factors are important, the mechanical part is however the easiest to quantify. We may distinguish two types of mechanical stability, absolute and relative. Absolute stability is defined as rigid fixation that does not allow any micro motion between the fractured fragments under physiologic loading. It is best obtained by interfragmentary compression and is based on preload and friction. More elastic fixation as provided by internal or external splinting of the bone is defined as relative stability which allows limited motion at the fracture site under functional loading. The degree of stability determines the type of fracture healing which is either by primary or direct bone remodeling (Fig. 7-1) or by secondary or indirect healing with callus formation. Indirect fracture healing by callus can take place in a much wider spectrum of mechanical environments than primary or direct bone remodeling (Fig. 7-2). Callus will not form if there is no motion; however, if there is excessive movement, healing will equally be delayed. 
Figure 7-1
Direct or primary fracture healing as observed with absolute stability.
 
A new Havers osteon transversing the osteotomy, thereby interdigitating across the osteotomy line.
A new Havers osteon transversing the osteotomy, thereby interdigitating across the osteotomy line.
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Figure 7-1
Direct or primary fracture healing as observed with absolute stability.
A new Havers osteon transversing the osteotomy, thereby interdigitating across the osteotomy line.
A new Havers osteon transversing the osteotomy, thereby interdigitating across the osteotomy line.
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Figure 7-2
Secondary healing by callus as observed with relative stability.
 
Schematic drawing of vessel ingrowth from the periphery to the fracture gap.
Schematic drawing of vessel ingrowth from the periphery to the fracture gap.
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Figure 7-2
Secondary healing by callus as observed with relative stability.
Schematic drawing of vessel ingrowth from the periphery to the fracture gap.
Schematic drawing of vessel ingrowth from the periphery to the fracture gap.
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The strain theory13,64 describes, in a simplified manner, what occurs at a cellular level in a fracture gap. Strain is the deformation of a material (e.g., granulation tissue within a gap) when a given force is applied relative to its original form, thus it has no dimension. The amount of deformation a tissue can tolerate before it breaks varies greatly. The strain of normal intact bone until it breaks is “low,” about 2%, while granulation tissue has a high-strain tolerance of 100%.64 In a narrow fracture gap a defined distracting force will disrupt the few cells within it (Fig. 7-3). The same force applied to a wider gap filled with granulation tissue will however only deform this tissue and not cause any rupture (Fig. 7-3B). If we look at a specific fracture type we may appreciate, that in a simple transverse or short oblique fracture any deforming force is acting very locally on the single fracture gap, corresponding to a concentration of stress, while in complex, multifragmentary fractures the same force will be distributed over a wide range of different fracture fragments or gaps (stress distribution). By applying the strain theory we may deduct that in a simple diaphyseal fracture we have a situation of “high strain.” Therefore such a fracture is best reduced anatomically and fixed by interfragmentary compression (lag screw and plate), a method that produces a high degree or absolute stability (Fig. 7-4). 
Figure 7-3
Strain theory by Perren.
 
A: Within a narrow gap (10 μm) a single cell will rupture upon minimal distraction (high strain), B: In a wide gap (30 μm) with room for several layers of cells the same amount of distraction will only deform or stretch these cells (low strain).
A: Within a narrow gap (10 μm) a single cell will rupture upon minimal distraction (high strain), B: In a wide gap (30 μm) with room for several layers of cells the same amount of distraction will only deform or stretch these cells (low strain).
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Figure 7-3
Strain theory by Perren.
A: Within a narrow gap (10 μm) a single cell will rupture upon minimal distraction (high strain), B: In a wide gap (30 μm) with room for several layers of cells the same amount of distraction will only deform or stretch these cells (low strain).
A: Within a narrow gap (10 μm) a single cell will rupture upon minimal distraction (high strain), B: In a wide gap (30 μm) with room for several layers of cells the same amount of distraction will only deform or stretch these cells (low strain).
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Figure 7-4
 
A simple tibia and fibula spiral fracture by indirect trauma (A) is reduced anatomically and fixed with interfragmentary compression (lag screw and protection plate) providing absolute stability (B). C: Healing occurs without callus formation, at 1-year follow-up.
A simple tibia and fibula spiral fracture by indirect trauma (A) is reduced anatomically and fixed with interfragmentary compression (lag screw and protection plate) providing absolute stability (B). C: Healing occurs without callus formation, at 1-year follow-up.
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Figure 7-4
A simple tibia and fibula spiral fracture by indirect trauma (A) is reduced anatomically and fixed with interfragmentary compression (lag screw and protection plate) providing absolute stability (B). C: Healing occurs without callus formation, at 1-year follow-up.
A simple tibia and fibula spiral fracture by indirect trauma (A) is reduced anatomically and fixed with interfragmentary compression (lag screw and protection plate) providing absolute stability (B). C: Healing occurs without callus formation, at 1-year follow-up.
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On the other hand a more complex, multifragmentary diaphyseal fracture corresponds to a “low strain” situation, which profits from correct axial and rotational alignment and less rigid fixation (locked intramedullary nail, bridge plate, or external fixator) providing relative stability (Fig. 7-5). It appears most important that in simple fracture types treated with rigid fixation that persistent gaps at the fracture site are avoided, while in complex fractures treated with less rigid fixation such gaps may be tolerated (Table 7-1). Bhandari71 and Audigé2 have independently shown in large clinical series of surgically stabilized tibia shaft fractures that persistent fracture gaps of over about 2 mm were closely related or predictive for the development of a healing delay or nonunion. 
Figure 7-5
Complex, distal tibia and fibula fractures by direct trauma.
 
A: Fixed after axial and rotational alignment with a locked intramedullary nail providing relative stability. B: Healing occurred after proximal dynamization with callus formation. C: The fibula fracture was fixed because of the vicinity to the ankle joint.
A: Fixed after axial and rotational alignment with a locked intramedullary nail providing relative stability. B: Healing occurred after proximal dynamization with callus formation. C: The fibula fracture was fixed because of the vicinity to the ankle joint.
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Figure 7-5
Complex, distal tibia and fibula fractures by direct trauma.
A: Fixed after axial and rotational alignment with a locked intramedullary nail providing relative stability. B: Healing occurred after proximal dynamization with callus formation. C: The fibula fracture was fixed because of the vicinity to the ankle joint.
A: Fixed after axial and rotational alignment with a locked intramedullary nail providing relative stability. B: Healing occurred after proximal dynamization with callus formation. C: The fibula fracture was fixed because of the vicinity to the ankle joint.
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Table 7-1
Relation of the Stability of Fixation (Absolute vs. Relative), the Type of Fracture (Simple or Complex), and the Size of the Fracture Gap to Fracture Healing
Fracture Gap
Simple Small (<2 mm) Complex Large (>2 mm)
Relative stability Bone resorption, healing delay, or nonunion Secondary bone healing (callus)
Absolute stability Primary bone healing, osteonal remodeling Bone resorption, healing delay, or nonunion
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In articular fractures the anatomical congruity of the joint surface must be restored and the fragments should be fixed rigidly by interfragmentary compression, while associated metaphyseal comminution or a diaphyseal extension of the fracture can be correctly aligned in all planes and bridged by an appropriate device (Fig. 7-30). 

Soft Tissue Injury and Fracture Healing

Every fracture is associated to a certain extent with an injury to the tissues surrounding the bone. The energy, direction, and concentration of forces inducing the fracture will determine the fracture type and the associated soft tissue lesions.58 As a result of the displacement of the fragments, periosteal and endosteal blood vessels may be disrupted and the periosteum will be stripped.74 There is the statement that “every fracture is a soft tissue injury, where the bone happens to be broken,” which should emphasize the great importance of the soft parts, which unfortunately are still often not considered and respected enough. 
The healing process of a fracture starts with the formation of granulation tissue within the fracture hematoma and is dependent on a preserved or restored blood supply to the area. The more extensive the zone of injury and the tissue destruction, the higher is the risk for a delay of the healing process or for other complications. Depending on the mechanism and the magnitude or energy of the insult that caused the bone to break, direct and indirect fracture mechanisms are distinguished, which can usually be deducted from the radiographic appearance of the fracture pattern. An indirect fracture mechanism like a rotation or bending will cause a spiral or butterfly fracture, respectively, with relatively little soft tissue injury. Adequately reduced and immobilized by nonoperative or operative means these fractures generally heal rather uneventfully (Fig. 7-4). In contrast a direct blow will induce, at a minimum, a local contusion of the skin, or more often will result in an open transverse or wedge type fracture with an extensive area of soft tissue injury (Fig. 7-6). In open fractures the severity or extent of the lesion is usually much more evident than in closed fractures.19 The latter may however also involve important neurovascular structures surrounding the bone. In closed fractures occult injuries are therefore more often missed.52 A careful assessment, classification, and documentation of the fracture and the soft tissue injury is therefore of greatest importance in the planning and especially for correct timing of surgery. As a rule and if there are any doubts about the extent of the soft tissue injury, it is much safer to temporarily immobilize the zone of injury by traction or more adequately by an external fixator, postponing definitive fixation until the soft tissues have recovered (Fig. 7-6). 
Figure 7-6
Zone of injury around a tibia and fibula fracture caused by direct trauma (A).
 
Bridging external fixator to protect the zone of injury in a severely contused distal tibia fracture (B) and (C).
Bridging external fixator to protect the zone of injury in a severely contused distal tibia fracture (B) and (C).
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Figure 7-6
Zone of injury around a tibia and fibula fracture caused by direct trauma (A).
Bridging external fixator to protect the zone of injury in a severely contused distal tibia fracture (B) and (C).
Bridging external fixator to protect the zone of injury in a severely contused distal tibia fracture (B) and (C).
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In open fractures with a soft tissue defect or an associated vascular injury, it may be advisable to perform emergency fixation of the bone, followed by vessel repair and immediate or early plastic reconstructive procedure to cover the tissue defect. Decision making under such circumstances requires much experience and it may be advisable to involve a senior surgeon or the entire team including a plastic-reconstructive surgeon (see also Chapter 10, Initial Management of Open Fractures). 
As we cannot influence the extent of soft tissue lesions caused by the injury mechanism, we must do our best to limit any additional injury to the blood supply of the bone and surrounding structures. Minimally invasive surgical approaches without exposure of the fracture, indirect reduction techniques and fixation devices that do not additionally harm the blood supply to the bone should be used wherever possible. 

Preoperative Planning

Every fracture needs a careful preoperative assessment and planning process, which is essential in order to obtain a predictable outcome and to prevent intraoperative problems, hazards and unnecessary delays. 
The preoperative assessment should take into consideration the patient, the fracture, and the soft tissues. Planning includes the evaluation not only of the fracture and limb per se, but of the whole patient. Factors like the history and mechanism of the accident, the age of the patient, pre-existing vascular and metabolic diseases, the use of drugs, alcohol, and nicotine all may greatly influence the outcome and therefore must be included in the decision making. The expectations of the patient, their profession, and recreational activities should be known and discussed. The treatment plan is adapted accordingly. 
For the fracture as such, plain x-rays are studied and additional imaging requested if considered necessary. CT scans with 2D or 3D reconstruction usually give more information,12,48,60 while traction views may still be helpful in greatly displaced articular fractures. The classification of the fracture will help to communicate and discuss the type of treatment, to evaluate the problems, and to make a prognosis as to the outcome. The soft tissues and neurovascular conditions are then assessed carefully, as also closed fractures may have severe involvement of these structures. The timely diagnosis of a compartment syndrome and its correct treatment may save a critically injured limb. The assessment and classification of the soft tissue injury is often more difficult than that of the fracture per se and requires much experience. 
The components of a preoperative plan include the following. 
  •  
    Timing of surgery
  •  
    Surgical approach
  •  
    Reduction maneuvers
  •  
    Fixation construct
  •  
    Intraoperative imaging
  •  
    Wound closure/coverage
  •  
    Postoperative care
  •  
    Rehabilitation

Pre-, Peri-, and Postoperative Care

While the anatomical location and pattern of a fracture may dictate a certain method of fixation, for example, a complete articular fracture will require open reduction and stable internal fixation; other fracture types may be approached by different fixation techniques or even by nonoperative treatment. The conditions of the soft tissue such as severe swelling or a skin contusion may preclude immediate surgery and make a staged procedure recommendable. Once the indication and best time for surgery has been established, the type of anesthesia, positioning of the patient, use of a tourniquet, the need for prophylactic antibiotics or a bone graft has to be communicated to the anesthesia and OR team as well as the method of fixation, approach, reduction aids, type of implant, and intraoperative imaging. The more complex the fracture and the procedure, the more detailed the planning must be. Drawing the outlines of a fracture on tracing paper will help to recognize the number, shape, position, and relationship of the different fragments. Thereby the character and challenges of a fracture will be appreciated and the experienced surgeon will be able to decide how to reduce and fix the fracture without additional damage to the most vulnerable blood supply of the area. 

Planning Technique on Paper

Two good orthogonal x-rays of the injured and also the uninjured side including the adjacent joints, tracing paper, colored pens, templates of the implants, a set of goniometers, and an x-ray screen are needed for preoperative templating. Step one: The outlines of the intact bone(s) are drawn. Step two: The outlines of the fractured bone(s) are drawn, with the different fragments separated from each other. Step three: The main fragments and the intermediate pieces are reassembled on the drawing of the intact bones. To do so, the separate fragments can be copied on different pieces of drawing paper or cut with scissors. The restored fracture on paper helps indicate how to best reduce the fracture and which function of the fixation device, absolute or relative stability will be utilized (Fig. 7-7). The plan also indicates what size implant is needed and where and how to place or introduce it to minimize additional soft tissue injury. Finally, the reduced fracture with the implant in place is drawn, and the different steps of applying the fixation device are numbered. For an open fracture, the question of wound closure or coverage should be addressed. The OR team will be grateful if a list of the required equipment, instrument sets, reduction tools, intraoperative imaging, etc. is provided. 
Figure 7-7
Planning on paper.
 
A: First the different fracture fragments are drawn separately on tracing paper. B: They may be cut out with a scissor to be assembled again, or they may be copied onto the outlines of the intact bones of the opposite side. C: Finally, the implants are added in the correct position, length, and function providing absolute (compression) or relative (bridging) stability.
A: First the different fracture fragments are drawn separately on tracing paper. B: They may be cut out with a scissor to be assembled again, or they may be copied onto the outlines of the intact bones of the opposite side. C: Finally, the implants are added in the correct position, length, and function providing absolute (compression) or relative (bridging) stability.
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Figure 7-7
Planning on paper.
A: First the different fracture fragments are drawn separately on tracing paper. B: They may be cut out with a scissor to be assembled again, or they may be copied onto the outlines of the intact bones of the opposite side. C: Finally, the implants are added in the correct position, length, and function providing absolute (compression) or relative (bridging) stability.
A: First the different fracture fragments are drawn separately on tracing paper. B: They may be cut out with a scissor to be assembled again, or they may be copied onto the outlines of the intact bones of the opposite side. C: Finally, the implants are added in the correct position, length, and function providing absolute (compression) or relative (bridging) stability.
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With digital x-ray imaging becoming standard equipment in most newer radiology departments, online planning tools and templates are under development and will soon be available, which hopefully will make the whole planning process on personal laptops more attractive, easier, and less time consuming. A good preoperative plan will reduce OR time, make a procedure more efficient and thus be beneficial to the patient. 

Prophylactic Antibiotics and Thromboembolic Prophylaxis

While the use of prophylactic antibiotics in operative fracture fixation of open as well as closed fractures is an evidence-based standard treatment today,8,60 discussion concerns the kind of antibiotic and the duration of application. As there is a large variation in the recommendations depending on national, regional and local factors, we suggest that the infectious disease specialist of a specific hospital should be consulted to determine a local standard. In general a second generation cephalosporin with a broad spectrum is recommended, applied as single dose 30 minutes before the start of surgery or for a period of a maximum of 24 to 48 hours postoperatively. Furthermore frequent wound irrigation with saline during surgery is recommended (“Keep the soft tissues wet and they will love you”) to reduce the risk for infection.4 The addition of antibiotics or antiseptics to irrigate solutions is however debatable and not proven to be effective. The detailed treatment of open fractures is discussed in Chapter 10
The risk of venous thromboembolism depends on multiple factors including age, type of surgery, duration of immobilization, and pre-existing disposition. The incidence of deep vein thrombosis (DVT) is high in patients with fractures of the hip, pelvis, spine and lower extremity, while upper limb injuries are rarely the source of thrombosis. DVT has a considerable morbidity with significant complications and mortality. However and similar to the use of antibiotics, the recommendations for a thromboembolic prophylaxis vary greatly from one institution to the other. Early postoperative mobilization of the entire patient is probably the most effective prophylaxis but not always possible. Low molecular heparin, aspirin, intermittent compression devices applied to the feet as well as warfarin or cumarines are all recommended by some but also rejected by others, as there is no evidence of superiority of one single method. 

Postoperative Care and Rehabilitation

The postoperative care starts with the wound bandage and/or splinting, positioning of the injured limb, and the initiating of physiotherapy exercises. A general goal is to move the joints, the injured limb as well as the whole patient as soon as possible, usually by 24 hours after surgery, provided the fixation of the fracture is stable and the soft tissues permit such an aggressive management. In the case of lower limb injuries and if the patient is considered compliant, a plan for early start of partial weight bearing should be made. In patients that are not compliant (old age, mental disturbances), the fixation must be able to tolerate early full weight bearing or the fracture has to be protected externally by a splint or cast. 

Fracture Reduction

The gentle and atraumatic reduction of a fracture is not only one of the most important and most challenging steps in fracture management, operative as well as nonoperative, but probably also the most difficult part to teach and practice. The goal of reduction is to restore the anatomical relationship of the fractured bone and the limb by reversing the mechanism of fragment displacement during the injury. It seems a fact that due to the muscle insertions to the bone, a fracture tends to redisplace in the direction and degree of the original displacement. It is therefore important not only to assess imaging studies carefully, but also to appreciate the vectors and forces of fragment displacement by muscle pull (Fig. 7-8). 
Figure 7-8
Typical displacement of a subtrochanteric fracture with external rotation, abduction, and flexion of the proximal and adduction of the distal fragment.
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In the diaphysis and regardless of whether the fracture is simple, multifragmentary or has a bone defect the correct restoration of length, axial alignment, and rotation is considered an adequate reduction. In the epiphyseal segment however a meticulous, anatomical reconstruction of the articular surface and joint congruency is advocated in order to obtain a good functional result. Such ambitious aims are sometimes difficult to achieve without risks—such as long incisions and a wide exposure. A careful balance between a perfect reconstruction and the necessary respect for the soft tissue biology has to be chosen. Furthermore, irreparable damage to the joint cartilage may be a limiting factor. 
Mast et al.49 created the term of “biologic fracture fixation” which refers not only to the method of fixation, but also to the reduction techniques. Accordingly, distinctions between direct and indirect as well as open and closed reduction will be made. Although direct and open reduction and indirect and closed techniques are usually associated, they are not necessarily synonymous. At the end, the essentials are that any reduction or fragment manipulation occurs atraumatic and gently, minimizing any additional harm to the vascularity of the already compromised fracture fragments and soft tissues envelope. 

Direct Reduction

Direct reduction means that the fracture fragments are manipulated directly by the application of different instruments or hands, which usually requires an open exposure of the fracture site. Some newly developed instruments and devices may however also be applied directly to the bone through very small incisions and without wide exposure of the fracture such as joysticks, large pointed reduction forceps, the collinear clamp (Fig. 7-9), or new cerclage wire tools. The application of these new techniques is called minimally invasive surgery (MIS) or when applied to plating, minimally invasive plate osteosynthesis (MIPO) inspite of the fact that thanks to the new instruments direct fragment manipulation has occurred. 
Figure 7-9
Collinear reduction clamp for minimally invasive approaches.
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The advantages of direct reduction are a precise restoration of anatomy; however, at the cost of more interference with bone and soft tissue biology. A higher risk of infection and possibly a delay in bony union that accompany striping of the soft tissues are further potential disadvantages. 

Indirect Reduction

Indirect reduction means that the reduction and alignment of the fracture fragments is being achieved without exposing the fracture site as such by applying reduction forces indirectly—via the soft tissue envelope—to the main fragments by manual or skeletal traction, a distractor, or some other means. The classical example of indirect reduction is the “closed” insertion of an intramedullary nail on a fracture table (Fig. 7-10), where reduction has been obtained by traction on the lower leg, while the nail provides the final alignment of the fragments. The advantages of indirect reduction are that there is virtually no exposure of the fracture site which reduces the risk of additional damage to the vascularity of the tissues, as well as that of an infection. The disadvantages are that it is a demanding technique and that the correct overall alignment of the fracture is more difficult to assess, especially in rotation. 
Figure 7-10
(Copyright by AO Foundation, Switzerland.)
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Figure 7-10
Fracture table with patient in supine position for femoral nailing.
(Copyright by AO Foundation, Switzerland.)
(Copyright by AO Foundation, Switzerland.)
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Open Reduction

Open reduction implies that the fracture site is exposed, allowing to watch and inspect the adequacy of reduction with our eyes. It is usually combined with direct manipulation of some fragments, but can also involve indirect techniques such as the use of a joint bridging distractor in an articular fracture. 
Indications for open reduction are the following. 
  •  
    Displaced articular fractures with impaction of the joint surface
  •  
    Fractures which require exact axial alignment (e.g., forearm fractures, simple metaphyseal fractures)
  •  
    Failed closed reduction due to soft tissue interposition
  •  
    Delayed surgery where granulation tissue or early callus has to be removed
  •  
    Where there is a high risk for harming neurovascular structures
  •  
    In cases of no or limited access to perioperative imaging to check reduction
Careful preoperative planning including adequate imaging is essential to choose the best approach, the tools for a gentle reduction and the appropriate implant. In articular fractures it is usually sufficient to be able to see into the joint, in order to carefully clear it from hematoma and debris and to judge the cartilage damage as well as the quality of reduction after the reconstruction. The periosteum and any soft tissue attachments must be preserved wherever possible, while separate stab incisions may help the placement of pointed reduction clamps, temporary K-wires or the insertion of lag screws. 

Closed Reduction

Closed reduction relies entirely on indirect fragment alignment by ligamentotaxis or the pull of the soft tissue envelope. Longitudinal traction is the main force which may be modified by adduction or abduction, flexion, or extension and rotation as well as supporting bolsters, etc. These maneuvers may be quite demanding and usually require the presence of an image intensifier. Profound knowledge of the anatomy (location of muscle insertion and direction of muscle pull) as well as careful planning are prerequisites. Percutaneously applied joysticks, and special instruments may be helpful.18,43 If correctly applied, the advantages of closed reduction are minimal additional damage to the soft tissues, safer, and more rapid fracture repair as well as lower risk of infection. 
Indications for closed reduction are the following. 
  •  
    Most diaphyseal fractures, where correct axial alignment, length, and rotation is considered sufficient for a good outcome.
  •  
    Minimally displaced articular fractures suited for percutaneous fixation.
  •  
    Geriatric femoral neck fractures, trochanteric fractures, subcapital humerus fractures, and certain distal radius fractures.
The size of an incision will not necessarily be indicative of the amount of damage done to the biology of a fracture. Much harm can be done through a short incision, but also little harm through a larger exposure. All that matters is the gentleness of the surgeon’s hands and his skills in managing the reduction process. 

Techniques and Instruments for Fracture Reduction

Traction and Distraction

Traction is the most common means to reduce a fracture. This can occur manually, with the help of a fracture table or by applying a distractor directly to the main fragments of a long bone or in an articular fracture across the joint (Fig. 7-11). While longitudinal traction will usually correct shortening, it may be difficult to align the fragments in both the sagittal and coronal planes. There are a number of tricks described to overcome the problem. The fracture table has the disadvantage that traction is usually applied across a joint and that there are limited possibilities to move the limb. The distractor on the other hand offers many possibilities and more freedom of movement, but it is quite demanding to manipulate and requires considerable practice (Fig. 7-12).3,5 
Figure 7-11
Joint bridging distractor to support reduction of a distal femur fracture with joysticks.
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Figure 7-12
Femoral distractor applied in two planes to allow axial and rotational alignment such as for IM nailing or minimally invasive plating.
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Reduction Forceps

There is a great variety of reduction forceps available, some for general use, others for rather specific applications (Table 7-2). The reduction forceps with sharp points (Weber forceps) (Fig. 7-13) is the most commonly used as it comes in many different dimensions. The points provide an excellent purchase on the fragments without stripping or squeezing the periosteum; in osteopenic bone they can however penetrate through the thin cortex. Occasionally a small hole, created with a drill or K-wire, is helpful to gain purchase for the tip. The forceps may be applied directly through a surgical wound or percutaneously through stab incisions. 
Figure 7-13
Pointed reduction forceps (Weber), which allows safe purchase of the bone without stripping of the periosteum.
 
By manipulating the forceps (arrows) a simple oblique fracture can be easily reduced.
By manipulating the forceps (arrows) a simple oblique fracture can be easily reduced.
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Figure 7-13
Pointed reduction forceps (Weber), which allows safe purchase of the bone without stripping of the periosteum.
By manipulating the forceps (arrows) a simple oblique fracture can be easily reduced.
By manipulating the forceps (arrows) a simple oblique fracture can be easily reduced.
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Table 7-2
Useful and Frequently Used Instruments for Reduction
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Table 7-2
Useful and Frequently Used Instruments for Reduction
Instrument Image of Instrument Description Application Technique, Degrees of Freedom
Reduction forceps with points (Weber forceps)  

 

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Different sizes and angulations of the branches available, different mechanisms One-forceps technique, two-forceps technique, three linear and two rotational degrees of freedom
Reduction forceps, toothed  

 

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Different sizes Mainly used for alignment of a plate on a diaphyseal bone and reduction
Bone holding forceps, self-centering (Verbrugge forceps)  

 

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Four different sizes
Bone spreader  

 

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Different sizes and angulations Only for distraction, one linear degree of freedom
Collinear reduction forceps  

 

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Different insertable branches (hooks) Only for compression, one linear degree of freedom
Pelvic reduction forceps with ballpoints (“King Tong,” “Queen Tong”)  

 

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Symmetric and asymmetric, two spikes and three spikes, spiked mountable washer
Angled pelvic reduction forceps (Matta forceps)  

 

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Large and small
Pelvic reduction forceps (Faraboeuf forceps)  

 

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Different sizes, 3.5- and 4.5-mm screws
Pelvic reduction forceps (Jungbluth forceps)  

 

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Two different sizes, 3.5- and 4.5-mm screws Can be used in different directions, as the screw directly links the forceps to the bone fragment
Periarticular reduction forceps with ball points (“Ice Tong,” “King Kong”)  

 

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Multiple sizes, spiked mountable washer Mainly used for periarticular fractures, large radius prevents soft tissue crush
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Two special forceps (Faraboeuf and Jungbluth) have originally been developed for pelvic and acetabular fractures. Both are applied to the heads of two screws that are inserted on either side of a fracture (Fig. 7-14). The newest reduction forceps is the collinear forceps which is no longer based on a hinge between the two branches but on a sliding mechanism that allows a linear movement (Fig. 7-9). Thanks to this, the new reduction tool can be introduced through very short incisions or through narrow openings in the pelvis which makes it ideal for minimally invasive techniques. 
Figure 7-14
The Jungbluth forceps is applied with the help of the head of two screws that are inserted close to the fracture.
 
Distraction as well as translation movements may be performed, which is helpful especially in the pelvis.
Distraction as well as translation movements may be performed, which is helpful especially in the pelvis.
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Figure 7-14
The Jungbluth forceps is applied with the help of the head of two screws that are inserted close to the fracture.
Distraction as well as translation movements may be performed, which is helpful especially in the pelvis.
Distraction as well as translation movements may be performed, which is helpful especially in the pelvis.
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Other reduction tools include joysticks (preferably Schanz screws), Hohmann retractors for intrafocal manipulation and cerclage wires, while every surgeon has additional tricks and tools in his personal armamentarium (Fig. 7-15). 
Figure 7-15
Hohmann retractor for direct reduction of a simple fracture.
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There are furthermore situations where the implant, intramedullary nail, plate or modular external fixator, may be used for the reduction and fixation at the same time. Especially in conventional nonlocked plating, angle blade and precontoured plates can be used to reduce the fracture toward the plate. 
Computer assisted surgery (CAS) with navigation software has promised to open completely new applications especially for hip and knee replacement, but appears at present to be still in an early stage for acute fracture reduction and management.31,36 

Intra- and Postoperative Assessment of the Reduction

After the reduction of a fracture, the position of the fragments should be held reduced with temporary K-wires and/or a forceps and then the reconstruction and axial alignment must be carefully assessed in at least two planes preferably with the image intensifier. However, the resolution of the images is not as precise as that of x-rays, and the size of the field or picture is usually too small to allow to evaluate the longitudinal axis of a bone or its rotation. Another shortcoming of the image intensifier is the often prolonged exposure to radiation for the patient, surgeon, and staff. Several tricks have been described to overcome these drawbacks, some of them will be described in the chapter on IM nailing where axial and rotational alignment is particularly difficult. In articular fractures, inspection of the joint surface occurs best with our eyes or with the image intensifier. The most reliable way to assess an articular reconstruction is with a CT scan, which is becoming more available in the OR integrated into the new 2D and 3D fluoroscopes. Arthroscopy has also been advocated for minimally invasive surgical control of articular fractures.30,50 It offers advantages to evaluate menisci and ligaments as well as the consistency of articular cartilage; however, for the judgment of axial alignment open reduction usually appears to be superior. 

Techniques and Devices for Internal Fixation

Operative fracture fixation can be performed with devices applied either externally (percutaneously) or internally (underneath the soft tissue cover). The former include the many different types of external fixators that will be described in Chapter 8. Internal fixation devices stabilize the bone from within the medullary canal (intramedullary nails) or are fixed to the exterior of the bone (conventional nonlocked screws and plates and locked plates as well as tension band wires). 

Screws

Screws are the basic and most efficient tool for internal fixation especially in combination with plates. A screw is a powerful element that converts rotation into linear motion. 
Most screws are characterized by some common design features (Fig. 7-16). 
  •  
    A central core that provides strength.
  •  
    A thread which engages the bone and is responsible for the function and purchase.
  •  
    A tip that may be blunt or sharp, self-cutting or self-drilling and -cutting.
  •  
    A head that engages in bone or a plate.
  •  
    A recess in the head to attach the screw driver.
Figure 7-16
Schematic illustration of a conventional 4.5-mm cortex screw.
 
A: Spherical screw head allowing a congruous fit in the plate hole. B: Core diameter (3.2 mm), C: Outer diameter (4.5 mm), and D: The thread pitch are commonly referenced screw design parameters.
A: Spherical screw head allowing a congruous fit in the plate hole. B: Core diameter (3.2 mm), C: Outer diameter (4.5 mm), and D: The thread pitch are commonly referenced screw design parameters.
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Figure 7-16
Schematic illustration of a conventional 4.5-mm cortex screw.
A: Spherical screw head allowing a congruous fit in the plate hole. B: Core diameter (3.2 mm), C: Outer diameter (4.5 mm), and D: The thread pitch are commonly referenced screw design parameters.
A: Spherical screw head allowing a congruous fit in the plate hole. B: Core diameter (3.2 mm), C: Outer diameter (4.5 mm), and D: The thread pitch are commonly referenced screw design parameters.
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Screws are provided in different forms, sizes, and materials. They are typically named according to their design, function, or way of application. 
  •  
    Design (partially or fully threaded, cannulated, self-tapping, etc.)
  •  
    Dimension of major thread diameter (most common used 1.5, 2, 2.4, 2.7, 3.5, 4.5, 6.5, 7.3 mm, etc.)
  •  
    Area of typical application (cortex, cancellous bone, bicortical, or monocortical)
  •  
    Function (lag screw, locking head screw [LHS], position screw, etc.)
  •  
    One and the same screw can have different functions, which depend on the screw design and way of application. The two basic principles of a conventional screw are to compress a fracture plane (lag screw) and to fix a plate to the bone (plate screw). The more recent designed LHS provide angular stability between the implant and the bone (Figs. 7-17 and 7-18). The LHS have a head with a thread that engages with the reciprocal thread of the plate hole.15 This creates a screw-plate device with angular stability. Locking screw tightening does not press plate against the bone surface. The load transfer occurs through the locking screws and the plate, similarly as with an external fixator, and not by friction and preload. As the locked plate lies underneath the soft tissues the principle of this purely locked construct has been termed internal fixator (Fig. 7-19). A more recent development offers the option of variable angular stability, which allows angulating locking screws within the plate hole to address specific fracture configurations (e.g., for complex comminuted metaphyseal fractures especially distal radius fractures).
Figure 7-17
A conventional cortical screw applied as a plate screw.
 
It presses the plate against the bone surface thereby creating friction and preload.
It presses the plate against the bone surface thereby creating friction and preload.
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Figure 7-17
A conventional cortical screw applied as a plate screw.
It presses the plate against the bone surface thereby creating friction and preload.
It presses the plate against the bone surface thereby creating friction and preload.
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Figure 7-18
Locking head screw.
 
The screw head is firmly locked in the screw hole without pressing the plate against the bone. It provides angular stability.
The screw head is firmly locked in the screw hole without pressing the plate against the bone. It provides angular stability.
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Figure 7-18
Locking head screw.
The screw head is firmly locked in the screw hole without pressing the plate against the bone. It provides angular stability.
The screw head is firmly locked in the screw hole without pressing the plate against the bone. It provides angular stability.
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Figure 7-19
Dynamic compression principle: The holes of the DC-plate are shaped like an inclined and transverse cylinder (A).
 
Like a ball, the screw head slides down the inclined cylinder (B). Due to the shape of the plate hole, the plate is being moved horizontally relative to bone when the screw is driven home (C) and (D).
Like a ball, the screw head slides down the inclined cylinder (B). Due to the shape of the plate hole, the plate is being moved horizontally relative to bone when the screw is driven home (C) and (D).
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Figure 7-19
Dynamic compression principle: The holes of the DC-plate are shaped like an inclined and transverse cylinder (A).
Like a ball, the screw head slides down the inclined cylinder (B). Due to the shape of the plate hole, the plate is being moved horizontally relative to bone when the screw is driven home (C) and (D).
Like a ball, the screw head slides down the inclined cylinder (B). Due to the shape of the plate hole, the plate is being moved horizontally relative to bone when the screw is driven home (C) and (D).
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Lag screws (Fig. 7-20) can be applied independently or through a plate hole. In both situations compression between two fragments or between the plate and the bone produces preload and friction, which oppose fragment displacement by other forces including shear. Interfragmentary compression is the basic element responsible for absolute stability of fracture fixation. 
Figure 7-20
To insert a lag screw the first step consists of drilling the glide hole in the near cortex with a drill bit slightly larger than the major screw diameter (A).
 
Into this hole a drill sleeve is inserted to correctly centre the pilot or threaded hole in the opposite or far cortex, which is drilled with a drill bit the same size as the minor diameter of the screw (B). After measuring the screw length with the depth gauge and tapping the thread in the far cortex, the cortex screw is inserted. Driving home the screw, the fracture surfaces will be compressed (interfragmentary compression) (C). While the ideal screw direction to generate compression is at right angles to the fracture plane, this is only rarely possible. Therefore the screw is directed halfway between the perpendicular to the fracture plane and to that of the bone (D).
Into this hole a drill sleeve is inserted to correctly centre the pilot or threaded hole in the opposite or far cortex, which is drilled with a drill bit the same size as the minor diameter of the screw (B). After measuring the screw length with the depth gauge and tapping the thread in the far cortex, the cortex screw is inserted. Driving home the screw, the fracture surfaces will be compressed (interfragmentary compression) (C). While the ideal screw direction to generate compression is at right angles to the fracture plane, this is only rarely possible. Therefore the screw is directed halfway between the perpendicular to the fracture plane and to that of the bone (D).
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Figure 7-20
To insert a lag screw the first step consists of drilling the glide hole in the near cortex with a drill bit slightly larger than the major screw diameter (A).
Into this hole a drill sleeve is inserted to correctly centre the pilot or threaded hole in the opposite or far cortex, which is drilled with a drill bit the same size as the minor diameter of the screw (B). After measuring the screw length with the depth gauge and tapping the thread in the far cortex, the cortex screw is inserted. Driving home the screw, the fracture surfaces will be compressed (interfragmentary compression) (C). While the ideal screw direction to generate compression is at right angles to the fracture plane, this is only rarely possible. Therefore the screw is directed halfway between the perpendicular to the fracture plane and to that of the bone (D).
Into this hole a drill sleeve is inserted to correctly centre the pilot or threaded hole in the opposite or far cortex, which is drilled with a drill bit the same size as the minor diameter of the screw (B). After measuring the screw length with the depth gauge and tapping the thread in the far cortex, the cortex screw is inserted. Driving home the screw, the fracture surfaces will be compressed (interfragmentary compression) (C). While the ideal screw direction to generate compression is at right angles to the fracture plane, this is only rarely possible. Therefore the screw is directed halfway between the perpendicular to the fracture plane and to that of the bone (D).
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To insert a screw, a hole has to be drilled into the bone with a drill bit slightly larger in diameter than the minor diameter of the selected screw. To ensure safe purchase of the screw it is recommended to cut a thread with a matching tap before the screw is inserted especially in cortical as well as in hard cancellous bone in young patients. In bone of softer quality such as cancellous bone, screw insertion may be done without tapping. Alternatively there are also self-tapping screws, which reduce insertion time but require some practice. Turning the screw within the bone creates friction and thereby heat is generated, which may in turn cause thermal necrosis of the adjacent bone. The screw design and the technique of screw insertion influence the amount of damage done and ultimately the holding power of a screw. Thermal necrosis may also be caused by dull drill bits or by inserting pins and wires with a diameter larger than 2 mm without predrilling, leading to loosening, and ring sequester. It is the surgeon’s responsibility to adequately prepare the holes. 
In general, three different types of screws are differentiated as follows. 
  1.  
    The cortex screw thread is designed for use in cortical bone (Fig. 7-16). It is typically fully threaded but maybe partially threaded and is commonly available in diameters from 1 to 4.5 mm. Each size has a pair of drill bits corresponding to the screws major and minor diameter and a tap. The drill corresponding to the major diameter is used for drilling the gliding hole for a lag screw while the drill corresponding to the minor diameter is used for drilling the threaded hole. Today self-tapping cortex screws are available and also recommended, except for hard cortical bone of the young adult. Some of the screws are also available in a cannulated version.
  2.  
    The cancellous bone screw has a deeper thread, a larger pitch, and typically a larger outer diameter (4 to 8 mm) than the cortex screws. They are indicated for meta-epiphyseal cancellous bone. The screw may be partially or fully threaded. Tapping is recommend to open the cortex and in dense bone of the young adult.
  3.  
    The LHS of locking plate systems (Fig. 7-18) are primarily characterized by the threaded screw head. They may have a larger core diameter and a relatively shallow thread with blunt edges. This increases the strength and interface between screw and cortical bone compared to conventional screws. Locking screws are used in combination with plates that have holes able to accommodate the threaded screw head. Variable angle locking screws follow the same locking principle, but offer in addition that the locking screws can be angulated to some degree. Certain comminuted metaphyseal fractures required the fixation of small fragments, still providing angular stability. This development has become more broadly available specially for complex unstable or displaced metaphyseal fracture fixation of the distal radius,62 the proximal humerus,40,81 distal femur,22,59,84 and proximal tibia.21,56 These types of screws certainly provide a greater versatility and flexibility in both screw and plate placement but may at the same time cause reduction of ultimate fatigue strength. Thus, for clinical use it needs to be taken in consideration that an increase in screw angulation can cause reduction of locking strength and thereby potential load failure.29,84

Different Functions of a Screw

Various different screw functions are listed in Table 7-3. Three examples are given in more depth due to their importance in daily operative fracture care. 
 
Table 7-3
Various Screw Functions and Clinical Examples
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Table 7-3
Various Screw Functions and Clinical Examples
Function
Name Mechanism Clinical Example
Nonlocked plate screw Preload and friction is applied to create force between the plate and the bone Forearm plating
Lag screw The glide hole allows compression between bone fragments Fixation of a butterfly or wedge fragment or medial malleolus fracture
Position screw Holds anatomical parts in correct relation to each other without compression (i.e., thread hole only, no glide hole) Syndesmotic screw
Locking head screw Used exclusively with locked plates; threads in the screw head allow mechanical coupling to a reciprocal thread in the plate and provide angular stability Complex metaphyseal fracture
Osteoporotic
Variable locking screw Used exclusively with special locked plates; same mechanical angular stability as locking head screw, but allows some variability in screw angulation within the plate hole Complex comminuted metaphyseal fractures and periprosthetic fractures
Interlocking screw Couples an intramedullary nail to the bone to maintain length, alignment, and rotation Interlocked femoral or tibial intramedullary nail
Anchor screw A point of fixation used to anchor a wire loop or strong suture Tension band anchor in a proximal humerus fracture
Push–pull screw A temporary point of fixation used to reduce a fracture by distraction and/or compression Use of an articulated compression device
Reduction screw Conventional screw used through a plate to pull fracture fragments toward the plate; the screw may be removed or exchanged once alignment is obtained Minimally invasive plate osteosynthesis technique to reduce multifragmentary fracture onto the plate
Poller screw Screw used as a fulcrum to redirect an intramedullary nail Proximal tibial fracture during IM nailing
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Lag Screw.
One of the basic principles of modern internal fixation is absolute stability thanks to interfragmentary compression as it is provided by a lag screw.65 A fully threaded conventional cortex screw is acting as a lag screw when the thread engages only in the cortex opposite to the fracture line (far cortex) and not in the cortex close to the screw head (near cortex). This is obtained by first drilling a glide hole with a drill bit slightly larger than the major diameter of the cortex screw. Next a drill sleeve is inserted into the gliding hole to precisely centre the threaded or pilot hole in the opposite cortex collinear with the gliding hole, which is drilled with a smaller drill bit corresponding to the minor diameter of the screw. After measuring the screw length with a depth gauge, the thread in the far cortex is cut with a tap or a self-tapping screw is inserted. As the screw advances in the threaded hole, the head will engage in the near cortex and create preload and compression between the two fragments. It is advisable to apply only about two-third of the possible torque to a lag screw corresponding to about 2,000 to 3,000 N.68,75 The ideal direction of a lag screw, for generation of compressive force, is perpendicular to the fracture plane. As this is often not practical, an inclination halfway between the perpendiculars to the fracture and to the long axis of the bone is typically chosen (Fig. 7-20). The head of an independent lag screw should be countersunk in the underlying cortex, which increased the area of contact between the screw and the bone and reduces the risk of stress risers producing cracks. A further advantage of countersinking consists of reducing the protuberance of the large screw head underneath the skin (e.g., on the tibial crest). 
The partially threaded cancellous bone screw will also produce interfragmentary compression, provided that the thread engages only in the fragment opposite to the fracture plane. A washer may prevent the screw head from sinking into the thin metaphyseal cortex (Fig. 7-21). 
Figure 7-21
A partially threaded 6.5-mm cancellous bone screw will act as a lag screw, provided that the thread has its purchase opposite to the fracture line only.
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Plate Screws.
Conventional nonlocked screws used to fix a plate to the bone are called plate screws. They are introduced with a special drill guide that fits into the plate hole either centrally or eccentrically depending on whether axial compression is demanded. The drill bit has the diameter of the minor diameter of the screw, which may be self-tapping or not. By driving home the plate screws the plate is pressed against the bone which produces preload and friction between the two surfaces. 
Positioning Screw.
A positioning screw is a fully threaded screw that joins two anatomical parts at a defined distance without compression. The thread is therefore tapped in both cortices. An example is a screw placed between fibula and tibia in a malleolar fracture to secure the syndesmotic ligaments (Fig. 7-22). 
Figure 7-22
A thread is cut in every cortex thus preventing compression between the two bones.
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Figure 7-22
Example of a cortex screw in the function as a position screw between fibula and tibia to secure the ruptured syndesmosis.
A thread is cut in every cortex thus preventing compression between the two bones.
A thread is cut in every cortex thus preventing compression between the two bones.
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Plates

Besides the lag screw as a basic principle of operative fracture fixation, conventional compression plating is the other principle providing absolute stability and inducing primary or direct bone healing without visible callus. Today the classical open reduction with considerable exposure of the fracture and internal fixation by plates and screws is being challenged by less invasive and more elastic fixation methods, so-called biologic techniques. Nevertheless plating with absolute stability still has its definitive place in operative fracture treatment, especially since we have learned to better protect the delicate soft tissues also during open approaches. Fractures of the forearm bones as well as simple metaphyseal fractures of other long bones are good indications for conventional nonlocked plating, so are mal- and nonunions. In articular fractures that require anatomical reduction and rigid fixation by interfragmentary compression, plates will often support lag screws and/or buttress the metaphysis. However, for most diaphyseal fractures of the femur and tibia IM nailing is the golden standard today. 
Absolute stability results in direct fracture healing, which generally takes longer than healing by callus. Appearance of callus after attempted rigid plate fixation is unexpected and a sign of unplanned instability, which may lead to implant failure, healing delay or nonunion. The classical technique of compression plating relies on pressing the plate to the bone surface, which may disturb the blood flow to the underlying cortex, leading to local cortical necrosis. This so called footprint of the plate induces a slow cortical remodeling by creeping substitution and revascularization. What was considered as stress protection in former times is now interpreted as disturbed vascularity of the cortex and has been addressed by new plate designs with limited bone contact or more effectively by the internal fixator principle, where there is no direct compression between the plate and the bone.67 

Plate Design

Early modern plates had round holes in which the conical screw head had a firm fit. Axial compression was obtained with a removable external device. In 1967 the dynamic compression plate (DCP) designed by Perren introduced a new principle of applying axial compression by leveraging the interaction of a spherical screw head and an inclined oval screw hole (Fig. 7-19). The oval hole also allowed angulation of the screw in different directions.66 The use of special drill guides precisely placed the screws in relation to the plate hole in neutral or compression mode. These features of the DCP greatly extended and facilitated the possibilities of application of plates. 
While the original plates were all straight and of two sizes only, 4.5 narrow and broad, soon smaller sizes followed and also different designs for special applications such as the angle blade plates for the proximal and distal femur, tubular plates, reconstruction plates, the sliding hip screw and dynamic condylar screws, and other form plates (Fig. 7-23). 
Figure 7-23
Different types and forms of early plates.
 
A: 95-degree and B: 130-degree angle blade plates, C: T and D: L plates, and E: Small fragment 3.5 distal radius plate.
A: 95-degree and B: 130-degree angle blade plates, C: T and D: L plates, and E: Small fragment 3.5 distal radius plate.
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Figure 7-23
Different types and forms of early plates.
A: 95-degree and B: 130-degree angle blade plates, C: T and D: L plates, and E: Small fragment 3.5 distal radius plate.
A: 95-degree and B: 130-degree angle blade plates, C: T and D: L plates, and E: Small fragment 3.5 distal radius plate.
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A further advancement was the LC-DCP (limited contact-DCP) which featured a new design of the under surface reducing the area of contact between the plate and the bone to reduce the adverse effects of pressure and friction on bone vascularity (Fig. 7-24). This plate generation, designed with finite-element analysis displayed an even distribution of strength throughout its length and irrespective of the plate holes. All conventional plates usually had to be contoured to match the shape of the bone, as the plate was either pressed against the bone or the bone was pulled toward the plate. 
Figure 7-24
More recent plate designs (like the LC-DCP, limited contact-dynamic compression plate) feature the dynamic compression unit and have undercuts between the screw holes to reduce the area of contact between the plate and the bone.
This plate design has uniform strength throughout.69
This plate design has uniform strength throughout.69
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The most recent and most revolutionary design changes to modern plates that also introduced a completely new principles of fixation, the internal fixators or locking plates, will be discussed later in a separate section of this chapter. 

Plate Functions

While there are many different designs and dimensions of plates, the function that is assigned to a plate by the surgeon and how it is applied is decisive for the outcome. There are five key functions or modes any plate can have. In order to assign a specific function to a plate, the preoperative plan has to take into account the fracture pattern, its location, the soft tissues and biomechanical surrounding. 
The five functions are the following. 
  •  
    Neutralization or protection
  •  
    Compression
  •  
    Buttressing
  •  
    Tension band function
  •  
    Bridging
Neutralization or Protection Plate for Absolute Stability.
A simple, torsion or butterfly fracture of the diaphysis or metaphysis, caused by indirect rotational forces, is best reduced anatomically and fixed by one or two lag screws providing interfragmentary compression. It is normally recommended to protect the lag screw fixation with the addition of a plate in order to protect it or to neutralize any shearing or rotational forces, thereby improving the stability (Fig. 7-25). This type of classical plate application can also be performed with minimal exposure of the fracture site and percutaneous reduction with the help of pointed reduction forceps. 
Figure 7-25
Protection or neutralization plate to protect a simple fracture of the radius.
 
The oblique screw inserted through the plate is a lag screw crossing the fracture plane, which adds to the absolute stability of the fixation.
The oblique screw inserted through the plate is a lag screw crossing the fracture plane, which adds to the absolute stability of the fixation.
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Figure 7-25
Protection or neutralization plate to protect a simple fracture of the radius.
The oblique screw inserted through the plate is a lag screw crossing the fracture plane, which adds to the absolute stability of the fixation.
The oblique screw inserted through the plate is a lag screw crossing the fracture plane, which adds to the absolute stability of the fixation.
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Compression Plate.
Axial compression of a transverse fracture of a forearm bone is best obtained by a compression plate. By slightly over bending the plate in relation the shape of the bone and by eccentric placement of the screws axial compression is obtained. In short oblique fractures in addition to axial compression a lag screw inserted through the plate and across the oblique fracture plane will significantly increase the stability of the fixation. In oblique fractures the plate must be fixed first to the fragment with an obtuse angle, so that when compression is added on the opposite side of the fracture the fragment locks in the axilla between the plate and the bone (Fig. 7-26). 
Figure 7-26
Axial compression with a plate can be obtained with the removable, articulated tension device.
 
The plate is first fixed on one side of the fracture and then compressed in the axial direction. In case of an oblique fracture (A) a lag screw across the fracture plane will increase stability and compress the opposite cortex. In order to obtain an equal compression of both cortices of a transverse fracture (B) the plate has to slightly over contoured before axial compression is applied.
The plate is first fixed on one side of the fracture and then compressed in the axial direction. In case of an oblique fracture (A) a lag screw across the fracture plane will increase stability and compress the opposite cortex. In order to obtain an equal compression of both cortices of a transverse fracture (B) the plate has to slightly over contoured before axial compression is applied.
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Figure 7-26
Axial compression with a plate can be obtained with the removable, articulated tension device.
The plate is first fixed on one side of the fracture and then compressed in the axial direction. In case of an oblique fracture (A) a lag screw across the fracture plane will increase stability and compress the opposite cortex. In order to obtain an equal compression of both cortices of a transverse fracture (B) the plate has to slightly over contoured before axial compression is applied.
The plate is first fixed on one side of the fracture and then compressed in the axial direction. In case of an oblique fracture (A) a lag screw across the fracture plane will increase stability and compress the opposite cortex. In order to obtain an equal compression of both cortices of a transverse fracture (B) the plate has to slightly over contoured before axial compression is applied.
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Buttress Plate (Antiglide Function).
In articular fractures such as malleolar fractures, tibia plateau or distal radius fractures, we can observe how a large fragment has been displaced by shearing forces.9 To counter act these forces and keep the reduced fragment in place, a plate is best applied in a position that locks the spike of the fragment back in place thereby preventing any further shearing or gliding of the fragment. Buttress plates are often combined with lag screws either through the plate or independently (Fig. 7-27). 
Figure 7-27
A buttress plate or antiglide plate has the function of preventing any secondary displacement of an oblique fracture in the metaphysis of a bone.
 
The example shows the application in a malleolar fracture, where the plate is positioned on the posterolateral aspect of the distal fibula. The different steps and the sequence of introducing the screws are illustrated.
The example shows the application in a malleolar fracture, where the plate is positioned on the posterolateral aspect of the distal fibula. The different steps and the sequence of introducing the screws are illustrated.
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Figure 7-27
A buttress plate or antiglide plate has the function of preventing any secondary displacement of an oblique fracture in the metaphysis of a bone.
The example shows the application in a malleolar fracture, where the plate is positioned on the posterolateral aspect of the distal fibula. The different steps and the sequence of introducing the screws are illustrated.
The example shows the application in a malleolar fracture, where the plate is positioned on the posterolateral aspect of the distal fibula. The different steps and the sequence of introducing the screws are illustrated.
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Tension Band Plate.
Certain bones such as the femur are loaded eccentrically. We know from the studies of Pauwels63 that with weight bearing the concave, medial side of the femur is undergoing compressive forces, while the convex, lateral cortex is under tension. An eccentrically applied plate on the convex side of the bone will theoretically convert tensile forces into compression, provided the opposite medial cortex is stable. In a subtrochanteric fracture that is fixed with a plate, this implant will function as a tension band provided the medial cortex, opposite to the plate, has been reduced anatomically without any residual gap (Fig. 7-28). 
Figure 7-28
By placing the plate in a transverse femur fracture (A) to the lateral aspect of the femur (B) this implant will undergo tensile forces which are theoretically converted into compression at the fracture site.
 
A precondition is however that the bone opposite to the plate has close contact to resist the compressive forces. If the essential medial support is missing, the plate is more likely to break due to fatigue (C).
A precondition is however that the bone opposite to the plate has close contact to resist the compressive forces. If the essential medial support is missing, the plate is more likely to break due to fatigue (C).
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Figure 7-28
By placing the plate in a transverse femur fracture (A) to the lateral aspect of the femur (B) this implant will undergo tensile forces which are theoretically converted into compression at the fracture site.
A precondition is however that the bone opposite to the plate has close contact to resist the compressive forces. If the essential medial support is missing, the plate is more likely to break due to fatigue (C).
A precondition is however that the bone opposite to the plate has close contact to resist the compressive forces. If the essential medial support is missing, the plate is more likely to break due to fatigue (C).
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Bridge Plate.
Since the introduction of more biologic indirect reduction and minimally invasive techniques with less rigid or elastic fixations providing relative stability, a plate can also be applied as an internal bridging device, similar to an external fixator.24,79 The best indications for bridge plating9 are comminuted diaphyseal or metaphyseal fractures that are not suited for IM nailing. While we do not know precisely the ideal working length of a plate, it is recommended to choose a plate about three times as long as the fracture zone and to fix it with only a few firmly anchored screw proximally and distally (Fig. 7-29). 
Figure 7-29
 
A, B: Bridge plating can be performed with any plate of the adequate length. Nevertheless, the new locking plate systems are considered ideally suited for bridge plating and simplify the technique of minimal invasive application. The bridging device should be about three times the length of the fracture zone providing relative stability.
A, B: Bridge plating can be performed with any plate of the adequate length. Nevertheless, the new locking plate systems are considered ideally suited for bridge plating and simplify the technique of minimal invasive application. The bridging device should be about three times the length of the fracture zone providing relative stability.
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Figure 7-29
A, B: Bridge plating can be performed with any plate of the adequate length. Nevertheless, the new locking plate systems are considered ideally suited for bridge plating and simplify the technique of minimal invasive application. The bridging device should be about three times the length of the fracture zone providing relative stability.
A, B: Bridge plating can be performed with any plate of the adequate length. Nevertheless, the new locking plate systems are considered ideally suited for bridge plating and simplify the technique of minimal invasive application. The bridging device should be about three times the length of the fracture zone providing relative stability.
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From Biologic to Minimally Invasive Plate Fixation (MIPO)

Although the protagonists of modern operative fracture fixation or ORIF, starting with Albin Lambotte—stressed already 100 years ago the importance of gentle soft tissue handling and minimal stripping of the periosteum in order to preserve bone vascularity, the request for anatomical reduction seemed somehow in contradiction with this principle. In inexperienced hands too wide exposures and extensive denudation of bone occurred all too often, resulting in catastrophes such as delayed or nonunions or infections or the combination of the two. Mast et al.49 described in detail the advantages of indirect reduction techniques without exposing the fracture fragments and created the term of biologic plate fixation with long bridging angle blade or straight plates. In a study comparing a series of subtrochanteric fractures treated by conventional “open” technique with indirection and bridge plating demonstrated that in the latter group the time for union was shorter and predictable even without bone graft, the complication rate was lower and the functional outcome better.37 An important prerequisite was however that the procedure was carefully planned and well performed. 
We have learned from closed IM nailing with interlocking that in complex diaphyseal fractures correct axial and rotational alignment is all that is needed for early callus formation and that anatomical reduction of every fragment is not required. 
Krettek et al.44 have further developed these observations and ideas by minimizing the approaches to quite short incisions far away from the fracture focus and by inserting extra long plates via a bluntly prepared submuscular space close to the bone and across the fracture (Fig. 7-30). The screws were inserted through equally short incisions and straight through the muscles. In cadaver studies Farouk et al.14 could show that the perforator vessels were not injured by these tunneling maneuvers. Similar to the rapid appearance of callus in IM nailing, the healing of these minimally exposed fractures fixed with only relatively stable bridge plates occurred very consistently with early callus formation. 
Figure 7-30
Minimally invasive plate osteosynthesis (MIPO) with blunt percutaneous tunneling from distally (A) and insertion of a plate without exposing the comminuted fracture zone from proximally (B).
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The drawback of minimally invasive techniques is the higher incidence of axial and rotational malalignment just as in IM nailing,77 especially of the femur. Furthermore the intraoperative radiation exposure of the patient and staff is higher, but may be reduced when navigation techniques are refined and used more in the future. 
For high energy articular fractures of the distal femur, proximal and distal tibia that often show extensions into the diaphysis a combination of open anatomical reduction and stable fixation (ORIF) of the articular block with minimally invasive bridging fixation of the meta-diaphysis (MIPO) can be recommended (Fig. 7-31). 
Figure 7-31
A combination of conventional open reduction and internal fixation (ORIF) with minimally invasive plate osteosynthesis (MIPO) in a pilon fracture.
 
After temporary fixation with a bridging external fixator, the articular block is reconstructed anatomically and held with K-wires (A). The articular fragments are then fixed by lag screws (B) To secure the screw fixation and to bridge the metaphysis, an anterolateral L-shaped pilon plate is inserted percutaneously in MIPO technique (C).
After temporary fixation with a bridging external fixator, the articular block is reconstructed anatomically and held with K-wires (A). The articular fragments are then fixed by lag screws (B) To secure the screw fixation and to bridge the metaphysis, an anterolateral L-shaped pilon plate is inserted percutaneously in MIPO technique (C).
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Figure 7-31
A combination of conventional open reduction and internal fixation (ORIF) with minimally invasive plate osteosynthesis (MIPO) in a pilon fracture.
After temporary fixation with a bridging external fixator, the articular block is reconstructed anatomically and held with K-wires (A). The articular fragments are then fixed by lag screws (B) To secure the screw fixation and to bridge the metaphysis, an anterolateral L-shaped pilon plate is inserted percutaneously in MIPO technique (C).
After temporary fixation with a bridging external fixator, the articular block is reconstructed anatomically and held with K-wires (A). The articular fragments are then fixed by lag screws (B) To secure the screw fixation and to bridge the metaphysis, an anterolateral L-shaped pilon plate is inserted percutaneously in MIPO technique (C).
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Locked Plating—Internal Fixator Principle

In an endeavor to further reduce or abolish the area of contact and friction between a plate and the bone surface Tepic and Perren80 reported about a new principle of fracture fixation based on what they called the internal fixator (Fig. 7-32). The first development was the PC-Fix (point contact fixator), where every screw head was locked in the plate hole through a tight fit between the conical shape of the head and the plate hole (Fig. 7-33). The stability of the fixation was thereby not based on compressing the plate onto the bone nor on preload and friction, but depended on the stiffness of the plate screw construct. As the locked plate is not based on friction between the plate and the bone, there is no requirement for contact with the bone surface. Leaving a narrow free space between the implant and the bone preserves the periosteal blood flow and the underlying cortex remains vital, which appears to increase resistance against infection.1,80 Further features of the LHS are the angular stability of the construct, which prevents any secondary displacement or collapse of fixation. There is no need for a precise contouring of the plate to the shape of the bone with a pure locked plate construct, as plate is not pressed against bone as in conventional nonlocked plating. Last but not least the LHS often have a larger core diameter (4 vs. 3 mm), which increases their strength, while the thread may be shallow as it adds very little to the resistance to pull out. Thanks to the angular stability of the screws, any bending forces will have to displace and pull out the entire screw-plate construct together and not one screw after the other as in conventional plating (Fig. 7-34). This feature has proven most useful in poor quality or osteoporotic bone as well as in periprosthetic fractures, where often only monocortical screws can be inserted besides the shaft of a prosthesis.33 
Figure 7-32
The principle of the “Internal Fixator” is based on moving an external fixator (A) close to the bone and underneath the soft tissue envelope (B).
 
A plate replaces the longitudinal rod and the locking head screws (LHS) provide the angular stability of the clamps and Schanz screws.
A plate replaces the longitudinal rod and the locking head screws (LHS) provide the angular stability of the clamps and Schanz screws.
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Figure 7-32
The principle of the “Internal Fixator” is based on moving an external fixator (A) close to the bone and underneath the soft tissue envelope (B).
A plate replaces the longitudinal rod and the locking head screws (LHS) provide the angular stability of the clamps and Schanz screws.
A plate replaces the longitudinal rod and the locking head screws (LHS) provide the angular stability of the clamps and Schanz screws.
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Figure 7-33
The force transfer in the internal fixator principle occurs primarily through the locking head screws (LHS) across the plate and fracture.
 
It is not dependent on preload and friction as in conventional plating, but rather on the stiffness of the fixator device. The locked plate does not have to touch the bone surface and therefore interferes less with the periosteal blood flow.82
It is not dependent on preload and friction as in conventional plating, but rather on the stiffness of the fixator device. The locked plate does not have to touch the bone surface and therefore interferes less with the periosteal blood flow.82
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Figure 7-33
The force transfer in the internal fixator principle occurs primarily through the locking head screws (LHS) across the plate and fracture.
It is not dependent on preload and friction as in conventional plating, but rather on the stiffness of the fixator device. The locked plate does not have to touch the bone surface and therefore interferes less with the periosteal blood flow.82
It is not dependent on preload and friction as in conventional plating, but rather on the stiffness of the fixator device. The locked plate does not have to touch the bone surface and therefore interferes less with the periosteal blood flow.82
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Figure 7-34
In conventional plating (A) the screw head is allowed to toggle under loading.
 
This process of load concentration starts at the end screw and continues from one screw to the next until the plate is completely pulled out. In locked plates (B) the angular stable screws prevent a load concentration at a single bone screw interface, by distributing the load more evenly. To pull out a locked plate, much greater forces are needed as all screws have to be loosened at the same time.17,71
This process of load concentration starts at the end screw and continues from one screw to the next until the plate is completely pulled out. In locked plates (B) the angular stable screws prevent a load concentration at a single bone screw interface, by distributing the load more evenly. To pull out a locked plate, much greater forces are needed as all screws have to be loosened at the same time.17,71
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Figure 7-34
In conventional plating (A) the screw head is allowed to toggle under loading.
This process of load concentration starts at the end screw and continues from one screw to the next until the plate is completely pulled out. In locked plates (B) the angular stable screws prevent a load concentration at a single bone screw interface, by distributing the load more evenly. To pull out a locked plate, much greater forces are needed as all screws have to be loosened at the same time.17,71
This process of load concentration starts at the end screw and continues from one screw to the next until the plate is completely pulled out. In locked plates (B) the angular stable screws prevent a load concentration at a single bone screw interface, by distributing the load more evenly. To pull out a locked plate, much greater forces are needed as all screws have to be loosened at the same time.17,71
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Advantages of the internal fixator due to angular stability of the construct are the following. 
  •  
    No requirement for direct contact to the underlying bone, preservation of periosteal blood flow
  •  
    Improved construct stability in osteopenic bone
  •  
    Resistance to secondary collapse or screw displacement
  •  
    No need for precise plate contouring
About 10 years before Tepic and Perren80 a group of Polish surgeons70 had apparently developed a similar system with conventional plates and screws, which was applied to the medial aspect of the tibia but outside the skin and where the so-called “platform screws” were locked with some sort of washers in the screw holes (Fig. 7-35). In 1931 Paul Reinhold and in 1987 Wolter85 had apparently already described the idea of angular stability or locked plating. 
The screws are locked with some sort of washers in the plate holes (B).
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Figure 7-35
A locked plate as it was developed by the Polish Zespol Group in the 1980s, where the plate remains outside the skin cover (A).
The screws are locked with some sort of washers in the plate holes (B).
The screws are locked with some sort of washers in the plate holes (B).
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The clinical applicability and validity of the internal fixator principle was proven in a series of over 350 forearm fractures that were successfully fixed with the PC-Fix.20 
The next development was the locked plate (less invasive stabilization system [LISS]) for the distal femur.41 It combines the fixed angle device with the possibility of a minimally invasive plate insertion technique (MIPO) using a special jig and monocortical, self-drilling and self-tapping screws that are introduced through short stab incisions. The advantages of the monocortical screws were seen in the precise, single-step insertion through stab incisions and a jig, as well as the fact that the endosteal blood supply is hardly disturbed. The LISS (Fig. 7-36 and 7-37) has advanced the surgical fixation of distal femur fractures by making the clinical results more reliable especially in complex fracture situations, osteoporotic and periprosthetic fractures.41,43,44,77 While the LISS did only accept LHS, there was a rising demand for a possibility to also use conventional screws in this new plate. This led to the idea of the combination hole43 which can accommodate either a smooth, conventional nonlocked screw or a threaded locking head screw (Fig. 7-38) and resulted in the dynamic locking plate (LCP).15 With the further development of locked plates, more and more plates have become precontoured fitting the periarticular anatomical regions (Fig. 7-39). 
Figure 7-36
Locking plate (LISS) for distal femur fractures.
 
After reconstruction and preliminary fixation of the articular fracture components under direct vision, the LISS can be inserted in a submuscular space with a special jig. The locking head screws (LHS) are introduced percutaneously through the jig.
After reconstruction and preliminary fixation of the articular fracture components under direct vision, the LISS can be inserted in a submuscular space with a special jig. The locking head screws (LHS) are introduced percutaneously through the jig.
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Figure 7-36
Locking plate (LISS) for distal femur fractures.
After reconstruction and preliminary fixation of the articular fracture components under direct vision, the LISS can be inserted in a submuscular space with a special jig. The locking head screws (LHS) are introduced percutaneously through the jig.
After reconstruction and preliminary fixation of the articular fracture components under direct vision, the LISS can be inserted in a submuscular space with a special jig. The locking head screws (LHS) are introduced percutaneously through the jig.
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Figure 7-37
Clinical example of a “floating knee,” proximal tibia combined with distal femur fractures, extending into both shaft and extensive open soft tissue injury (A), fixed by locking plates (B).
 
After reconstruction of articular congruency with lag screws, the locking plates were placed percutaneously to the lateral aspect of the tibia. C: Follow-up after 1 year with good restitution of function.
After reconstruction of articular congruency with lag screws, the locking plates were placed percutaneously to the lateral aspect of the tibia. C: Follow-up after 1 year with good restitution of function.
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Figure 7-37
Clinical example of a “floating knee,” proximal tibia combined with distal femur fractures, extending into both shaft and extensive open soft tissue injury (A), fixed by locking plates (B).
After reconstruction of articular congruency with lag screws, the locking plates were placed percutaneously to the lateral aspect of the tibia. C: Follow-up after 1 year with good restitution of function.
After reconstruction of articular congruency with lag screws, the locking plates were placed percutaneously to the lateral aspect of the tibia. C: Follow-up after 1 year with good restitution of function.
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Figure 7-38
The combination hole of the LCP allows conventional screws in the smooth DC unit part of the hole and locking head screws (LHS) in the threaded part.
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Figure 7-39
Precontoured implants, like the locking plate for the distal femur, can facilitate reduction in complex fracture situations (A).
 
This open fracture had significant metaphyseal bone loss. In accordance to the anatomical fit of the plate, the distal screws were placed parallel to the AP joint line of the distal femur. Following this intraoperative guideline the postoperative films (B) show a good alignment similar to the uninjured contralateral side (C) (further secondary bone graft was required to bridge the defect).
This open fracture had significant metaphyseal bone loss. In accordance to the anatomical fit of the plate, the distal screws were placed parallel to the AP joint line of the distal femur. Following this intraoperative guideline the postoperative films (B) show a good alignment similar to the uninjured contralateral side (C) (further secondary bone graft was required to bridge the defect).
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Figure 7-39
Precontoured implants, like the locking plate for the distal femur, can facilitate reduction in complex fracture situations (A).
This open fracture had significant metaphyseal bone loss. In accordance to the anatomical fit of the plate, the distal screws were placed parallel to the AP joint line of the distal femur. Following this intraoperative guideline the postoperative films (B) show a good alignment similar to the uninjured contralateral side (C) (further secondary bone graft was required to bridge the defect).
This open fracture had significant metaphyseal bone loss. In accordance to the anatomical fit of the plate, the distal screws were placed parallel to the AP joint line of the distal femur. Following this intraoperative guideline the postoperative films (B) show a good alignment similar to the uninjured contralateral side (C) (further secondary bone graft was required to bridge the defect).
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Available plates now cover the full range of plate functions including the advantages of both locked and nonlocked plating.23 
  •  
    Conventional compression-, protection-, or buttress plate with conventional nonlocked screws
  •  
    Pure locked plating with all LHS
  •  
    Hybrid plating with a combination of conventional nonlocked screws (to use plate as template for reduction) and locked screws (for advantages of fixed angle support of end segment fractures and improved fixation in osteoporotic bone)
When using hybrid plating technique, certain technical aspects have to be followed to avoid failures. Once a locking head screw has been inserted in a bone segment, no conventional screws should be added in the same segment, as this would create unwanted tension forces within the plate and bone. The sequence should be “lag first, lock second.” A reduction screw may be used to approximate a fragment to the locked plate as an indirect reduction tool, it should however not be applied in a compression mode after a locked screw has been applied to the same fracture fragment, as this would counteract the bridging effect and bend the plate or crack the bone. 

Intramedullary Fixation Techniques

Introduction and History

The medullary canal of a long bone offers itself to accept splinting devices of different designs and sizes. The major advantages are that any intramedullary implant is mostly with some bony contact between the main fragments weight sharing and not weight bearing. Only in very comminuted shaft fractures the nail is a weight-bearing device, while no weight is transferred by the bony structures. 
On the other hand a major problem is how to control axial displacement or to neutralize rotational forces. The interlocking techniques have helped to solve these drawbacks to a great extent. Depending on the anatomy, the insertion can usually occur closed, without exposure of the fracture focus, in an ante- or retrograde direction. A closed procedure would of course require the availability of an image intensifier in the operating room for reduction and interlocking. 
Today intramedullary nails are the implant of choice for the femoral and tibial diaphysis and recently with new nail designs the spectrum of indications has been extended to even intra-articular fractures of these bones (Fig. 7-40). For the humeral shaft IM nails are an option competing with the still very popular and more versatile plating techniques. Flexible nails as used in pediatric fractures46 have been advocated for the clavicle, while nailing of the forearm bones has not yet proved to be equal or superior for the fixation for ulna and radius fractures due to the difficulty of reliable locking systems, that can control the rotational forces. 
Figure 7-40
Intramedullary nailing (IM) systems offer possibilities to stabilize simultaneously ipsilateral trochanteric and shaft fractures.
 
A 38-year-old multitrauma patient stabilized with an antegrade femoral with a retrograde locking (A). The healing of both fractures was already reliable after 14 weeks (B–D).
A 38-year-old multitrauma patient stabilized with an antegrade femoral with a retrograde locking (A). The healing of both fractures was already reliable after 14 weeks (B–D).
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Figure 7-40
Intramedullary nailing (IM) systems offer possibilities to stabilize simultaneously ipsilateral trochanteric and shaft fractures.
A 38-year-old multitrauma patient stabilized with an antegrade femoral with a retrograde locking (A). The healing of both fractures was already reliable after 14 weeks (B–D).
A 38-year-old multitrauma patient stabilized with an antegrade femoral with a retrograde locking (A). The healing of both fractures was already reliable after 14 weeks (B–D).
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Historically the first description of an intramedullary splinting with ivory pegs goes back to the 19th century78 Hey-Groves27 used solid metal rods for femur fractures and pointed to the rapid healing, preservation of soft tissues and periosteum as well as the abolition of prolonged plaster cast immobilization. The Rush brothers72 presented their technique with multiple flexible intramedullary pins in 1927. The most important contributions to intramedullary fixation came however from Küntscher (1900 to 1972)45 who performed a number of animal experiments and perfected not only the nailing technique but also the implant shape and design. He requested a tight fit between nail and bone to achieve a higher stability and to allow compression of transverse fractures under load. To extend the area of contact within the medullary cavity he started to ream the canal in order to insert thicker, longer, and slotted cloverleaf nails. Herzog,26 in 1950, introduced the tibia nail with a proximal bend and lateral slots at the distal end to accept antirotational wires. Shortly before his death Küntscher designed the “detensor nail” for comminuted femur fractures with a sort of interlocking device. This idea was further developed by Klemm and Schellmann39 in Germany and Kempf et al.35 in France and were precursors to today’s interlocking nails. 

Mechanics of IM Nailing

The original concept of Küntscher was based on the principle of elastic deformation or “elastic locking” of the nail within the medullary canal. To increase the elasticity, the hollow cloverleaf nail was slotted and reaming of the canal enlarged the area of contact and friction between the nail and the bone (working length). Nails with larger diameters had an increased bending and torsional stiffness. The weak point of the first nails remained the poor resistance to axial (telescoping) forces and rotation especially in comminuted fractures. The introduction of interlocking screws and bolts at the proximal and distal end of the nail addressed these issues rather well, there remains however the problem of the strength and purchase of the locking screws in the bone. This problem is not yet completely solved as twisted blades and an increase in screw diameter and number (larger and more holes) may weaken the nail ends. Based on the positive experience and data of Lottes47 who presented very low infection rates in open tibia fractures with the use of solid nails that were introduced without reaming, thinner, solid tibia nails with holes for interlocking were developed. At the beginning those thin nails were to be inserted without reaming with mandatory interlocking as a temporary splint in open tibia fractures.73 Animal experiments showed that after nail insertion the endosteal blood supply was not destroyed to the extent as after reaming and also that the resistance to infection was much higher if solid nails were compared with tubular ones.51 The clinical experience as to the infection rate in open fractures was most encouraging however the time to union took longer, especially as in the majority of cases the original concept of secondary exchange nailing to a thicker nail was not followed. The enthusiasm for the new nails without reaming rapidly extended their indications and use also to closed and highly complex tibia and femur fractures. This resulted in a higher incidence of delayed and malunions due to a poorer mechanical stiffness of the construct especially in long bone fractures of the lower extremity.11,73 

Pathophysiology of IM Nailing

Depending on the surgical technique, nail design, and anatomical region the use of intramedullary nails has both local and systemic effects, some of which may be beneficial, others however detrimental to the patient and fracture healing. 

Local Effects

The insertion of a nail into the medullary canal is inevitably associated with damage of the endosteal blood supply, which was shown to be reversible within 8 to 12 weeks.76 Experimental data have also shown that the cortical blood perfusion is significantly reduced after reaming of the medullary canal, if compared to a series without reaming.38 Accordingly the return of cortical blood flow takes considerably longer after reaming than in the unreamed cases, which may have an influence on the resistance to infection especially in open fractures. Furthermore tight-fitting nails appear to compromise the cortical blood flow to a higher degree than loose fitting ones.32 Reaming of a narrow medullary canal may be associated with a risk of heat necrosis of the bone and surrounding tissues especially if blunt reamers and/or a tourniquet are used.57 On the other hand the bone debris produced during the reaming has been shown to act like an autogenous bone graft enhancing fracture healing.16,28 Meta-analysis of current clinical studies found “gentle” reaming superior to the undreamed technique for reliable healing of long bone fractures in closed and low-degree open fractures.11 

Systemic Response

Reaming of the medullary canal has been associated with pulmonary embolization, coagulation disorders, humoral, neural, immunologic, and inflammatory reactions. The development of post-traumatic pulmonary failure after early femoral nailing in the polytrauma patient with chest injury appears to be more frequent following reaming of the medullary canal than without it.61 In clinical and experimental studies the passage of large thrombi into the pulmonary circulation has been demonstrated with intraoperative echocardiography especially during the reaming process and to lesser extent, already when introducing the reaming guide.83 Measurements of the intramedullary pressure have shown values between 420 and 1,510 mm Hg during reaming procedures compared with 40 to 70 mm Hg when thin solid nails were inserted without reaming.53,54 Nevertheless there is an ongoing controversy between the advocators of reamed nailing also in the multiply injured patient and those who are recommending the use of thinner solid or cannulated nails without reaming. Especially the young adult with a simple transverse femoral shaft fracture and a high ISS (>25) appears to have an increased risk for pulmonary complications, which is why there is the recommendation for a staged nailing procedure according to the concept of damage control surgery (DCS) under such circumstances. DCS starts as soon as possible with the stabilization of the femoral shaft fracture with an external fixator followed by a conversion to an intramedullary nail after 5 to 10 days (window of opportunity).34 The described systemic responses of IM nailing of femoral shaft fractures seem to be much more critical than in tibial shaft fractures, where such effects have hardly ever been observed. 

Implants for Nailing

There is a great variety of intramedullary nails and entire nailing systems available for the femur, tibia, and humerus. Forearm nails are also on the market, but until now they have not proven to be superior or as versatile as the fixation with plates. Originally intramedullary nails were offered in a tubular, usually slotted form, while today solid and especially cannulated nails are most popular. In children the elastic nails according to Ligier et al.46 have become the implant of choice for long bone fractures. The implant material is either stainless steel or a titanium alloy. The holes or openings for interlocking devices are usually situated at either end of the implant and oriented in different directions, some nails have also locking possibilities throughout the entire nail length. 
Accordingly the indications have increased from originally midshaft fractures to fractures involving the proximal and distal femur and tibia as well as the proximal humerus. 
The nail design and the dimensions have to be adapted to the shape of the medullary cavity and the bone. The correct diameter and length of the nail should to be selected beforehand, unfortunately the accuracy of templates is rather poor. The best tool is probably a radiolucent ruler placed on the intact contralateral leg under C-arm control or the measurement with the intramedullary guidewire. 
A very important issue is the correct entry point and starting trajectory of the nail, which varies from one type of nail to the other (Fig. 7-41). 
Figure 7-41
The correct entry point is crucial, but may vary from one type of nail to the other.
 
(Always study the recommendations of the manufacturer as to the recommended nail entry point.)
(Always study the recommendations of the manufacturer as to the recommended nail entry point.)
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Figure 7-41
The correct entry point is crucial, but may vary from one type of nail to the other.
(Always study the recommendations of the manufacturer as to the recommended nail entry point.)
(Always study the recommendations of the manufacturer as to the recommended nail entry point.)
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A misplaced starting point may lead to axial and/or rotational malalignment, that is usually tricky to correct, and even additional stress fractures have been described. It is therefore advisable to study the technical guide of a specific type of nail carefully and to check the correct entry point and direction of the guidewire with the image intensifier preferably in two planes. 

Positioning of the Patient for IM Nailing and Reduction

Every surgeon has his preferred way of how to nail a specific bone, with or without a fracture table, or with the help of a distractor, in a supine or in a lateral decubitus position, etc. As each way has its pros and cons, much depends on the experience of the OR team and the surgeon. It appears most important for any patient positioning that the nail entry point can be clearly seen in two projections with the C-arm and the same holds true for the distal locking procedure. 
Reduction of fresh diaphyseal fractures is rarely a problem. The guidewire can usually be inserted easily into the opposite fragment, or a solid nail or reduction device can be used as a joystick. In metaphyseal fractures the correct alignment may be much more difficult especially in the proximal or distal tibia. Blocking or Poller screws42 may be helpful to guide the nail in the right direction (Fig. 7-42). The technique of the Poller screws can be used to decrease the functional width of a wide metaphyseal cavity or to force and redirect the nail into a particular direction for a better alignment or improved stabilization. The use of the screw can be temporary or definitive. This technique is especially helpful to steer the nail into another “right” direction, after it had been misplaced in the first attempt. 
Figure 7-42
Example of Poller screws in the femur to correct a valgus malalignment of the distal fragment (A).
 
After the nail was backed out, a 3.5-mm cortical screw was placed (B, C) to steer the nail into the appropriate position (D–F). Postoperative control and healing after 1 year (G–I). To correct valgus with a blocking screw, the screw must be placed lateral to the nail and near the fracture or medial to the nail and far from the fracture.
After the nail was backed out, a 3.5-mm cortical screw was placed (B, C) to steer the nail into the appropriate position (D–F). Postoperative control and healing after 1 year (G–I). To correct valgus with a blocking screw, the screw must be placed lateral to the nail and near the fracture or medial to the nail and far from the fracture.
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Figure 7-42
Example of Poller screws in the femur to correct a valgus malalignment of the distal fragment (A).
After the nail was backed out, a 3.5-mm cortical screw was placed (B, C) to steer the nail into the appropriate position (D–F). Postoperative control and healing after 1 year (G–I). To correct valgus with a blocking screw, the screw must be placed lateral to the nail and near the fracture or medial to the nail and far from the fracture.
After the nail was backed out, a 3.5-mm cortical screw was placed (B, C) to steer the nail into the appropriate position (D–F). Postoperative control and healing after 1 year (G–I). To correct valgus with a blocking screw, the screw must be placed lateral to the nail and near the fracture or medial to the nail and far from the fracture.
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Locking Technique

Most nails are inserted with a special handle, which also serves as an aiming device for locking the driving end of the nail with bolts, blades, or more commonly locking screws. Placement of the far locking device is usually more difficult as during the insertion most nails are more or less distorted, so that the locking holes are not in the original alignment anymore. Far locking must therefore be done in a “free hand” technique or with the aid of aiming devices usually mounted on the drill. Tight-fitting nails tend to distract the fractures resulting in wide gaps, which may lead to increased compartment pressure as well as to delayed or nonunion.6 It is therefore recommended to lock first at the far end, then to backslap the nail, and finally to lock the driving end. Finally locking can be done in a static or dynamic mode, while it is advisable to use at least two locking screws at either end of the nail to control rotation in a reliable way. Static locking is recommended for complex fractures to prevent telescoping, while dynamic locking is advisable in short oblique or transverse fracture, to allow fracture compression during weight bearing. 

Assessment of Axial Alignment and Rotation in IM Nailing

In simple fractures axial alignment is not a problem. However in more complex, segmental, or comminuted fractures or in floating knee injuries it may be difficult to judge the correct axial alignment. The most useful intraoperative indicator of an acceptable coronal plane alignment is, when the nail entrance point is correct and the nail is centrally placed in the distal fragment (or proximal segment in retrograde nailing). In the lower extremity the long cable of electrocautery, a C-arm and the patient in supine position is helpful to judge the right direction. The cable is centered to the femoral head and distally to the middle of the ankle joint under x-ray view. At the level of the knee the cable should now run exactly through the centre of the joint as well. Any deviation indicates an axial malalignment in the coronal plane. 
The clinical assessment of the rotation intraoperatively is more difficult and less accurate. There are several radiologic signs like the size of the diameter of two adjacent fragments or the projection of the greater trochanter in relation to the patella in the AP view, but they are all not very reliable. With the patient still on the OR table internal and external rotation can be performed to reliably check the rotation in comparison with the uninjured side. The most accurate evaluation is with a few CT slices through the knee and the hip joint allowing also a comparison with the uninjured side.25 
The intramedullary nail to fix diaphyseal fractures of the long bones is the golden standard today. It is a minimally invasive procedure allowing early weight bearing and with a good chance of rapid and undisturbed fracture healing. 

Tension Band Principle

Pauwels was the one who observed that a curved tubular structure when subjected to an axial load, always presents a tension side on the convexity and a compression side on the concavity. The same occurs when a straight tube or bone is loaded eccentrically like in the femur, where we have tensile forces on the lateral and compression on the medial side. By applying a tension band device laterally these tensile forces are converted to compression forces provided the opposite side is stable and has good contact. 
In fractures where muscle pull tends to displace fragments as in the olecranon, patella or the avulsion fracture of the greater tuberosity of the humerus, a tension band will neutralize the distraction forces and under flexion of the joint the fragments will be compressed (Fig. 7-43). We therefore speak of dynamic tension band providing absolute stability and encourage the patients with tension band fixation of one of these joints to regularly make flexion exercises. 
Figure 7-43
 
A: Atypical example of tension band fixation of the olecranon with two K-wires and a figure-of-eight tension band wiring. B: Tension band fixation of a transverse patella fracture with a tension band wire loop. Note that the tension band device must lie eccentrically on the tensile side of the bone and that this dynamic fixation is enhanced by flexion of the joint.
A: Atypical example of tension band fixation of the olecranon with two K-wires and a figure-of-eight tension band wiring. B: Tension band fixation of a transverse patella fracture with a tension band wire loop. Note that the tension band device must lie eccentrically on the tensile side of the bone and that this dynamic fixation is enhanced by flexion of the joint.
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Figure 7-43
A: Atypical example of tension band fixation of the olecranon with two K-wires and a figure-of-eight tension band wiring. B: Tension band fixation of a transverse patella fracture with a tension band wire loop. Note that the tension band device must lie eccentrically on the tensile side of the bone and that this dynamic fixation is enhanced by flexion of the joint.
A: Atypical example of tension band fixation of the olecranon with two K-wires and a figure-of-eight tension band wiring. B: Tension band fixation of a transverse patella fracture with a tension band wire loop. Note that the tension band device must lie eccentrically on the tensile side of the bone and that this dynamic fixation is enhanced by flexion of the joint.
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In principle any fixation device, plate, wire loop and even an external fixator, if applied correctly to the tension of a fractured bone can act as a tension band. The tension band device must withstand tensile forces, while the bone must resist compressive forces, while the cortex opposite to the tension band must be exactly reduced without a gap. 
The most commonly used 1.4- or 1.6-mm metal wire can be inserted through a drill hole in the bone, or it can be placed through the Sharpey fibers of a tendon insertion such as at the patella or it may be looped around a screw head or a K-wire. The wire loop should always be placed eccentrically to the load axis, for example, in front of the patella, and not around it (Fig. 7-43). Wire withstands tensile forces quite well; however, if bending forces are added it will easily break. The same is true for any type of plate. 
In mal- and nonunions we often can observe an angular deformity. Any fixation device should therefore be applied to the convex side of the deformity, in such a way as to act as a tension band, which then automatically induces compression and enhances bony union (Fig. 7-44). 
Figure 7-44
In a mal- and nonunions with deformity as the plate to the convex or tension side of the bone (A) acts as a tension and compresses the bone ends (B).
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