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Fractures of the Distal Femur
Pathology
Relevant Anatomy
The distal end of the femur traditionally encompasses the lower third of this bone. This zone varies greatly in the literature, from the distal 7.6 cm to the distal 15 cm of the femur; another definition is that the distal length is equal to the transverse diameter. This chapter deals only with fractures that involve the supracondylar (metaphyseal) and intercondylar (epiphyseal) areas of the distal end of the femur. Distal femoral fractures that are purely diaphyseal are discussed in Chapter 58 .
Bone, Muscles, and Tendons
Anteriorly, the extensor compartment contains the quadriceps femoris, the single largest muscle in the body. It consists of four heads: the rectus femoris more superficially and, in the deeper layer from lateral to medial, the vastus lateralis, vastus intermedius, and vastus medialis. The anterior extensor compartment is separated from the posterior compartment by the lateral and medial intermuscular septa.
Of surgical importance, the shaft of the femur in the sagittal view is aligned with the anterior half of the condyles, whereas the posterior half of both condyles lies behind the femoral shaft axis. In addition, the condyles are wider posteriorly than anteriorly ( Fig. 59.1 ; see and ). A transverse cut through the condyles shows the shape of a trapezoid with a 10-degree inclination of the lateral surface from the vertical and 25-degree inclination of the medial surface. In addition, there is a 10-degree posterior-to-anterior inclination with a decrease in width on the medial side. Metaphyseal bone is well perfused ( Fig. 59.2 ; see ).
Alignment
The anatomic axis of the shaft of the femur is different from the mechanical (weight-bearing) axis ( Fig. 59.3 ). The latter passes through the head of the femur and the middle of the knee joint. Generally, the mechanical axis subtends an angle of 3 degrees from the vertical.
The anatomic axis has an average valgus angulation of 9 degrees relative to the vertical axis. The knee joint line is normally parallel to the ground, and the anatomic femoral axis subtends an 81-degree lateral distal femoral angle relative to the knee joint. For each patient, it is important to confirm this angle from the opposite femur because individual variations do occur. During surgical reconstruction, the correct femoral valgus angulation (anatomic axis) can be re-created, and the knee joint is kept parallel to the ground. This is discussed further in Preoperative Planning and also in Chapter 68 .
Anatomic and Functional Consequences of the Injury
Fractures in the supracondylar area characteristically deform with femoral shortening and posterior angulation and displacement of the distal fragment. In more severe fractures with intercondylar involvement, one often sees rotational malalignment of the condyles relative to each other in the frontal plane, a result of their muscle attachments.
Even with significant supracondylar comminution and displacement of the distal fragment, axial alignment can often be regained with traction, but the alignment is hard to maintain. Conversely, with intercondylar involvement and malrotation of the condyles, reduction is almost impossible by traction alone and is often difficult even with surgery. The aims of treatment must be the restoration of length, torsion, and frontal- and sagittal-plane alignment and anatomic reconstitution of the articular surface to avoid long-term morbidity.
Incidence of Fractures
Distal femoral fractures have been reported to account for between 4% and 7% of all femoral fractures, which in Sweden corresponds to an annual incidence of 51 per million inhabitants older than 16 years of age. In the United States, it has recently been reported to be 31 per million. If fractures of the hip are excluded, 31% of femoral fractures involve the distal end. With the modern trends of high-energy lifestyles combined with increased longevity, this incidence is probably increasing.
Distal femoral fractures occur predominantly in two patient populations: young persons, especially young men, after high-energy trauma and elderly persons, especially elderly women, after low-energy injuries. In one series from Sweden, up to 84% of distal femoral fractures occurred in patients older than 50 years of age. In a Rochester, Minnesota, study of patients aged 65 years or older, 84% of the femoral fractures occurred in women. The conclusion of this epidemiologic study was that the incidence rates for distal femoral fractures do indeed rise exponentially with age and are greater among elderly women than men. In the older group, most of the injuries occur after moderate trauma, such as a fall on a flexed knee. Two-thirds of the fractures caused by moderate trauma were “preceded by prior age-related fractures (hip, proximal humerus, distal forearm, pelvis or vertebra) or with roentgenographic evidence of generalized osteopenia.”
In the younger group, distal femoral fractures occur after high-energy trauma. These fractures are often open, comminuted, and most probably the result of the direct application of a load to a flexed knee. Most are caused by vehicular accidents, including motorcycle accidents, but they can also result from industrial accidents or falls from heights. Most of these patients are younger than 35 years of age, with a definite male preponderance.
Surprisingly, the degree of comminution in the supracondylar region is often equivalent in both these groups. However, younger patients experiencing high-energy trauma have a greater incidence of additional intraarticular disruption or segmental or more proximal shaft comminution.
Periprosthetic fractures after knee replacement present a different entity of fractures of the distal femur. Because there is actually increasing demand for joint arthroplasties (patients tend to live longer, with a more active life, leading to greater rates of arthrosis), rates of periprosthetic fractures are also noted to be increasing. The incidence after primary and after revision arthroplasty is described as up to 5.5% and 30%, respectively.
Commonly Associated Injuries
High-energy distal femoral fractures, especially in young patients, are often only one of several injuries sustained by the individual. The whole patient must be carefully evaluated by a multidisciplinary team approach (see Chapter 10 ). This section addresses only commonly associated injuries in the involved lower extremity.
The most common mechanism of distal femoral fracture is direct trauma to a flexed knee, typically impact against the dashboard of a moving vehicle or crash against a pole in motorcycle accidents. The position of the leg at the time of the injury determines the presence and type of injury. Care must be taken to exclude concomitant acetabular fractures; hip dislocations; and femoral neck, femoral shaft, and patella fractures ( Figs. 59.4 and 59.5 ; see ).
Soft Tissue Injuries
Significant soft tissue injuries of the knee are often associated with distal femoral fractures. Associated ligamentous disruptions of the knee joint have been reported in approximately 20% of these fractures. They are hard to diagnose until the distal part of the femur has been stabilized because both clinical examination and stress radiographs require stability above the knee.
In a polytraumatized patient, distal femoral fractures commonly occur with associated injuries to the tibia. Associated tibial plateau fractures occur after a predominantly varus or valgus force. Careful evaluation of the plateau is needed and often requires tomograms. Associated tibial shaft fractures, often comminuted or open, mandate aggressive treatment of both injuries to avoid the morbidity associated with the “floating knee” syndrome.
Vascular Injuries
The femoral artery in the adductor canal is in close proximity to the medial cortex of the distal end of the femur as it passes through to the posterior compartment only 10 cm above the knee joint ( Fig. 59.6 ).
With high-energy, gunshot, or open distal femoral injuries, the artery is at significant risk of injury. With associated ligament disruptions of the knee (especially a posterior dislocation), the popliteal artery is at great risk of injury—up to 40% in some series.
Complex Trauma of the Knee
For severe knee-region injuries involving multiple structures, the term complex trauma of the knee has been defined and includes a distal supracondylar or intercondylar femoral fracture combined with a proximal tibial fracture (“floating knee”; type 1), a supracondylar or intercondylar femoral fracture with a second- or third-degree closed or open soft tissue injury (type 2), and complete knee joint dislocation (type 3; Table 59.1 ).
Table 59.1
Definition of “Complex Knee Trauma”
From Krettek C, Tscherne H. Distal femoral fractures. In Fu FH, Harner CD, Vince KC, eds. Knee Surgery . Baltimore: Williams & Wilkins; 1994:1027-1035.
| Complex Knee Trauma | Soft Tissue Injury | Fracture Pattern |
|---|---|---|
| Type 1 | Supracondylar-intercondylar fracture of distal end of femur and proximal end of tibia (floating knee) | |
| Type 2 | Second- or third-degree closed or open soft tissue damage | Supracondylar-intercondylar fracture of distal end of femur or proximal end of tibia |
| Type 3 | Complete knee dislocation |
The thin soft tissue coverage on the anterior aspect of the distal end of the femur is a frequent problem. Neurovascular injuries are mostly observed in type 3 “distal femur complex trauma.” Because of the need for interdisciplinary management (vascular surgery, plastic surgery), the high technical demands (joint reconstruction, alignment, ligamentous instability, soft tissue coverage), and the risk of complications (nonunion, infection, malalignment), we recommend that “complex knee trauma” should be treated in trauma centers with a high caseload and significant experience.
Diagnosis
A careful evaluation of the whole patient, as well as the involved lower extremity, is mandatory, especially in a polytraumatized patient.
Classification
One of the original and simpler classification schemes of supracondylar-intracondylar femoral fractures was that of Neer and associates. They subdivided intracondylar fractures into the following categories: minimal displacement (grade I); displacement of the condyles (grade II), including medial (A) and lateral (B) displacement; and concomitant supracondylar and shaft fractures (grade III). This classification system is very basic and does not provide the surgeon with much clinical and prognostic information.
Seinsheimer classified fractures of the distal femur into four basic types: I, nondisplaced; II, supracondylar, without articular surface involvement; III, involving the intercondylar notch with one or both condyles separate; and IV, fractures disrupting the articular surface of one or both condyles. Seinsheimer found that patients with type I nondisplaced fractures and type II simple, two-part supracondylar fractures all had preexisting pathologic osteoporosis before their injury. At the other end of the spectrum, patients with type IV fractures involving the articular surface were the youngest patients, and all fractures resulted from high-energy trauma.
Müller and colleagues, in an updated Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification system for distal femoral fractures, separated these fractures into three main groups ( Fig. 59.7 ). The AO and Orthopaedic Trauma Association (OTA) classification of distal femoral fractures (see Fig. 59.7 ) is type A (extraarticular), type B (unicondylar), and type C (bicondylar). The three groups are each further separated into three subgroups. Type A (extraarticular) fractures are classified as simple, two-part supracondylar fractures (type A1), metaphyseal wedge fractures (type A2), and comminuted supracondylar fractures (type A3). Type B (unicondylar) fractures are classified as lateral condyle sagittal fractures (type B1), medial condyle sagittal fractures (type B2), and coronal fractures (type B3, the so-called Hoffa fractures). Type C (bicondylar) fractures are classified as noncomminuted supracondylar (T or Y) fractures (type C1), fractures with supracondylar comminution (type C2), and those with comminution in both supracondylar and intercondylar regions (type C3). In progressing from A to C, the severity of the fracture increases, whereas the prognosis for a good result decreases.
The Müller updated classification system meets these criteria and is used for classifying and describing fractures in the remainder of this chapter.
Classification systems for periprosthetic fractures are the classifications of Rorabeck and Taylor and Su and coworkers, which are described in Chapter 69 .
Patient History and Physical Examination
A careful evaluation of the whole patient as well as the involved lower extremity is mandatory, especially in a polytraumatized patient. The assessment must include careful scrutiny of the hip joint above the fracture and the knee and leg below it. Distal pulses must be checked. In cases where vascularity to the lower leg is a concern, Doppler pulse pressure readings should be obtained. If they are not normal, or they deteriorate, prompt investigation is mandatory, as described in Chapter 16 , with appropriate vascular imaging (discussed in the following section) if the arterial pressure index (API) is less than 0.9. Rarely, if tense swelling of the thigh is noted, a thigh compartment syndrome must also be ruled out by examination and possibly compartment pressure monitoring.
Grossly open and contaminated wounds are easily identifiable. However, when the injury results from direct trauma, skin abrasions are frequently present and must be differentiated from open fracture wounds of the soft tissues.
Radiographic Evaluation
Routine anterior-posterior (AP) and lateral radiographs of the knee and supracondylar region are standard. When fractures are comminuted or displaced, an exact classification of the fracture is sometimes difficult. AP and lateral radiographs, both with manual traction applied to the lower extremity, frequently demonstrate the fracture morphology more clearly. These studies can be performed in the emergency department or, even better, in the operating room. Stress radiographs to identify ligamentous disruptions of the knee or associated tibial plateau fractures are not usually indicated until the distal femoral injury is stabilized.
If there is doubt about intraarticular involvement ( Fig. 59.8 ), computed tomography (CT) scans help (1) in the detection of an undisplaced or minimally displaced fracture; (2) in better understanding complex fracture patterns; and (3) in planning the surgical approach, especially for minimally invasive techniques.
CT scans may also be useful for osteochondral lesions or impression fractures. We recommend a routine CT scan for better operative planning (fracture: intraarticular or extraarticular; approach: minimally invasive plate osteosynthesis [MIPO] or transarticular access and retrograde plate osteosynthesis [TARPO]; type of fixation: nail or plate; Fig. 59.9 ; see ). If plain films clearly exclude an intraarticular fracture, a CT scan is unnecessary. Also, if significant intraarticular extension of the fracture requires a TARPO approach for reduction, a CT scan adds little. However, if there is uncertainty whether a displaced fracture extends into the intercondylar region, a CT scan should be obtained. Similarly, magnetic resonance imaging (MRI) can be helpful if chondral or ligamentous lesions are suspected, but only if this test is likely to influence the planning of the surgical procedure.
Radiographs should include an AP view of the whole femur to determine frontal-plane alignment and AP and lateral views of the distal end of the femur with the entire tibia to allow superimposition of the fracture fragments on the normal template (see Preoperative Planning ).
Unless a thorough vascular examination (palpation of pulses, Doppler-assisted API, sensation, and motor strength) is normal and unless frequent, skillful repeat examinations are feasible, arteriography is indicated in patients with an associated frank dislocation of the knee joint because of the high incidence of arterial injuries reported with knee dislocations (see Chapters 16 and 61 ). Absent or diminished pulses typically indicate the need for vascular imaging, either with computed tomographic arteriography or digital subtraction angiography (DSA). If the limb is frankly ischemic and the location of the vascular injury is clear, vascular exploration and early restoration of perfusion should not be delayed for imaging. There is no reason for a routine MRI.
It needs to be kept in mind that when radiographs do not raise any suspicion for a pathologic fracture, but the history of trauma or the physical examination does, further radiologic and/or histologic diagnostic examinations might be necessary.
Key Points: Diagnosis
-
The distal end of the femur traditionally encompasses the lower third of this bone. The shaft of the femur in the sagittal view is aligned with the anterior half of the condyles. In addition, the condyles are wider posteriorly than anteriorly. A transverse cut through the condyles shows the shape of a trapezoid with a 10-degree inclination of the lateral surface from the vertical and 25-degree inclination of the medial surface. In addition, there is a 10-degree posterior-to-anterior inclination with a decrease in width on the medial side. The anatomic axis has an average valgus angulation of 9 degrees relative to the vertical axis.
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Distal femoral fractures occur predominantly in bimodal distribution: young persons after high-energy trauma and elderly persons as a result of low-energy injuries. Periprosthetic fractures after knee replacement present a different entity of fractures of the distal femur.
-
A careful evaluation of the whole patient, as well as the involved lower extremity, is mandatory. The AO/OTA classification of distal femoral fractures separates these fractures into three main groups: type A (extraarticular), type B (unicondylar), and type C (bicondylar).
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Routine AP and lateral radiographs of the knee and supracondylar region are standard for evaluation. CT scans may also be useful for better operative planning.
Treatment
History
The past five decades have seen many approaches to the treatment of distal femoral fractures. The following sections review them briefly.
Traction and Cast
In the first half of the 20th century, the treatment of choice for the management of femoral fractures, including supracondylar fractures, was traction and subsequent mobilization in cast braces. The traction technique used was either a single pin in the proximal end of the tibia or a two-pin system with an additional pin through the supracondylar fragment.
Early Attempts of Open Reduction and Internal Fixation
Neer and associates in 1967 reported on 110 supracondylar fractures treated at New York Orthopaedic Hospital over a 24-year period. They proposed a three-part classification system as well as a rating system for evaluation based on a functional and anatomic assessment. Ninety percent of those treated by closed methods had satisfactory results versus only 52% of those treated by open procedures. They considered patients to be “satisfied” in this rating system as long as they had strong extensor power and could flex the knee 70 degrees. In their summary, Neer and associates stated that “no category of fracture at this level seemed well suited for internal fixation, and sufficient fixation to eliminate the need for external support or to shorten convalescence was rarely attained.” In fact, almost all their surgically treated patients had prolonged postoperative immobilization because of the inadequacy of the fixation techniques used at that time. In conclusion, these authors believed that operative intervention should be limited to débridement of open fractures or internal fixation of a fracture with an associated problem such as an arterial injury.
Such papers definitely prejudiced the North American orthopaedic community against internal fixation during the 1960s and 1970s. As a result, more advanced techniques of closed treatment were proposed in the early 1970s by Connolly and Dehne and by Mooney. To shorten traction time and allow earlier ambulation and knee motion, they recommended the use of early cast bracing for femoral shaft and supracondylar fractures.
Arbeitsgemeinschaft für Osteosynthesefragen Compression Plating Techniques
In 1958 the Swiss AO Group was formed, thus commencing a new era in fracture care. The AO Group's desire was to restore full function to the limb and the patient and to avoid the so-called fracture disease associated with prolonged immobilization. They recommended the principles of anatomic reduction of the fracture fragments; preservation of the blood supply; stable internal fixation and early, active, pain-free mobilization. It was not until 1970 that the AO published its first results on the treatment of supracondylar femoral fractures according to these principles. Wenzel and colleagues reported on 112 patients, 73.5% of whom had good or excellent results. For open reduction, these results were far superior to the 52% satisfactory results reported by Neer and associates, even though the criteria used by Wenzel and colleagues were much more stringent.
Schatzker and coworkers reported on 71 distal femoral fractures, 32 of which were treated by open reduction and internal fixation (ORIF). They were able to achieve good or excellent results in 75% of fractures treated with the AO method as compared with only 32% in the conservatively treated group. They concluded that “if normal function or near normal function is to be achieved … then unquestionably, if correctly employed, open reduction internal fixation ensures a very high rate of success.” However, they did emphasize that ORIF is not appropriate for all patients. For fractures that are not displaced or are easily reduced, especially in elderly persons, immediate mobilization in weight-bearing functional braces is the treatment of choice. They also cautioned against internal fixation in severely osteoporotic patients. In 1979, Schatzker and Lambert reviewed an additional 35 patients with supracondylar distal femoral fractures treated by ORIF; only 49% had good or excellent results.
When they analyzed the 17 cases treated in accordance with the principles of rigid internal fixation as promoted by the AO group, 71% had good to excellent results. Among the 18 patients treated with AO implants but not AO technique, only 21% had a good to excellent outcome. Critical review of these 18 patients revealed that most were elderly with severely comminuted fractures; however, surgical technical error (incomplete reduction, lack of interfragmentary compression, lack of use of bone graft to fill defects or comminution, ineffective use of acrylic cement to supplement screw fixation in osteoporotic bone, implant choice or position) was the common denominator contributing to the poor results.
Schatzker and coworkers recommended that elderly patients with thin, osteoporotic bone and comminuted fractures “are better treated by such methods as closed reduction and early cast bracing, than an attempt at operative reduction.” In such patients, the only clear indication for ORIF is an intraarticular fracture in which adequate joint congruity cannot be restored by manipulation. In conclusion, these authors stated, “Rigid fixation is difficult to achieve with osteoporotic bone because of the degree of comminution and the poor holding power of the bone.” The mere use of the appropriate implant does not ensure rigid fixation. Failure to meticulously observe all the details of the method of rigid fixation resulted in a high complication rate with failures. These factors must be considered in evaluating criteria for surgical treatment.
Slätis and associates in 1971 reported on 21 “severe” fractures of the lower end of the femur that were treated by open reduction according to the AO method. Among the 16 patients available for follow-up longer than 1 year, 83% had good to excellent results. These authors recommended the technique as “reliable” but stated that it “should be restricted to fractures of considerable severity and to selected cases among patients with multiple injuries.” Olerud, in 1972, reviewed 15 patients with complex articular fractures of the distal end of the femur. He reported 92% good to excellent results with the use of the angled blade plate but concluded that satisfactory osteosynthesis of fractures of this type is a difficult procedure and should not be attempted without experience with the technique.
In 1974, Chiron and colleagues reviewed 137 patients with distal femoral fractures who underwent stable internal fixation with the 95-degree condylar blade plate (CBP). Seventy-two percent of patients fulfilled their criteria for good to excellent results (i.e., 135 degrees of motion and only mild swelling on prolonged weight bearing). In 1982, Mize and colleagues reported on 30 supracondylar and intracondylar fractures of the femur that were reduced and stabilized with the AO technique. They reported good to excellent results in 80% of patients and also recommended the use of an extensile surgical exposure with elevation of the tibial tuberosity to facilitate exposure of the condyles in more complex fractures with intraarticular comminution. Healy and Brooker in 1983 reviewed 98 distal femoral fractures to compare open and closed treatment methods; 38 of the 47 fractures treated by open methods but only 18 of 51 treated by closed methods had good functional results. Of significance in this review was that age, with an increasing degree of osteoporosis, did not adversely affect the operative results. The authors concluded that fractures of the distal part of the femur, except in more simple cases, are best managed by open methods.
From all recent reports, it would appear that better functional results can be obtained with ORIF in all but the most simple fracture types. However, the superior outcome seems to depend on the use of improved fixation devices, meticulous surgical technique, and adherence to principles of the AO Group: anatomic reduction, stable internal fixation, preservation of tissue vascularity, and early mobilization.
Antegrade Intramedullary Nailing
Although AO techniques initially relied on plates and screws, intramedullary (IM) nailing has also found an important and increasing role in the treatment of distal femoral fractures, particularly extraarticular type A and, increasingly, total articular (type C1 and C2) injuries.
Given the appropriate fracture patterns, Leung and coworkers and Butler and associates demonstrated that antegrade interlocking IM nailing is an acceptable treatment for supracondylar and intercondylar femoral fractures. Leung and coworkers included in their study only fractures of 9 cm or less from the knee and found the technique of antegrade femoral nailing applicable to AO and Association for the Study of Internal Fixation (ASIF) type A fractures and to selected type C (C1 and C2) fractures. Variables that determined the applicability of distal femoral fractures for closed nailing were the pattern and reducibility of the intercondylar fracture and the extent of metaphyseal and condylar comminution. The condylar fragment had to be reducible by closed traction and manipulation, and it had to be sufficiently large to permit stable fixation with supplementary percutaneously inserted lag screws placed under fluoroscopic guidance. The authors found that type B and type C3 fractures were not amenable to this form of treatment. Given these limitations, they had 95% good to excellent results, and normal healing was achieved in all but 1 of their 37 cases. Butler and associates used a similar method to specifically treat ipsilateral femoral shaft and supracondylar-intercondylar distal femoral fractures. Fractures of the femoral condyle in the coronal plane (type B3) and type C3 injuries were relative contraindications to this technique. In their series, no patients had loss of fixation or alignment or implant failure. The authors warned, however, that the rigidity of fixation of distal femoral fractures achieved with interlocking nails must be regarded with caution, and weight-bearing activity must be restricted. The advantage of treating ipsilateral femoral shaft and supracondylar femoral fractures with this method of antegrade interlocking femoral nailing is the ability to treat both fractures with one device.
Retrograde Intramedullary Nailing
Several series have investigated the treatment of supracondylar-intercondylar distal femoral fractures with the Green-Seligson-Henry (GSH) supracondylar IM nail (Smith and Nephew, Richards, Memphis, TN). Henry and associates reported in 1991 that “by virtue of the IM position, the GSH nail has a biomechanical advantage over the laterally placed conventional devices. The IM position decreases the lever arm, reducing varus/valgus angulation.” In 1995, Firoozbakhsh and colleagues mechanically tested the retrograde IM nail and the 95-degree angled screw and side plate in composite bone with an intercondylar split and a medial segmental shaft defect. They found that the bending stiffness of both constructs was not significantly different in varus compression and in flexion. The plate-and-screw device was three times stiffer in lateral bending and 1.6 times stiffer with torsion than the retrograde supracondylar nail. Clinically, medial comminution or a defect with varus collapse is the most common cause of failure of implant fixation in a supracondylar femoral fracture. The authors concluded that the supracondylar nail has biomechanical rigidity comparable to that of the screw and side plate with varus loading, thus making it a reasonable alternative to plate fixation for the treatment of these fractures.
Lucas and coworkers in 1993 reported follow-up on 25 AO type A and type C distal femoral fractures treated with the GSH nail. All the fractures healed, but 4 of the 19 type C fractures eventually required a bone graft. Danziger and associates in 1995 found similar success with the GSH nail: 15 of 16 patients with supracondylar-intercondylar distal femoral fractures had union with good to excellent results. They also found that postoperative alignment was maintained in this group.
Not all investigators have had similar success with the GSH nail, however. Iannacone and colleagues in 1994 reported on 41 complex distal femoral fractures treated with the GSH nail; they had 4 nonunions, 5 delayed unions (2 of which required revision of the fixation), and 4 fatigue fractures. The authors stated that fatigue fractures occurred only with the 11- and 12-mm nails and 6.4-mm interlocking screws. They had no nail failures when the rod system was modified to use 12- and 13-mm-diameter nails with 5-mm interlocking screws. Aside from the theoretical biomechanical advantage of this IM locked nail over plating techniques, both Lucas and coworkers and Danziger and associates reported that treatment of complex distal femoral fractures with this system was also associated with decreased blood loss, operative time, and periosteal stripping and allowed the IM reaming debris to be used as bone graft. In addition, the use of the median parapatellar approach for surgical exposure and nail insertion permitted direct visualization of the articular surface, thus facilitating anatomic reduction.
In 2016 Hoskins and coworkers published their retrospective results from the Victoria Orthopaedic Trauma Outcomes Registry with 297 patients, of whom 195 patients were treated with a locking plate and 102 patients were treated with an IM nail. Health-related quality-of-life, functional, and radiographic results were compared at 6 months and 1 year. Patients were identified using the ICD-10 diagnostic codes and the ICD-10 procedure codes. The authors concluded that IM treatment may be superior to anatomic locking plates.
Dynamic Compression Screw
The dynamic condylar screw (DCS) was one of the first widely used plates with angular stability. The distal screw was initially considered as having a compressive function.
Giles and associates reported in 1982 on the use of a supracondylar lag screw and side plate for fixation of 26 supracondylar-intercondylar fractures of the distal end of the femur. They stated that “the advantages of this device over others are that the lag screw supplies not only interfragmentary compression across the intracondylar fractured surfaces, but also better purchase in osteopenic bone,” thereby allowing earlier aggressive restoration of knee motion and muscle strength. In their series, they did not have any nonunions or infections, and the average postoperative range of motion (ROM) was 120 degrees, which compares favorably with other reported series of similar fractures. These authors concluded that “meticulous open reduction and stable internal fixation of supracondylar fractures with supracondylar plate and lag screw, combined with autograft in patients with severe comminution, provide an excellent opportunity to secure bone union and restore limb alignment, joint congruity and range of motion.” Similar excellent results with the use of this device have been reported by Hall, Pritchett, Regazzoni and colleagues, Sanders and associates, and Shewring and Meggitt.
In 2016 the Canadian Orthopaedic Trauma Society reported the results of a prospective multicenter randomized controlled trial comparing the less invasive stabilization system (LISS) with the minimally invasive DCS system. Fifty-two patients with a mean age of 59 years were randomized. Twenty-eight patients were treated with the LISS and 24 with the DCS. The primary outcome measure was the time to radiologic union and number of delayed unions/nonunions at 12 months. The study could not show an advantage for the locking plate design.
Double Plating (Lateral and Medial Plates)
Brown and D'Arcy reported on the use of a nail plate with an additional adapted medial compression plate to provide stable fixation on both sides of the femoral condyles. They recommended this technique to obtain better fixation in elderly, osteoporotic patients; in their series, all but one patient obtained knee flexion better than 55 degrees, and the average time to walking was only 4 weeks. Sanders and coworkers reported on the use of double-plate fixation for complicated, comminuted, intraarticular fractures of the distal part of the femur; union was obtained in all patients, and nonlocking plates were used in all their patients ( Fig. 59.10 ).
Fernandez developed a medial plating technique (helical plate) using a torqued narrow plate, which is proximally fixed on the anterolateral cortex of the femur. This gives strong medial buttress and avoids the problems related to a medial standard approach. He uses narrow plates that are helically shaped with torque pliers. The shape is checked with a steel rod, which is used as a template ( Fig. 59.11 ).
Bone Cement and Medial Bone Grafts
The use of bone cement as an adjunct to stable internal fixation for supracondylar fractures in osteoporotic femurs was advocated by Benum in 1977. He reviewed 14 patients with an average age of 75 years. Eighty-six percent (12 patients) healed uneventfully despite early mobilization. The two failures were the result of a technical error in the application of the plate and not loosening of the screw from the bone cement. Although all fractures in this study were extraarticular, Struhl and colleagues in 1990 reviewed 17 supracondylar femoral fractures in osteoporotic patients, 8 of which were of the T-intercondylar type. Using a modification of Benum's bone cement technique, they achieved bony union in all cases and overall 79% satisfactory to excellent results. They concluded that the use of bone cement for adjunctive fixation was effective in restoring patient and joint mobility while avoiding the complication of implant failure in osteoporotic patients. Especially in situations with significant soft tissue damage and periosteal stripping (see Fig. 59.10 ), medial bone grafting can be necessary.
Minimally Invasive Plating
Biologic plating, in which soft tissue attachments and bone vascularity are preserved through indirect reduction, was soon found to promote metadiaphyseal fracture healing and avoid the need for previously recommended bone grafting. Optimal soft tissue preservation may be achieved in the distal femur by inserting a plate submuscularly past the fracture zone along the lateral surface of the femur. These techniques are discussed in more detail in the following sections. Minimally invasive techniques add their own challenges regarding achievement and verification of satisfactory alignment. They are not suitable for displaced articular surface fractures.
Bridge Plating
The bridge plating concept of plate use is related to those of biologic fixation. Soft tissues are preserved, while a comminuted fracture zone is bypassed with a plate that is attached securely to proximal and distal bone segments but not to the intervening fragments. Axis alignment, length, and rotation must be restored. Healing usually occurs without bone grafting.
Locking Plates
Angular stable screws, secured to a plate with threaded holes, represent a significant advance in fracture fixation and were introduced in 1994 with the LISS plate. Such plates do not depend on being compressed to the underlying bone and behave more like internal fixators, with each screw as a separate fixation point. They are described in detail in Chapter 9 . Locking plates offer more stable fixation of many distal femur fractures (see the later discussion in the Malunion and Malalignment section).
In 2016, the Southeast Fracture Consortium published the results of a retrospective multicenter trial comparing the LISS with the locking compression plate (LCP) for open and closed distal femoral fractures. In this trial, 185 patients were treated with a LISS plate and compared with 154 patients treated with an LCP. The authors concluded that postoperative infection, implant failure, and nonunion rates are comparable between both for open and closed distal femoral fracture fixation.
Dynamic Locking Screw
The interface between the plate and the screw in an angular-stable plate fixation has been described as rigid. There have been attempts to decrease the stiffness of locked plating constructs by various measures, mainly by reducing the locking to the far cortex or by modifying the number and position of plate screws. “Bridge plate” techniques decrease the bending stiffness but are noted to increase the interfragmentary motion predominantly on the far cortical side by bending the plate. The dynamic locking screw (DLS) was developed to address this problem by allowing motion not only on the far side but also underneath the plate (see ).
The DLS is made from cobalt-chromium-molybdenum (CoCrMo) alloy, which enables the DLS to be as strong as standard stainless-steel locking screws. The DLS is mentioned as being used with all Synthes’ titanium or stainless-steel locking plates.
External Fixation With Taylor Spatial Frame
The history and principles of the Ilizarov technique are described in Chapter 8 . The Taylor spatial frame (TSF; Smith & Nephew, Memphis, TN) presents a modern multiplanar external hexapod frame consisting of rings connected with six telescopic struts. Only a few studies describe the use of the Ilizarov technique as a definitive treatment in distal femur fractures. In a recent study by Sala and coworkers, the authors reported favorable results in terms of bony consolidation, axis alignment, and functional outcome in a subset of open supracondylar-intracondylar femoral fractures with extended soft tissue damage and frequent bacterial contamination. The authors emphasize the ability to align the fracture with the TSF after the initial frame application ( Figs. 59.12 and 59.13 ).
![Fig. 59.12, The Taylor spatial frame (TSF) is shown applied to a fracture of the distal femur with articular involvement (Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association [AO/OTA] type 33C1). A standard spatial frame consisted of a condylar ring, a mid-femoral ring, and a proximal femoral arch. The frame is mounted orthogonally to the mechanical axis of the femur. An external rotation offset of 90 degrees in a proximal femoral two-thirds ring allows clearance for soft tissue and patient comfort. The standard configuration for hybrid osteosynthesis uses half-pins and only a limited number of wires. Detail of proximal fixation: This type of assembly is particularly stable with three-dimensional mechanical control and axial elasticity. It is also better tolerated by the patient. Detail of distal fixation: The medial and lateral surfaces of the femur can also be used for fixation by means of two half-pins inserted in posteromedial and posterolateral positions, respectively. For comminuted intraarticular distal femoral fractures, multiple screws and pins are placed in the fragments to reconstruct the condylar block. The screws and wires are placed in the best orientation possible to reconstruct the fracture fragments. A minimum of three tensioned wires in the metaphysis is used, and where a stable osteosynthesis is not guaranteed, a further level of stability can be achieved by extending the fixation to the tibia. The TSF construct is always the same: six struts that connect the two rings are attached between the two rings. The master tab is always on the proximal ring and faces anteriorly. The distal segment is generally used as the reference fragment. TSF struts are used to allow for both multiplanar correction of the limb axis and further fine-tuning reduction of the fracture. The six struts were adjusted gradually following the computer-generated daily adjustment schedule, and the fracture deformity was thereby reduced.](https://storage.googleapis.com/dl.dentistrykey.com/clinical/FracturesoftheDistalFemur/11_3s20B9780323611145000598.jpg "Fig. 59.12, The Taylor spatial frame (TSF) is shown applied to a fracture of the distal femur with articular involvement (Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association [AO/OTA] type 33C1). A standard spatial frame consisted of a condylar ring, a mid-femoral ring, and a proximal femoral arch. The frame is mounted orthogonally to the mechanical axis of the femur. An external rotation offset of 90 degrees in a proximal femoral two-thirds ring allows clearance for soft tissue and patient comfort. The standard configuration for hybrid osteosynthesis uses half-pins and only a limited number of wires. Detail of proximal fixation: This type of assembly is particularly stable with three-dimensional mechanical control and axial elasticity. It is also better tolerated by the patient. Detail of distal fixation: The medial and lateral surfaces of the femur can also be used for fixation by means of two half-pins inserted in posteromedial and posterolateral positions, respectively. For comminuted intraarticular distal femoral fractures, multiple screws and pins are placed in the fragments to reconstruct the condylar block. The screws and wires are placed in the best orientation possible to reconstruct the fracture fragments. A minimum of three tensioned wires in the metaphysis is used, and where a stable osteosynthesis is not guaranteed, a further level of stability can be achieved by extending the fixation to the tibia. The TSF construct is always the same: six struts that connect the two rings are attached between the two rings. The master tab is always on the proximal ring and faces anteriorly. The distal segment is generally used as the reference fragment. TSF struts are used to allow for both multiplanar correction of the limb axis and further fine-tuning reduction of the fracture. The six struts were adjusted gradually following the computer-generated daily adjustment schedule, and the fracture deformity was thereby reduced.")
Decision Making
It is essential to appreciate the following goals of operative management of periarticular fractures: (1) anatomic reconstitution of the articular surface; (2) reduction of the metaphyseal component of the fracture to the diaphysis and restoration of frontal and sagittal alignment, length, and rotation; (3) stable internal fixation; (4) undisturbed fracture healing; and (5) early motion and functional rehabilitation of the limb.
Assessment for Surgery: Patient, Fracture, and Surgeon Factors
In assessing any patient for surgery, it is important to evaluate not only the “personality” of the fracture but also the personality of the patient.
Patient factors to consider in deciding between operative and nonoperative treatment must include age, activity level, medical condition, hemodynamic status, the presence of infection, the presence of implants, ipsilateral or contralateral injuries, the cause and energy uptake of the injury (high- or low-velocity trauma), and the personality of the distal femoral fracture itself. However, deciding that both the patient and the fracture are candidates for surgery is not enough. It is important that potential surgeons honestly assess their own experience in the management of these difficult problems, including a clear understanding of the pathomechanics and morphology of the fracture, and have the necessary practical experience, equipment, and knowledgeable operating personnel and assistants (surgeon factors).
Indications for Surgery
Extraarticular Fractures (Type A)
Today, almost all distal displaced and undisplaced extraarticular fractures are treated operatively because a randomized controlled study comparing operative treatment (DCS, n = 17) and nonoperative treatment (traction, n = 19) resulted in good or excellent results in 53% of the patients treated operatively compared with 31% treated nonoperatively. The authors of one study reported no nonunion or deep infection in both groups and one fixation failure (6%) in the operative (DCS) group.
Unicondylar and Hoffa Fractures (Type B)
Because of the pull of the gastrocnemius muscle, most unicondylar fractures are displaced by posterior rotation of the condyle relative to the knee joint axis ( Fig. 59.14 ). This causes joint incongruency and axial malalignment and subsequent posttraumatic arthritis. These fractures almost always require open reduction to achieve anatomic reconstitution. Of particular importance is a B3 or coronal fracture (so-called Hoffa fracture), in which the only soft tissue attachment is the posterior capsule. Such a fracture behaves like a large loose fragment in the joint. Traction and closed means do not reduce this fracture. Internal fixation is required to maintain stability, and surgical intervention is thus necessary. Impression zones are often present, and the shape of the condylar fragments makes the judgment of anatomic reduction difficult. Recently, a significant frequency of bicondylar involvement with coronal-plane type B distal femoral fractures has been recognized. A CT scan, especially a three-dimensional (3-D) analysis, is extremely helpful to clarify this pathology (see Fig. 59.5 ).
![Fig. 59.14, Pathomechanics of distal femoral fractures: Two-dimensional (2-D) reconstruction of a distal femoral fracture (Arbeitsgemeinschaft für Osteosynthesefragen [AO] type 33C2) through the medial condyle. The gastrocnemius muscle (red arrows) pulls the distal main fragment in recurvatum deformity (green hashed angle) .](https://storage.googleapis.com/dl.dentistrykey.com/clinical/FracturesoftheDistalFemur/13_3s20B9780323611145000598.jpg "Fig. 59.14, Pathomechanics of distal femoral fractures: Two-dimensional (2-D) reconstruction of a distal femoral fracture (Arbeitsgemeinschaft für Osteosynthesefragen [AO] type 33C2) through the medial condyle. The gastrocnemius muscle (red arrows) pulls the distal main fragment in recurvatum deformity (green hashed angle) .")
Bicondylar Fractures (Type C)
The predominant deforming force on the condyles is the gastrocnemius muscle, whose medial and lateral origins cause posterior angulation and rotation. This deformity is compounded by shortening and anterior displacement of the shaft by the unrestrained pull of the quadriceps and hamstring muscles. Traction, if applied early, usually corrects the shortening but rarely affects the rotational displacement of the condyles in relation to each other. Surgery is required to gain anatomic reduction of the articular surface.
Special Circumstances
Open Fractures.
All open fractures require aggressive surgical débridement. Most would agree that joint congruity should be restored immediately, which can be accomplished in most cases by limited internal fixation of the condyles. Whether stable internal fixation of the condyles to the shaft should be performed primarily, however, is still questioned by some surgeons. Experimental and clinical evidence suggests that the rate of sepsis can be decreased by stabilizing the bony skeleton and, hence, the surrounding soft tissues.
In grade I and most grade II soft tissue injuries, after adequate débridement of all contaminated and devitalized bone and soft tissue and stabilization of the reduced condyles to the shaft can be performed in standard fashion. Skin closure is usually possible.
The most difficult problems are grades IIIB and IIIC fractures, which are often associated with high-energy bone and soft tissue injury and significant contamination. Absolute and aggressive débridement of all contaminated and devitalized soft tissue and bone is mandatory. Copious irrigation should be performed according to standard principles for the management of open fractures.
In C-type fractures the surgeon has three options: (1) the immediate repair of the articular condyles with minimal internal fixation; however, it needs to be kept in mind that this can also trap bacteria inside the fixed construct. Another decision is whether to attempt (2) a stable internal fixation of the condyles to the shaft or (3) stabilization of the bony skeleton and soft tissues by the application of a bridging external fixator across the knee joint (probably the safer option; Table 59.2 ).
Table 59.2
Surgical Options for Different Levels of Intracondylar and Supracondylar Repair
| Degree of contamination Complexity of fracture pattern General condition Resources |
||
| No reconstruction of articular surface | Partial reconstruction of articular surface | Complete reconstruction of articular surface |
| + | + | + |
| External fixation | External fixation | Internal fixation |
The latter choice allows immediate stabilization of bone and soft tissue and permits adequate access for débridement and care of the wounds. Eventual control of the soft tissues is usually obtained with either delayed wound closure and/or tissue transfer for wound coverage. Preliminary vacuum-assisted closure (VAC) dressings may be helpful. Once adequate soft tissue control has been achieved, delayed internal fixation can be performed for reattachment of the condyles to the shaft.
Associated Vascular Compromise.
Injury to the superficial femoral artery in the adductor canal or to the popliteal artery in the popliteal fossa associated with a distal femoral fracture is a limb-threatening emergency. This needs to be diagnosed with the help of an arteriogram ( Fig. 59.15 ; see Chapter 16 ). If reinstitution of blood flow to the distal end of the extremity is not accomplished within 6 hours of injury, the chance for successful limb salvage decreases exponentially with greater delay. The timing of vascular repair in relation to stable fixation of the fracture is critical. Optimally, the wound should be débrided, if open, and rapid but stable skeletal fixation should be performed before the vascular repair. If the vascular repair is done before bony stabilization is accomplished, length is hard to determine, and manipulation may disrupt the repair. If débridement and skeletal stabilization require a delay of more than 6 hours after injury, Johansen and colleagues recommended the use of a temporary arterial shunt to restore flow. They reported an average time of only 35 minutes to shunt and restore arterial blood flow to an ischemic limb. This technique allows sufficient time for adequate débridement and skeletal stabilization without compromising salvage of the extremity.
Ipsilateral Fractures of the Tibial Shaft.
An ipsilateral fracture of the tibia associated with a femoral fracture is a well-described injury complex: the floating knee. The best method of restoring knee motion and function in these severe injuries is by surgical fixation of both sides of the knee joint. Such fixation may be done definitively in the initial procedure (often by IM fixation of both fractures with a retrograde femoral and an antegrade tibial nail through the same anterior knee incision). However, patients with this injury complex are frequently severely injured, so complex extremity surgery should be deferred. Depending on the patient's condition, both the distal femoral and tibial fracture sites may be temporarily spanned by external fixation (orthopaedic damage control surgery). Alternatively, definitive fixation might be carried out for one bone while the other is externally fixed or otherwise immobilized, and definitive repair deferred until after the acute period.
Ipsilateral Fractures of the Tibial Plateau.
Ipsilateral fractures of the tibial plateau in association with a distal femoral fracture should be addressed like any complex intraarticular fracture (i.e., anatomic reduction of the articular surface, stable internal fixation, and early functional mobilization). Because the reduction and fixation of these fractures are difficult and time-consuming and because soft tissue damage and other injuries are frequently common, temporary bridging external fixation (orthopaedic damage control surgery) is indicated in most cases.
Bilateral Femoral Fractures.
Patients with bilateral femoral fractures do not tolerate traction well. Nursing care is extremely difficult, and functional rehabilitation is decidedly impaired. As a result, ORIF is indicated to allow patient mobilization, as well as for reasons enumerated later. If the patient is not a candidate for immediate internal fixation, damage control with temporary external fixation is a good alternative because these patients are usually severely injured and need adequate fracture immobilization even if definitive repair must be delayed.
Polytraumatized Patients and Burns.
A severely injured patient with multisystem involvement and an associated femoral fracture has a significant risk of mortality and prolonged morbidity. Bone demonstrated the value of femoral shaft fixation within the first 24 hours. The incidence of multisystem organ failure and adult respiratory distress syndrome, the number of respirator and intensive care unit days, and the incidence of sepsis were all decreased by immediate stabilization of the femoral shaft fracture. Conversely, traction and prolonged bed rest in patients with high injury severity scores and multisystem trauma had a significant detrimental effect on mortality rate and long-term morbidity. In a polytraumatized patient, the same indications for early stabilization of femoral shaft fractures and patient mobilization also apply to distal femoral fractures.
Patients with distal femoral fractures and associated head injuries represent a group of the polytrauma patient population with complex management issues. Impaired consciousness, often with associated spasticity, makes reduction difficult to maintain by traction or closed means. In addition, avoidance of skin breakdown and joint contractures is particularly difficult. Early ORIF facilitates nursing care and allows easier maintenance of skeletal alignment.
Patients with significant burns in addition to their femoral fractures require skilled nursing, frequent immersion in tubs, and multiple dressing changes. Treatment by closed methods and traction severely compromises the management of burns that are potentially life threatening. Definitive operative stabilization before burn colonization is the treatment of choice if the patient's condition permits. However, for most polytrauma scenarios, orthopaedic damage control with temporary knee bridging external fixation is safer.
Pathologic Fractures.
In pathologic fractures, especially with bone loss, healing cannot be expected to occur with treatment by closed means and prolonged immobilization. Surgical options depend not only on the type of tumor (primary or metastatic) but also on many patient factors, including medical status, life expectancy, and functional demands. Decision making must be individualized (see Chapter 21 ). ORIF of pathologic distal femoral fractures is technically demanding and often requires multiple forms of internal fixation and additional stabilization with methyl methacrylate. Healy and Lane in 1990 reviewed 14 patients with pathologic supracondylar fractures treated by Zickel nailing and augmented with bone cement. In 11 of the 14 patients, their goals of pain relief and functional restoration were achieved. They concluded that IM fracture fixation was the method of choice in treating pathologic fractures of the distal end of the femur because of the presence of bone defects and the rarity of bone healing. However, the authors cautioned that in patients with massive bone destruction of the femoral condyles, an IM device is not indicated; in such cases, they recommended distal femoral knee arthroplasty ( Fig. 59.16 ).
Similar to pathologic fractures resulting from tumors or metastases, pathologic fractures occur from severe osteoporosis related to age, inactivity, or metabolic changes. Retrograde nailing and, most recently, locked plates with multiple angular-stable fixation points (locked screws) have significantly improved the treatment options for these injuries. They offer better fixation strength and reduced incidence of fixation failure. Although angular-stable plates seem not to provide better fixation than nonlocked CBPs in normally dense bone, such angular-stable devices provide better fixation and less failure in osteoporotic bone and periprosthetic fractures. The positive effect of locked screw fixation is also found with retrograde nails.
Especially in the elderly, arthroplasty has been shown to be an excellent alternative to ORIF because of the option of immediate full weight bearing ( Fig. 59.17 ; see ).
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