Mechanisms of Injury
Signs and Symptoms
Imaging and Other Diagnostic Studies
Pathoanatomy and Applied Anatomy
Applied Anatomy of the Distal Femur Bone
Applied Anatomy of the Knee Joint
Applied Anatomy of the Soft Tissues About the Distal Femur
Management of Expected Adverse Outcomes and Unexpected Complications
Infection After Operative Treatment
Implant-Related Problems After Surgical Treatment
Author’s Preferred Method of Treatment
Summary, Controversies, and Future Directions
Reduction: Traction is critical, usually with a universal distractor (or external fixator, if present). Sagittal plane alignment with a well-placed large bump or towel roll. Coronal plane alignment can be corrected with Schantz pin joysticks, well applied clamps, or plate application itself.
The vast majority of displaced distal femur fractures in adults are best treated with internal fixation. We recommend locked plating or closed retrograde intramedullary nailing for these fractures (Table 53-9). We still use the 95-degree ABP in the management of selected nonunions or after corrective osteotomies in the distal femur. Regardless of which implant is used, the goal is anatomic reduction of the joint surface and stable internal fixation to allow early range of knee motion. In isolated closed fractures, internal fixation should be performed within the first 24 to 48 hours. If surgery must be delayed for more than 24 to 36 hours, a temporary external fixator or tibial pin traction should be considered.
Because the spectrum of injuries to the distal femur is so great, no single implant or approach will be optimal for every case. Careful assessment of the patient and critical review of the x-rays and the “personality” of the fracture are essential. Some factors to be considered in the surgical decision-making process include (1) patient age, (2) ambulatory status, (3) degree of osteopenia, (4) degree of comminution, (5) condition of the soft tissues, (6) presence or absence of open wounds, (7) involvement of the joint surfaces, and (8) whether the fracture is an isolated injury or part of a multiply injured patient.
In younger patients, restoration of length and axial alignment with stable fixation and early functional rehabilitation remain the goal of surgery. In elderly osteoporotic patients, impaction of metaphyseal fragments with small amounts of shortening may be a reasonable trade-off for rapid fracture union, and occasionally, with a highly comminuted fracture in incompetent bone with or without a knee, a pre-existing knee prosthesis, knee replacement using a tumor prosthesis may be indicated. With the widespread use of periarticular locked plates, these techniques are not widely indicated.
With open distal femur fractures, the literature supports immediate or early internal fixation after debridement in type I, II, and IIIA fractures in stable patients in whom the wounds can be made “clean.” However, in type IIIB and IIIC open fractures with massive wounds and gross contamination, external fixation with delayed internal fixation is preferred. Temporizing knee spanning external fixation is a valuable tool to treat this subset of patients. A variety of frame configurations are possible, but typically two pins are placed anteriorly in the proximal tibia and two anteriorly or laterally in the midproximal femur superior to the anticipated proximal extent of plate fixation (Fig. 53-5). When the soft tissues have recovered and the patient’s condition has improved, internal fixation can be performed. Repeat debridement at 48-hour intervals until all devitalized tissue is removed from the wound is necessary to reduce the risk of infection. A wound VAC or antibiotic beads may be a useful adjunct to stabilize the zone of injury, prevent infection, and promote soft tissue healing. Once a clean wound has been achieved and the patient is stable, internal fixation is carried out.
The sequential steps in the surgical management of supracondylar femoral fractures include (1) restoration of the articular surface, if needed, (2) stable internal fixation, (3) grafting of bone loss, if necessary, (4) impaction of the fracture in osteoporotic elderly patients, (5) repair of associated ligament injuries and patellar fractures, as indicated, (6) early range of motion of the knee, and (7) delayed protected weight bearing. Nonarticular injuries can be treated using a variety of implants. The method of fixation should be based on a preoperative plan that incorporates the fracture pattern, soft tissue injury, patient factors, surgeon’s preference/familiarity, and hospital resources. In patients with more complex intra-articular involvement (the vast majority of C2 and C3 fractures), the authors prefer the modified lateral (or medial) parapatellar approach to allow access to the joint. In these cases our preference is to use small fragment fixation for the condylar injuries in conjunction with distal femoral locked plates. Temporarily, secure articular fragments using K-wires and/or reduction forceps. Provisional and/or definitive fixation using 3.5- and 4.5-mm cortical screws must be strategically placed to avoid interference with the plate. If a posterior coronal or Hoffa fracture is present, fixation can be obtained by placing countersunk 2.7- or 3.5-mm cortical, or 4-mm cancellous screws through the articular surface from anterior to posterior. After adequate surgical exposure, the femoral condyles are reduced and provisionally fixed with K-wires. Once reduction is confirmed clinically and/or radiographically, the condyles are definitively fixed with long screws anterior and/or posterior in the condyles, allowing sufficient room for the plate. The condylar block can then be reattached to the shaft segment using whichever fixation method the surgeon prefers, plate or nail.
Knowledge of fracture biomechanics is vital to maximizing a patient’s chances for union. The use of direct reduction requires a thorough understanding of Perren’s strain theory, and residual gapping at the fracture site should be avoided because it increases the incidence of nonunion and hardware failure. Eight cortices of fixation above and below the fracture site are recommended to provide adequate stability to prevent early torsional and axial failure. A common technical error encountered during indirect reduction and bridge plating is the placement of an overly stiff implant. The use of longer plates with well-spaced cortical screws limits implant stiffness and encourages secondary bone healing. If a locking construct is chosen, a plate of sufficient length to allow no more than 50% of screw holes to be filled is important to prevent stress concentration and premature implant breakage. Newer techniques to modulate locking plate stiffness have recently been reported. Far cortical locking, slotting of near cortical holes, and threaded screw head inserts are all new methods designed to give surgeons control of implant stiffness and direct modulation of the healing environment at the fracture site.