Postoperative Orthopaedic Rehabilitation of Distal Femur Fractures

H. Michael Frisch, MD

Neither Dr. Frisch nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this article.

Introduction

Distal femur fractures encompass a wide spectrum of injuries with various characteristics that must be considered when developing a treatment plan with respect to both surgery and rehabilitation. On one end of the spectrum are the high-energy injuries, such as those seen in young patients after a motor vehicle crash. These are often open, comminuted, and intra-articular, but have better bone quality. On the other end of the spectrum are low-energy injuries that tend to occur in elderly patients after a fall. These are often closed and extra-articular, but with osteoporotic bone.

Distal femur fractures are classified based on the anatomy of the fracture pattern. The extra-articular group includes the supracondylar and periprosthetic types. The intra-articular group includes the unicondylar and the much more common bicondylar types. The AO/OTA classification system is most commonly used to further subdivide these fractures based on comminution. The surgical approach, extent of the exposure, and form of fixation are driven by the fracture pattern and its severity.

The location and severity of fracture comminution, as well as bone loss, all have a negative impact on the stability of the fracture fixation and must be taken into consideration when developing a rehabilitation plan. Signs of fracture healing usually dictate progression in strengthening and weight bearing.

When developing an operative and rehabilitation treatment plan, it is critical to consider other components of the injury rather than just the fracture pattern. The soft tissue envelope often dictates not only operative timing but also rehabilitation timing. Swelling, open wounds, and degloving injuries risk infection with definitive internal fixation necessitating the placement of a provisional external fixator until adequately resolved. Incisions and exposures must take open wounds into account. Rehabilitation may be delayed by wound healing considerations. Muscle injury and loss, most commonly the quadriceps, affect fracture coverage and time to union but also result in scaring and adhesions, which impact range of motion (ROM) and strength.

The patient’s comorbidities must also be considered in the overall treatment plan. Underlying osteoporosis should be evaluated and treated, as it will affect fixation stability and rehabilitation progression. Nutritional deficiencies should be corrected to improve healing and muscle recovery. The overall medical condition of the patient and ability to compensate for the increased energy and oxygen consumption associated with weight bearing restrictions. The additional challenges and increased complications associated with obesity must also be taken into account, such as decreased ability to comply with weight bearing restrictions.

In the past, the operative treatment of distal femur fractures was associated with high complication rates, including nonunion, malunion, hardware failure, infection, and decreased ROM. Although these fractures remain a challenge, recent advances in surgical technique and implants have significantly improved clinical outcomes. Complete fracture exposure and precise fracture reduction, which resulted in significant stripping and devitalization of bone and tissue, has been replaced with less invasive techniques utilizing minimal exposures and indirect reductions. The use of precontoured plates with locking-screw technology and insertion guides has facilitated insertion, reduction, and alignment while improving fixation and decreasing hardware and fracture displacement.

Surgical Procedure

Procedure: Knee Bridging External Fixation

Knee bridging external fixation is utilized primarily as provisional stabilization in damage control orthopedics if the patient requires further resuscitation or medical optimization prior to definitive fixation. It is also utilized in the treatment of open fractures that require serial débridements. The femoral half pins are placed percutaneously through the quadriceps, which may result in scaring and adhesions that limit motion and contribute to quadriceps dysfunction and atrophy.

Procedure: Lateral Plating

The majority of distal femur fractures can be addressed with a lateral plate for fixation. The major exception is medial condyle fractures.

A lateral incision is centered over the lateral femoral condyle. The iliotibial band is split in line with its fibers. The distal edge of the vastus lateralis is then elevated anteriorly to expose the femoral condyle. For supracondylar fractures and periprosthetic fractures, a closed reduction is performed over a bump. The plate is attached to the insertion guide and passed submuscularly between the vastus lateralis and periosteum. The plate is pinned distally to the condyles and proximally to the shaft while ensuring proper plate position, fracture reduction, and alignment. Particular attention is paid to varus valgus and flexion extension alignment. Proximal screw placement is performed percutaneously through the vastus lateralis using the insertion guide. If more proximal exposure is needed, the vastus lateralis can be elevated off the lateral intermuscular septum and retracted anteriorly. Great care should be taken to limit medial dissection and exposure to preserve vascularity.

The exposure can be extended distally for simple intra-articular fracture by curving the incision towards the tibial tubercle and making a lateral parapatellar arthrotomy. Fractures with articular comminution may require an anterior incision and lateral parapatellar arthrotomy. Anatomic reduction of the articular surface is ensured, then fixed with screws placed so as not to interfere with subsequent plate placement (Figure 73.1).

Procedure: Medial Plating

A medial buttress plate is placed to address medial condyle fractures and oblique supracondylar fractures that exit distally on the lateral cortex just before the articular surface. A medial incision is centered over the medial femoral condyle, the fascia is incised, and the vastus medialis is elevated off the intermuscular septum and adductor tendon to expose the medial condyle. Reduction and plating is performed in standard fashion.

Procedure: Retrograde Intramedullary Nail Fixation

Retrograde intramedullary nail fixation is predominantly utilized to address supracondylar and periprosthetic fractures, but may be used in select bicondylar fractures as well. The nail can be inserted percutaneously by splitting the patella tendon for supracondylar fractures. A medial parapatellar approach is utilized for periprosthetic fractures to ensure that the prosthesis is not damaged during reaming and bicondylar fractures to assess the articular reduction (Figure 73.2). As with plating, flexion extension alignment as well as varus valgus are important to maintain during fixation.

Figure 73.1 Young patient with open comminuted intercondylar distal femur fracture with Hoffa fragments after motor vehicle crash. A, Anteroposterior radiograph of injury. B, Lateral radiograph of injury. C, Anteroposterior postoperative radiograph. D, Lateral postoperative radiograph.

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