Key points

Background

Supracondylar femur fractures are severe injuries that can be technically challenging to operatively treat. Although they account for less than 1% of all fractures and between 3% and 6% of femur fractures, their incidence is likely to increase with the rising geriatric populations and the increasing number of peri-prosthetic injuries. Injuries to the distal femur follow a bimodal distribution between geriatric low energy fractures and high-energy trauma. As with all fractures involving periarticular metaphyseal bone, treatment invariably includes understanding the fracture characteristics, careful preoperative planning, assessment of patient goals and health, bone quality, surgeon experience and implant selection.

In the early 1960s, most distal femur fractures were managed conservatively with fracture bracing and traction, achieving acceptable results in 67% to 90% of patients. However, with the advent of new surgical techniques and implants, the pendulum shifted from conservative management to surgical stabilization of these injuries. Through historical review, Henderson and colleagues chronicled the increasing success rates with operative fixation from 52% to 54% in the 1960s, 73.5% to 75% in the 1970s, to 74% to 80% in the 1980s. Steady advances in our understanding of distal femoral anatomy and fracture biology have heralded various implant designs that further optimized successful treatment of these injuries. These modalities, each with their own merits and drawbacks, range broadly from external fixation, fixed-angle device (blade or sliding barrel implants), plate fixation (locked and unlocked), intramedullary nailing, arthroplasty, and distal femoral replacement (DFR) ( Box 1 ). The authors intend to review these modalities and examine their success and pitfalls to provide a primer for the current clinical care of adult supracondylar femur fractures.

Background

Supracondylar femur fractures are severe injuries that can be technically challenging to operatively treat. Although they account for less than 1% of all fractures and between 3% and 6% of femur fractures, their incidence is likely to increase with the rising geriatric populations and the increasing number of peri-prosthetic injuries. Injuries to the distal femur follow a bimodal distribution between geriatric low energy fractures and high-energy trauma. As with all fractures involving periarticular metaphyseal bone, treatment invariably includes understanding the fracture characteristics, careful preoperative planning, assessment of patient goals and health, bone quality, surgeon experience and implant selection.

In the early 1960s, most distal femur fractures were managed conservatively with fracture bracing and traction, achieving acceptable results in 67% to 90% of patients. However, with the advent of new surgical techniques and implants, the pendulum shifted from conservative management to surgical stabilization of these injuries. Through historical review, Henderson and colleagues chronicled the increasing success rates with operative fixation from 52% to 54% in the 1960s, 73.5% to 75% in the 1970s, to 74% to 80% in the 1980s. Steady advances in our understanding of distal femoral anatomy and fracture biology have heralded various implant designs that further optimized successful treatment of these injuries. These modalities, each with their own merits and drawbacks, range broadly from external fixation, fixed-angle device (blade or sliding barrel implants), plate fixation (locked and unlocked), intramedullary nailing, arthroplasty, and distal femoral replacement (DFR) ( Box 1 ). The authors intend to review these modalities and examine their success and pitfalls to provide a primer for the current clinical care of adult supracondylar femur fractures.

Anatomy and classification

The distal femur is descriptively divided into a supracondylar region encompassing the region between the meta-diaphyseal junction and the condyles and an intercondylar region that encompasses the condyles and articular surfaces. The periarticular/supracondylar region enjoys a better blood supply than that of the distal shaft, enabling adequate healing when stabilized. The normal anatomic axis of the femoral shaft is oriented between 6° and 11° of valgus in relation to the joint line ( Fig. 1 A). Restoration of this mechanical axis and prevention of varus collapse is a crucial factor in the success of distal femoral reconstruction and ultimate longevity of the joint. The medial and lateral cortices of the distal femur also taper anteriorly toward the midline at angles of approximately 25° and 10°, respectively (see Fig. 1 B). This taper must be taken into account when selecting screw lengths and confirmed with internal rotation views to prevent hardware irritation from prominent screws medially. Knowledge of anatomy is crucial during placement of plates, which are often designed to be positioned along the anterior distal femur, approximating the border of the articular surface while avoiding intra-articular penetration of screws within the notch posteriorly or the trochlea anteriorly. Care must be taken during patient positioning and prep to allow for satisfactory imaging to be obtained intraoperatively in order to avoid such pitfalls. Other considerations during the preoperative setup include obesity, body habitus, other prostheses, and wounds.

( A ) Anatomic and mechanical axis of femur. ( B ) Dimensions of distal femur.

The distal femur is spanned by several muscle groups that can create deformities across fractures. Depending on the fracture plane and comminution, the quadriceps typically cause shortening, whereas in the coronal plane varus/valgus deformity can be imparted by the adductors or iliotibial (IT) band. Additionally, the distal segment can be deformed by the two heads of the gastrocnemius, causing an apex posterior deformity best seen on lateral radiographs or in the form of a “paradoxic notch view” on an anteroposterior (AP) image.

The most commonly used classification system for distal femur fractures is the AO/Orthopedic Trauma Association (OTA) system ( Fig. 2 ). Fractures are broadly classified into types A, B, and C corresponding to extra-articular, partial articular, and intra-articular injuries, respectively. They are further subclassified (1–3) based on pattern and degree of comminution. Type B1 involves sagittal splits of the lateral condyle; B2 involves sagittal splits of the medial condyle; B3 involves coronal patterns commonly known as Hoffa fractures. Type C fractures are divided into C1 (simple articular, simple metaphyseal), C2 (simple articular, multi-fragmentary metaphyseal), and C3 (multi-fragmentary). Careful scrutiny of radiographs and additional studies may be needed to accurately describe fracture patterns.

AO/OTA classification for distal femoral fractures.

( Adapted from Gwathmey FW Jr, Jones-Quaidoo SM, Kahler D, et al. Distal femoral fractures: current concepts. J Am Acad Orthop Surg 2010;18(10):597–607.)

Diagnosis and imaging

Initial evaluation of patients begins with an accurate history and physical examination to identify the mechanism and time course of the injury. Identification of high- versus low-energy mechanism may also allow insight into the patients’ bone quality and general health condition. Swelling and soft tissue condition should be critically evaluated to identify effusions/hemarthrosis, compartment syndrome, and open fractures. A baseline neurovascular examination of both lower extremities can aid in the documentation of prior neurologic compromise or vascular insufficiency. If weak pulses are found, a Doppler probe should be used and ankle brachial index should be performed to aid in assessing possible arterial compromise.

Imaging studies should always begin with plain radiographs (AP and lateral) of the knee and the hip to rule out any additional trauma. If excessive shortening or deformity obscures initial radiographs, traction views can aid in the preoperative visualization. Although not always necessary in extra-articular supracondylar femur fractures, computed tomography (CT) scans can play a key role in identifying intercondylar extension in patients with inadequate radiographs or osteoporotic bone. Type B3 fractures or coronal plane Hoffa fractures of the posterior femoral condyle are prevalent in up to 38% of intercondylar fractures and may elude initial detection on orthogonal plain films. These injuries can often be open and involve both condyles, and evaluation with a CT scan is strongly recommended.

Management

Current treatment options broadly include conservative management (cast/splint, traction), external fixation, locked and unlocked plating, lateral fixed-angle device (blade or sliding barrel options), intramedullary nailing, and arthroplasty. Despite the myriad of techniques available, the primary goal of surgical treatment remains: restoration of the articular unit to the shaft and anatomic alignment while maintaining stability to enable early range of motion (ROM) and rehabilitation.

Nonoperative

Although most distal femoral fractures tend to be operatively treated, there still exists a consistent role for conservative management. Indications include nondisplaced fracture, nonambulatory patients or spinal cord injury, unreconstructable injuries, or those patients with multiple comorbidities that preclude operative fixation. A study comparing operative versus conservative management of distal femur fractures in myelopathic, nonambulatory patients found a 90% union rate, with complications including skin and wound issues in patients treated conservatively and no wound complications in patients treated operatively. Surgeon experience and implant availability must also be taken into consideration when approaching such injuries.

Various methods of immobilization include long leg splints, casts, or skin/skeletal traction. Splinting or casting paired with non–weight-bearing restrictions must be maintained for 4 to 6 weeks with routine interval radiographs to monitor healing progress. Initial stabilization of supracondylar fractures may be performed with skin or Buck traction and may be converted to skeletal traction through the insertion of a proximal tibial traction pin. Balanced skeletal traction is advised in patients for whom traction will be definitive treatment, as it avoids excessive exertion of force through the skin and soft tissue layers. Regardless of modality, conservative management with prolonged immobilization has inherent complications: joint stiffness, decubitus ulcers, pulmonary complications, deep vein thrombosis, and deconditioning.

Surgical approaches

Distal femur fractures can be operatively treated through minimally invasive submuscular techniques involving small lateral incisions or through conventional exposures performed anteriorly, laterally, or medially based on the fracture pattern and surgeon comfort. The workhorse approach proven in fractures involving the articular surface is the lateral para-patellar arthrotomy with varying degrees of proximal extension. The swashbuckler and mini swashbuckler approaches have been described, enumerating techniques to extend the laterally based arthrotomy proximally between the IT band and vastus lateralis by following the lateral intermuscular septum to expose the distal femur. Depending on the fracture pattern, a medial approach may also be used in conjunction to the arthrotomy to access the fracture for reduction or fixation purposes. This accessory approach may also be used to secure vertical or coronal fractures in type B injuries with interfragmentary screws if necessary. Retrograde intramedullary nailing requires astute knowledge of anatomy and selection of an optimal starting point. Many investigators agree that a small 3- to 4-cm arthrotomy positioned medial to the patellar tendon allows best access to the notch, because the patellar tendon and tibial tubercle are slightly laterally oriented structures.