Distal Femur Fracture- Supracondylar Femur Fracture

Supracondylar femur fractures can occur in young patients due to high energy trauma and when it occurs in older patients; it usually occurs due to low energy trauma such as a fall (osteoporotic bone). When you see a supracondylar fracture of the distal femur involving the joint, you need to achieve anatomic reduction of the joint, provide stable fixation for the fracture, and achieve the proper length, alignment, and rotation. We hope that the stable fixation will allow the patient to have early range of motion and this will help in cartilage repair.

 Supracondylar fracture of the femur is a complicated injury. The distal femur is usually shattered and the joint can be involved. The patient may have poor bone quality. There may be prosthesis or a previous fracture that may complicate management of this fracture. The fracture can be open in about 5%-10% of the patients and there is an increased incidence of nonunion and malunion with these fractures. Sometimes there will be a vascular injury. The patient may have decreased pulses compared to the other side. You should get the ankle brachial index (ABI) for the injured side. You may want to get CTA or arteriogram. In this situation, you may want to use an external fixator initially. From the joint to the metaphyseal/diaphyseal area is about 15 cm. The distal femur is trapezoidal in shape. The posterior portion is wider than the anterior portion. The medial aspect of the trochlear groove is lower. The medial side shows a 25 degree decrease in width from posterior to anterior. Hardware inserted from the lateral side may penetrate into the joint. Try to direct the screws away from the joint to avoid joint penetration. When placing screws across the condyles, the x-ray may appear as if the screws are within the bone, however the screws may be long and protruding medially, causing occult post-operative irritation and pain. The screw should end 1 cm short of the projected medial cortex. An internal rotation view of the distal femur will help you to see the prominent and long screws. The posterior half of both condyles lies posterior to the femoral shaft so the lateral axis of the femur is anterior. Coronal fracture of the posterior lateral condyle of the femur that could be missed. Suspect Hoffa fracture in comminuted fractures. You may see double density on an AP view. The fracture line can be seen on the lateral or the oblique view. CT scan will definitely show the fracture. This fracture may require different and separate fixation than the supracondylar plate fixation. The gastrocnemius muscle pulls the distal fracture fragment into recurvatum (extension). The hamstrings and the quadriceps cause shortening of the fracture. Nonoperative treatment is rare. It is used for nondisplaced fractures in patient with comorbidities and for non-ambulatory patients. Surgery will probably require preoperative planning. You may want to sue a plate or a rod in this situation (external fixator is rarely used). Retrograde femoral nailing is a minimally invasive surgical approach. It is ideal for ipsilateral femoral neck and shaft fractures when two devices are used. The rod should be inserted proximally to the level of the lesser trochanter. It is important to select proper location for insertion of the rod. The starting point is the center and intercondylar notch just superior to the Blumensaat’s line. You should check proper depth to avoid prominence in the joint, check the distal screws (may be long with medial prominence), and you may need internal rotation view for the diagnosis. Plating of the distal femur can be approached laterally, anterolaterally, or medially. In the lateral approach, the surgical approach is usually done laterally and minimally invasive. In the anterolateral approach, this will allow you to see the joint and reduce the intra-articular fracture under direct vision. The joint fragments must be reduced anatomically and the fixation has to be stable. In the medial approach, you may use anti-glide plate for medial condylar fracture of the distal femur. Fracture distal femur after total knee replacement (periprosthetic fracture) can be treated surgically. If the prosthesis is stable, then you will do fixation. You should do fixation with a plate or a rod (short rod or long rod) if the rod can be done through the femoral component or if the prosthesis is not stable then you will do revision of the prosthesis. The whole idea is limited incisions with exposure of the joint if necessary and no soft tissue stripping. The plating is usually done percutaneous or submuscular. It is called biological fixation or minimally invasive plate fixation. You will do direct reduction for the intra-articular fracture; however, for the metaphyseal diaphyseal fracture, you will do indirect reduction.

You will use traction without disturbing the soft tissue to align and approximate the bony fragments together. Watch the length, the rotation and the alignment of the extremity and then apply the plate onto the bone. This indirect reduction and biologic plating will preserve the soft tissue and the blood supply, allowing for earlier and better healing of the fracture. The indirect reduction may cause more malunions. You will reduce the articular surface with lag screws, and you will place the screws where it will not interfere with the plate fixation. In osteoporotic bone, a locking plate system is usually used. The locking compression plate will allow better control of the coronal fracture (Hoffa fracture) and the comminuted fracture fragments. The locking plates may be too stiff and nonunions may occur. It is better to use plates that allow for the use of locking and regular screws. Try not to use the older condylar buttress plates because they do not allow locking and if the fracture is comminuted, it may go to Varus (locking screws will prevent Varus malalignment. Proper plate placement will prevent malreduction. If you place the plate too distal and posteriorly, you may get a golf club deformity and medialization of the condyles. Fixation of the distal femur fractures is not without complications.

Nabil Ebraheim, MD

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