Femoral Neck Fracture Nonunion

Femoral Neck Fracture Nonunion

Femoral neck fracture nonunion has multiple facets and is important to understand all aspects of this important problem.

Example:

40 year old patient had a displaced femoral neck fracture, fixed with multiple cancellous screws about 9 months ago. The patient still has persistent groin pain. The patient cannot bear full weight on the hip. The patient has a painful limb, antalgic gait, and difficulty in walking. X-rays are not clear and show a possible nonunion. CT scan shows the nonunion with some Varus angulation. The treatment for this would be removal of the hardware and valgus osteotomy. The scenario can be more complicated by adding a healed femoral shaft fracture to the nonunion of the femoral neck. In this case, you will do removal of the hardware from the femur and removal of the screws from the femoral neck nonunion. You will do valgus osteotomy and fixation with a plate, preferably a blade plate, to treat the nonunion of the femoral neck.

Intracapsular fractures of the proximal part of the femur are not common in adults younger than 50 years old, but they are associated with a high incidence of avascular necrosis and nonunion. About 10-30 % of femoral neck fractures go to nonunion after ORIF. It is usually the vertical fracture pattern, such as Type III in Pauwels Classification. These fractures are more prone to nonunion due to shear stress, rather than compression forces across the fracture site. In Garden Classification fracture Type IV, where the fracture is completely displaced, the greater the displacement, the higher the incidence of nonunion and reoperation rate after fixation of the femoral neck. The inverted triangle pattern of fixation of femoral neck fractures is the one that is commonly used with the inferior screw posterior to the midline and adjacent to the calcar. Achieving and maintaining anatomic reduction is important for femoral neck fracture fixation and healing. The femoral neck fractures are intracapsular. There will be no abundant callus formation during the healing (healing is intraosseous only). Sometimes it is difficult to know if the fracture healed or not. There is no correlation between age, gender, and rate of nonunion. Varus malreduction correlates with failure of fixation after reduction and cannulated screw fixation. Posterior comminution of the fracture does not allow stable fixation and can lead to nonunion. The comminution of the femoral neck is usually posteriorly and inferiorly. Some recommend adding a fourth screw in this situation. High energy fractures have a worse prognosis for healing, especially in patients with metabolic bone disease and nutritional deficiency. When you see a femoral neck nonunion after fixation, you need to get blood work and rule out infection (get sedimentation rate and CRP).

For the high angle femoral neck fracture, follow the patient up closely with clinical exam and x-rays. There might be a Varus collapse on the x-rays. You may see a femoral neck nonunion or a failed internal fixation. The patient walks with a limp, the limb is shortened, and the patient may have rotational deformity of the extremity. In the young patient with a femoral neck nonunion, arthroplasty is not a desirable option. In a young patient with femoral neck fracture nonunion, valgus intertrochanteric osteotomy with plate fixation produces a good result in the majority of cases. Valgus intertrochanteric osteotomy with plate fixation produces approximately 80% union rate and the procedure makes a vertical fracture more horizontal, converting the shear forces into compressive forces. It is done in a healthy, young patient with no joint arthritis and when the femoral head is intact. This procedure also corrects the Varus malalignment. Basically, the procedure changes the vertical fracture orientation to a horizontal fracture to achieve compression. Other procedures done in the young patient include revision ORIF with or without bone graft, but this is rarely done. Other procedures done in the young patient also include free vascularized fibular graft which is done in some patients especially in the younger patient with a nonviable femoral head. Hemiarthroplasy is done in patients with low physical demands. The articular cartilage of the patient is preserved with no evidence of infection. Total hip arthroplasty is done in patients that are older, in patients that have hip arthritis, if the femoral head is not viable, or if the hardware is cut out. It can also be done in younger patients that are active, when the femoral head is not viable and the patient does not want a free vascularized fibular graft or if the patient had collapse of the femoral head with nonunion. The problem with total hip replacement in this situation is more dislocations of the hip postoperatively.