Megaprosthesis as a treatment modality for persistent distal femoral nonunion in middle aged adults

INTRODUCTION: Managing distal femur non-union can be a struggle for any orthopedician as it brings along many perplexities which may not lead to satisfactory patient outcome. The target in these cases should be to reduce the morbidity and allow early rehabilitation of the patient and to accomplish this, megaprostheses can be a feasible option. The orthodox use of megaprostheses is in the musculo-skeletal oncologic surgeries but its use can be extended to traumatic etiologies. These can be offered as a single stage definite procedure in patients who have already undergone several previous surgeries. Here we report a series of four cases of persistent non-union of distal femur treated with megaprostheses and recommend this modality for achieving the desired goal but the indication should be meticulously selected. HYPOTHESES: Megaprosthesis as a definitive treatment option in persistent distal femur non-union and prevention of repeated surgical intervention. METHODS: Four cases of persistent distal femur nonunion with failed osteosynthesis were selected who were initially treated with a distal femur locking plate. Results were assessed in terms of range of motion, limb length discrepancy, knee society score and osteointegration of the components. RESULTS: The mean age of the patients at the time of DFEPR was 49 years (42-55). The mean follow up of patients was for approximately 2 years, with the longest follow up being 3.5 years for the first operated case of the series. The range of motion was from full extension to about 105 degrees of flexion with two patients having an extension lag of 10 degrees. Patients were ambulatory without support. Postoperatively, the mean knee society score was 83 (78–88) at last follow-up as compared to 29 (21-36) in the pre-operative period. No case of infection or loosening was reported. There was 1 cm of shortening in one patient in the operated limb which was compensated by giving shoe raise. Good osseointegration of the megaprosthesis was revealed on both anteroposterior and lateral radiographs. CONCLUSION: Although there are very limited studies on the use of megaprosthesis for traumatic cases, it can be considered as an alternative when we are left with only arthrodesis or amputation as the final option. Despite the operative challenges, there is marked improvement in pain and functional capacity as experienced by these severely limited patients, which are the hallmarks of a successful salvage. The use of distal femur mega-prosthesis is a novel acumen in cases, where bone stock at the fracture site at distal end of femur is so severely compromised that traditional revision osteosynthesis would not provide stable and durable fixation. The indications for this surgery must be rigorously selected and should only complement osteosynthesis procedures, which remain the reference treatment option.