Frozen autograft-prosthesis composite reconstruction with total hip arthroplasty for proximal femoral osteosarcoma: a case report.

Introduction and importance: Reconstruction after proximal femoral resection requires restoration of both a large osseous defect and stable hip joint function. Frozen autograft-prosthesis composite (FAPC) reconstruction using liquid nitrogen-treated autograft represents a viable biological option for this indication. We present a case of proximal femoral osteosarcoma managed with this technique. Case presentation: A 25-year-old man presented with a 3-month history of atraumatic right hip pain. Imaging and biopsy confirmed Enneking stage IIB high-grade osteosarcoma of the proximal femur. Wide resection resulted in an 18-cm defect, reconstructed using a free, liquid nitrogen-treated autograft combined with total hip arthroplasty (THA) and plate fixation. Nonunion at the distal junction was identified at 8 months and managed with supplementary iliac crest bone grafting at 10 months, achieving complete union at 26 months. At 43 months, there was no evidence of recurrence or metastasis, and the Musculoskeletal Tumor Society (MSTS) score was 90%. Clinical discussion: This case suggests that THA can be incorporated into the FAPC construct in a young, active patient. A trochanteric hook plate with cerclage cables was used to stabilize the construct, avoiding cortical screw fixation into the brittle, recycled bone while enabling reattachment of the abductor mechanism. Distal junction nonunion, a recognized complication of liquid nitrogen freezing, was successfully managed with secondary bone grafting. Conclusion: Combining liquid nitrogen-treated autograft with THA may be a feasible limb-salvage strategy for proximal femoral osteosarcoma, achieving satisfactory oncological and functional outcomes at medium-term follow-up. This approach may be particularly relevant in resource-limited settings.