A new technique of endoprosthetic replacement for osteosarcoma of proximal femur with intra-articular extension

Abstract INTRODUCTION Osteosarcoma is the most common primary malignant tumour of bone and commonly involved sites are the distal femur, proximal tibia, and humerus. Osteosarcoma of proximal femur usually arises at the metaphysis and articular cartilage acts as a relative barrier to tumour spread, with extension into the hip joint being extremely rare. PRESENTATION OF CASE A previously fit and well sixteen-year-old male presented with a 2 month history of right hip pain and a limp. Plain radiographs and magnetic resonance imaging (MRI) showed an expansile lesion in the right femoral neck, extending 16 cm distally from the proximal femoral articular surface through the intertrochanteric region into the upper right femoral shaft. There was also clear evidence of intra-articular extension into the acetabulum. DISCUSSION Endoprosthetic replacement following resection is a good treatment option for proximal femoral tumours due to the low complication rate and achievement of good postoperative function. However, treatment of a proximal femoral lesion with intra-articular involvement by prosthetic reconstruction is challenging. We report a patient who presented with osteosarcoma of the proximal femur extending into the hip joint and describe the technique of en-bloc extra-articular resection of the acetabulum and proximal femur with reconstruction using a custom made prosthesis. CONCLUSION We conclude that extra-articular resection and endoprosthetic reconstruction using a coned hemi-pelvic implant with fluted stem and a modular femoral implant is a useful treatment option in the management of a proximal femoral lesion involving the hip-joint. It allows adequate tumour clearance and stable reconstruction for rapid post-operative recovery with early mobilisation.