Non-invasive expandable prosthesis in musculoskeletal oncology paediatric patients for the distal and proximal femur. First results

Purpose The non-invasive expandable prosthesis for skeletally immature patients is used after limb salvage surgery following tumor resection. The aim of the study was to assess the effectiveness of this treatment. Methods Seven paediatric patients with femoral tumors had resection and limb salvage with an uncemented non-invasive growing prosthesis. Mean age at the time of surgery was 9.8 (range 8-12) years. There were six distal femur osteosarcomas and one proximal femur Ewing sarcoma. Six total knee prosthesis were implanted at the time of primary tumor resection and one bipolar hip prosthesis was a revision from a failed osteoarticular hip allograft. Functional outcomes and emotional acceptance were assessed using the MSTS score. Results The mean follow-up was 65.3 months (range 29-91) months. Two patients died of pulmonary metastasis and there was no local recurrence. The mean femoral resection was 18 cm (range 17-19) on the knee, and 24 cm on the hip. Mean total expansion was 36.4 mm (range 12.3-63.5). The mean MSTS score after rehabilitation was 26.3 (range 21-29). There was one lengthening device failure, one late infection and one patient who required iliofemoral bypass grafting surgery for a pelvic metastasis. No local recurrence occurred. Conclusions The non-invasive expandable prosthesis reduces the final limb-length discrepancy in growing patients with an acceptable function and appears to have an advantage as compared to invasive expandable prostheses which require multiple surgical procedures, but the complications rate is still high.