High Above-Knee Amputations for Femoral Osteosarcomas Treated with Free Microsurgical Tibial Reconstruction in the Pediatric Population.

Summary: Improvements in the management of pediatric sarcoma, including imaging, neo- and adjuvant therapy, and surgical technique, have enhanced long-term survival. Pediatric patients diagnosed with a femoral osteosarcoma undergoing oncologic resection who are ineligible for limb-preservation reconstruction or rotationplasty are offered an above-knee amputation (AKA). Limb amputation in the skeletally immature patient poses particular problems specific to endosteal bone overgrowth and spiking. Approximately half of these patients undergo revision of their amputation site. Furthermore, a high AKA often requires a hip-based prosthesis, which can be uncomfortable, leading to poorer outcomes and higher energy expenditures. The authors have completed 4 "spare parts" microvascular free tibial transfers for pediatric patients diagnosed with femoral osteosarcoma who were treated with an AKA. Two of these patients are ambulatory with their prosthesis and have not required long-term revision of their amputation site. One patient demonstrated radiographic evidence of bony union 4 months postoperatively, but subsequently died of chemotherapy-resistant metastases. The fourth patient is in the process of prosthetic fitting and rehabilitation. This is a novel technique, and the authors present the first series describing both proximal and distal free microvascular tibial bone transfers as a reconstructive option for pediatric patients with femoral osteosarcomas. This reliable flap, which has possible variations in vascular anatomy, offers multiple benefits, including prevention of bony spiking, AKA stump augmentation, and facilitation of appropriate prosthetic fitting, improving functional outcomes and leading to decreased energy expenditure. The soft-tissue coverage must be well-planned.