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

ABSTRACT

SUMMARY: Improvements in the management of pediatric sarcoma including imaging, neo- and adjuvant therapy, and surgical technique has enhanced long-term survival of patients. 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 amputations 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.We have completed four 'spare parts' microvascular free tibial transfers for pediatric patients diagnosed with femoral osteosarcoma who were treated with an AKA. Two of these patients are currently ambulatory with their prosthetic and have not required long-term revision of their amputation site. One patient demonstrated radiographic evidence of bony union four months post-operatively, but subsequently succumbed to chemotherapy-resistant metastases. The fourth patient is in the process of prosthetic fitting and rehabilitation.This is a novel technique and the first series describing both proximal and distal free microvascular tibial bone transfers as a reconstructive option for pediatric patients with femoral osteosarcomas. It is a reliable flap with possible variations in vascular anatomy. Furthermore, it offers multiple benefits including the prevention of bony spiking, AKA stump augmentation, and facilitation of appropriate prosthetic fitting improving functional outcomes and decreased energy expenditure. However, the soft tissue coverage must be well planned.