Long-term Results in Children With Massive Bone Osteoarticular Allografts of the Knee for High-grade Osteosarcoma

Abstract

Reconstruction of distal femur or proximal tibia in growing patients is a challenge for the high rate of complications and limb length discrepancy at the end of growth. The purpose of this study was to evaluate the long-term outcome of children affected by high-grade osteosarcoma of the knee region, reconstructed by osteoarticular bone allograft of distal femur, and proximal tibia. We retrospectively reviewed 25 patients treated for high-grade osteosarcoma, 13 in the distal femur and 12 in the proximal tibia. The mean follow-up was 124 months. Clinical and radiologic evaluation was carried out in the 20 long-term survivors with a minimum follow-up of 7 years from surgery. The rates of survival of the implants were estimated with use of the Kaplan-Meier method. Functional and radiographic evaluation was done according to the Musculoskeletal Tumor Society scoring system at the time of the latest follow-up in all the patients that still had the allograft. Five patients died during the first 2 years of follow-up for disease-related causes. Of the remaining 20 osteoarticular allografts (10 of the distal femur and 10 of the proximal tibia), 12 failed: 4 in the distal femur and 8 in the proximal tibia. All the failures were related to a graft fracture, but in 4 patients with subchondral collapse the graft was maintained and converted into an allograft prosthetic composite. No deep infection of the primary reconstruction was observed. The overall rate of allograft survival was 70% at 5 years and 58% at 10 years in the distal femur, and 45% at 5 years and 20% at 10 years in the proximal tibia. At final follow-up, 8 patients still walked on the primary implant, 6 in the distal femur, and 2 in the proximal tibia. The functional outcome of these patients was evaluated as good in 5 patients (3 with distal femoral and 2 with proximal tibial allograft), and poor in 3. Although mechanical complications significantly affect the outcome, osteoarticular allografts may represent a viable option for reconstruction in children older than 8 with high-grade sarcomas about the knee. Level IV.