Growth prediction in extendable tumor prostheses in children

Limb salvage procedures for malignant bone tumors of the lower limb in chil dren usually involve resection of at least one growing physis. To achieve e qual leg length, reconstruction relies on accurate prediction of the remain ing growth potential of the child. The current authors present the results of predicted growth versus actual prosthetic elongation observed in a group of 15 children fitted with extendable tumor endoprostheses of the lower li mb who subsequently have reached skeletal maturity. All patients had at lea st one of the distal femoral or proximal tibial physes resected for a prima ry malignant bone tumor. Eight patients underwent distal femoral resection, four patients underwent proximal tibial resection, and three patients had total resection of the femur. All patients received custom-made Howmedica e xtendable prostheses. In two patients, a newly developed automatic elongati on module was used. At followup, between 70 and 158 months, the patients ac hieved a mean elongation of the surgically treated limb of 10.4 cm (range, 1.1-19.5 cm), which exceeded the predicted growth by 24.3%. Final leg lengt h discrepancies did not exceed 1 cm. Using incremental extendable tumor end oprostheses, individual adaptation of the elongation procedures could be ac hieved for equalization of leg length discrepancies in children after resec tion of primary malignant bone tumors of the lower limb.