A REVIEW OF NON-INVASIVE GROWING ENDOPROSTHETIC REPLACEMENTS

Abstract

Introduction: The use of extendible endoprosthetic implants in the skeletally immature has been used for just under 30 years. Limb salvage has become a realistic alternative to those children presenting with primary bone sarcomas. We aim to review the use of an implant which uses a non-invasive mechanism of adjusting the length of the prosthesis, during the growth phase.

Method: A retrospective review of consecutive patients undergoing primary or revision endoprosthetic replacement with non-invasive extensible implants, was undertaken. Between January 1993 and February 2008, 34 children were treated with non-invasive extensible endoprosthetic replacements, 26 distal femur, 5 total femurs, 3 proximal tibias and 1 proximal femur.

Results: The underlying pathology, requiring excision, was Ewings sarcoma in 4 patients and osteosarcoma in the remaining 30 patients. Most underwent pre-operative chemotherapy and 2 patients died of their disease.

Four operations were secondary procedures following previous non-grower implant failures (1 infection of previous EPR, 1 IM nail non-union, 1 failed allograft and a revision of a proximal femoral EPR to a total femoral prosthesis). Five patients required revision of the primary prosthesis (2 with motor failures, 3 due to prosthesis infections).

Mean time to start lengthening from surgery was 12.2 months. The mean number of lengthenings was 4 with an average total length of 30 mm achieved, mean leg length difference was 0.8 cm. All lengthenings were undertaken with the patient fully alert, no adverse incidents occurred at the time or after lengthening.

Discussion: The non-invasive prostheses show promise in handling the difficult problem of limb preservation in a growing child, with similar complication rates to that of an invasive type, but without the need for multiple anaesthetics for lengthening.