EXTENDIBLE TUMOR ENDOPROSTHESES FOR THE LEG IN CHILDREN

From 1986 to 1991 we fitted 20 children endoprostheses after resection of malignant tumours of the leg; six have reached skeletal maturity a nd are the subject of this study. Reconstruction of defects in growing limbs in which the eventual shortening can be predicted requires the use of extendable prostheses. The mean age at operation was 11 years ( 9.2 to 13.7) and the average follow-up period was 6.3 years (4.3 to 7. 6). The diagnosis was osteosarcoma in five patients and Ewing's sarcom a in one. All tumours were Enneking stage-IIB. When seen for follow-up all patients were free from disease. The extendable implants used inc luded the Pafford-Lewis prosthesis and the Kotz Modular Femur Tibia Re construction system with a compatible, newly-designed growth module. T elescope-like elongation of the prostheses was performed by insertion of a screwdriver through a small skin incision, Active epiphyseal grow th in the adjacent growth plate was preserved by using prosthetic stem s with a smooth surface. The mean length gained was 13.15 cm (4.5 to 1 9.5) requiring 53 planned procedures, Seven revision operations were n ecessary for complications, Functional evaluation showed excellent and good results in all cases. Stress-shielding at the site of anchorage of the prosthesis was more pronounced than in adults. Implantation of extendable endoprostheses in children provides a reasonable alternativ e to rotationplasty, but limb salvage requires more operations.