[Knee prostheses for tumors]

Because of the advances achieved in conservative surgery for bone cancers of the limbs, megaprostheses of the knee are increasingly used to replace the epiphysio-metaphysio-diaphyseal region resected. Initially, these prostheses were metallic ones, and as such they did not lend themselves to satisfactory reinsertion of the extensor system and exposed the patients to the risk of decementation--a risk which is particularly high in adolescents whose prognosis for life is now excellent. For this reason we have been using, since 1984, a combination of long-tail titanium prosthesis made to measure, and bank allografts. The titanium prosthesis provides immediate solidity, whereas the allograft ensures long-term stability of the material and better functional result.