CAN A TOTAL KNEE REPLACEMENT PROSTHESIS BE MADE ENTIRELY OF POLYMERS

We have prospectively studied 63 total knee replacements (TKR) in whic h the femoral component was polyacetal, and 138 TKRs in which the femo ral component was conventional cobalt chrome. The tibial and patellar components were of ultrahigh molecular weight polyethylene (UHMWPE). P atients were followed-up for at least 10 years. In the polyacetal grou p, a number of patients have died or have been revised, for reasons un related to the presence of polyacetal. There were no instances of femo ral component fracture, nor failure by wear. One postmortem specimen, retrieved at 9 years after surgery, showed no measurable polyacetal we ar and negligible HDP wear. The histology of tissue in contact with po lyacetal was indistinguishable from that adjacent to polymethyl methac rylate and UHMWPE in the same knee. We believe that polyacetal could b e used for the femoral component of a TKR and that a further trial sho uld be undertaken.