Functional evaluation of total knee replacement.

The assessment of patients following prosthetic knee replacement suffers from a lack of objective criteria. An automated method of laboratory assessment that permits the objective evaluation of knee joint function is described. Nine biomechanical parameters were statistically selected, weighted, and combined to develop a Performance Index (Ip). One hundred ninety-two patients (274 diseased knees) were studied prior to total knee replacement surgery, with 107 patients (138 knees) returning for a 1-year postoperative study. Preoperative rheumatoid knees were found to have significantly poorer function than those involved with degenerative disease. Overall, the patients experienced a marked improvement 1 year post-total knee replacement (TKR), with their functional scores approaching the lower limits of normal. Prostheses were assessed according to generic classes as well as specific design types. The newer generation devices were found to produce better functional results. In the patients receiving Anametric and Total Condylar total knee devices, a patellar resurfacing component was found to produce improved knee function in comparison with patients receiving the same prosthesis but without patellar resurfacing.