10-year evaluation of compartmental knee arthroplasty.

The author describes the clinical outcome 10 years after unicompartmental knee arthroplasty according to a knee assessment system, developed by Tew and Waugh, that includes a detailed operational identification of the clinical examination. Sixty percent had a good or excellent results using this method, versus 75% using the Hospital for Special Surgery knee assessment system. Seventy percent of the patients were still satisfied with their knee at follow-up evaluation, 59% could step up and 48% down from a 30-cm platform in a normal way. About 35% of the patients who could not step up and down from a 30-cm platform were handicapped by factors other than their knee. There was no extensor lag. The median for coronal tibiofemoral angle was 176 degrees, for coronal bidirectional instability was 1 degree, for active flexion was 109 degrees, for active extension was 5 degrees, for range of motion was 107 degrees, and for change of flexion from before arthroplasty was 0 degrees. In 56% of the knees the patellofemoral joint alone or in combination with the tibiofemoral joint had abnormal symptoms or signs.