Unicompartmental Knee Arthroplasty

Sixty-two consecutive cemented modular unicompartmental knee arthroplasties in 51 patients were studied prospectively. At surgery, the other compartments had at most Grade 2 chondroma-lacia. The average age of the patients at arthroplasty was 68 years (range, 51–84 years). One patient was lost to followup and 10 died with less than 6 years followup. The average followup of the remaining 51 knees was 7.5 years (range, 6–10 years). The preoperative Hospital for Special Surgery knee score of 55 points (range, 30–79 points) improved to 92 points (range, 60–100 points) at followup; 78% (40 knees) had excellent and 20% (10 knees) had good results. The mean range of motion at followup was 120° with 26 knees (51 %) having range of motion greater than 120°. One patient underwent revision surgery for retained cement, one patient underwent knee manipulation, and one patient underwent revision surgery at 7 years for opposite compartment degeneration and pain. Radiographically, 26 knees (51%) had at least one partial radiolucency. There were no complete femoral radiolucencies, but there were three complete tibial radiolucencies, all less than 2 mm. No component was loose as seen on radiographs. At final followup, five of the opposite compartments (10%) and three of the patellofemoral joints (6%) had some progressive radiographic joint space loss; this was less than a 25% loss in all but one knee component that was revised. At 6− to 10-years followup, cemented unicompartmental knee arthroplasty yielded excellent clinical and radiographic results. The 10-year survival using radiographic loosening or revision as the end point was 98%. Using stringent selection criteria, unicompartmental knee replacement can yield excellent results and represents a superb alternative to total knee replacement.