RESULTS OF UNICOMPARTMENTAL KNEE ARTHROPLASTY AT A MINIMUM OF TEN YEARS FOLLOW UP

Abstract

There is a renewed interest in unicompartmental knee arthroplasty. The present report describes the minimum ten-year results associated with a – unicompartmental knee arthroplasty design that is in current use.

Sixty-two consecutive unicompartmental knee arthroplasties that were performed with cemented modular Miller-Galante implants in 51 patients were studied prospectively both clinically and radiographically. All patients had isolated unicompartmental disease without patellofemoral symptoms. No patient was lost to follow-up. Thirteen patients (13 knees) died after less than 10 years of follow-up, leaving 38 patients (49 knees) with a minimum of 10 years of follow-up. The average duration of follow-up was 12 years.

The mean Hospital for Special Surgery knee score improved from 55 points preoperatively to 92 points at the time of the final follow-up. Thirty-nine knees (80%) had an excellent result, six (12%) had a good result, and four (8%) had a fair result. At the time of final follow-up, 39 knees (80%) had flexion to at least 120 degrees. Two patients (two knees) with well-fixed components underwent revision to total knee arthroplasty, at seven and 11 years, because of progression of patello-femoral arthritis. At the time of the final follow-up, no component was loose radiographically and there was no evidence of peri-prosthetic osteolysis. Radiographic evidence of progressive loss of joint space was observed in the opposite compartment of nine knees (18%) and in the patello-femoral space of seven knees (14%). Kaplan-Meier analysis revealed a survival rate of 98.0% +/−2.0% at ten years and of 95.7% +/− 4.3% at 13 years, with revision or radiographic loosening as the end point. The survival rate was 100% at 13 years with aseptic loosening as the end point.

After a minimum duration of follow-up of 10 years, this cemented modular uni-compartmental knee design was associated with excellent clinical and radiographic results. Although the 10 year survival rate was excellent, radiographic signs of progression of osteoarthritis in the other compartments continued at a slow rate. With appropriate indications and technique, this uni-compartmental knee design can yield excellent results into the beginning of the second decade of use.