Total knee arthroplasty with posterior cruciate retention in patients with rheumatoid arthritis

The objective of the present study was to evaluate posterior cruciate ligament retention in total knee arthroplasty for patients with rheumatoid arthritis to determine long term ligamentuous stability. The study concerns an average 11-year followup (range, 10-13 years) of 52 patients (81 knees) with rheumatoid arthritis who had a total knee arthroplasty using a contemporary posterior cruciate retaining prosthesis. Particular attention was given to component survivorship and clinical stability. Fourteen patients (20 knees) died; none of these patients required revision surgery. No patients were lost to followup. Sixty-one knees in 38 patients were examined. In this group, the Knee Society knee score averaged 95 points (range, 63-100 points) and function score averaged 74 points (range, 0-100 points). Postoperative flexion averaged 112 degrees and extension averaged 0 degree. Four knees had 3 degrees asymptomatic hyperextension; one knee with 5 degrees hyperextension occasionally gave way. Five well aligned knees had between 6 degrees and 9 degrees varus or valgus laxity in extension, but no patient reported subjective instability. Two patients underwent revision surgery. One patient had a worn metal backed patella component replaced and the other patient had an open synovectomy for recurrent active rheumatoid synovitis. Thirteen-year survivorship based on need for revision surgery was 97% with the 95% confidence limits between 88% and 100%. There was no radiographic loosening or subsidence of prosthetic components. At 11-year followup, patients with rheumatoid arthritis whose knees were replaced with posterior cruciate retention prostheses experienced results equivalent to or better than those reported for patients with osteoarthritis at a similar followup. Late hyperextension and subsequent instability may be a concern in the second decade of followup.