抄録
Objective: Many authors have reported good clinical results with total knee arthroplasty (TKA) in rheumatoid arthritis (RA) . We investigated the long-term clinical results of TKA in RA followed-up for more than ten years postoperatively.
Methods: From July 1989 to July 1997, we performed TKA in 108 knees of 66 patients with RA. Of these, 45 knees in 28 RA patients (4 males and 24 females) were followed up more than ten years postoperatively. The mean age at the operation was 55.7 years (43 to 71), and the mean follow-up period was 13 years (10 years and one month to 16 years and six months) . We used two types of TKA prostheses, Nagoya City University (NCU) type and Natural Knee (Zimmer) . NCU and Natural Knee were applied to 27 and 18 knees respectively. Clinical evaluation was based on the Japanese Orthopaedic Association RA knee score (JOA score), and we also assessed the range of motion, radiographic results and complications.
Results: The mean JOA score improved from 40.8 to 77.7. However, the mean flexion range decreased from 108.4° to 103.3°, whereas the mean extension range improved from -14.8° to -4.4°. Radiographically, 16 of 45 knees showed a radiolucent line. The rate of this phenomenon tended to be higher in cementless cases. One case required reoperation due to aseptic loosening of the femoral component.
Conclusions: We have obtained good clinical results with TKA in RA more than 10 years postoperatively. The improvement of flexion angle may be dependent on the preoperative joint contracture and the decreased activity of RA patients. To prevent radiographic change, each component of TKA in RA should be fixed with cement.
