Introduction: The purpose of this study was to evaluate clinical results of total knee arthroplasty with three different implants for patients with osteoarthritis (OA) and rheumatoid arthritis (RA) in our institution.

Materials and methods: From January 1993 to October 1998, 41 total knee arthroplasties were done at our institution. Clinical assessment was performed preoperatively and at most recent follow-up using the Japan Orthopaedic Association scoring system (JOA score). The Knee Society Radiological Evaluation System was used to evaluate a series of 41 total knee arthroplasties. The population consisted of 41 patients, 37 women and four men, with an average age of 71.8 (55-85) who had total knee arthroplasty, and the average BMI was 24.5 (18.1-36.0). Preoperative diagnoses were osteoarthritis in 25 patients and rheumatoid arthritis in 16 patients. Used implants were Miller-Garante 2 (Zimmer) in 15 knees, KU3 (Kyocera) in seven knees and Nexgen (Zimmer) in 19 knees.

Results: The average preoperative JOA score were 48.0 points and postoperative score were 74 points. Preoperative and postoperative maximum extension was −16.4 ± 10.9° and –2.86 ± 4.9°. Preoperative and postoperative maximum flexion was 105 ± 21.6° and 106 ± 15.0°. On the AP radiographs, the average angulation of the femoral component was 96.9 ± 2.2° and tibial component position was 88.0 ± 2.5°. The lateral radiographs revealed an average femoral component flexion of 3.03 ± 3.9° The average tibial component flexion was 3.53 ± 3.02°. And there was no significant difference in radiographic evaluation among those implants.

Conclusion: In the middle term results, there was a significant correlation between preoperative and postoperative flexion and a significant improvement of maximum extension of the knee after total knee arthroplasty.