Long-term clinical and radiological outcomes of hybrid total knee arthroplasty.

OBJECTIVES: The purpose of this study was to evaluate the clinical effectiveness and radiological results of hybrid total knee arthroplasty (TKA). METHODS: This study recruited 105 patients (169 cases) who underwent hybrid TKA for osteoarthritis and rheumatoid arthritis from 1999 to 2002. Maxim (Biomet Inc., Warsaw, IN, USA) prosthesis was used, and average follow-up was 8.6 years. Radiologically, femorotibial angle was measured in a standing anteroposterior (AP) view, and a femoral flexion angle and a tibial angle were measured using the Knee Society roentgenographic evaluation and scoring system. Radiolucent lines were detected at the last follow-up. Clinically, range of joint motion and the Knee Society clinical rating system scores were evaluated. RESULTS: The femorotibial angle was improved from varus 4.5° to 6.4° at the last follow-up. The femoral flexion in an AP view at the postoperative and last follow-up was 96.5° and 95.7°, respectively, and the tibial angle was 89.1° and 88.7°, respectively. In lateral view, the femoral flexion was 2.6° and 2.7°, respectively, and the tibial angle was 88.4° and 87.8°, respectively. Total scores of radiolucencies were 4 points or less in all cases, and the average width was 1.1 mm. Flexion contracture was improved from 10.0° to 3.5°, and further flexion was increased from 110.5° to 130.4°. Knee score and function score were also enhanced from 47.6 and 46.8 preoperatively to 89.7 and 88.4 after the operation, respectively. CONCLUSION: Hybrid technique for TKA can be effective clinically and radiologically on longterm follow-up.