Computer-navigated TKA for the treatment of osteoarthritis associated with extra-articular femoral deformity

The purpose of this study was to evaluate the efficacy of computed-navigated total knee arthroplasty for the treatment of osteoarthritis associated with extra-articular femoral deformity. Between January 2008 and June 2010, twelve patients (12 knees) with osteoarthritis combing extra-articular femoral deformity underwent total knee arthroplasty using the Stryker Navigation System 3.1 (Kalamazoo, Michigan), a wireless and imageless system. Average follow-up was 12.3 ± 8.2 months (range, 3-24 months). Full-length weight-bearing anteroposterior radiographs, knee range of motion, and Knee Society Score were obtained for all patients pre- and postoperatively. The data were analyzed with SPSS version 12.0 statistical software (SPSS, Inc, Chicago, Illinois). Average preoperative overall mechanical axis of the 12 knees was -10.0° ± 4.4° of varus (range, -5° to -18.5°) and average postoperative mechanical axis was -0.9° ± 0.8° (range -2° to 0°). Average Knee Society Score increased from 40.8 ± 7.7 preoperatively to 94.9 ± 2.4 postoperatively, and average function score increased from 39.6 ± 12.3 preoperatively to 95.4 ± 4.0 postoperatively. Average knee range of motion improved from 83.7° ± 18.7° preoperatively to 115.0° ± 8.2° postoperatively. The results of the study showed that computer-navigated total knee arthroplasty may be a valuable option for patients with deformed femurs in which conventional instruments are difficult to use. Follow-up observation of the long-term therapeutic effect of computer-navigated total knee arthroplasty is still needed.