A985. COMPUTER ASSISTED TOTAL KNEE ARTHROPLASTY FOR ARTHRITIS WITH EXTRA-ARTICULAR DEFORMITY

Abstract

Total knee arthroplasty becomes more challenging when knee arthritis is associated with an extra-articular deformity of the femur or tibia. We evaluated the outcome of navigated total knee arthroplasty in a large series of arthritic knees with extra-articular deformity.

We retrospectively reviewed the records of 950 patients who had undergone navigated TKA between January 2005 and February 2008. There were 40 extra-articular deformities in 34 patients, with bilateral involvement in 6 patients which were included in the study. Twenty-two limbs had deformity in the femur and the tibia had deformity in 18 limbs. There were 24 females and 10 males with a mean age of 63.1 years (range, 46–80 years).

The etiologies included malunited fractures (13 patients), stress fractures (4 patients), post high tibial osteotomy (3 patients), and excessive coronal bowing (14 patients). The mean femoral extra-articular deformity in the coronal plane was 9.3° varus (range, 24° varus to 2.8° varus) and the mean tibial extra-articular deformity in the coronal plane was 6.3° varus (range, 20° varus to 8.5° valgus). Three limbs underwent simultaneous corrective osteotomy and the rest were treated with intra-articular correction during computer-assisted total knee arthroplasty. The limb alignment changed from a mean of 166.7° preoperatively to 179.1° postoperatively. At a mean follow-up of 26.4 months, the Knee Society knee score improved from a mean pre-operative score of 49.7 points to 90.4 points postoperatively; function score improved from 47.3 points to 84.9 points.

The results of our study indicate that computer-assisted total knee arthroplasty is a useful alternative to conventional total knee arthroplasty for knee arthritis with extraarticular deformity where accurate restoration of limb alignment may be challenging due to the presence of a deformed tibia or femur or in the presence of hardware.