Does Residual Varus Alignment Cause Increasing Varus Laxity at a Minimum of Five Years After Total Knee Arthroplasty?

Background: The purpose of this study is to investigate whether varus-valgus laxity of cruciate-retaining (CR) total knee arthroplasty (TKA) changes between 1 year and >5 years after surgery based on postoperative limb alignment. Methods: One hundred twenty-one varus osteoarthritic knees that underwent CR TKA were included. The minimum follow-up was 5 years. Weight-bearing full-leg radiographs were obtained postoperatively and the hip-knee-ankle (HKA) angle was measured. Knees were grouped in varus (HKA angle <= -3 degrees, 47 knees) and neutral groups (-3 degrees < HKA angle < 3 degrees, 70 knees). The range of motion was measured and a Hospital for Special Surgery score was obtained at the last follow-up. Varus-valgus laxity at 15 degrees of knee flexion was measured with stress radiographs after 1 year and at the last follow-up. Results: No knees required revision surgery. The mean knee flexion angle (121.0 degrees vs 117.1 degrees) and Hospital for Special Surgery score (90.3 vs 90.4) at the last follow-up were not significantly different between the varus and neutral groups. In both groups, there was no significant change in varus or valgus laxity between 1 year and at the last follow-up. Conclusion: Postoperative residual varus limb alignment did not lead to increasing varus laxity after CR TKA in the mid-term. (C) 2017 Elsevier Inc. All rights reserved.