Does residual varus alignment cause increasing varus laxity at a minimum of five years after total knee arthroplasty?

Abstract Background The purpose of this study was to investigate whether varus-valgus laxity of cruciate-retaining (CR) total knee arthroplasty (TKA) changes between 1 year and more than 5 years after surgery based on postoperative limb alignment. Methods One hundred and 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˚, 47 knees) and neutral groups (-3˚ < HKA angle < 3˚, 70 knees). The range of motion was measured and a Hospital for Special Surgery (HSS) score was obtained at the last follow-up. Varus-valgus laxity at 15˚ 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˚ vs 117.1˚) and HSS (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.