Kinematic Alignment Compared With Mechanical Alignment Techniques Results in Greater Peak Three-Dimensional Knee Joint Moments During Stair Negotiation.

Abstract

This study investigated the influence of surgical alignment techniques on knee joint biomechanics during stair negotiation tasks. Our hypothesis was that a more personalized joint alignment would result in reduced medial knee loading biomechanics to negotiate the stairs. There were 28 adults (14 mechanical alignments [MAs] and 14 kinematic alignment [KA]) who underwent total knee arthroplasty at least one year postoperatively and performed five stair ascent and descent trials at their preferred velocities. The three-dimensional knee joint moments were calculated using a six-degree-of-freedom model in Visual 3D. Data were tested for normality using the Shapiro-Wilk test. Cohen's d was used to quantify effect size magnitude. The KA technique methods were associated with greater knee moments compared with the MA technique. Due to the minimal differences in joint line between the groups, the greater trunk lean observed in the MA technique, and the preservation of soft tissue structures in the KA technique, the KA technique's lower extremity biomechanics enabled patients to move in a more symmetric manner within the frontal plane. This contrasted with the MA technique, which might result in an avoidance strategy during stair negotiation. Since our joint line did not significantly change between technique groups, future work is warranted to understand the effects of joint line-driven changes on lower extremity joint biomechanics in total knee arthroplasty populations. Level 2 prospective cohort study.