Gait kinematics and knee stability 10‐years following posterior‐stabilised total knee arthroplasty comparable to healthy adults >55

Abstract Purpose The purpose of this study was to compare the long‐term objective biomechanical and functional parameters of a high‐flexion total knee arthroplasty (TKA) design against healthy older adults to determine whether knee biomechanics are comparable in both populations. Methods One cohort of patients with a primary TKA, and a cohort of healthy adults over 55 years old with no musculoskeletal deficits or arthritis participated. Bilateral knee range of motion (RoM) was assessed with a goniometer, and gait patterns were analysed with a three‐dimensional‐motion capture system. An arthrometer quantified the anterior‐posterior laxity of each knee. Statistical analyses were performed in SPSS software ( α = 0.05). Results Twenty‐three knees were replaced in 20 patients. At 9.8 ± 3.1 years postoperatively, patients' knees had a statistically significantly poorer RoM than healthy controls' knees ( n = 23) due to limited flexion; p < 0.0001. Patients also failed to achieve the same degree of knee flexion as controls during downhill gait. No kinematic differences were observed during mid‐flexion in level nor downhill gait; a state that has been associated with instability ( p = 0.614; not significant [n.s]). There were no differences between groups in knee laxity (n.s). Conclusion Patients in this study had similar gait patterns to healthy older adults during mid‐flexion and were no more likely than the healthy controls to exhibit anterior‐posterior translation of the knee > 7 mm; a known risk factor of instability. However, the knee flexion range was poorer. This likely led to bilateral pathological knee flexion patterns during downhill gait. Level of Evidence: Level III.