Impact of Massive Weight Loss Following Bariatric Surgery on Gait Mechanics After Total Knee Arthroplasty: A Case Report

This case report describes longitudinal gait mechanics in a 62-year-old man who underwent left total knee arthroplasty (TKA) and subsequently laparoscopic sleeve gastrectomy with massive weight loss. Gait was evaluated using a wearable inertial sensor system at 6 months (T1) and 12 months (T2) after arthroplasty, alongside functional mobility and endurance tests (Timed Up and Go and 2-minute walk). Body mass decreased from 120 kg (BMI approximately 43 kg/m2) to 69 kg (BMI approximately 25 kg/m2) between T1 and T2. Despite the substantial reduction in mechanical loading, spatiotemporal gait parameters and pelvic kinematics remained largely stable, with persistent asymmetry and a compensatory gait strategy. Acceleration-derived estimates suggested approximately 42.5% mechanical offloading after weight loss. These findings indicate that, in this patient, massive postoperative weight loss did not translate into marked improvements in gait mechanics within the first year after TKA, underscoring the need for targeted rehabilitation even after successful weight reduction.