Monitoring Gait Recovery After Total Knee Arthroplasty Using Wearable Sensors: Responsiveness of Gait Accelerations

Functional recovery after total knee arthroplasty (TKA) varies widely among individuals, and traditional assessments often fail to detect subtle changes in real-world walking ability. Wearable sensors offer continuous and objective tracking of gait outside of clinical settings. In this prospective, longitudinal study, thirty-one patients undergoing unilateral TKA wore thigh-mounted accelerometers continuously from 2 weeks before surgery through 90 days postoperatively. We analyzed temporal gait features (stride time and duty factor) and frequency-domain metrics (power of the first five frequencies of triaxial acceleration), along with weekly EQ-5D-3L index scores (a summary measure of health-related quality of life) and visual analog scale (VAS) ratings (patient's self-reported health on a 0-100 scale). Gait acceleration profiles demonstrated significant postoperative disruptions, particularly during mid-stance and terminal swing, followed by gradual normalization, approaching baseline by day 90. Gait temporal parameters also exhibited transient alterations and recovery trends. Using LASSO logistic regression, Fourier-derived gait features discriminated responders and non-responders based on improvements in EQ-5D-3L outcomes above the minimal clinically important difference (AUC: 0.80-0.81). Specific harmonic changes across the vertical, mediolateral, and anteroposterior axes were significantly associated with the perceived health gains. The results indicated that frequency-based gait metrics from wearable sensors are sensitive digital biomarkers for short-term functional improvements.