Sensor-Based Gait Recovery Analysis After Total Hip and Knee Arthroplasty: A One-Year Follow-Up Study Integrating Muscle Strength and Patient-Reported Outcomes.

BACKGROUND: Functional recovery after total joint arthroplasty is multifactorial. This study aimed to characterize the 1-year recovery trajectory in elderly patients undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA) by integrating objective gait analysis, muscle strength assessment, and patient-reported outcome measures.

METHODS: In this prospective cohort study, 84 patients (THA: 36, TKA: 48; age ≥70 years) with Kellgren-Lawrence grade III or IV osteoarthritis were evaluated preoperatively and at 2 weeks and 1, 3, 6, and 12 months postsurgery. Spatiotemporal gait parameters were collected using foot-mounted inertial sensors. Isokinetic dynamometry measured hip abductor (THA) or quadriceps (TKA) strength. The Hip Disability and Osteoarthritis Outcome Score for Joint Replacement and Knee Injury and Osteoarthritis Outcome Score for Joint Replacement were collected at all timepoints. Correlation and regression analyses identified predictors of recovery.

RESULTS: The TKA patients demonstrated significant and persistent gait asymmetry up to three months, which normalized by six months. The THA recovery was more symmetrical, with only transient asymmetry at one month. Preoperative muscle strength was the strongest predictor of 12-month gait speed (β = 0.42, P < 0.001), while radiographic severity (Kellgren-Lawrence grade III versus IV) did not significantly predict functional gait recovery (P = 0.38). By 12 months, both groups approached normative values for gait and strength, with 94.0% of the THA and 92.0% of the TKA patients achieving the patient acceptable symptom state.

CONCLUSIONS: Muscle strength, rather than radiographic severity, is the critical determinant of functional gait recovery after total joint arthroplasty in the elderly. Preoperative muscle strength assessment should be incorporated into surgical planning to guide personalized rehabilitation. Randomized trials with intervention arms are warranted to establish causality.

LEVEL OF EVIDENCE: Level II, prospective cohort study.