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 (TJA) is multifactorial. This study aimed to characterize the one-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 (PROMs). METHODS: In this prospective cohort study, 84 patients (THA: 36, TKA: 48; age ≥ 70 years) with Kellgren-Lawrence (K-L) grades III or IV osteoarthritis were evaluated pre-operatively and at two weeks and one, three, six, and 12 months post-surgery. Spatiotemporal gait parameters were collected using foot-mounted inertial sensors. Isokinetic dynamometry measured hip abductor (THA) or quadriceps muscle (TKA) strength. The PROMs, including the Hip Disability and Osteoarthritis Outcome Score for Joint Replacement (HOOS-JR) and the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR), were collected at all time points. Correlation and regression analyses were performed to identify 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. Pre-operative muscle strength was the strongest predictor of 12-month gait speed (β = 0.42, P < 0.001), while radiographic severity (K-L 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 THA and 92.0% of TKA patients achieving the patient acceptable symptom state (PASS). CONCLUSION: Muscle strength, rather than radiographic severity, is the critical determinant of functional gait recovery after TJA in the elderly. Pre-operative muscle strength assessment should be incorporated into surgical planning to guide personalized post-operative rehabilitation strategies. Future prospective randomized trials incorporating pre-operative gait analysis and intervention arms are warranted to establish causal relationships.