Continuous preoperative activity patterns measured by wearable sensors are associated with recovery after total knee arthroplasty.

Objective: Physical activity is increasingly recognized as an important factor in recovery after orthopedic surgery, but objective evidence remains limited. This study examined whether wearable-derived preoperative activity levels were associated with recovery outcomes following Total Knee Arthroplasty (TKA). Methods: In this prospective longitudinal study, 30 adults undergoing unilateral TKA for knee osteoarthritis wore validated thigh-mounted accelerometers for up to two weeks preoperatively and for three months postoperatively. Participants were classified into low-, moderate-, and high-activity groups based on preoperative 24-hour activity intensity profiles. Recovery was assessed using continuous accelerometer-derived activity metrics and patient-reported outcomes (PROMs), including the Knee injury and Osteoarthritis Outcome Score (KOOS). Results: Higher preoperative activity levels were associated with more favorable objective recovery after TKA. Compared with the low-activity group, the high-activity group showed higher postoperative activity intensity and total steps, with 2.6-fold higher activity intensity and 2.2-fold higher total steps. During the first postoperative month, the high-activity group also showed faster increases in activity intensity and total steps. In contrast, KOOS subscale scores improved over time but did not differ significantly between activity groups. Conclusion: The findings of this study highlight the importance of accounting for baseline activity when interpreting wearable-derived postoperative recovery patterns. They also suggest that objective monitoring can provide information on functional recovery that may not be captured by PROMs.