JOA - 2026-06-01 - Journal Article
Preoperative Activity Levels in Patients Who Undergo Total Hip Arthroplasty Distinctively Affect the Postoperative Recovery Process and Forgotten Joint Score-12: A Prospective Cohort Study Using a Triaxial Accelerometer.
Kaneoka T, Imagama T, Matsuki Y, Kawakami T, Numa M, Sakai T
Topics
Key Takeaway
Higher preoperative objective physical activity predicts better FJS-12 at 12 months post-THA (p=0.004), but these patients only recover to baseline activity levels, while lower-activity patients exceed their preoperative step counts by 12 months.
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Summary
This prospective cohort study examined whether preoperative objective physical activity (OPA), measured via triaxial accelerometer, predicts postoperative recovery trajectory and FJS-12 at 12 months in 212 patients undergoing THA for unilateral hip OA. Patients were stratified by age and preoperative activity level; total exercise time increased from median 2.23 to 3.45 MET-hours postoperatively (p<0.001), and FJS-12 improved from 60.2 at 1 month to 75.0 at 12 months (p<0.001). Higher preoperative activity independently predicted better 12-month FJS-12 (p=0.004), yet these patients only returned to baseline OPA, while lower-activity patients surpassed their preoperative levels.
Key Limitation
Patients were not stratified by surgical approach or implant type, meaning unmeasured variables known to affect early recovery (e.g., direct anterior vs. posterolateral approach) could confound the observed activity trajectories.
Original Abstract
BACKGROUND
This study aimed to evaluate changes in objective physical activity (OPA) after total hip arthroplasty (THA) and their impact on patient-reported outcomes.
METHODS
This prospective cohort study involved 212 patients who underwent THA for unilateral hip osteoarthritis and were followed up for 12 months. Step count, exercise, and wearing time were measured using a compact triaxial accelerometer before surgery and at one, two, three, six, and 12 months postoperatively. This study investigated the recovery process of OPA in patient groups classified by age and preoperative activity levels and examined its impact on patient-reported outcomes, including the Forgotten Joint Score-12 (FJS-12).
RESULTS
Multiple regression analyses revealed a significant association between preoperative activity levels and FJS-12 at 12 months postoperatively (P = 0.004). The median value of total exercise increased from 2.23 (interquartile range [IQR], 1.32 to 3.35) preoperatively to 3.45 (IQR, 2.01 to 4.78) at 12 months postoperatively (P < 0.001), whereas FJS-12 improved from 60.2 (IQR, 39.6 to 75) at one month to 75 (IQR, 62.5 to 89.6) at 12 months postoperatively (P < 0.001). In patients who had higher preoperative activity, the 12-month FJS-12 significantly increased from six months postoperatively in both younger (P = 0.008) and older groups (P = 0.002). The mixed-design analyses of variance revealed time-related changes and group differences in OPA levels and trajectories (P < 0.001). Post hoc analysis showed that OPA at 12 months exceeded preoperative levels (P < 0.001) in patients who had lower preoperative activity; however, it remained lower than in those who had higher activity. Conversely, patients who had higher preoperative activity experienced a significant decline postoperatively (P < 0.001), followed by recovery to preoperative baseline levels.
CONCLUSIONS
The relationship between the subjective experience of "forgetting" the joint and actual physical activity levels was clarified, providing a new perspective on postoperative functional assessment. Preoperative OPA may predict FJS-12 at 1 year postoperatively.