Longitudinal Changes in Exercise Adherence and Associations with Rehabilitation Outcomes After Total Knee Arthroplasty: A Prospective HAPA-Informed Study.

BACKGROUND

Exercise adherence is important after total knee arthroplasty (TKA), but its postoperative pattern and behavioral correlates remain unclear.

OBJECTIVE

To characterize exercise adherence and examine its associations with HAPA-related factors and rehabilitation outcomes.

METHODS

This prospective study included 128 patients undergoing unilateral TKA. HAPA-related variables were assessed preoperatively. EARS, VAS, HSS, and range of motion (ROM) were assessed at 1, 3, and 6 months. Linear mixed-effects models, correlations, and regression were used.

RESULTS

EARS scores changed over time (P<0.001), increasing from 17.78±3.27 at 1 month to 18.43±3.64 at 3 months and remaining stable at 6 months (18.36±3.68). Compared with 1 month, EARS was higher at 3 months (difference=0.651, 95% CI 0.340-0.962) and 6 months (difference=0.601, 95% CI 0.290-0.912; both adjusted P<0.001); 3- and 6-month scores did not differ. VAS decreased, whereas HSS and ROM increased (all P<0.001). At 6 months, action self-efficacy (B=0.248, 95% CI 0.065-0.431) and maintenance self-efficacy (B=0.209, 95% CI 0.032-0.387) were independently associated with higher EARS scores. EARS correlated with VAS (r=-0.360), HSS (r=0.326), and ROM (r=0.361; all P<0.001).

CONCLUSION

Exercise adherence improved mainly during the first 3 months and then stabilized. Self-efficacy was associated with adherence, while higher adherence was associated with less pain and better function. These findings do not establish causality.