The Role of Eccentric Contraction Training in the Postoperative Rehabilitation of Patients With Total Knee Arthroplasty

ABSTRACT Background Eccentric contraction training may be associated with improved functional recovery after total knee arthroplasty (TKA), but its effects on pain, range of motion, and patient‐reported outcomes during the early postoperative period remain unclear. This randomized controlled trial evaluated the addition of eccentric training to standard rehabilitation. Methods Forty‐four patients scheduled for primary TKA were randomly assigned to an eccentric–concentric (ECC–CON) group ( n = 22) or a concentric‐only (CON) group ( n = 22). An 8‐week rehabilitation program began 1 week after surgery, consisting of five sessions per week. The ECC–CON group performed supervised eccentric quadriceps exercises on an isokinetic dynamometer in addition to standard closed‐chain functional exercises. The CON group received the same closed‐chain functional exercises without isokinetic training. The total session duration was matched between groups. Primary outcomes were the Western Ontario and McMaster Universities osteoarthritis index (WOMAC) total score and the knee society score (KSS) functional score. Secondary outcomes included the visual analogue ecale (VAS) for pain, active and passive range of motion (AROM/PROM), and KSS joint score. Assessments were conducted at baseline, 4 weeks, and 8 weeks post‐intervention. Data were analyzed using linear mixed models under the intention‐to‐treat principle, including all 44 randomized participants. Results A significant group‐by‐time interaction emerged for the KSS functional score ( p < 0.001) and WOMAC total score ( p < 0.001), favoring the ECC–CON group. Among secondary outcomes, significant interactions were found for AROM extension ( p = 0.006) and VAS pain ( p = 0.011). The between‐group difference in VAS at 8 weeks was not statistically significant (mean difference −0.30, 95% CI −0.69 to 0.08, Cohen's d = 0.48). No significant interactions were observed for the KSS joint score ( p = 0.938), PROM extension ( p = 0.853), AROM flexion ( p = 0.105), or PROM flexion ( p = 0.184). Conclusion Adding eccentric training to standard rehabilitation after TKA was associated with greater improvements in selected outcomes, including the KSS functional score, WOMAC total score, and active knee extension, compared with concentric‐only training. The significant group‐by‐time interaction for pain indicates different trajectories of pain reduction favoring the eccentric group although the final pain level at 8 weeks was comparable between the groups. Eccentric training confers specific benefits for certain functional domains; it does not uniformly improve all outcomes. Trial Registration Chinese clinical trial registry (ChiCTR), URL: https://www.chictr.org.cn/ . Registration number: ChiCTR2300067493. date of registration: December 20, 2022. PID: 188941. Trial registry name: Effect of eccentric contraction training on postoperative rehabilitation of patients undergoing total knee arthroplasty