Effects of preoperative maximal strength training on muscle strength and function in total knee arthroplasty: A randomized controlled trial

BACKGROUND: The efficacy of prehabilitation through preoperative strength training for individuals undergoing total knee arthroplasty (TKA) remains inconclusive. OBJECTIVE: The present study aimed to evaluate the effects of maximal strength training (MST) before operation on muscle strength and physical function 3 weeks following TKA. METHODS: 48 individuals scheduled for fast-track unilateral primary TKA were randomized to MST (n = 24), performing 4 sets at 4 repetition maximum in seated leg press 3 times per week for 8 weeks, or control usual care (CON, n = 24). The primary outcome was bilateral leg press maximal strength. Secondary outcomes were performance-based physical function, including 10-step stair climbing, 30 s sit-to-stand, 40 m fast-paced walking, and unipedal stance tests, and self-reported physical function as knee injury and osteoarthritis outcome score-physical function short form (KOOS-PS), European quality of life 5 dimension, 5 Level, and forgotten joint score. RESULTS: MST improved bilateral leg press 1RM relative to body weight after intervention (mean change 0.45, P < 0.0001), and there were between-group differences in the delta changes from baseline to preoperation (mean difference 0.43, P < 0.0001) and postoperation (mean difference 0.27, P < 0.001), favoring MST. MST also led to better maintenance of postoperative stair climbing (mean difference -3.38 s, P = 0.0013). Although the MST group experienced a significant preoperative improvement in sit-to-stand (mean change 2 repetitions, P = 0.0019), walking ability (mean change -2.28 s, P < 0.001), and KOOS-PS (mean change 8, P < 0.0001), these effects did not extend to postoperative outcomes. CONCLUSIONS: The findings indicate that preoperative MST is safe and effective in improving muscle strength and preserving stair-climbing ability for individuals undergoing TKA, positioning MST as a pragmatic prehabilitation strategy. CLINICAL TRIAL REGISTRATION: NCT05892133.