The effect of multi-joint lower-limb training on lower-limb function after total knee arthroplasty: a randomised controlled clinical trial

Total knee arthroplasty (TKA) can effectively relieve pain and restore lower-limb joint function in patients with end-stage knee osteoarthritis (OA), but postoperative recovery remains suboptimal for some patients. Conventional rehabilitation is knee-centred and neglects training of the adjacent hip and ankle joints. This study explored whether integrating hip–ankle training into standard knee rehabilitation would promote lower-limb function recovery. A single-centre, assessor-blinded randomised controlled trial was conducted. Between March 2024 and March 2025, 128 patients undergoing primary unilateral TKA were enrolled and randomised 1:1. The control group ( n = 64) received conventional knee-centred rehabilitation; the intervention group ( n = 64) received the same programme plus concurrent hip–ankle joint training. The primary outcome was the Lower Extremity Functional Scale (LEFS) score at postoperative week 4. Secondary outcomes included the Timed Up and Go Test (TUGT), 6-minute walk test (6MWT), WOMAC Osteoarthritis Index, knee range of motion (ROM), and numeric rating scale (NRS) for pain. Assessments were performed the day before surgery, at discharge, and at postoperative weeks 4, 8, and 12. Linear mixed-effects models were used to evaluate between-group differences and time trends, with sensitivity analyses conducted on the complete-case sample ( n = 127). Ultimately, 127 patients completed the full training protocol and follow-up; one patient in the intervention group withdrew because of pulmonary embolism. The intention-to-treat (ITT) analysis included all 128 participants. For the primary outcome, the between-group difference in LEFS at postoperative week 4 was + 1.55 points (95% CI 0.02 to 3.07, P = 0.047). Sensitivity analyses ( n = 127) showed a consistent direction of effect, although the difference did not reach statistical significance ( P = 0.052). By week 8, the difference in LEFS had diminished (+ 1.30 points, P = 0.095). For the WOMAC Osteoarthritis Index, a difference was evident at discharge (− 1.71 points, P = 0.016), but it began to attenuate by week 4 (− 1.39 points, P = 0.050). No difference in TUGT was observed early postoperatively, but significant differences emerged at week 8 (− 2.95 s, P < 0.001) and week 12 (− 1.97 s, P = 0.004). There were no significant between-group differences in 6MWT, pain NRS, or baseline-adjusted ROM. Integrating hip–ankle training into conventional rehabilitation modestly improved early postoperative LEFS at 4 weeks after TKA, but the magnitude did not reach a clinically important threshold, and the advantage was no longer evident by week 12. The intervention yielded a statistically significant improvement in mobility (TUGT) but offered no additional benefits for walking endurance or pain relief. These findings do not yet establish routine superiority of this approach, and longer-term follow-up is needed to validate them. This trial was prospectively registered with the Chinese Clinical Trial Registry (ChiCTR) on 2 November 2023 (registration No. ChiCTR2300077275).