Effects of lower-limb active resistance exercise on mobility, physical function, knee strength and pain intensity in patients with total knee arthroplasty: a systematic review and meta-analysis

Total knee arthroplasty (TKA) successfully alleviates pain from knee osteoarthritis, but muscle strength and function are reduced for a long period postoperatively. Postoperative active resistance exercise may play a relevant role. To systematically evaluate effects of lower-limb active resistance exercise (ARE) on mobility, physical function, muscle strength and pain intensity in patients with TKA. A search was conducted in PubMed, EMBASE, and Cochrane Library databases from inception to September 2023. Only randomized controlled trials (RCTs) that compared the effects of ARE and no intervention or other rehabilitation program without PRE were included. The outcome variables were mobility (Maximal walking speed [MWS]/6-Minute Walk Test[6MWT]), physical function (Stair Climb Test [SCT]/Timed Up and Go [TUG]), knee extension/ flexion power(KEP/KFP), joint range of motion (ROM) and pain. Standardized Mean Differences (SMD) or Mean Differences (MD) and 95% confidence intervals (CI) were calculated and combined in meta-analyses. The Cochrane Collaboration’s Handbook were used for the methodological quality assessments. GRADE was used to assess the quality of evidence. The meta-analysis was performed using the RevMan 5.4 software. A total of 14 randomized controlled trials, involving 880 patients, were finally included. The lower-limb ARE exhibited significantly greater improvement in MWS (MD 0.13, 95%CI 0.08–0.18, P < 0.00001), TUG(MD -0.92, 95%CI -1.55– -0.28, P = 0.005), KEP (SMD 0.58, 95%CI 0.20–0.96, P = 0.003), KFP (SMD 0.38, 95%CI 0.13–0.63, P = 0.003), ROM-flexion (MD 2.74, 95%CI 1.82–3.67, P < 0.00001) and VAS (MD − 4.65, 95% CI − 7.86– -1.44, p = 0.005) compared to conventional exercise(CE) immediately post-intervention. However, there were no statistically significant differences between both groups in regard to 6MWT (MD 7.98, 95%CI -4.60–20.56, P = 0.21), SCT (MD -0.79, 95%CI -1.69–0.10, P = 0.08) and ROM-extension (MD -0.60, 95%CI -1.23–0.03, P = 0.06). According to the results of meta-analysis, patients undergoing TKA who receive the lower extremity ARE show better clinical effects in terms of pain relief, strength recovery and knee ROM. Simultaneously, it may be beneficial to improve mobility and physical function of patients after TKA.