The impact of exercise therapy on rehabilitation outcomes after anterior cruciate ligament reconstruction: a network meta-analysis

Background Injuries to the anterior cruciate ligament (ACL) often result in postoperative declines in muscle strength and functional deficits, which increase the risk of secondary injuries. Exercise therapy is widely regarded as the cornerstone of postoperative rehabilitation; however, substantial variation exists in the reported efficacy of different rehabilitation modalities. Methods A comprehensive search was conducted across several databases, including Wanfang, VIP, CNKI, PubMed, Web of Science, Embase, The Cochrane Library, and EBSCO, to identify randomized controlled trials (RCTs) examining the effects of exercise on quadriceps strength, hamstring strength, and knee function following ACL reconstruction. The search included studies published from the inception of these databases up until October 2024. Two independent researchers screened the studies, extracted data, and assessed the risk of bias. Data were analyzed using network meta-analysis in Stata 17.0. Results A total of 38 RCTs were included, with 31 studies evaluating quadriceps strength, 18 assessing hamstring strength, and 19 focusing on knee joint function. The network meta-analysis revealed that both whole-body vibration training (WBVT) and water rehabilitation training (WR) significantly improved quadriceps strength, with effect sizes of (SMD = 1.66, 95% CI: 0.44, 2.87, P < 0.05) for both, although the evidence quality was low. The SUCRA rankings indicated WR as the most effective intervention for improving quadriceps strength (SUCRA = 83.6). WR demonstrated the greatest effect on hamstring strength (SMD = 2.05, 95% CI: 0.32, 3.79, P < 0.01), with moderate-quality evidence. In contrast, WBVT did not have a significant effect on knee joint strength recovery (SMD = 0.96, 95% CI: -0.37, 2.28, P > 0.05), with very low-quality evidence. Conclusion WR shows superior efficacy in restoring quadriceps and hamstring strength, whereas WBVT has limited benefits for knee joint recovery. Given the variability in evidence quality, clinicians should interpret these findings with caution and prioritize WR as the optimal intervention for recovery following ACL reconstruction. Further high-quality trials are needed to strengthen these conclusions.