Effects of Low-Load Blood Flow Restriction Training on Muscle Volume After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis

Background: After anterior cruciate ligament (ACL) reconstruction (ACLR), the function and strength of the quadriceps muscle are essential for a successful recovery. Low-load blood flow restriction training (LL-BFRT) is believed to reduce muscle atrophy and restore muscle function. Purpose: To systematically analyze the evidence on the effectiveness of LL-BFRT in early rehabilitation after ACLR. Study Design: Systematic review; Level of evidence, 1. Methods: A systematic review and meta-analysis were conducted consistent with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Comprehensive literature searches were performed in several electronic databases—including Cochrane Library (trials), PubMed, Embase, Web of Science, China National Knowledge Infrastructure, WanFang, China Science and Technology Journal Database, and Sinomed—from inception to October 1, 2023. Included were randomized controlled trials in Chinese and English comparing LL-BFRT within 6 weeks after ACLR with conventional rehabilitation training. Bias risk was assessed using the Cochrane Risk-of-Bias 2 tool. The outcomes measured were quadriceps muscle size, knee joint functional scores, balance function, and complications. The effects of LL-BFRT versus conventional rehabilitation were analyzed using standardized mean differences (SMDs) or weighted mean differences (WMDs). Results: A total of 362 studies were initially identified, and 8 were included for analysis. LL-BFRT was significantly more effective in improving quadriceps muscle volume (SMD, 0.37 [95% CI, 0.08 to 0.66]; P = .01) and Lysholm scores (SMD, 0.74 [95% CI, 0.43 to 1.05]; P < .0001) compared with conventional rehabilitation training. However, no significant improvements were observed in the 3 directions of the Y-balance test: anterior (WMD, 0.55 [95% CI, –6.37 to 7.46]; P = .88), posteromedial (WMD, –2.24 [95% CI, –8.76 to 4.29]; P = .50), and posterolateral (WMD, 0.02 [95% CI, –13 to 13.03]; P = 1.0). No complications were reported in any of the included studies. Conclusion: The results of this meta-analysis suggested that LL-BFRT within 6 weeks after ACLR has a more pronounced effect on increasing quadriceps muscle volume and improving Lysholm scores compared with conventional rehabilitation training, with no apparent complications.