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.