Blood Flow Restriction Training After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Background: Anterior cruciate ligament reconstruction (ACLR) is frequently followed by significant quadriceps atrophy and strength loss due to postoperative pain and the necessity for low-load rehabilitation. Blood flow restriction (BFR) training is an emerging modality that may facilitate muscle strength and hypertrophy under low-load conditions, but its efficacy for improving functional outcomes after ACLR remains to be conclusively determined. Purpose: To systematically evaluate the effects of BFR training on lower limb function, quadriceps strength, and knee pain in patients following ACLR. Study Design: Systematic review; Level of evidence, 3. Methods: A comprehensive literature search was conducted in PubMed, Embase, Cochrane Library, Web of Science, PEDro, EBSCO and CNKI for randomized controlled trials (RCTs) published between January 2015 and August 2025. A total of 606 records were identified through database searching, and 9 RCTs were included after screening. Data on functional scores (Lysholm, International Knee Documentation Committee [IKDC]), quadriceps peak torque (PT), pain (visual analog scale [VAS]), and range of motion (ROM) were extracted and analyzed using RevMan 5.4, and risk of bias was assessed using the Cochrane tool. Meta-analyses were performed using weighted mean differences (WMDs) with fixed- or random-effects models as appropriate, and heterogeneity was assessed using the I 2 statistic. Results: Nine RCTs involving 372 participants were included. Meta-analysis revealed that BFR training significantly improved Lysholm scores (WMD, 5.75; 95% CI, 0.60-10.90; P = .03) and quadriceps PT (WMD, 8.34; 95% CI, 7.47-9.22; P < .00001), and increased total work output ( P = .006). However, no significant differences were observed in IKDC scores, VAS pain scores, or ROM ( P > .05). Sensitivity analyses confirmed the robustness of the primary findings. Conclusion: Our study demonstrated that BFR training may promote early recovery of quadriceps strength and selected aspects of knee function after ACLR under low-load conditions. BFR appears feasible and generally well tolerated in the included trials; however, safety conclusions are limited by inconsistent adverse-event reporting. Its effects on pain relief, joint mobility, and long-term functional recovery require further investigation.