Blood flow restriction training after anterior cruciate ligament reconstruction: A scoping review

Quadriceps atrophy and weakness are persistent challenges after anterior cruciate ligament reconstruction (ACLR). Blood flow restriction training (BFRT) allows strength gains with low mechanical loads, making it an attractive adjunct during early rehabilitation. While meta-analyses have confirmed average benefits, the influence of specific protocol parameters and the breadth of outcome reporting remain unclear. To map existing evidence on BFRT after ACLR, identify how protocol features (timing, occlusion pressure, exercise prescription) relate to clinical outcomes, and highlight knowledge gaps. Following PRISMA-ScR guidelines, MEDLINE, Embase, and CENTRAL were searched from June 1995 to June 2025. Eligible studies enrolled adults undergoing ACLR and applied BFRT during prehabilitation or postoperative rehabilitation. Data were extracted on study design, patient characteristics, BFRT protocols, comparators, outcomes, adherence, and safety. Evidence was synthesized narratively, in structured tables, and with a protocol-outcome heatmap. Thirteen studies met inclusion criteria: 7 RCTs, 2 pilot RCTs, 1 quasi-randomized prehab trial, 1 retrospective comparative study, 1 pre-post with controls, and 1 acute biomechanics study. Sample sizes ranged 18-46. Twelve of 13 studies enrolled young adults after primary ACLR (hamstring or bone–patellar tendon–bone autografts typical). BFRT timing ranged from two weeks pre-op to five years post-op. Strength and hypertrophy outcomes were assessed in 11 studies: 6 of 11 (55%) favored BFRT over control, 5 of 11 (45%) showed no difference, and none reported inferiority. Functional performance was assessed in 6 studies: 2 of 6 (33%) favored BFRT, 4 of 6 (67%) showed no difference, and none reported inferiority. PROMs were assessed in 6 studies: 3 of 6 (50%) favored BFRT at ≤12 weeks, with convergence by 3–6 months. No serious adverse events were reported; cuff intolerance contributed to attrition in 2 studies. Adherence among completers was ≥90%. Protocol mapping revealed that individualized occlusion pressures near 80% AOP/LOP, early initiation (≤2 weeks post-op), and 2–3 sessions per week for 6–12 weeks consistently aligned with superior short-term muscle outcomes. BFRT after ACLR is safe and can accelerate early quadriceps recovery when protocols employ individualized high occlusion pressures, low-load high-effort exercise, and moderate frequency. Benefits are c learest in the first 6-12 weeks and generally converge with standard rehabilitation by 3-6 months. BFRT should be viewed as an early-phase bridge to conventional high-load training or as a secondary option for persistent deficits. The evidence heatmap highlights the importance of protocol fidelity – “not all BFRT is equal” – and underscores research priorities, including pressure-dose comparisons, timing trials, and long-term functional endpoints.