Evidence Quality and Follow-Up Limitations in Blood Flow Restriction Training Trials for Knee Rehabilitation: A Meta-Epidemiological Systematic Review

Blood flow restriction (BFR) training combines low-load exercise with controlled limb occlusion to stimulate strength and hypertrophy adaptations while reducing joint loading. BFR has been increasingly used in knee rehabilitation pathways, including after anterior cruciate ligament reconstruction and in knee osteoarthritis, where high-load resistance training may be limited by pain or surgical precautions. However, trial evidence is heterogeneous and often constrained by short follow-up periods, incomplete reporting, and variable methodological quality. These features can bias effect estimates and limit clinical inference. This systematic review will identify randomized and quasi-randomized trials of BFR training for knee rehabilitation and quantify (1) the overall effects of BFR versus non-BFR comparators on key rehabilitation outcomes and (2) how evidence quality and follow-up duration relate to the magnitude of reported effects using meta-epidemiological analyses. The review follows PRISMA 2020 guidance (Page et al., 2021), uses dual independent screening and extraction, and applies Cochrane RoB 2 for risk of bias appraisal (Sterne et al., 2019). Random-effects meta-analysis and meta-regression will be used when data permit. By mapping follow-up limitations and linking methodological features to effect size patterns, the review will clarify how confidently BFR benefits can be interpreted in knee rehabilitation and will provide actionable recommendations for future trial design, reporting, and implementation.