Blood flow restriction training compared to conventional training in people with knee pain: a systematic review with meta-analysis

OBJECTIVE: Evaluate the efficacy of blood flow restriction training (BFRT) in people with knee conditions. METHODS: We searched Medline, Web of Science, and Sport DISCUS from inception until October 2023, seeking randomised controlled trials (RCTs) involving participants with any knee condition and BFRT in at least one intervention arm. We used a random-effects model meta-analysis to pool methodologically homogeneous data and the Grading of Recommendations, Assessment, Development, and Evaluations approach to categorise certainty of evidence. RESULTS: 15 RCTs involving 418 participants were eligible, investigating people post-anterior cruciate ligament reconstruction (n = 7) and cartilage surgery (n = 2), or with knee osteoarthritis (n = 3) and patellofemoral pain (n = 3). There is very low certainty evidence that adding BFRT to resistance training is superior to resistance training for pain outcomes (small SMD 0.47, 95 % CI 0.09, 0.85). There is very low certainty evidence that adding BFRT to resistance training is equivalent to resistance training for function and strength outcomes. CONCLUSIONS: BFRT offers a significant effect on short-term pain that is of questionable clinical relevance, and no significant effects on function or quadriceps strength. Future high-quality RCTs are required to appropriately explore clinical efficacy, and clinicians should exercise caution in offering BFRT to people with knee conditions.