Effects of Blood Flow Restriction Therapy in Individuals With Knee Osteoarthritis: Overview of Systematic Reviews

Abstract

Background: Knee osteoarthritis (KOA) is frequently accompanied by quadriceps weakness. Resistance training is recommended, but high-intensity resistance training (HIRT) may be poorly tolerated in some patients, whereas low-intensity resistance training (LIRT) may yield smaller strength gains. Low-intensity blood flow restriction training (LIBFR) has been proposed as a low-load strategy to stimulate muscle adaptations; however, the evidence base has been summarized in multiple systematic reviews with variable conclusions. Objective: To synthesize and appraise the evidence on the efficacy and safety of LIBFR in individuals with KOA through an overview of systematic reviews. Methods: We searched MEDLINE, EMBASE, Cochrane Database, Web of Science, CINAHL, SPORTDiscus, PEDro, Epistemonikos, and gray literature (ProQuest, Global ETD) for systematic reviews of randomized clinical trials comparing LIBFR with LIRT and/or HIRT. Reviews were eligible if they evaluated supervised exercise-based LIBFR delivered ⩾2 to 3 sessions/week for ⩾4 weeks. Two reviewers independently screened, extracted data, and assessed methodological quality (AMSTAR 2). Certainty of evidence was appraised using Grading of Recommendations Assessment, Development, and Evaluation (GRADE) based on KOA-specific quantitative syntheses, applying a hierarchical approach in the presence of overlap across reviews. Results: Eighteen systematic reviews (57 randomized trials; 5656 participants) were included. Compared with LIRT, LIBFR was associated with greater improvements in quadriceps strength (standardized mean difference [SMD] = 0.75; 95% confidence interval [CI] = [0.40 to 1.10]) and muscle hypertrophy (SMD = 0.81; 95% CI = [0.10 to 1.52]), although certainty of evidence was very low. Compared with HIRT, LIBFR was associated with fewer adverse events (risk ratio [RR] = 0.26; 95% CI = [0.09 to 0.72]).Across comparisons, effects on pain and functional outcomes were generally similar, and between-group differences were not consistently observed. Conclusions: The LIBFR may improve quadriceps strength and hypertrophy relative to LIRT and may have a more favorable adverse-event profile than HIRT, but confidence in these estimates is limited by low-/very low-certainty evidence and variability in protocols and reporting. Well-designed, longer-term randomized trials with standardized LIBFR parameters and robust safety reporting are needed to clarify patient-important outcomes.