This systematic review and meta-analysis aimed to investigate the efficacy of adding EMG-BF to exercise programs on pain, knee functions, functional limitations, quadriceps strength, and electromyographic (EMG) activity of vastus medialis obliquus (VMO) and vastus lateralis (VL) in patients with PFPS.
PubMed, Cochrane CENTRAL, Web of Science, Scopus, PEDro, and Google Scholar were searched from inception up to June 2024 for randomized controlled trials (RCTs) investigating the effectiveness of EMG-BF training in patients with PFPS. Two reviewers independently screened the titles and abstracts of the retrieved studies with Rayyan web-based tool, and another pair of reviewers screened the full texts of the potentially relevant articles. Two reviewers extracted the data and assessed the risk of bias using the PEDro scale. Meta-analyses were conducted where applicable, and data not appropriate for quantitative synthesis were synthesized narratively. The certainty of the evidence was assessed using the GRADE framework.
Nine RCTs involving 352 participants were included. Three studies were of good quality, and six studies were of fair quality. The pooled analysis revealed no significant differences between EMG-BF and control groups in pain (MD: -0.8; 95% CI: -2.34, 0.75; P = 0.31), functional limitation (MD: -0.02, 95% CI -0.57, 0.54; P = 0.96), quadriceps strength (MD: 0.85, 95% CI -0.04, 1.74; P = 0.06), and EMG activity of the VMO and VL; however, EMG-BF training may have some effect on improving the knee function (MD: 6.71, 95% CI 4.36, 9.06; P = 0.001).
Very low to low quality evidence suggests that EMG-BF combined with exercises may improve knee function in patients with PFPS, but it is not superior compared to the control for pain relief, quadriceps strength, EMG activity, or functional limitation. Given the current quality of evidence and the methodologic limitations, further studies with proper blinding, adequate concealment, and extended periods are essential to provide stronger evidence.
The current meta-analysis support the addition of EMG-BF to an exercise treatment program for improving knee function but not for relieving pain, improving quadriceps strength, or decreasing functional limitations in patients with PFPS. However, short-term assessments (6-12 weeks) of a chronic condition may not fully capture the benefits of an intervention. Therefore, long-term RCTs are needed to draw more incisive conclusions.
Patellofemoral Pain Syndrome
Pain
