The Effectiveness of Photobiomodulation Therapy on Pain and Function in Patients with Patellofemoral Pain Syndrome—A Systematic Review and Meta-Analysis

<b>Objectives</b>: The aim of this systematic review was to evaluate the effectiveness of photobiomodulation (PBM) on pain and function in individuals with Patellofemoral Pain Syndrome (PFPS). <b>Methods</b>: A systematic review and meta-analysis were conducted in accordance with PRISMA guidelines. Search was performed across PubMed/Midline, Scopus, Web of Science, EBSCO, ScienceDirect, Wiley Online Library, Springer, Cochrane CENTRAL, PEDro, ResearchGate, and Google Scholar from inception to January 2025. Randomized controlled trials (RCT) examining PBM in individuals with PFPS were included. Data extraction, risk-of-bias assessment (RoB 2), and quality of evidence evaluation (GRADE) were performed independently by multiple reviewers. Primary and secondary outcomes were pain and function, respectively. A random effect meta-analysis was performed to estimate the standardized mean difference (SMD) at 95% confidence interval (CI) and overall effect size. <b>Results</b>: Eight trials (340 participants) met the inclusion criteria. PBM significantly reduced pain compared with the control (SMD = -0.83; 95% CI -1.40 to -0.27). Functional outcomes demonstrated a significant improvement favoring PBM (SMD = 0.68; 95% CI 0.08 to 1.27), although substantial heterogeneity was present (I² = 83%). RoB2 showed five high-risk studies. GRADE showed a very low quality of evidence due to study limitations, imprecision, and inconsistency which limit the confidence to the effect estimate. <b>Conclusions</b>: PBM, combined with exercise, provides improvements in pain and knee function in individuals with PFPS. While findings support PBM as an effective adjunct modality, standardized dosing protocols and larger, high-quality RCTs are needed to strengthen future clinical recommendations.