Electrical stimulation modalities for patellofemoral pain: a systematic review and meta-analysis

Patellofemoral pain (PFP) is a common knee disorder associated with persistent pain and functional limitations. Electrical stimulation modalities have been proposed as adjuncts to exercise-based rehabilitation; however, their effectiveness may differ according to modality and therapeutic target. This systematic review and meta-analysis evaluated the effects of different electrical stimulation modalities on pain, knee function, and muscle-related outcomes in adults with PFP.

This systematic review was prospectively registered in PROSPERO (CRD420251108421) and conducted in accordance with the PRISMA 2020 statement. PubMed, Web of Science, Scopus, and Embase were searched from inception to June 2026 for randomized controlled trials evaluating electrical stimulation interventions in adults with PFP. Risk of bias was assessed using the Cochrane Risk of Bias 2 tool, and certainty of evidence was evaluated using the GRADE approach.

Random-effects meta-analyses were performed when studies were sufficiently comparable, using mean differences (MDs) with 95% confidence intervals (CIs). Twenty-six randomized controlled trials involving 1,217 participants evaluated seven electrical stimulation modalities. NMES was investigated in 13 trials, EMS in five, and the remaining modalities in one or two trials each.

Quantitative synthesis was conducted only for outcomes with sufficient clinical and methodological comparability. Compared with exercise-based rehabilitation, sham stimulation, or other prespecified control interventions, NMES was associated with reduced pain (MD = − 0.59, 95% CI: −0.94 to − 0.23; P