Neuromuscular Electric Stimulation Improves Early Isometric Knee Strength After Anterior Cruciate Ligament Reconstruction and Repair: A Meta‐analysis of Randomized Controlled Trials

Purpose To assess the effectiveness of neuromuscular electrical stimulation (NMES) on quadriceps strength and knee function after anterior cruciate ligament surgery. Methods A comprehensive search of PubMed, Ovid MEDLINE, and Embase from inception until February 2025 was conducted. Randomized controlled trials on adults undergoing anterior cruciate ligament surgery with NMES as an intervention and standard rehabilitation as a control were included. Study selection, data extraction, and quality assessment using the Cochrane Risk of Bias tool were performed independently by 2 reviewers. Meta‐analysis including subgroup and heterogeneity analysis was conducted using Cochrane RevMan 10.0.1. Results Twenty‐one randomized controlled trial studies met our inclusion criteria (n = 687 patients, 314 control and 373 NMES patients). The frequency‐weighted mean age of included patients across all studies was 27.0 years. Mean follow‐up time was 18.4 weeks (4‐54). Pooled analysis for isometric knee extension strength showed statistically significant improvements in absolute strength between NMES (n = 54 patients) and control (n = 55 patients) groups (n = 109 patients, mean difference 0.24; 95% confidence interval 0.2‐0.27; P < .01, I 2 = 9%) and strength as a percentage of the uninvolved limb between NMES (n = 131) and control (n = 133 patients) groups (n = 264 patients, standardized mean difference 0.87; 95% confidence interval 0.11‐1.64; P = .03, I 2 = 87%) in the early (6‐12 weeks) but not late postoperative period (>12 weeks). Similar statistical significance was noted with improvements in knee flexion ( P = .01), thigh circumference ( P = .04), and Lysholm scores ( P = .02) but not International Knee Documentation Committee scores. Four studies reporting isokinetic muscle strength were pooled, and no statistically significant difference was found. Conclusions The use of NMES as an adjunct to a standard physical therapy program after anterior cruciate ligament reconstruction appears to modestly improve isometric strength at a faster rate than standard rehabilitation alone. No conclusion can be made regarding the functional recovery or improvements in knee strength beyond the 3‐month postoperative period. Level of Evidence Level I, meta‐analysis of randomized controlled trial studies.