Neuromuscular Electrical Stimulation Combined With Progressive Resistance Training Versus Resistance Training Alone on Muscle Strength and Functional Outcomes in Post–Anterior Cruciate Ligament Reconstruction Patients: A Randomized Controlled Trial

Abstract

Background: Persistent quadriceps weakness after anterior cruciate ligament reconstruction (ACLR) is common and is partly driven by arthrogenic muscle inhibition, limiting voluntary activation and delaying functional recovery. Objective: To compare the effects of neuromuscular electrical stimulation (NMES) combined with progressive resistance training (PRT) versus PRT alone on quadriceps strength and functional outcomes in post-ACLR patients. Methods: In this assessor-blinded randomized controlled trial conducted at Therapy Plus Clinic, 60 participants (18–40 years; 4–8 weeks post-primary unilateral ACLR) were randomized (1:1) to NMES+PRT or PRT alone for 8 weeks (3 sessions/week). Quadriceps strength (Nm/kg) and limb symmetry index (LSI) were primary outcomes; functional hop tests (single-leg hop, triple hop, 6-m timed hop) and IKDC subjective scores were secondary outcomes. Analyses followed intention-to-treat with multiple imputation for missing data, using repeated-measures ANOVA and between-group comparisons at α=0.05. Results: At 8 weeks, NMES+PRT produced greater strength gains than PRT alone (Δ+0.59±0.21 vs +0.39±0.19 Nm/kg; between-group difference 0.20, 95% CI 0.09–0.31; p=0.001) and higher LSI improvement (+21.3±6.8% vs +13.5±7.2%; difference 7.8, 95% CI 4.2–11.4; p<0.001). NMES+PRT also improved single-leg hop distance (difference 12.1 cm; p=0.003), triple hop distance (difference 32.8 cm; p=0.002), 6-m timed hop (difference −0.21 s; p=0.016), and IKDC change (difference 7.7 points; p<0.001). Conclusion: NMES added to PRT yields statistically and clinically meaningful improvements in quadriceps strength, symmetry, functional performance, and patient-reported knee function after ACLR compared with PRT alone.