Gait-triggered neuromuscular electrical stimulation as an adjunct to an offloading knee brace in medial knee osteoarthritis: a pilot randomized controlled trial

Medial compartment knee osteoarthritis (KOA) is a disabling condition with a growing prevalence. Off-loading bracing is a treatment commonly used to reduce medial knee loading and improve symptoms. This study evaluated whether combining gait-triggered neuromuscular electrical stimulation (NMES) with an off-loading brace provides additional clinical and biomechanical benefits over bracing alone. Twenty-eight patients with mild-to-moderate KOA (14 per group) were randomized to a brace-only or brace plus gait-triggered-NMES group and were instructed to complete twelve walking sessions over 4 weeks with daily brace use. Primary and key secondary outcomes were WOMAC total score and VAS pain, respectively. Biomechanical assessments included kinematic, kinetic, and electromyographic analyses during gait, sit-to-stand, and balance tasks. Of the 23 patients who completed the interventions (Control = 12, NMES = 11), no significant between-group difference was found in the primary outcome (WOMAC: MD = 3.48; 95% CI –3.47 to 10.44, p = 0.309). For the secondary outcome, a modest reduction in VAS pain was observed in the NMES group (MD = –1.11; 95% CI –2.20 to –0.03). Bracing alone produced greater reductions in peak KAM and KAM impulse, whereas the NMES group showed reduced postural sway and reduced muscle activation. Taken together, these findings do not support the superiority of adding NMES to bracing for overall clinical function or mechanical unloading; NMES may offer only limited analgesic and localized neuromuscular responses. The intervention was feasible and safe. Future studies should explore whether refined NMES parameters can provide clinical benefit without interfering with brace mechanical unloading. These multi-task findings may help guide the design of future focused clinical studies.