Grant: Master's Award: Canada Graduate Research Scholarships - Master's program

Introduction. Women are two to eight times more likely to experience anterior cruciate ligament (ACL) injuries than men. After ACL reconstruction (ACLR), women are often unable to fully regain thigh muscle strength due to reduced muscle mass and impaired neuromuscular activation. Functional Electrical Stimulation (FES), which activates muscles through surface electrodes during functional movement, has shown to improve quadriceps strength in men after ACLR, but its effectiveness in women remains unknown. This pilot RCT will investigate whether adding FES to standard rehabilitation improves quadriceps strength and activation in women following ACLR. Methods. Twenty women aged 18–40 undergoing ACLR with a patellar or quadriceps tendon graft will be randomly assigned to rehabilitation only or rehabilitation+FES. All participants will complete standard postoperative rehabilitation, while the FES group will receive quadriceps stimulation three times per week for six weeks. Stimulation will begin four weeks post-operation during stationary cycling and progress to walking-based FES at six weeks once full weight bearing is typically achieved. Stimulation intensity will be increased throughout each session and over the six week protocol. Quadriceps strength, activation, and patient-reported outcomes will be assessed at ten weeks post-surgery. Preliminary pilot testing in two women demonstrated that stimulation intensity could be increased by nearly 88% within sessions without adverse events, supporting the feasibility and safety of the protocol. Significance. This study will generate sex-specific evidence on FES use after ACLR and may inform strategies to improve quadriceps recovery, enhance long-term knee function, and reduce risk of post-traumatic knee osteoarthritis in women.