Effect of Surface EMG Biofeedback on Quadriceps Inhibition Release During Postoperative Knee Rehabilitation

Arthrogenic muscle inhibition (AMI) is a common neurological impairment following knee surgery that limits voluntary quadriceps activation and delays functional recovery. Persistent AMI may contribute to muscle weakness, altered gait, and poorer rehabilitation outcomes. Although several rehabilitation strategies have been proposed, no complementary intervention has consistently demonstrated strong evidence for improving AMI. This prospective single-case experimental study aims to evaluate whether visual biofeedback based on surface electromyography (sEMG) improves quadriceps motor performance during standard rehabilitation. Each participant will complete eight standardized rehabilitation sessions, including four sessions with visual sEMG biofeedback and four sessions without visual feedback. The order of the two conditions will be randomized, allowing each participant to serve as his or her own control. The primary objective is to determine whether visual sEMG biofeedback improves the accuracy of quadriceps contraction, assessed by the percentage deviation from a predefined target. Secondary objectives include evaluation of motor engagement, motor control, muscle activation, perceived exertion, and pain. Between three and five adult patients presenting AMI after knee surgery will be included. Because recovery patterns are highly individualized, a Single-Case Experimental Design (SCED) with repeated within-subject measurements has been selected to characterize individual treatment responses while minimizing inter-individual variability

Inclusion Criteria: * AMI following knee surgery, as classified by the Santi classification system * Aged 18 or older * Enrolled in or covered by a social security program * Able to understand instructions and participate in standardized rehabilitation sessions Exclusion Criteria: * Acute pain. * Neurological condition. * Skin lesion at the electrode site. * Allergy to the electrode. * Under legal protective measures such as guardianship or court-ordered protection