Biomechanical Analysis of Gait in Patients with Anterior Cruciate Ligament (ACL) Injuries

Background: Anterior cruciate ligament (ACL) injuries are among the most common and debilitating musculoskeletal conditions affecting physically active individuals.These injuries not only compromise mechanical stability but also alter neuromuscular control and gait biomechanics, potentially leading to long-term functional deficits and increased risk of osteoarthritis.Despite advances in diagnosis and surgical reconstruction, many patients fail to restore normal gait patterns post-injury. Objective:To analyze and compare the gait biomechanics of individuals with ACL injuries and healthy controls, focusing on spatiotemporal, kinematic, kinetic, and electromyographic (EMG) parameters to identify specific deviations that may inform clinical rehabilitation strategies. Methods:A comparative cross-sectional study was conducted involving 30 participants with unilateral ACL injuries (3-12 months post-injury) and 30 age-and sex-matched healthy controls.Gait data were collected using a 3D motion capture system, embedded force plates, and wireless surface EMG sensors.Key outcome variables included gait speed, stride length, knee joint angles, ground reaction forces, joint moments, and muscle activation patterns.Statistical analyses were performed using independent samples t-tests, with significance set at p < 0.05. Results:The ACL-injured group demonstrated significantly slower gait speed (1.11 0.16 m/s vs. 1.28 0.14 m/s, p = 0.01), shorter stride length (p = 0.03), and prolonged double support time (p = 0.02) compared to controls.Kinematic analysis revealed reduced peak knee flexion during stance (39.5 vs. 47.1,p = 0.001) and reduced knee extension during swing (p = 0.004).Kinetic findings indicated lower peak vertical ground reaction forces and knee extensor moments in the ACL group (p < 0.01).EMG results showed delayed quadriceps activation and increased hamstring co-contraction (p < 0.01), indicating compensatory neuromuscular adaptations. Conclusion:ACL injuries result in significant alterations in gait biomechanics, characterized by joint loading asymmetries, restricted knee motion, and disrupted muscle activation.These findings underscore the need for comprehensive rehabilitation programs that integrate biomechanical assessments, neuromuscular retraining, and objective gait monitoring to facilitate functional recovery and prevent secondary joint degeneration.