Changes and Compensatory Gait Mechanisms in Lower Extremity Kinematics in Patients With ACL Rupture: A Cross-sectional Controlled Study

Background: Anterior cruciate ligament (ACL) rupture is associated with knee instability and compensatory gait adaptations, which are relevant to rehabilitation planning. Hypothesis: Patients with ACL rupture would show altered bilateral hip, knee, and ankle gait kinematics. Study Design: Cross-sectional study. Level of Evidence: Level 3. Methods: A total of 40 participants were enrolled, including 22 patients with recent ACL ruptures and 18 healthy subjects. Participants walked on a treadmill at 4 km/h while wearing 17 inertial sensors. Ten normalized gait cycles were used to compare bilateral hip, knee, and ankle kinematics. Results: Patients with ACL rupture demonstrated altered lower-extremity kinematics compared with healthy subjects. Hip external rotation was reduced bilaterally ( P < 0.01), and hip adduction was reduced on both the affected ( P < 0.05) and nonaffected ( P < 0.01) sides. Maximum knee flexion was lower on the affected side than in healthy subjects ( P < 0.01) and the nonaffected side ( P < 0.05). Maximum ankle internal rotation was reduced bilaterally (affected side P < 0.05; nonaffected side P < 0.01), suggesting bilateral gait adaptations after ACL rupture. Conclusion: ACL rupture was associated with gait alterations involving both lower extremities, with bilateral hip and ankle kinematic changes and reduced maximum knee flexion mainly on the affected side. Clinical Relevance: Recognition of bilateral kinematic changes after ACL rupture may help clinicians assess both limbs and guide rehabilitation focused on restoring functional gait patterns.