Alterations in Trunk and Lower Extremity Joints Mechanics during Shod Walking in Individuals with Chronic Ankle Instability

Background: Trunk and hip joint stability and strength are important for proper gait mechanics and foot position during heel strike. So, it is important to consider the patency of all the leg joints for stability during gait. Objective: To examine the effect of unilateral chronic ankle instability on kinematics and kinetics of trunk and lower extremity joints during shod walking. Materials and Methods: 3-D motion analysis system was used to record the gait kinematics and kinetics of trunk and hip joint of fifty subjects during shod walking (25 chronic ankle instability (CAI), and 25 healthy control group matched with CAI group in age, gender, and activity). Kinematic and kinetics pattern differences were established at 90%, zero%, 10% and 30% of gait cycle in the sagittal and frontal planes. Statistical analysis: Analysis of variance (ANOVA) was used to investigate the effect of unilateral chronic ankle instability on kinematics and kinetics of trunk and the lower extremity joints. The level of significant was set at 0.05 for all statistical tests. Results: Chronic ankle instability subjects were significantly (P< 0.05) more inverted in the frontal plane compared with controls in the entire studied parts of gait cycle. Subtalar joint motions are controlled by invertors moment compared with evertors moment in the controls. In addition to significant increase of ankle joint plantar flexion (P < 0.05), there was significant increase in ipsilateral hip joint adduction and lateral trunk lean towards the affected side. These proximal adaptations are significantly correlated to ankle adaptation in the same plane. Conclusion: Chronic ankle instability leads to kinematic and kinetic changes of trunk and hip caused by mechanical changes of ankle joint that should be considered during establishment of rehabilitation programs for persons suffering from chronic ankle instability.