Purpose: We evaluated and compared kinematics of bilateral ankle, knee, and hip joints in patients with chronic unilateral ankle instability (CAI) with healthy controls.
Methods: Fifteen individuals diagnosed with CAI and a control group of 16 individuals were matched. Different peaks within the gait cycle (at different intervals) for the dorsiplantar, inversion/eversion, and abduction/adduction axis were compared between injured and uninjured sides of patients with CAI with a control group.
Results: Comparison of the uninjured ankle in CAI with the control group showed higher dorsiflexion in one peak of the stance phase (p = 0.003), higher inversion in one peak of the stance phase (p = 0.022), and the swing phase (p = 0.004). The hip joint of the uninjured side showed higher extension in one peak of the stance phase (p < 0.001), and two peaks of the swing phase (p < 0.05). Furthermore, it showed higher adduction in one peak of the foot flat to mid-stance phase (p = 0.001), higher abduction in one peak of the late swing phase (p = 0.047), and the swing phase (p = 0.032). The knee joint of the uninjured side showed higher flexion in all measured peaks of the gait cycle (p < 0.05) (except for one peak in the late swing phase) compared to the control group.
Conclusion: Chronic ankle instability results in altered biomechanics of the ipsilateral knee as well as the contralateral ankle, knee, and hip joints. The alterations caused by CAI may predispose patients to overuse and/or acute injuries of other joints of lower extremities during routine and sporting activity.
Keywords: Biomechanics; Chronic ankle instability; Joint; Kinematic; Lower extremity.
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