June 2018

Identifying CAI Through Specific Movement Patterns

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Looking to identify specific movement strategies and describe lower extremity stiffness of the subgroups of patients with CAI compared to an uninjured control group, J. Ty Hopkins, PhD, professor of human performance research center at Brigham Young University, Provo, UT, examined 200 CAI participants (109 male) and 100 controls (54 male).

In the study, Joint Stiffness Alterations, Grouped by Movement Strategy, in Chronic Ankle Instability,5 participants performed five successful trials of a jump landing/cutting task, and by using principle component analysis, lower extremity sagittal and frontal plane kinematics were decreased to single representative curves. In all, six unique clusters were identified, and calculations were based on joint stiffness values for each. The data were then compared to a control group.

The researchers concluded that multiple distinct movement patterns were found in a high percentage of CAI subjects and each person likely incorporates unique positions and loads that contribute to the chronic nature of instability. Additionally, the data revealed distal joint stiffness was lower in those with CAI than controls generally, while proximal joint stiffness was greater than controls. These data support the theory that the hop plays a vital role in controlling lower extremity movement in CAI subjects.

“There are multiple unique movement strategies demonstrated by patients who have chronic ankle instability, and those strategies demonstrate unique stiffness characteristics,” Hopkins said. “Patients with ankle instability must be treated with specific movement characteristics in mind. One approach does not fit all.”


5. Hopkins JT, Son SJ, Kim J, et al. Joint Stiffness Alterations, Grouped by Movement Strategy, in Chronic Ankle Instability.

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