Step-Down Task Identifies Differences in Ankle Biomechanics Across Functional Activities.

Currently, there is no clinical exam to evaluate ankle frontal plane kinematics. The purpose of this study was to determine whether individuals identified as "lateral" landing during a video-recorded step-down task have differences in ankle inversion as measured with 3-dimensional motion capture during walking, step-down, and jump-landing tasks compared to individuals identified as "non-lateral". Fifty-seven recreationally active adults completed the descriptive laboratory study. During walking, step-down, and jump-landing tasks, participants had their ankle frontal plane kinematics measured using a 3-dimensional motion capture system. In addition, during the step-down task, participants had a posterior view video of their foot recorded using a commercial camera. Following testing, a blinded-investigator scored the step-down video of all participants by classifying them as "lateral" landing or "non-lateral" landing. Ankle frontal plane kinematics during the walking, step-down, and jump-landing tasks were compared between the two groups (lateral (N=24) and non-lateral (N=33) using a binary logistic regression and time-series confidence interval analysis. During walking, stepping-down, and jump-landing, the lateral group had significantly more inversion at initial contact and during various other phases specific to each task. This study found that a clinical screening tool could identify individuals who have significantly more inversion during three tasks.