Relationship between ankle frontal plane kinematics during different functional tasks

Increased inversion following lateral ankle sprain and in patients with chronic ankle instability (CAI) is thought to contribute to recurrent injury and feelings of instability, however, there are no biomechanic assessment tools readily available to evaluate for excessive inversion prior to or following lateral ankle sprains. Before establishing a clinically useful biomechanic assessment tool, it is important to understand whether there is a relationship in the extent of ankle frontal plane motion across various tasks to help determine if one task or a combination of tasks would be most appropriate when evaluating patients. The purpose of this preliminary study was to analyze the relationship between ankle frontal plane kinematics during walking, step-down, and jump-landing tasks. Fifty-six recreationally active adults (gender=M:26;F:30, age=21.2±3.2, height=171.3±8.0cm, mass=75.6±15.4) volunteered. Main outcome measures were ankle frontal plane motion at initial contact and peak inversion during aerial phases across 3 tasks (walking, step-down, and jump-landing). Relationships between ankle frontal plane kinematics were analyzed by Pearson product-moment correlation coefficient (r). There were strong correlations in peak inversion during the aerial phase between the step-down and walking (r=0.68; p<0.001) and step-down and jump-landing (r=0.75; p<0.001) and at initial contact between step-down and walking (r=0.73; p<0.001) and step-down and jump-landing (r=0.72; p<0.001). Moderate correlations were identified during aerial (r=0.32; p=0.015) and at initial contact (r=0.46; p<0.001) between walking and jump-landing. The strong relationship between the amount of inversion exhibited across various tasks suggest that a single evaluation test may be sufficient in the identification of abnormal ankle biomechanics.