Hindfoot and forefoot kinematic differences among individuals with and without Functional Ankle Instability

Abstract

HINDFOOT AND FOREFOOT KINEMATIC DIFFERENCES AMONG INDIVIDUALS WITH AND WITHOUT FUNCTIONAL ANKLE INSTABILITY By Cynthia J. Wright, M.Ed. A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University. Virginia Commonwealth University, 2011. Major Director: Dr. Brent L. Arnold, Associate Professor, Department of Health and Human Performance Introduction: Following lateral ankle sprain, many individuals experience recurrent injury and symptoms of giving-way, known as Functional Ankle Instability (FAI). It has been proposed that altered joint kinematics during activity may contribute to instability in these individuals, however research findings have been inconsistent. Objective: To capture foot and ankle kinematic data during two common tasks (walking gait and jump landing) among three groups: individuals with FAI, healthy controls and copers. Design: 3-group observational cross-sectional study. Participants: Participants included 23 individuals with a history of ≥ 1 ankle sprain and at least 2 episodes of giving-way in the past year (FAI: M±SD; age=23.30±3.84years; height=1.71±0.11m, weight=68.66±14.60kg; Cumberland Ankle Instability Tool [CAIT]=20.52±2.94, episodes of giving-way=5.81±8.42 per month), 23 subjects with no history of ankle sprain or instability in their lifetime (Controls: age=23.17±4.01years, height=1.72±0.08m, weight=68.78± 13.26kg, CAIT: 28.78±1.78), and 23 individuals with a history of a single ankle sprain and no subsequent episodes of instability (Copers: age=23.52±3.68years, height=1.72±0.07m, weight=69.57±13.94kg; CAIT: 27.74 ± 1.69). Interventions: Ten trials of natural walking gait and 10 single leg drop jumps were recorded using a ViconMX motion monitoring system (OMG, Oxford, UK) and two imbedded force plates (Bertec, Columbus, Ohio, USA). Main Outcome Measures: Forefoot and hindfoot sagittal and frontal plane angles were calculated at initial contact (IC) and toe-off (TO) of walking gait, and IC and maximal vertical ground reaction force of jump landing. Results: At walking IC, there was a significant group difference in forefoot inversion (F2,66=4.68, p=0.013). Post hoc testing revealed that individuals with FAI were significantly more inverted than controls, but copers were not significantly different from the FAI or control groups. At jump landing IC, there were significant group differences in hindfoot motion (F2,66=6.12, p=0.004). Specifically, individuals with FAI were significantly more dorsiflexed than the control or coper groups. There were no other significant group differences (all p>0.05). Conclusions: Kinematic differences exist between healthy controls, copers and individuals with FAI. Copers and individuals with FAI have both experienced ankle sprain injury, yet copers do not experience subsequent instability. Analysis of coper movement patterns compared to control and FAI groups may provide insight into coping mechanisms.