LOWER EXTREMITY BIOMECHANICS OF AN ANKLE 'GIVING WAY' CASE DURING THE DROP LANDlNG

Abstract

The purpose of our study was to present an accidental ankle 'giving way' case of a participant with chronic ankle instability (CAI) during drop landing test and compare lower extremity biomechanics with that of the participant's normal landing trials. A 7-camera Vicon system was used to capture motions of the participant drop landing from a 30-cm high box. Ground reaction forces were collected using two force plates. Lower extremity joint angles and moments were generated. Subjective comparisons were made between the giving way trial and normal trials. For the giving way trial, the participant exhibited greater ankle inversion, internal rotation and less hip abduction angle in pre-landing phase compared to the normal trials. In addition, the ankle exhibited greater eversion moment and external rotation moment in the landing phase. Center of pressure was more lateral in the giving way trial. We suggest that a more inverted and internally rotated ankle position before landing may place ankle at a high risk of giving way and sprain for CAI individuals.