Altered ankle kinematics and shank-rear-foot coupling in those with chronic ankle instability.

CONTEXT: Kinematic patterns during gait have not been extensively studied in relation to chronic ankle instability (CAI). OBJECTIVE: To determine whether individuals with CAI demonstrate altered ankle kinematics and shank-rear-foot coupling compared with controls during walking and jogging. DESIGN: Case control. SETTING: Motion-analysis laboratory. PARTICIPANTS: 7 participants (3 men, 4 women) suffering from CAI (age 24.6 +/- 4.2 y, height 172.6 +/- 9.4 cm, mass 70.9 +/- 8.1 kg) and 7 (3 men, 4 women) healthy, matched controls (age 24.7 +/- 4.5 y, height 168.2 +/- 5.9 cm, mass 66.5 +/- 9.8 kg). INTERVENTIONS: Subjects walked and jogged on a treadmill while 3-dimensional kinematics of the lower extremities were captured. MAIN OUTCOME MEASURES: The positions of rear-foot inversion-eversion and shank rotation were calculated throughout the gait cycle. Continuous relative-phase angles between these segments were calculated to assess coupling. RESULTS: The CAI group demonstrated more rear-foot inversion and shank external rotation during walking and jogging. There were differences between groups in shank-rear-foot coupling during terminal swing at both speeds. CONCLUSIONS: Altered ankle kinematics and joint coupling during the terminal-swing phase of gait may predispose a population with CAI to ankle-inversion injuries. Less coordinated movement during gait may be an indication of altered neuromuscular recruitment of the musculature surrounding the ankle as the foot is being positioned for initial contact.

Dorsiflexion deficit during jogging with chronic ankle instability.

The purpose of the study was to determine whether individuals with chronic ankle instability (CAI) demonstrate altered dorsiflexion/plantar flexion range of motion (ROM) compared to controls during jogging. The case control study took place in a university motion analysis laboratory. Fourteen volunteers participated in the study, seven suffered from CAI (age 25+/-4.2 years, height 173+/-9.4 cm, mass 71+/-8.1kg) and seven were healthy, matched controls (age 25+/-4.5 years, height 168+/-5.9 cm, mass 67+/-9.8kg). All subjects jogged on an instrumented treadmill while a ten-camera motion analysis system collected three-dimensional kinematics of the lower extremities. The main outcome measure was sagittal plane (dorsiflexion/plantar flexion) range of motion of the ankle throughout the gait cycle. CAI subjects had significantly less dorsiflexion compared to the control group from 9% to 25% during jogging (4.83+/-0.55 degrees ). CAI subjects demonstrated limited ankle dorsiflexion ROM during the time of maximal dorsiflexion during jogging. Limited dorsiflexion ROM during gait among individuals with CAI may be a risk factor for recurrent ankle sprains. These deficits should be treated appropriately by rehabilitation clinicians.