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Unilateral Chronic Ankle Injury Affects the Kinematic Parameters of the Uninjured Ankle

Key findings

  • In 15 patients with a unilateral chronic ankle injury (CAI), this study compared the kinetic and kinematic patterns of the injured and uninjured ankles, along with comparing the biomechanical parameters of the injured ankle with 15 healthy controls
  • The uninjured ankles of patients with unilateral CAI had substantially negative biomechanical alterations compared with the uninjured control population
  • The uninjured ankles demonstrated a significantly greater degree of inversion and a significantly decreased dorsiflexion during various stages of the gait cycle than contralateral, healthy ankles in the same individuals
  • Any rehabilitation protocol should include both the unstable and stable ankles, and earlier surgery for the injured ankle may be needed to retain stability and reduce the complications on both sides

Biomechanical research on the gait parameters of patients with a unilateral chronic ankle injury (CAI) has shown substantial changes in the kinematics and kinetics of the unstable ankle compared with the uninjured contralateral ankles in those patients and bilateral ankles in healthy individuals.

Addressing a longstanding debate, researchers at Massachusetts General Hospital have found that unilateral CAI can lead to biomechanical dysfunction of the contralateral, uninjured ankle. Elaheh Ziaei Ziabari, MSc, a biomechanical engineering PhD student in the Department of Orthopaedic Surgery's Foot and Ankle Research and Innovation LabSoheil Ashkani-Esfahani, MD, director of the Lab, Christopher W. DiGiovanni, MD, chief of the Foot and Ankle Service, and colleagues report the findings and their implications for patient care in Orthopaedic Surgery.


The researchers compared two groups between November 2018 and October 2019:

  • 15 individuals (eight men, seven women; mean age, 30; age range, 18–50) diagnosed with unilateral functional CAI
  • 15 randomly selected individuals (nine men, six women; mean age, 31; age range, 18–65) with no foot and ankle abnormalities on physical examination and no history of ankle sprain or fracture

Body markers were placed on each study participant's arms, legs and torso, and motion-capture cameras were used to measure three-dimensional kinematic variables as they walked barefoot around a path at their normal speed, in their usual way.

Unstable vs. Stable Ankles Within Each Group

In the CAI group, there were several significant differences between unstable and stable ankles in biomechanical responses. The unstable ankles exhibited:

  • Significant decreases in the ankle–toe angle
  • Significant increases in inversion–eversion range of motion
  • Significant decreases in dorsiflexion positioning during the midstance phase of the gait
  • Significant decreases in inversion–eversion positioning during initial contact and terminal stance and significant increases during the pre-swing and swing phases

In the control group, there were no significant differences between ankles for any gait parameter studied.

Patients vs. Controls

When the uninjured ankles of the CAI group were compared with the right and left ankles of the control group:

  • Ankle–toe velocity and acceleration of movement during gait were significantly decreased in the CAI group
  • Dorsiplantar flexion and inversion–eversion were significantly altered in all phases of the gait cycle in the CAI group, with a tendency for plantarflexion and inversion

Treatment Implications

These data suggest any rehabilitation protocol for unilateral CAI should include both unstable and stable ankles. Earlier surgery for the injured ankle should be considered to retain stability, as delayed surgery or conservative approaches might predispose the uninjured contralateral side to progressive biomechanical deterioration, degeneration due to continuous microtraumas, and increased risk for similar stability issues and gait derangements.

Refer a patient to the Foot & Ankle Service

Learn more about Mass General's Foot and Ankle Research and Innovation Laboratory (FARIL)


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