Gait kinematics and kinetics in patients with chronic ankle instability and healthy controls: A statistical parametric mapping analysis.

BACKGROUND: Chronic ankle instability (CAI) is associated with changes in gait biomechanics which may be related to chronic dysfunction. Traditional statistical models may be limited in their ability to assess the complex 3D movement of the lower extremity during gait. Multivariate analysis of the lower extremity kinematics may reveal unique biomechanical differences associated with CAI.

RESEARCH QUESTION: Do patients with CAI differ from healthy controls in their lower extremity biomechanics and GRF when comparing 3D biomechanics?

METHODS: Thirty-nine young, active adults participated in this study. Data was collected using a 3D motion analysis system while patients walked and jogged. Statistical parametric mapping (SPM) was used to explore 3D GRF, kinematics and kinetics of the of the lower extremity of CAI and healthy patients.

RESULTS: During walking, patients with CAI had greater inversion from 68-100% of gait cycle (p < 0.001, mean difference=3.2°). During jogging, patients with CAI had greater inversion from 20-92% (p < 0.001, mean difference=4.6°). Greater plantar flexion moments were found from 65-71% (p = 0.05, mean difference=347.4Nm/kg) and greater eversion moments were found from 95-100% (p = 0.03, mean difference=74.6Nm/kg) in the CAI group. No differences in GRF were found.

SIGNIFICANCE: Greater inversion may present a potentially injurious position. A faulty position of the rearfoot may require greater muscle function in order to correct the position of the joint resulting in greater eversion moments at the ankle. However, this kinetic change does not appear to correct the ankle position.