Individuals with chronic ankle instability exhibit altered landing knee kinematics: Potential link with the mechanism of loading for the anterior cruciate ligament

BackgroundAlterations in sagittal plane landing biomechanics in the lower extremity have been observed within the chronic ankle instability (CAI) population. Interestingly, a potential link between the risk of anterior cruciate ligament (ACL) injury and ankle sprain history has been proposed. However, it is not known if the observed biomechanical changes associated with CAI could mimic factors related to the mechanism of ACL injury. We investigated the influence of CAI on anterior tibial shear force (ATSF), lower extremity sagittal plane kinematics, and posterior ground reaction force (GRF) in a jump landing task.MethodsNineteen participants with CAI and 19 healthy control participants performed a vertical stop jump. Peak ATSF was calculated during the first landing of the stop jump, with sagittal-plane kinematics and posterior GRF measured at peak ATSF. Independent t-tests, multiple linear regression, and Pearson bivariate correlation were used for statistical analysis.FindingsParticipants with CAI demonstrated less knee flexion at peak ATSF compared to the controls (P = .026). No group-differences were found for peak ATSF or the other biomechanical variables. Knee flexion was moderately correlated with peak ATSF (r = −0.544, P = .008); however, the contributing factor that most explained the variance in ATSF was posterior GRF (R2 = 0.449; P = .002) in the CAI group.InterpretationOur findings indicate that the CAI group may be exhibiting altered knee function during functional movement. Screening knee movement patterns in individuals with CAI may help develop preventative measures for future joint injury throughout the kinetic chain.