title: Alterations in knee kinematics and dynamic stability associated with chronic ankle instability.
abstract: BACKGROUND
  Chronic ankle instability (CAI) has been previously and separately associated with deficits in dynamic stability and proximal joint neuromuscular alterations, but how the 2 factors relate is unclear.
  
  
  OBJECTIVE
  To examine the contributions of lower extremity kinematics during an assessment of dynamic stability in participants with CAI.
  
  
  METHODS
  Repeated-measures case-control design.
  
  
  METHODS
  Research laboratory.
  
  
  METHODS
  Thirty-eight volunteers were categorized into groups of those with unilateral CAI (10 men, 9 women; age = 20.3 +/- 2.9 years, height = 1.77 +/- 0.1 m, mass = 76.19 +/- 13.19 kg) and those without (10 men, 9 women; age = 23.1 +/- 3.9 years, height = 1.72 +/- 0.1 m, mass = 72.67 +/- 16.0 kg).
  
  
  METHODS
  Participants performed 10 jump landings on each limb with a rest period between test limbs.
  
  
  METHODS
  Ankle plantar flexion, knee flexion, and hip flexion were captured with an electromagnetic tracking device at the point of ground impact. Ground reaction force data were used to calculate time to stabilization in the anteroposterior and mediolateral planes.
  
  
  RESULTS
  For the anteroposterior plane, we found a group-by-side interaction (P = .003), with the injured side of the CAI group demonstrating reduced dynamic stability. For knee flexion, a group main effect (P = .008) showed that the CAI group landed with less knee flexion than the control group.
  
  
  CONCLUSIONS
  Diminished dynamic stability and decreased knee flexion angle at initial contact were apparent in the CAI group and may play a role in contributing to CAI. This altered kinematic pattern may influence preventive and therapeutic interventions for those with CAI.
authors: The University of Toledo, Toledo, OH 43606, USA. phillip.gribble@utoledo.edu
authors: Phillip A
authors: PA
authors: Gribble
authors: Richard H
authors: RH
authors: Robinson
mesh_terms: D000328:Adult; D016512:Ankle Injuries / Q000209:etiology*; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D002908:Chronic Disease; D016001:Confidence Intervals; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D007537:Isometric Contraction; D007593:Joint Instability / Q000209:etiology*; D008297:Male; D018482:Muscle, Skeletal; D010865:Pilot Projects; D011187:Posture; D012307:Risk Factors