title: Intrinsic functional deficits associated with increased risk of ankle injuries: a systematic review with meta-analysis.
abstract: BACKGROUND
  A history of ankle injury is known to be associated with an increased risk of future injuries. Prevention of a first-time injury to an ankle will also prevent subsequent re-injury; yet these participants are often overlooked in reports of preventive testing. Determining the functional deficits which promote injury risk in all ankles, through studies inclusive of previously injured and never injured ankles, will enable training to be directed at improving known deficits in all sports participants.
  
  
  OBJECTIVE
  To review studies investigating the measurement of intrinsic functions in healthy ankles and assess their predictive value for injury.
  
  
  METHODS
  Systematic review and meta-analysis of journal articles from selected electronic databases. Using all papers that included sufficient data for extraction in any paradigm, the authors pooled results for measures of strength, postural control, proprioception, muscle reaction time in response to perturbation, range of movement and ligament stability.
  
  
  RESULTS
  Thirteen papers were found with adequate data reporting to allow calculation of pooled standardised mean difference (SMD) or pooled RR. The following are all associated with an increased risk of ankle injury: higher postural sway (SMD=0.693, 95% CI=0.151 to 1.235, p=0.012), being in the lower postural stability group (RR=2.06, 95% CI=1.364 to 3.111, p=0.001), lower inversion proprioception (0.573, 0.244 to 0.902, <0.001), higher concentric plantar flexion strength at faster speeds (0.372, 0.092 to 0.652, 0.009) and lower eccentric eversion strength at slower speeds (0.337, 0.117 to 0.557, 0.003).
  
  
  CONCLUSIONS
  There is a set of intrinsic functional and structural ankle deficits associated with significantly increased risk of ankle injury. These findings will enable clinicians and sports trainers to measure and train specific deficits in sports people for the prevention of ankle injury.
authors.affiliation: Department of Physical Therapies, Australian Institute of Sport, Leverier Crescent, Australian Capital Territory 2617, Canberra, Australia. jeremy.witchalls@ausport.gov.au
authors.forename: Jeremy
authors.initials: J
authors.lastname: Witchalls
authors.forename: Peter
authors.initials: P
authors.lastname: Blanch
authors.forename: Gordon
authors.initials: G
authors.lastname: Waddington
authors.forename: Roger
authors.initials: R
authors.lastname: Adams
mesh_terms: D016512:Ankle Injuries / Q000209:etiology* / Q000503:physiopathology; D001265:Athletic Injuries / Q000209:etiology*; D015982:Bias; D056228:Feedback, Sensory / Q000502:physiology; D006801:Humans; D007593:Joint Instability / Q000209:etiology / Q000503:physiopathology; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D011187:Posture / Q000502:physiology; D011434:Proprioception / Q000502:physiology; D012307:Risk Factors; D055502:Secondary Prevention; D013180:Sprains and Strains / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology