title: The impact of previous knee injury on force plate and field-based measures of balance.
abstract: BACKGROUND
  Individuals with post-traumatic osteoarthritis demonstrate increased sway during quiet stance. The prospective association between balance and disease onset is unknown. Improved understanding of balance in the period between joint injury and disease onset could inform secondary prevention strategies to prevent or delay the disease. This study examines the association between youth sport-related knee injury and balance, 3-10years post-injury.
  
  
  METHODS
  Participants included 50 individuals (ages 15-26years) with a sport-related intra-articular knee injury sustained 3-10years previously and 50 uninjured age-, sex- and sport-matched controls. Force-plate measures during single-limb stance (center-of-pressure 95% ellipse-area, path length, excursion, entropic half-life) and field-based balance scores (triple single-leg hop, star-excursion, unipedal dynamic balance) were collected. Descriptive statistics (mean within-pair difference; 95% confidence intervals) were used to compare groups. Linear regression (adjusted for injury history) was used to assess the relationship between ellipse-area and field-based scores.
  
  
  RESULTS
  Injured participants on average demonstrated greater medio-lateral excursion [mean within-pair difference (95% confidence interval); 2.8mm (1.0, 4.5)], more regular medio-lateral position [10ms (2, 18)], and shorter triple single-leg hop distances [-30.9% (-8.1, -53.7)] than controls, while no between group differences existed for the remaining outcomes. After taking into consideration injury history, triple single leg hop scores demonstrated a linear association with ellipse area (β=0.52, 95% confidence interval 0.01, 1.01).
  
  
  CONCLUSIONS
  On average the injured participants adjusted their position less frequently and demonstrated a larger magnitude of movement during single-limb stance compared to controls. These findings support the evaluation of balance outcomes in the period between knee injury and post-traumatic osteoarthritis onset.
authors.affiliation: Human Performance Laboratory (HPL), Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada. Electronic address: jbaltich@ucalgary.ca.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Baltich
authors.affiliation: Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Canada; The Alberta Children's Hospital Research Institute for Child and Maternal Health, Cumming School of Medicine, University of Calgary, Calgary, Canada.
authors.forename: Jackie
authors.initials: J
authors.lastname: Whittaker
authors.affiliation: Human Performance Laboratory (HPL), Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Vinzenz
authors.initials: V
authors.lastname: Von Tscharner
authors.affiliation: Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Canada; The Alberta Children's Hospital Research Institute for Child and Maternal Health, Cumming School of Medicine, University of Calgary, Calgary, Canada; Department of Pediatrics and Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, Canada.
authors.forename: Alberto
authors.initials: A
authors.lastname: Nettel-Aguirre
authors.affiliation: Human Performance Laboratory (HPL), Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Benno M
authors.initials: BM
authors.lastname: Nigg
authors.affiliation: Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Canada; The Alberta Children's Hospital Research Institute for Child and Maternal Health, Cumming School of Medicine, University of Calgary, Calgary, Canada.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Emery
mesh_terms: D000293:Adolescent; D000328:Adult; D000886:Anthropometry; D001265:Athletic Injuries / Q000503:physiopathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000503:physiopathology*; D008137:Longitudinal Studies; D008297:Male; D009068:Movement; D053580:Muscle Strength; D010003:Osteoarthritis / Q000503:physiopathology*; D004856:Postural Balance; D011446:Prospective Studies; D013177:Sports; D055815:Young Adult; D000067009:Youth Sports
keywords: Balance; Knee injury; Osteoarthritis; Star excursion balance test; Triple single leg hop