title: Stiff Landings Are Associated With Increased ACL Injury Risk in Young Female Basketball and Floorball Players.
abstract: Few prospective studies have investigated the biomechanical risk factors of anterior cruciate ligament (ACL) injury.
  
  
  
  To investigate the relationship between biomechanical characteristics of vertical drop jump (VDJ) performance and the risk of ACL injury in young female basketball and floorball players.
  
  
  
  Cohort study; Level of evidence, 3.
  
  
  
  At baseline, a total of 171 female basketball and floorball players (age range, 12-21 years) participated in a VDJ test using 3-dimensional motion analysis. The following biomechanical variables were analyzed: (1) knee valgus angle at initial contact (IC), (2) peak knee abduction moment, (3) knee flexion angle at IC, (4) peak knee flexion angle, (5) peak vertical ground-reaction force (vGRF), and (6) medial knee displacement. All new ACL injuries, as well as match and training exposure, were then recorded for 1 to 3 years. Cox regression models were used to calculate hazard ratios (HRs) and 95% CIs.
  
  
  
  Fifteen new ACL injuries occurred during the study period (0.2 injuries/1000 player-hours). Of the 6 factors considered, lower peak knee flexion angle (HR for each 10° increase in knee flexion angle, 0.55; 95% CI, 0.34-0.88) and higher peak vGRF (HR for each 100-N increase in vGRF, 1.26; 95% CI, 1.09-1.45) were the only factors associated with increased risk of ACL injury. A receiver operating characteristic (ROC) curve analysis showed an area under the curve of 0.6 for peak knee flexion and 0.7 for vGRF, indicating a failed-to-fair combined sensitivity and specificity of the test.
  
  
  
  Stiff landings, with less knee flexion and greater vGRF, in a VDJ test were associated with increased risk of ACL injury among young female basketball and floorball players. However, although 2 factors (decreased peak knee flexion and increased vGRF) had significant associations with ACL injury risk, the ROC curve analyses revealed that these variables cannot be used for screening of athletes.
authors.affiliation: Tampere Research Center of Sports Medicine, UKK Institute, Tampere, Finland.
authors.forename: Mari
authors.initials: M
authors.lastname: Leppänen
authors.affiliation: Tampere Research Center of Sports Medicine, UKK Institute, Tampere, Finland.
authors.forename: Kati
authors.initials: K
authors.lastname: Pasanen
authors.affiliation: Department of Health Sciences, University of Jyväskylä, Jyväskylä, Finland.
authors.forename: Urho M
authors.initials: UM
authors.lastname: Kujala
authors.affiliation: UKK Institute, Tampere, Finland.
authors.forename: Tommi
authors.initials: T
authors.lastname: Vasankari
authors.affiliation: Injury and Osteoporosis Research Center, UKK Institute, Tampere, Finland.|Medical School, University of Tampere, and Department of Orthopedics and Trauma Surgery, Tampere University Hospital, Tampere, Finland.
authors.forename: Pekka
authors.initials: P
authors.lastname: Kannus
authors.affiliation: Department of Mathematical Information Technology, University of Jyväskylä, Jyväskylä, Finland.
authors.forename: Sami
authors.initials: S
authors.lastname: Äyrämö
authors.affiliation: Oslo Sports Trauma Research Center, Norwegian School of Sports Sciences, Oslo, Norway.
authors.forename: Tron
authors.initials: T
authors.lastname: Krosshaug
authors.affiliation: Oslo Sports Trauma Research Center, Norwegian School of Sports Sciences, Oslo, Norway.
authors.forename: Roald
authors.initials: R
authors.lastname: Bahr
authors.affiliation: Department of Biology of Physical Activity, University of Jyväskylä, Jyväskylä, Finland.
authors.forename: Janne
authors.initials: J
authors.lastname: Avela
authors.affiliation: Tampere University of Applied Sciences, Tampere, Finland.
authors.forename: Jarmo
authors.initials: J
authors.lastname: Perttunen
authors.affiliation: Tampere Research Center of Sports Medicine, UKK Institute, Tampere, Finland.
authors.forename: Jari
authors.initials: J
authors.lastname: Parkkari
mesh_terms: D000293:Adolescent; D000070598:Anterior Cruciate Ligament Injuries / Q000453:epidemiology* / Q000209:etiology; D001265:Athletic Injuries / Q000453:epidemiology* / Q000209:etiology; D001490:Basketball / Q000293:injuries*; D001696:Biomechanical Phenomena; D002648:Child; D015444:Exercise; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007717:Knee / Q000502:physiology*; D015995:Prevalence; D011446:Prospective Studies; D012372:ROC Curve; D012307:Risk Factors; D055815:Young Adult
keywords: anterior cruciate ligament; basketball; biomechanics; female; floorball; screening; vertical drop jump