title: Hip Muscle Strength Predicts Noncontact Anterior Cruciate Ligament Injury in Male and Female Athletes: A Prospective Study.
abstract: BACKGROUND
  Prospective studies have reported that abnormal movement patterns at the trunk, hip, and knee are associated with noncontact anterior cruciate ligament (ACL) injuries. Impaired hip strength may underlie these abnormal movement patterns, suggesting that diminished hip strength may increase the risk of noncontact ACL injury.
  
  
  OBJECTIVE
  To determine whether baseline hip strength predicts future noncontact ACL injury in athletes.
  
  
  METHODS
  Case-control study; Level of evidence, 3.
  
  
  METHODS
  Before the start of the competitive season, isometric hip strength (external rotation and abduction) was measured bilaterally by use of a handheld dynamometer in 501 competitive athletes (138 female and 363 male athletes) participating in various sports. During the sport season, ACL injury status was recorded, and injured athletes were further classified based on the mechanism of injury (noncontact vs contact). After the season, logistic regression was used to determine whether baseline hip strength predicted future noncontact ACL injury. Receiver operating characteristic (ROC) curves were constructed independently for each strength measure to determine the clinical cutoff value between a high-risk and low-risk outcome.
  
  
  RESULTS
  A total of 15 noncontact ACL injuries were confirmed (6 females, 9 males), for an overall annual incidence of 3.0% (2.5% for males, 4.3% for females). Baseline hip strength measures (external rotation and abduction) were significantly lower in injured athletes compared with noninjured athletes (P = .003 and P < .001, respectively). Separate logistic regression models indicated that impaired hip strength increased future injury risk (external rotation: odds ratio [OR] = 1.23 [95% CI, 1.08-1.39], P = .001; abduction: OR = 1.12 [95% CI, 1.05-1.20], P = .001). Clinical cutoffs to define high risk were established as external rotation strength ≤20.3% BW (percentage of body weight) or abduction strength ≤35.4% BW.
  
  
  CONCLUSIONS
  Measures of preseason isometric hip abduction and external rotation strength independently predicted future noncontact ACL injury status in competitive athletes. The study data suggest that screening procedures to assess ACL injury risk should include an assessment of isometric hip abduction and/or external rotation strength.
authors.affiliation: College of Sport Sciences, University of Isfahan, Isfahan, Iran.
authors.forename: Khalil
authors.initials: K
authors.lastname: Khayambashi
authors.affiliation: College of Sport Sciences, University of Isfahan, Isfahan, Iran.
authors.forename: Navid
authors.initials: N
authors.lastname: Ghoddosi
authors.affiliation: Musculoskeletal Biomechanics Research Laboratory, Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, California, USA.
authors.forename: Rachel K
authors.initials: RK
authors.lastname: Straub
authors.affiliation: Musculoskeletal Biomechanics Research Laboratory, Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, California, USA powers@usc.edu.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Powers
mesh_terms: D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries; D056352:Athletes; D001265:Athletic Injuries / Q000453:epidemiology* / Q000503:physiopathology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000453:epidemiology* / Q000209:etiology; D007719:Knee Joint / Q000503:physiopathology; D016015:Logistic Models; D008297:Male; D009068:Movement; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000293:injuries* / Q000503:physiopathology; D009135:Muscular Diseases; D016017:Odds Ratio; D011446:Prospective Studies; D012399:Rotation; D017695:Soft Tissue Injuries / Q000453:epidemiology* / Q000503:physiopathology; D014481:United States / Q000453:epidemiology
keywords: anterior cruciate ligament (ACL) injury; hip abduction strength; hip external rotation strength; knee injury prevention; noncontact; prospective study