title: Single-legged hop tests as predictors of self-reported knee function in nonoperatively treated individuals with anterior cruciate ligament injury.
abstract: BACKGROUND
  Previous studies have found significant predictors for functional outcome after anterior cruciate ligament (ACL) reconstruction; however, studies examining predictors for functional outcome in nonoperatively treated individuals are lacking.
  
  
  OBJECTIVE
  Single-legged hop tests predict self-reported knee function (International Knee Documentation Committee [IKDC] 2000) in nonoperatively treated ACL-injured individuals 1 year after baseline testing.
  
  
  METHODS
  Cohort study (prognosis); Level of evidence, 2.
  
  
  METHODS
  Ninety-one nonoperatively treated patients with an ACL injury were tested using 4 single-legged hop tests on average 74 ± 30 days after injury in a prospective cohort study. Eighty-one patients (89%) completed the IKDC 2000 1 year later. Patients with an IKDC 2000 score equal to or higher than the age- and gender-specific 15th percentile score from previously published data on an uninjured population were classified as having self-reported function within normal ranges. Logistic regression analyses were performed to identify predictors of self-reported knee function. The area under the curve (AUC) from receiver operating characteristic curves was used as a measure of discriminative accuracy. Optimal limb symmetry index (LSI) cutoff for the best single-legged hop test was defined as the LSI with the highest product of sensitivity and specificity.
  
  
  RESULTS
  Single hop for distance symmetry indexes predicted self-reported knee function at the 1-year follow-up (P = .036). Combinations of any 2 hop tests (AUC = 0.64-0.71) did not give a higher discriminative accuracy than the single hop alone (AUC = 0.71). A cutoff of 88% (LSI) for the single hop revealed a sensitivity of 71.4% and a specificity of 71.7%.
  
  
  CONCLUSIONS
  The single hop for distance (LSI) significantly predicted self-reported knee function after 1 year in nonoperatively treated ACL-injured patients. Combinations of 2 single-legged hop tests did not lead to higher discriminative accuracy than the single hop alone.
authors.affiliation: Norwegian Research Center for Active Rehabilitation, Hjelp24 Norwegian Sports Medicine Clinic, Ullevål Stadion, Norway. hege.grindem@hjelp24.no
authors.forename: Hege
authors.initials: H
authors.lastname: Grindem
authors.forename: David
authors.initials: D
authors.lastname: Logerstedt
authors.forename: Ingrid
authors.initials: I
authors.lastname: Eitzen
authors.forename: Håvard
authors.initials: H
authors.lastname: Moksnes
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Axe
authors.forename: Lynn
authors.initials: L
authors.lastname: Snyder-Mackler
authors.forename: Lars
authors.initials: L
authors.lastname: Engebretsen
authors.forename: May Arna
authors.initials: MA
authors.lastname: Risberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries; D015331:Cohort Studies; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D007717:Knee / Q000502:physiology*; D007718:Knee Injuries / Q000628:therapy; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D012372:ROC Curve; D016896:Treatment Outcome; D055815:Young Adult