title: Individuals with an anterior cruciate ligament-deficient knee classified as noncopers may be candidates for nonsurgical rehabilitation.
abstract: METHODS
  Prospective cohort study.
  
  
  OBJECTIVE
  First, to classify a group of individuals with an anterior cruciate ligament (ACL)-deficient knee as potential copers or potential noncopers, based on an established screening examination. Second, to prospectively follow a cohort of individuals with an ACL injury and characterize the nonoperatively treated subjects as true copers and true noncopers 1 year after injury, and evaluate the outcomes in operatively treated individuals 1 year after ACL reconstruction. Finally, to calculate the predictive value of the screening examination based on a 1-year follow-up of the group of subjects with ACL tears treated nonoperatively.
  
  
  BACKGROUND
  A screening examination has been developed for early classification of individuals with ACL injuries. Potential copers have successfully been identified as rehabilitation candidates and have shown that they are able to continue preinjury activities without ACL reconstruction (true copers). However, the potential of individuals identified as noncopers to become true copers has not been studied.
  
  
  METHODS
  One hundred and twenty-five subjects with ACL injury were evaluated using a screening examination consisting of 4 single-legged hop tests, the Knee Outcome Survey activities of daily living scale, the global rating of knee function, and the numbers of episodes of giving way. Knee laxity measurements, the international knee documentation committee subjective knee form (IKDC2000), and return to sport were included as outcome measurements.
  
  
  RESULTS
  Thirty-seven percent (n = 46) of the subjects with ACL injury were classified as potential copers at the screening examination. Of the 102 subjects examined at follow-up, 51% (n = 52) had undergone nonoperative treatment. Sixty-five percent (n = 34) of the nonoperated subjects were classified as true copers at the 1 year follow-up. Among the potential copers, 60% were true copers, while 70% of the subjects initially classified as potential noncopers were true copers at the 1 year follow-up. The positive predictive value for correctly classifying true copers at the screening examination was 60% (95% confidence interval: 41%-78%), while the negative predictive value was 30% (95% confidence interval: 16%-49%).
  
  
  CONCLUSIONS
  A majority (70%) of subjects classified as potential noncopers were true copers after 1 year of nonoperative treatment. Individuals with nonoperative treatment and ACL reconstruction showed excellent knee function and were highly active at the 1 year follow-up. The prognostic accuracy of this screening examination for correctly classifying true copers was poor.
authors.affiliation: NAR, Orthopedic Center, Ullevaal University Hospital, Oslo, Norway. havard.moksnes@nimi.no
authors.forename: Håvard
authors.initials: H
authors.lastname: Moksnes
authors.forename: Lynn
authors.initials: L
authors.lastname: Snyder-Mackler
authors.forename: May Arna
authors.initials: MA
authors.lastname: Risberg
mesh_terms: D000222:Adaptation, Physiological; D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000503:physiopathology; D000070598:Anterior Cruciate Ligament Injuries; D004185:Disability Evaluation; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007718:Knee Injuries / Q000503:physiopathology / Q000534:rehabilitation*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity