title: Risk factors for recurrent anterior cruciate ligament reconstruction: a population study in Ontario, Canada, with 5-year follow-up.
abstract: BACKGROUND
  Anterior cruciate ligament reconstruction (ACLR) is routinely performed for symptomatic instability. Although it is a common procedure, there remain differences in surgical technique. Hospital administrative records in a public health care system were used to investigate the effect of patient, provider, and surgical factors on the risk of revision ACLR.
  
  
  OBJECTIVE
  To define the rate and risk factors for ACL reoperation in Ontario, Canada, including both ipsilateral revision and contralateral primary procedures.
  
  
  METHODS
  Cohort study; Level of evidence, 3.
  
  
  METHODS
  All primary elective ACLR procedures performed in Ontario (July 2003 to March 2008) in patients aged 15 to 60 years were identified via physician billing and hospital databases. Revision and contralateral ACLR were sought until January 2012. Patient factors (age, sex, comorbidity, income quintile, length of index hospital admission), provider factors (surgeon volume, academic hospital status), and surgical factors (allograft vs autograft; fixation type [screw, button, staple]; concomitant operative procedures) were used as covariates in a Cox proportional hazards survivorship model to generate hazard ratios (HRs) with confidence intervals (CIs) (α = .05). Kaplan-Meier survivorship curves with ACL revision as the end point were generated.
  
  
  RESULTS
  A total of 12,967 ACLR procedures with a mean follow-up of 5.2 years were eligible for study using preset criteria. The revision rate was 2.6% (mean ± SD, 2.91 ± 1.71 years to revision). The rate of primary contralateral ACLR was 4.6% (mean, 2.95 ± 1.81 years). In the Cox model, younger age (15-19 years) (HR, 2.1; 95% CI, 1.5-2.9; P < .001), ACLR performed at an academic hospital (HR, 1.6; 95% CI, 1.2-2.1; P < .001), and the use of allograft (HR, 1.7; 95% CI, 1.1-2.6; P = .02) significantly increased the risk of revision ACLR. Only younger age (HR, 2.1; 95% CI, 1.6-2.7; P < .001) was associated with an increased risk of contralateral ACLR.
  
  
  CONCLUSIONS
  Contralateral ACLR was more frequent than revision ACLR in this population, while both surgical procedures were most common in patients younger than 20 years. Academic hospital status, but not surgeon volume, as well as the use of allograft also increased the risk for revision ACLR.
authors.affiliation: University of Toronto Orthopaedic Sports Medicine (UTOSM) at Women’s College Hospital, Toronto, Ontario, Canada. david.wasserstein@mail.utoronto.ca
authors.forename: David
authors.initials: D
authors.lastname: Wasserstein
authors.forename: Amir
authors.initials: A
authors.lastname: Khoshbin
authors.forename: Tim
authors.initials: T
authors.lastname: Dwyer
authors.forename: Jaskarndip
authors.initials: J
authors.lastname: Chahal
authors.forename: Rajiv
authors.initials: R
authors.lastname: Gandhi
authors.forename: Nizar
authors.initials: N
authors.lastname: Mahomed
authors.forename: Darrell
authors.initials: D
authors.lastname: Ogilvie-Harris
mesh_terms: D000293:Adolescent; D000328:Adult; D059549:Anterior Cruciate Ligament Reconstruction / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D011183:Postoperative Complications / Q000453:epidemiology / Q000601:surgery*; D016016:Proportional Hazards Models; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D017211:Treatment Failure; D055815:Young Adult
keywords: anterior cruciate ligament; contralateral; population cohort; revision; risk factors