title: Meniscal injury after adolescent anterior cruciate ligament injury: how long are patients at risk?
abstract: BACKGROUND
  Delay of as much as 5 months between ACL injury and surgery is known to be associated with increased risk of a medial meniscal tear, but the risk of additional meniscal tear progression with a longer delay to surgery is unclear.
  
  
  OBJECTIVE
  We determined the (1) times of injury, MRI, and surgery in adolescents with ACL tears, and whether (2) timing of surgery, or (3) initial integrity of the meniscus seen on MR images predicted development of meniscal tears.
  
  
  METHODS
  We reviewed 112 adolescents who were 15 ± 1 years old (mean ± SD) (range, 11-16 years) with a torn ACL. These patients underwent surgical repair from 2005 to 2011 in a Canadian city. We compared dates of injury, MRI, and surgery. A pediatric and musculoskeletal fellowship-trained radiologist reread the MR images, and meniscal injuries were graded according to severity. This was compared with surgical findings described in the operative report.
  
  
  RESULTS
  Time after injury to MRI and surgery averaged 77 days (range, 1-377 days) and 342 days (range, 42-1637 days), respectively. Patients with new or worsened medial meniscal tears had waited longer for surgery (445 versus 290 days; p = 0.002). Bucket handle medial meniscal tears were more common in patients with surgery more than 1 year after injury than others (15 of 34 versus 14 of 75; p = 0.013). A medial meniscal tear observed on MR images was a significant covariate for a torn meniscus at surgery (relative risk, 5.7; 95% CI, 2.8-11.6). Medial meniscal survival continued to decline sharply greater than 1 year after injury.
  
  
  CONCLUSIONS
  Medial meniscal tears, especially bucket handle tears, increased steadily in frequency more than 1 year after ACL injury. Timely ACL reconstruction may be warranted to reduce the risk of further medial meniscal damage even in patients whose original injury occurred more than 1 year before.
  
  
  METHODS
  Level IV, prognostic study. See the Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Radiology and Diagnostic Imaging, University of Alberta, 2A2.42 Walter Mackenzie Health Sciences Centre, Edmonton, AB, T6G 2B7, Canada.
authors.forename: Zachary D
authors.initials: ZD
authors.lastname: Guenther
authors.forename: Vimarsha
authors.initials: V
authors.lastname: Swami
authors.forename: Sukhvinder S
authors.initials: SS
authors.lastname: Dhillon
authors.forename: Jacob L
authors.initials: JL
authors.lastname: Jaremko
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000416:Alberta; D000704:Analysis of Variance; D016118:Anterior Cruciate Ligament / Q000473:pathology / Q000601:surgery*; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction; D016009:Chi-Square Distribution; D002648:Child; D018450:Disease Progression; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000175:diagnosis / Q000209:etiology / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008592:Menisci, Tibial / Q000473:pathology; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D000070600:Tibial Meniscus Injuries; D013997:Time Factors; D061665:Time-to-Treatment