title: The anteromedial tibial rim sign: an indicator of patellotibial impaction in acute anterior cruciate ligament tears.
abstract: OBJECTIVE
  We have encountered unexplained anteromedial tibial rim edema in acute anterior cruciate ligament (ACL) tears. Our goal was to determine the incidence, internal derangements, and mechanism of injury in patients with anteromedial tibial rim edema (rim sign).
  
  
  METHODS
  A retrospective review of ACL tears diagnosed by magnetic resonance imaging over 7 years was performed. Patients were dichotomized into those with and without a rim sign.
  
  
  RESULTS
  There were 132 acute ACL tears. Individuals with a rim sign (31, 23%) had more contusions, fractures, ligament tears (P < 0.001), posterolateral corner injuries (P = 0.001), and posterior horn lateral meniscus tears (P = 0.042) than those without. Five individuals demonstrated edema in the inferior patella, consistent with patellotibial impaction.
  
  
  CONCLUSIONS
  The rim sign is common in ACL tears, indicating greater internal derangement. The rim sign represents patellotibial impaction with edema rarely present in the patella.
authors.affiliation: From the Department of Radiology, University of Cincinnati Medical Center, Cincinnati, OH.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Wissman
authors.forename: Eric
authors.initials: E
authors.lastname: England
authors.forename: Kaushal
authors.initials: K
authors.lastname: Mehta
authors.forename: Michael
authors.initials: M
authors.lastname: Burch
authors.forename: Ariyan
authors.initials: A
authors.lastname: Javadi
authors.forename: Keith
authors.initials: K
authors.lastname: Newton
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016118:Anterior Cruciate Ligament / Q000473:pathology*; D000070598:Anterior Cruciate Ligament Injuries; D003288:Contusions / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010329:Patella / Q000293:injuries* / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013977:Tibia / Q000293:injuries* / Q000473:pathology; D055815:Young Adult