title: Tram-track appearance of the posterior cruciate ligament (PCL): correlations with mucoid degeneration, ligamentous stability, and differentiation from PCL tears.
abstract: OBJECTIVE
  The purpose of our study was to describe the MRI findings in the posterior cruciate ligament (PCL) analogous to mucoid degeneration in the anterior cruciate ligament (ACL); to correlate MRI findings in the PCL with ligamentous stability; to differentiate the PCL tram-track appearance from the appearance of PCL tears; and to emphasize the coexistence of PCL and ACL mucoid degeneration, cruciate ganglia, and meniscal cysts.
  
  
  CONCLUSIONS
  The tram-track PCL appearance commonly coexists with ACL mucoid degeneration; ganglia; and, less frequently, meniscal cysts. Both PCL tears and MRI findings suggestive of PCL mucoid degeneration show ligament thickening and increased PCL signal intensity. Tram-track PCLs are usually asymptomatic and typically have no ligamentous instability.
authors.affiliation: Department of Radiology, Duke University Health System, Box 3808, Durham, NC 27710, USA. jscottmcm@gmail.com
authors.forename: J Scott
authors.initials: JS
authors.lastname: McMonagle
authors.forename: Clyde A
authors.initials: CA
authors.lastname: Helms
authors.forename: William E
authors.initials: WE
authors.lastname: Garrett
authors.forename: Emily N
authors.initials: EN
authors.lastname: Vinson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000070598:Anterior Cruciate Ligament Injuries; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016119:Posterior Cruciate Ligament / Q000293:injuries*; D012189:Retrospective Studies