title: Dural ossification associated with ossification of ligamentum flavum in the thoracic spine: a retrospective analysis.
abstract: To investigate the incidence, distribution and radiological characteristics of dural ossification (DO) associated with ossification of ligamentum flavum (OLF) in the thoracic spine.
  
  
  
  A retrospective radiographical analysis.
  
  
  
  This study was conducted at a single institution in China.
  
  
  
  53 patients with OLF who underwent posterior decompression surgery between January 2011 and July 2015 in a single institution were enrolled in this study. The decompression segments were grouped according to imaging evaluation and intraoperative evidences.
  
  
  
  The demographic distribution, radiological data and detailed surgical records were collected. First, preoperative CT images of decompressed segments were evaluated to identify imaging signs of DO. The 'tram tack sign' (TTS), 'comma sign' and 'bridge sign' were considered as characteristic imaging findings of DO in OLF. 4 kinds of confusing signs (false TTS) were identified and excluded. Then detailed surgical records were reviewed to finally identify segments with DO.
  
  
  
  The incidence of DO in patients with OLF was 43.4%. The incidence of DO in OLF segments was 21.5%. OLF was more common in the lower thoracic spine, and more than half (53.8%) of the DO was located in T9-T12. TTS was the most common sign, but it might be misdiagnosed. After excluding 4 kinds of false TTS, the sensitivity and specificity of imaging diagnosis were 94.23% and 94.21%, respectively.
  
  
  
  DO was relatively common in thoracic OLF, especially in T9-T12. TTS might be misdiagnosed. After excluding 4 kinds of false TTS, the accuracy of imaging diagnosis was relatively high.
authors.affiliation: Department of Orthopaedic Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Orthopaedic Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Guixing
authors.initials: G
authors.lastname: Qiu
authors.affiliation: Department of Trauma & Orthopaedic Surgery, Hillingdon Hospital, London, UK.
authors.forename: Shigong
authors.initials: S
authors.lastname: Guo
authors.affiliation: Department of Orthopaedic Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Orthopaedic Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Orthopaedic Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Huiming
authors.initials: H
authors.lastname: Peng
authors.affiliation: Department of Orthopaedic Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Chu
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Orthopaedic Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D000328:Adult; D000368:Aged; D002681:China; D019299:Decompression, Surgical; D004388:Dura Mater / Q000473:pathology*; D005260:Female; D006801:Humans; D015994:Incidence; D017843:Ligamentum Flavum / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology*; D010012:Osteogenesis; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013116:Spinal Cord / Q000473:pathology*; D013118:Spinal Cord Diseases / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology*; D013904:Thoracic Vertebrae; D014057:Tomography, X-Ray Computed
keywords: Dural ossification; Ossification of ligamentum flavum; Thoracic spine; imaging signs