title: Relationships between posterior ligamentous complex injury and radiographic parameters in patients with thoracolumbar burst fractures.
abstract: BACKGROUND
  The purpose of this study was to determine whether radiographic findings associated with thoracolumbar burst fractures could also indicate the presence of posterior ligamentous complex (PLC) injuries, which were identified through short-tau inversion-recovery (STIR)-weighted MRI.
  
  
  METHODS
  Sixty-four patients were surgically treated for thoracolumbar burst fractures between April 2007 and February 2014 at our institution. Twenty-four patients were excluded from this study because of the lack of STIR-weighted MRIs, and therefore 40 patients were included in this study. The patients were divided into two groups based upon the integrity of the PLC, which was evaluated using STIR-weighted MRI: a P group with a PLC injury and a C group without such injury. The following radiographic parameters were evaluated: loss of vertebral body height (LOVBH), local kyphosis (LK), vertebral body translation, canal compromise (sagittal transverse ratio, STR), interlaminar distance (ISD), supraspinous distance (SSD) and interspinous distance (ISD). Frankel scale score and total severity score (load sharing and thoracolumbar injury classification systems, respectively) were also evaluated.
  
  
  RESULTS
  Preoperative STIR-weighted MRI showed that 25 patients had a PLC injury (P group: 15 men and 10 women), and 15 patients did not have a PLC injury (C group: 8 men and 7 women). More patients in the P group had an LK>20°: 14 patients in the P group and 1 patient in the C group (p<0.01). The % SSD differed between the P and C groups (118.8%±53.4% and 88.0%±24.3%, respectively; p<0.05). Multivariate logistic analysis showed that an LK>20° was a risk factor for PLC injury in patients with thoracolumbar burst fractures (odds ratio, 55.5 [95% confidence interval, 1.30-2360.1]; p<0.05).
  
  
  CONCLUSIONS
  These results demonstrate that while LOVBH, vertebral body translation, and canal compromise do not correlate significantly with the presence of a PLC injury in patients with thoracolumbar fractures, an LK>20° and increased % SSD are associated with a PLC injury.
authors.affiliation: Department of Orthopaedic Surgery, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan. Electronic address: a.hiyama@tokai-u.jp.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Hiyama
authors.affiliation: Department of Orthopaedic Surgery, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan. Electronic address: masahiko@is.icc.u-tokai.ac.jp.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Watanabe
authors.affiliation: Department of Orthopaedic Surgery, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan. Electronic address: hero@tokai-u.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Katoh
authors.affiliation: Department of Orthopaedic Surgery, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan. Electronic address: sato-m@is.icc.u-tokai.ac.jp.
authors.forename: Masato
authors.initials: M
authors.lastname: Sato
authors.affiliation: Department of Orthopaedic Surgery, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan. Electronic address: zavi127@is.icc.u-tokai.ac.jp.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Nagai
authors.affiliation: Department of Orthopaedic Surgery, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan. Electronic address: jomo@is.icc.u-tokai.ac.jp.
authors.forename: Joji
authors.initials: J
authors.lastname: Mochida
mesh_terms: D005260:Female; D006801:Humans; D007738:Kyphosis / Q000209:etiology / Q000473:pathology*; D017843:Ligamentum Flavum / Q000000981:diagnostic imaging / Q000293:injuries / Q000473:pathology*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011859:Radiography; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D016103:Spinal Fractures / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D013904:Thoracic Vertebrae / Q000473:pathology* / Q000601:surgery
keywords: Computed tomography; Load sharing classification; Local kyphosis; Posterior ligamentous complex; Short-tau inversion-recovery weighted MR image; Stability; Thoracolumbar burst fracture; Thoracolumbar injury classification system