title: Correlation of posterior ligamentous complex injury and neurological injury to loss of vertebral body height, kyphosis, and canal compromise.
abstract: METHODS
  Retrospective, case-control study.
  
  
  OBJECTIVE
  The purpose of this study was to determine if thoracolumbar vertebral body collapse, translation, or canal compromise (CC) is associated with injury to the posterior ligamentous complex (PLC) or neurological elements.
  
  
  BACKGROUND
  Radiographical parameters, including loss of vertebral body height (LOVBH), vertebral body translation, local kyphosis (LK), and CC, are often used as indicators of spinal instability. The hypothesis of this study was that LOVBH greater than 50%, LK greater than 20°, translation greater than 3.5 mm, or CC greater than 50% is associated with ligamentous and neurological injury.
  
  
  METHODS
  Retrospective review of prospectively collected spinal cord injury database was performed. Inclusion criteria include consecutive patients with thoracolumbar burst fractures. Exclusion criteria include flexion-distraction injuries and pathological fractures. Computed tomographic scan measurements of the spine were performed by 2 experienced spine surgeons blinded to magnetic resonance imaging results. On magnetic resonance imaging, the supraspinous ligament, interspinous ligament, ligamentum flavum, facet joints, and disc were graded as intact, indeterminate, or disrupted. American Spinal Injury Association (ASIA) score and Frankel Scale score were recorded. Spearman correlation coefficients were calculated to evaluate relationships between vertebral body measurements, ligamentous injury, and neurological injury.
  
  
  RESULTS
  Forty-six patients were included in the study. Ten patients had kyphosis greater than 20°, 1 patient had kyphosis greater than 30°, and 9 patients had LOVBH greater than 50%. There were 34 patients with vertebral body translation greater than 3.5 mm and 15 patients with CC greater than 50%. Sixteen patients had ligamentous injury. There was a significant correlation between subjacent segment translation greater than 3.5 mm and ligamentous injury (R = 0.323, P = 0.029) and ASIA motor score (R = -0.379, P = 0.009). There was no significant correlation between ligamentous injury or neurological injury and the following threshold parameters: LOVBH greater than 50%, vertebral body kyphosis greater than 20°, caudal or cephalad interspinous widening greater than 7 mm, CC greater than 50%, and sagittal transverse ratio less than 0.48.
  
  
  CONCLUSIONS
  The results of this study indicate that LOVBH greater than 50% and LK greater than 20° are not predictive of PLC injury in thoracolumbar burst fractures. Translation greater than 3.5 mm was associated with PLC injury. The PLC and neural elements should be directly assessed with magnetic resonance imaging if there is clinical concern.
authors.affiliation: Department of Orthopaedic Surgery, Rothman Institute/Thomas Jefferson University, Philadelphia, PA, USA. kris.radcliff@rothmaninstitute.com
authors.forename: Kristen
authors.initials: K
authors.lastname: Radcliff
authors.forename: Brian W
authors.initials: BW
authors.lastname: Su
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Kepler
authors.forename: Todd
authors.initials: T
authors.lastname: Rubin
authors.forename: Adam L
authors.initials: AL
authors.lastname: Shimer
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Rihn
authors.forename: James A
authors.initials: JA
authors.lastname: Harrop
authors.forename: Todd J
authors.initials: TJ
authors.lastname: Albert
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Vaccaro
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000175:diagnosis / Q000209:etiology*; D017843:Ligamentum Flavum / Q000000981:diagnostic imaging / Q000293:injuries* / Q000473:pathology; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D015143:Philadelphia; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013115:Spinal Canal / Q000000981:diagnostic imaging / Q000473:pathology; D013119:Spinal Cord Injuries / Q000175:diagnosis / Q000209:etiology*; D016103:Spinal Fractures / Q000150:complications* / Q000175:diagnosis; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries* / Q000473:pathology; D014057:Tomography, X-Ray Computed