title: Reliability of clinical measurement for assessing spinal fusion: an experimental sheep study.
abstract: METHODS
  A sheep study designed to compare the accuracy of static radiographs, dynamic radiographs, and computed tomographic (CT) scans for the assessment of thoracolumbar facet joint fusion as determined by micro-CT scanning.
  
  
  OBJECTIVE
  To determine the accuracy and reliability of conventional imaging techniques in identifying the status of thoracolumbar (T13-L1) facet joint fusion in a sheep model.
  
  
  BACKGROUND
  Plain radiographs are commonly used to determine the integrity of surgical arthrodesis of the thoracolumbar spine. Many previous studies of fusion success have relied solely on postoperative assessment of plain radiographs, a technique lacking sensitivity for pseudarthrosis. CT may be a more reliable technique, but is less well characterized.
  
  
  METHODS
  Eleven adult sheep were randomized to either attempted arthrodesis using autogenous bone graft and internal fixation (n = 3) or intentional pseudarthrosis (IP) using oxidized cellulose and internal fixation (n = 8). After 6 months, facet joint fusion was assessed by independent observers, using (1) plain static radiography alone, (2) additional dynamic radiographs, and (3) additional reconstructed spiral CT imaging. These assessments were correlated with high-resolution micro-CT imaging to predict the utility of the conventional imaging techniques in the estimation of fusion success.
  
  
  RESULTS
  The capacity of plain radiography alone to correctly predict fusion or pseudarthrosis was 43% and was not improved using plain radiography and dynamic radiography with also a 43% accuracy. Adding assessment by reformatted CT imaging to the plain radiography techniques increased the capacity to predict fusion outcome to 86% correctly. The sensitivity, specificity, and accuracy of static radiography were 0.33, 0.55, and 0.43, respectively, those of dynamic radiography were 0.46, 0.40, and 0.43, respectively, and those of radiography plus CT were 0.88, 0.85, and 0.86, respectively.
  
  
  CONCLUSIONS
  CT-based evaluation correlated most closely with high-resolution micro-CT imaging. Neither plain static nor dynamic radiographs were able to predict fusion outcome accurately.
authors: Queensland University of Technology Institute of Health and Biomedical Innovation, Brisbane, Queensland, Australia.
authors: Sadahiro
authors: S
authors: Sugiyama
authors: Martin
authors: M
authors: Wullschleger
authors: Kathleen
authors: K
authors: Wilson
authors: Richard
authors: R
authors: Williams
authors: Ben
authors: B
authors: Goss
mesh_terms: D000818:Animals; D001175:Arthrography / Q000379:methods*; D016025:Bone Transplantation; D005260:Female; D017102:Fracture Healing; D016268:Internal Fixators; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery*; D023421:Models, Animal; D011542:Pseudarthrosis / Q000000981:diagnostic imaging / Q000209:etiology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012756:Sheep; D013123:Spinal Fusion / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery*; D036542:Tomography, Spiral Computed; D014057:Tomography, X-Ray Computed; D055114:X-Ray Microtomography; D021801:Zygapophyseal Joint / Q000601:surgery*