title: Thoracic pedicle morphometry in vertebrae from scoliotic spines.
abstract: METHODS
  A morphometric analysis of thoracic pedicles in vertebrae from scoliotic specimens.
  
  
  OBJECTIVE
  The objective of this study was to quantify the changes occurring in thoracic pedicles affected by a scoliotic deformity.
  
  
  BACKGROUND
  There exists a lot of controversy in the literature concerning the shape and size of thoracic pedicles in idiopathic scoliosis. In recent years, thoracic pedicle screws are being used more frequently in corrective spine surgery, but few studies have evaluated the morphology of scoliotic thoracic pedicles.
  
  
  METHODS
  Thirty scoliotic specimens with curves presenting various degrees of severity were studied using a three-dimensional digitizing protocol developed to create a precise three-dimensional reconstruction of the vertebrae. Twenty-two parameters describing specifically the pedicles were then calculated for each vertebra from these reconstructions. Every scoliotic specimen was then matched with a normal specimen to provide for a representative control group and comparisons were made on pedicle width, length, height, surface, and orientation.
  
  
  RESULTS
  A total of 683 thoracic vertebrae were measured (325 scoliotic and 358 normal vertebrae). Pedicles located on the concavity of typical right thoracic curves were found to be significantly thinner than their normal counterparts with a maximal mean difference of 1.37 mm at T8. The pedicles on the concavity of the high thoracic compensatory curve were also found to be significantly diminished with a maximal mean difference of 1.68 mm at T4. Mean left pedicle width at T8 (concavity) and mean right pedicle width at T4 (concavity) were found to be 4.08 mm and 2.60 mm, respectively. Pedicle length was found to be slightly increased, and pedicle height was found to be slightly decreased in pedicles from scoliotic spines with no preference for concavity or convexity. Pedicle orientation and inclination were unchanged with respect to each corresponding vertebral body.
  
  
  CONCLUSIONS
  These results are of critical importance for clinicians performing spinal corrective surgery in patients with AIS. Pedicle width is significantly diminished on the concavity of scoliotic curves. Our results advocate caution in the use of pedicle screws in the thoracic spine especially on the concave side of the curve.
authors.affiliation: Laboratoire Informatique sur la Scoliose 3-D, Centre de Recherche, Hôpital Ste-Justine, Montréal, Québec, Canada. parent97@sympatico.ca
authors.forename: Stefan
authors.initials: S
authors.lastname: Parent
authors.forename: Hubert
authors.initials: H
authors.lastname: Labelle
authors.forename: Wafa
authors.initials: W
authors.lastname: Skalli
authors.forename: Jacques
authors.initials: J
authors.lastname: de Guise
mesh_terms: D000328:Adult; D001863:Bone Screws; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D012600:Scoliosis / Q000473:pathology*; D013904:Thoracic Vertebrae / Q000033:anatomy & histology*