title: Pedicle morphometry of upper thoracic vertebrae: an anatomic study of 503 cadaveric specimens.
abstract: METHODS
  An anatomic study of pedicle dimensions was performed for upper thoracic vertebrae from American human subjects.
  
  
  OBJECTIVE
  To quantify the dimensions of the upper thoracic pedicles and to better define the demographic factors that could ultimately govern the caliber selection of pedicle screws.
  
  
  BACKGROUND
  Transpedicular screw fixation allows for segmental instrumentation into multiple vertebrae across multilevel fusion area, offering considerable biomechanical advantage over the conventional hook and lateral mass fixation. Large variations in morphology from previous studies may be related to differences in demographics, sample size, and methodology.
  
  
  METHODS
  For this study, T1-T6 vertebrae from 503 American human cadavers were directly measured with a digital caliper. Examiner measured each vertebra to determine medial-lateral pedicle width and cranial-caudal pedicle height. Demographic information regarding age, sex, and race, as well as body height and weight, was available for all 503 subjects.
  
  
  RESULTS
  Pedicle height generally increased in size caudally down the upper thoracic spine, but the highest pedicle height was at the T3 level with a mean of 12.25 mm. Pedicle width displayed a narrowing pattern moving down. The widest pedicle width was at the T1 level with a mean of 8.66 mm. The 2 older age groups had larger pedicles than the 2 younger age groups. Males have larger pedicles than females for all upper thoracic levels. The tallest and heaviest groups had larger pedicles than the shorter and lighter groups, respectively. Race was not a significant factor in affecting pedicle dimension.
  
  
  CONCLUSIONS
  Our large-scale study of American specimens characterized the relationship between pedicle dimensions and a variety of demographic factors such as age, sex, body height, and weight. With substantial statistical power, this study showed that male, older, taller, and heavier individuals had larger pedicles.
  
  
  METHODS
  N/A.
authors.affiliation: *Case Western Reserve University School of Medicine, Cleveland, OH †Department of Orthopedic Surgery, University of South Alabama School of Medicine, Mobile, AL ‡Department of Orthopedic Surgery and Rehabilitation, Yale University School of Medicine, New Haven, CT §New Hampshire NeuroSpine Institute, Bedford, NH; and ¶Department of Orthopedic Surgery, University Hospitals Case Medical Center, Cleveland, OH.
authors.forename: Charles C
authors.initials: CC
authors.lastname: Yu
authors.forename: Navkirat S
authors.initials: NS
authors.lastname: Bajwa
authors.forename: Jason O
authors.initials: JO
authors.lastname: Toy
authors.forename: Uri M
authors.initials: UM
authors.lastname: Ahn
authors.forename: Nicholas U
authors.initials: NU
authors.lastname: Ahn
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012727:Sex Characteristics; D013904:Thoracic Vertebrae / Q000033:anatomy & histology*; D055815:Young Adult