title: In vivo three-dimensional morphometric analysis of the lumbar pedicle isthmus.
abstract: METHODS
  In vivo noninvasive study.
  
  
  OBJECTIVE
  To properly quantify pedicle anatomic parameters, using subject-based CT three-dimensional models and compare the data from 2-dimensional transverse-CT images.
  
  
  BACKGROUND
  Accurate measurement of morphometric parameters of pedicle isthmus is important for transpedicular procedures. Anatomically, the lumbar pedicle is known to be elliptical cross-sectionally and slightly inclined in the vertical plane in the lower lumbar levels. Therefore, measurement of the pedicle isthmus may be overestimated when transverse images are used. More accurate measurement of the 3-dimensional geometry of the pedicle is therefore needed. To the best of our knowledge, 3-dimensional geometry of the pedicle has not been reported as the literature values are based on 2-dimensional image data.
  
  
  METHODS
  In vivo measurements of the lumbar pedicle isthmus were performed on the 3-dimensional subject-based CT models, using custom-developed software in 89 volunteers.
  
  
  RESULTS
  The least axis of pedicle, the longest axis of pedicle and the transverse plane width were largest at L5 in both genders. The isthmus angle declined in the lower levels. The ratio of the transverse plane width to the least axis of pedicle was largest at L5.
  
  
  CONCLUSIONS
  Our results showed that the least axis of pedicle, the longest axis of pedicle and the transverse plane width peaked at L5, and the transverse plane width became approximately twice as long in the lower levels compared to the upper levels. The ratio of the transverse plane width to the least axis of pedicle increased by about 40% at L5. These findings highlight the fact that measuring the isthmus width from CT transverse images leads to overestimation, especially in the lower lumbar spine. Therefore, a 3-dimensional inclination of the least axis of the pedicle should be taken into account for the determination of the pedicle diameter in the lower lumbar vertebrae.
authors.affiliation: Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612, USA.
authors.forename: Keizo
authors.initials: K
authors.lastname: Sugisaki
authors.forename: Howard S
authors.initials: HS
authors.lastname: An
authors.forename: Alejandro A
authors.initials: AA
authors.lastname: Espinoza Orías
authors.forename: Richard
authors.initials: R
authors.lastname: Rhim
authors.forename: Gunnar B J
authors.initials: GB
authors.lastname: Andersson
authors.forename: Nozomu
authors.initials: N
authors.lastname: Inoue
mesh_terms: D000328:Adult; D000886:Anthropometry / Q000379:methods; D001699:Biometry; D001837:Body Weights and Measures; D003951:Diagnostic Errors / Q000517:prevention & control; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008159:Lumbar Vertebrae / Q000033:anatomy & histology* / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000295:instrumentation / Q000379:methods; D011183:Postoperative Complications; D011237:Predictive Value of Tests; D012016:Reference Values; D012680:Sensitivity and Specificity; D012727:Sex Characteristics; D012984:Software; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult; D021801:Zygapophyseal Joint / Q000033:anatomy & histology / Q000601:surgery