title: Accurate determination of isthmus of lumbar pedicle: a morphometric study using reformatted computed tomographic images.
abstract: METHODS
  Lumbar pedicle isthmus, the narrowest section of pedicle, was investigated.
  
  
  OBJECTIVE
  To determine the lumbar pedicle isthmus accurately and measure related parameters.
  
  
  BACKGROUND
  Accurate anatomic knowledge of pedicle parameters is critical for a successful transpedicular procedure. Many studies on lumbar pedicle dimensions have been conducted, yet less is known about how to obtain these data and their veracity. In fact, the narrowest section is present in the pedicle, i.e., the isthmus of the pedicle. This is the bottleneck of the pedicle; to determine and measure it could illustrate the true morphologic characteristics of the lumbar pedicle.
  
  
  METHODS
  Ultra high-speed spiral CT scan of lumbar spine was performed in 41 patients of Chinese origin. After reformation of the original images, isthmus and transverse plane of pedicle axis were determined. Eleven dimensions of isthmus plane and three dimensions of transverse plane were calculated using software.
  
  
  RESULTS
  Pedicle endosteal width and height in female patients who were over the age of 50 were greater than those of female patients younger than 50 years old. The isthmus endosteal width from L1 to L5 was 5.2, 6.0, 7.5, 7.5, and 8.7 mm and 4.0, 4.1, 5.4, 5.7, and 7.1 mm, respectively, in men and women. Isthmus inclination inclined to midline with less than 10 degrees above L3 but increased in L4 and 30 degrees in L5.
  
  
  CONCLUSIONS
  An objective narrowest section, the pedicle isthmus, exists in lumbar pedicle axis. The parameters of isthmus, especially isthmus endosteal width, show the morphologic characteristics of the lumbar pedicle and are the most important data provided for transpedicular procedures. The small pedicles of female patients over the age of 50 also show certain primary osteoporosis. Isthmus inclination puts the pedicle in a more complicated space position. A better understanding of the complicated structure of the pedicle isthmus guarantees success in transpedicular procedures.
authors.affiliation: Department of Trauma & Orthopedics, People's Hospital of Peking University, Beijing, PR China.
authors.forename: Bing
authors.initials: B
authors.lastname: Li
authors.forename: Baoguo
authors.initials: B
authors.lastname: Jiang
authors.forename: Zhongguo
authors.initials: Z
authors.lastname: Fu
authors.forename: Diangying
authors.initials: D
authors.lastname: Zhang
authors.forename: Tianbing
authors.initials: T
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D000886:Anthropometry; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000000981:diagnostic imaging / Q000473:pathology; D009626:Terminology as Topic; D014057:Tomography, X-Ray Computed