Document Detail

New parameters to represent the position of the aorta relative to the spine for pedicle screw placement.
MedLine Citation:
PMID:  20127493     Owner:  NLM     Status:  MEDLINE    
Parameters of the position of the aorta in previous reports were determined for anterior surgery. This study evaluated the relative position of the aorta to the spine by new parameters, which could enhance the safety of pedicle screw placement. Three parameters were defined in a new Cartesian coordinate system. We selected an entry point of a left pedicle screw as the origin. The transverse plane was determined to include both the bases of the superior facet and to be parallel to the upper endplate of the vertebral body. A line connecting the entry points of both sides was defined as the X-axis. The angle formed by the Y-axis and a line connecting the origin and the center of the aorta was defined as the left pedicle-aorta angle. The length of a line connecting the origin and the aorta edge was defined as the left pedicle-aorta distance. Distance from the edge of the aorta to the X-axis was defined as the pedicular line-aorta distance. These parameters were measured preoperatively in 293 vertebral bodies of 24 patients with a right thoracic curve. We simulated the placement of the pedicle screw with variable length and with some direction error. We defined a warning pedicle as that when the aorta enters the expected area of the screw. Sensitivity analysis was performed to find the warning pedicle ratio in 12 scenarios. The left pedicle-aorta angle averaged 29.7 degrees at the thoracic spine and -16.3 degrees at the lumbar spine; the left pedicle-aorta distance averaged 23.7 and 55.2 mm; the pedicular line-aorta distance averaged 18.3 and 51.0 mm, respectively. The ratio of warning pedicles was consistently high at T4-5 and T10-12. When a left pedicle screw perforates an anterior/lateral wall of the vertebral body, the aorta may be at risk. These new parameters enable surgeons to intuitively understand the position of the aorta in surgical planning or in placement of a pedicle screw.
Katsushi Takeshita; Toru Maruyama; Takashi Ono; Satoshi Ogihara; Hirotaka Chikuda; Naoki Shoda; Yusuke Nakao; Ko Matsudaira; Atsushi Seichi; Kozo Nakamura
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Publication Detail:
Type:  Journal Article     Date:  2010-02-04
Journal Detail:
Title:  European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society     Volume:  19     ISSN:  1432-0932     ISO Abbreviation:  Eur Spine J     Publication Date:  2010 May 
Date Detail:
Created Date:  2010-04-21     Completed Date:  2010-07-15     Revised Date:  2011-07-28    
Medline Journal Info:
Nlm Unique ID:  9301980     Medline TA:  Eur Spine J     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  815-20     Citation Subset:  IM    
Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
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MeSH Terms
Aorta / surgery*
Bone Screws
Lumbar Vertebrae / radiography,  surgery*
Scoliosis / radiography,  surgery*
Spinal Fusion / instrumentation,  methods*
Surgery, Computer-Assisted
Thoracic Vertebrae / radiography,  surgery*

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