Morphology of the atlas pedicle revisited: a morphometric CT-based study on 120 patients.
OBJECTIVE
To quantify the dimensions of the atlas pedicles and to analyze the relationship between extra medullary height (EMH) with intra medullary height (IMH) of the atlas pedicle.


METHODS
The images of the patients who had CT scanning and three-dimensional (3D) reconstruction involving atlantoaxial complex between June 2011 and April 2012 and meet our inclusion criteria were studied retrospectively. After reformatting the original images, the EMH and IMH of the atlas pedicles were measured.


RESULTS
Extra medullary height and IMH were, respectively, 4.83 ± 1.13 and 1.29 ± 1.10 mm for males and 3.75 ± 0.93 and 0.60 ± 0.83 mm for females, with statistical difference (P < 0.05). EMH and IMH had some correlation (correlation coefficient r = 0.804) but showed a large variability. Of 240 pedicles of 120 cases, 47.92% (115 pedicles) were ≥1 mm; 12.08% (29 pedicles) were between 0 and 1 mm; and 40% (96 pedicles) were 0.


CONCLUSIONS
The EMH and the IMH of the atlas pedicles were measured by using CT images of the atlas, providing anatomic parameters for surgery. They showed a certain correlation but with a high variability. C1 pedicle screw fixation was well performed when the medullary canal was ≥1 mm, but the surgical procedure should be careful when it was between 0 and 1 mm, and avoided when there was no medullary canal in the atlas pedicle! So 3D CT reconstruction should be conducted to obtain data and establish individualized fixation strategy preoperatively.
Xi'an Jiaotong University College of Medicine, Xi'an, Shanxi, People's Republic of China.
Li-Xiong
LX
Qian
Ding-Jun
DJ
Hao
Bao-Rong
BR
He
Yong-Hong
YH
Jiang
D000293:Adolescent; D000328:Adult; D000368:Aged; D001863:Bone Screws; D001270:Cervical Atlas / Q000000981:diagnostic imaging* / Q000601:surgery; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed