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Radiological and Surgical Anatomy of Ventral C1-C2 Complex.

AIM
To evaluate anatomical data of the bony structures during exploration of the C1-C2 complex.


MATERIAL AND METHODS
This study included six formalin-fixed cadaveric head and neck specimens. Radiological images and anatomical measurements included: C1-C2 distance, bony distance between C1 anterior tubercle-nares and superior incisors, height of C1 anterior arch, and height and width of odontoid articular surface.


RESULTS
The mean distance between C1 anterior tubercle-nares and superior incisors on maxilla were 96.16 Â± 8.07 mm and 84.14 Â± 9.16 mm, respectively. The mean height of C1 anterior arch was 13.89 mm. The meandistance between medial borders of right-left C1 lateral masses was 19.10 Â± 1.80 mm. The mean distance between medial border of lateral midline on mass right and left sides were 9.43 Â± 0.88 mm and 9.68 Â± 0.97 mm, respectively. The mean height of C1 anterior arch at midline was 13.89 Â± 2.48 mm, and the mean distance between ventral surface of anterior arch and ventral joint of odontoid at midline was 6.43 Â± 1.29 mm. The anteroposterior, horizontal diameters of odontoid on its base were 12.12 Â± 0.38 mm, and 11.12 Â± 0.94 mm, respectively. The angles of transoral and transnasal approaches to C1 were 32.67 Â± 4.59Â° and 32.00 Â± 2.10Â°, respectively.


CONCLUSION
A safe transoral or transnasal odontoidectomy requires accurate measurements and imaging regarding ventral C1-C2 relationships, distances of odontoid, lateral mass and midline.