Surgical Anatomy of the C2 Pedicle

Object:

This study was performed to investigate the surgical and radiographic anatomy of the C2 pedicle as it pertains to transpedicular screw placement in occipitocervical stabilization surgery.

Methods:

The C2 pedicles in ten cadaveric spines were evaluated using both manual and computer assisted tomography measurements. Prior to dissection, each specimen was imaged with computer assisted tomography, and measurements of the following were made: pedicle height, width, and length, as well as the medial and rostrocaudal angulation of the pedicle. Pedicle height, width, and length were measured using CT generated values. The medial inclination was measured on a representative axial selection with a digital goniometer and recorded in 1–degree increments. The rostrocaudal angulation was measured similarly between a line parallel to the base of the inferior endplate of C2 and the pedicle on sagittal reconstructed images. Manual measurements were carried out, and these confirmed the radiographic findings. Pedicle screws were then placed based on the above measurements and direct visualization of the C2 pedicle through the Cl –2 interlaminar space. Repeat scans were then obtained to assess screw placement.

Results:

The average pedicle height, width, and length measured 9.1 mm, 7.9mm, and 16.6mm respectively, and the medial inclination and rostrocaudal angulation measured 35.2 degrees and 38.8 degrees respectively. The cortex of the pedicle was not violated in any of the twenty pedicles.

Conclusions:

Adequate preoperative studies in conjunction with direct visualization of the C2 pedicle make transpedicular fixation at this level safe and effective.