Anatomic relation between the cervical pedicle and the adjacent neural structures.

STUDY DESIGN

An evaluation of the anatomic relation between the cervical pedicles and the adjacent neural structures.

OBJECTIVES

To determine quantitatively the antomic relation of the cervical pedicles to the adjacent nerve roots and dural sac.

SUMMARY OF BACKGROUND DATA

Transpedicular screw fixation in the cervical spine has been reported, but little quantitative data regarding the anatomic relation between the cervical pedicles and the surrounding neural structures are known.

METHODS

Twenty cadavers were used for dissection to observe the relations of the cervical pedicles to the adjacent dural sac and nerve roots. After removal of whole posterior bony elements including the spinous processes, laminas, and lateral masses, the isthmus of the pedicles, the dural sac, and the nerve roots of C3-C7 were exposed. Direct measurements included the distance from the pedicle to the superior and inferior nerve roots and the dura. Also, the pedicle height and width were measured at its isthmus.

RESULTS

No distance was found between the pedicle and the superior nerve root, nor between the pedicle and the dural sac at C3-C7 for all specimens. The mean distances between the pedicle and the inferior nerve roots for all specimens ranged from 1.4 to 1.6 mm. The mean pedicle heights and widths for all specimens at C3-C7 ranged from 6.0 to 6.5 mm and 4.7 to 5.3 mm, respectively. A significant difference between male and female specimens was noted in the pedicle heights for all levels measured (P = 0.001), and in the pedicle widths for the levels of C4 and C6 (P = 0.05).

CONCLUSIONS

This study suggests that the incidence of neurologic injuries may be higher in screw penetration of the medial or superior cortex of the pedicle than in screw penetration of the inferior cortex of the pedicle.