Possible complications of anterior perforation of the vertebral body using cervical pedicle screws.

No previous studies have analyzed the possible complications of anterior perforation of the cervical vertebral body with pedicle screws. The objective of this study was to identify the possible implications of an anterior vertebral body perforation. Ten consecutive Euro-American cadavers (C2-C7) were used. The male-to-female ratio was 3:7. The average specimen age was 79.6 years (range: 65-97 years), and average height was 159 cm (range: 155-175 cm). Axial computed tomography scans through the isthmus of pedicles were taken. Five millimeter and 10 mm margins anterior to the vertebral bodies were defined. Within 5 mm anterior to the anterior cortex of the vertebral body, we found mostly muscles (at C2: m. longus colli and pharyngeal constrictors; at C3 and C4: m. scalenus medius, longus colli, pharyngopalatinus and pharyngeal constrictors; at C5 and C6: m. longus colli and longus capitis; and at C7: m. longus colli), except at C3, C4, and C7, where the pharynx and esophagus were within the margin. Between 6 and 10 mm, we found mostly hollow organs (at C2: pharynx and small veins; at C3 and C4: the same muscles as within the 5 mm margin, with addition of the pharynx and some small veins; at C5 and C6: pharynx, pharyngeal constrictors and the thyroid cartilage; and at C7: the esophagus). Except C2, there is no safe zone anterior to the cervical vertebral bodies in the cervical spine, which would allow bicortical purchase of pedicle screws without being close to important surrounding structures.