Morphometric analysis of the cervical pedicle and transverse foramen with vertebral artery: A donor-based, dry bone and radiologic study.

OBJECTIVES

This study aimed to quantify the anatomical relationship between the cervical pedicle, transverse foramen (TF), and vertebral artery (VA), emphasizing the incidence of anatomical variations affecting cervical pedicle screw (CPS) placement. The proximity of the VA to the cervical pedicle often limits CPS use at C3-C6 levels.

METHODS

A total of 640 pedicles from 80 dried cervical spines (C3-C6), 20 vertebral arteries from 10 donors and 120 cervical spine CT scans were analyzed. Measurements included pedicle diameter (PD), TF, and VA diameters (sagittal and coronal), pedicle angle, and vertebral body height. VA trajectory, entry level, and variations were assessed in donors, while TF morphology and pedicle dimensions were evaluated in dry bones and radiological images. Statistical analyses were performed to compare sides and levels.

RESULTS

Double or accessory transverse foramina were most frequently observed at C6 (38.8%), followed by C5 (30.8%) and C4 (10.6%); no double or accessory transverse foramina were identified at C3. Osteophytes and spur formations were uncommon but present. TF diameters increased progressively from C3 to C6 (right: 4.95 ± 0.62-5.49 ± 1.01 mm; left: 5.10 ± 0.56-5.86 ± 1.21 mm). Mean pedicle transverse angles were 46.65° on the left and 44.53° on the right. The smallest pedicle dimensions were observed at C4, while PD increased gradually from approximately 4.9 mm at C3-6.5 mm at C6. The VA entered the transverse foramina at C6 in all specimens, with rare variations.

CONCLUSION

These findings demonstrate considerable level-dependent anatomical variability in the cervical pedicle-TF-VA relationship. CT angiography is particularly valuable for identifying VA anomalies and assessing CPS feasibility, especially at C4 and C6, which exhibited greater variability and potential surgical risk. A detailed understanding of TF morphology and VA anatomy is essential for safe cervical spine instrumentation and for minimizing vertebrobasilar complications.