Study of the Transverse Foramen in the Subaxial Cervical Spine in Korean Patients With Degenerative Changes: An Anatomical Note

Abstract

Objective: The purpose of this study was to provide anatomical data on the dimensions and location of the subaxial transverse foramen (TF) in relation to surgical landmarks routinely used during anterior cervical procedures.

Methods: A total of 116 patients who underwent preoperative computed tomography (CT) evaluations for degenerative cervical disease were enrolled. Axial and coronal CT images of the cervical vertebrae from C3 to C6 were analyzed to measure interforaminal distance, the TF distance from the anterior and posterior vertebral body margin, TF dimensions, and the TF medial margin from the tip and medial margin of the uncus. Comparative and correlative analyses were also performed according to age, body mass index (BMI), and sex.

Results: All measurement values in male patients were larger than those in their female counterparts. The interforaminal distance gradually increased from C3 to C6. The distance of the TF medial margin from the tip of the uncus was found be above approximately 3 mm in all vertebrae except C6. Correlation analysis revealed that age had a significant negative relationship with the transverse diameter of TF. In contrast, BMI had a significant positive correlation with interforaminal distance. Moreover, the distances of the TF medial margin from the tip and medial margin of the uncus showed strong negative correlations with age.

Conclusion: Useful morphometric data were obtained that may help the operating surgeon to avoid vertebral artery injury. The safe distance from the tip of the uncus to the TF medial margin was found to be approximately 3 mm, and this distance should not be violated during lateral decompression. In addition, this value may decrease with age.

Keywords: Cervical spine; Transverse foramen; Uncus; Computed tomography.

Fig. 1.

Axial cervical vertebrae measurements. A, anterior to posterior diameter of the transverse foramen. B, transverse diameter of the transverse foramen. C, inter-foraminal distance. D, anterior margin. E, posterior margin.

Fig. 2.

Coronal cervical vertebrae measurement. Distances from the medial margin of the transverse foramen to the medial ridge of the uncovertebral joint (F) and to tip of the uncus (G). During measurement of distances, a best fit image of the vertebral body including right or left transverse foramen was obtained. The medial margin of the transverse foramen (black straight line). The medial ridge of the uncovertebral joint (black dotted line). Tip of the uncus (black dotted circle).