Radiologic Evaluation of Uncinate Processes of the cervical spine and the Relationship Between UP and Vertebral Artery: Implication in Anterior Cervical Spine Surgery

Abstract

The purpose of this study was to determine the relationship between the uncinate process and vertebral artery from a radiological view and to confirm the surgical safety margin in order to minimize the risk of vertebral artery injury during anterior cervical approaches. We retrospectively reviewed computed tomography angiography of 205 patients by using a contrast-enhanced CTA protocol of the vertebral artery. Four kinds of images were simultaneously reconstructed to measure all the parameters associated with vertebral artery and uncinate process of cervical spine. The shortest distance from the UP's tip to the VA's medial border (p<0.001) was at the C-6 level (2.9±0.9mm on the left and 3.2±1.3 on the right), and the longest distance (p<0.001) was at the C-3 level on both sides. The distance between UP's tip and the medial border of the ipsilateral VA was statistically significantly different at each cervical level, and the right distance was larger than the left (p<0.05). We found the height of UP gradually increased from C-3 to C5-level and then decreased from C-5 to C-7 level for both sides. The mean distance between the medial borders of left UP and left VA was on average 7.5±1.4mm. The diameter of VA was on average 3.4±0.6mm on the left side and 3.2±0.7mm on the right. The diameter of the VA was statistically significantly different on both sides, and the left side was larger than the right (p<0.05). Detailed radiologic anatomy of vertebral artery and uncinate process was reviewed in this study. A deep understanding of the correlation between the uncinate process and vertebral artery is essential to perform anterior cervical spine surgery safely and ensure adequate spinal canal decompression.