AIM: Iatrogenic vertebral artery (VA) injury during ventral approaches to the subaxial cervical spine ranges from 0.22% to 2.77%. Evaluation of the extent of safe lateral working distance before the V2 segment of the VA is reached can be helpful to avoid this complication.

MATERIAL and METHODS: In 100 patients (48 males and 52 females) axial computed tomographic scanning was used to measure the distance from the medial border of longus colli muscle (LCM) to the medial border of the foramen transversarium along the anterior border of the vertebral body at each level from C3-4 down to C6-7. The arithmetic mean of the 2 measurements at the upper and lower end-plates of the corresponding level was considered representative of the safe lateral working distance at this level. Statistical significance was set as P value< 0.001.

RESULTS: No statistically significant difference was found between the measurements in the whole study population at various levels or between subgroups. A gradual increase in the distances was noticed from C3-4 down to C6-7 level in all subgroups except for spondylotic males.

CONCLUSION: This study offers useful morphometric data that can help the surgeon avoid VA injury during anterior procedures to the subaxial cervical spine.