Anatomic Research of the Safe Space Between the Cervical Uncinate Process and the V2 Vertebral Artery.

Objective: A retrospective study was performed to observe and measure the safe distance between the uncinate process (UP) and the V2 vertebral artery (VA).

Methods: Two hundred and sixteen patients who underwent head and neck computed tomography angiography were selected and measured. The upper tip (UT) of the UP, the posterior tip of the UP (PT), and the center of the VA (CA) were identified. Then, the width between the UT and the CA, the depth between the UT and the CA, and the distance between the UT and the CA were measured. The width between the PT and the CA, the depth between the PT and the CA, and the length between the PT and the CA were measured. These values were compared between the left and right sides of the same vertebral body and also the results of the same side from C3 to C6 were compared.

Results: The width between the UT and the CA fluctuates between 6.1 and 4.4 mm on the left side with the narrowest at C5 and C6 (4.4 mm) and between 6.5 and 4.6 mm on the right side with the narrowest at C5 (4.6 mm). It could be concluded that the safe space for operation outside UP is about 4 mm and more care should be taken when operating on the caudal spine. The width between the PT and the CA fluctuates between 10.6 and 10.0 mm on the left side with the narrowest at C3 (10 mm) and between 11.0 and 9.9 mm on the right side with the narrowest at C4 (9.9 mm). The safe space for operation outside the PT is about 10 mm and more care should be taken when operating on the cephalad spine. Depth between the PT and the CA fluctuates between 6.5 and 4.6 mm on the left and is narrowest at C3 (4.6 mm) and between 6.5 and 4.7 mm on the right and narrowest at C3 (4.7 mm). The safe space for operation from the PT to the ventral side is about 4.5 mm, and more care should be taken when operating on the cephalad side of the cervical spine.

Conclusions: UP and PT could be seen as landmarks in the operations of anterior cervical discectomy and fusion. The safe space outside UP is about 4 mm and more care should be taken when operating on the caudal spine. The safe space outside PT is about 10 mm and more care should be taken when operating on the cephalad spine. The safe space for operation from the PT to the ventral side is about 4.5 mm, and more care should be taken when operating on the cephalad side of the cervical spine.