Original ArticlesC1-2 Transarticular Screw Fixation in High-riding Vertebral Artery: Suggestion of New TrajectoryLee, June Ho MD; Jahng, Tae-Ahn MD; Chung, Chun Kee MDAuthor Information Department of Neurosurgery, Seoul National University College of Medicine, Seoul, South Korea Supported in part by 2005 BK21 Project for Medicine, Dentistry and Pharmacy from Korean Ministry of Education and Human Resources Development, and by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea Government (MOST) (M10644000009-06N4400-00900). This study was partially presented at the 5th biennial Japan-Korea Conference on Spinal Surgery in 2005. Reprints: Chun Kee Chung, MD, Department of Neurosurgery, Seoul National University College of Medicine, 28 Yongon Dong Chongno Ku, Seoul, 110-744 South Korea (e-mail: firstname.lastname@example.org). Received for publication June 28, 2006; accepted December 13, 2006 Current Address: June Ho Lee, MD, Department of Neurosurgery, Wooridul Spine Hospital, Seoul, South Korea. Journal of Spinal Disorders & Techniques: October 2007 - Volume 20 - Issue 7 - p 499-504 doi: 10.1097/BSD.0b013e318031af51 Buy Metrics Abstract A significant drawback of atlantoaxial transarticular screw fixation is a potential risk of vertebral artery injury, especially with a high-riding type. The authors propose a relatively safe trajectory in cases of high-riding vertebral artery by using the 3-dimensional computerized tomography image reconstruction programs. Twelve consecutive patients with a pathologic condition in atlantoaxial complex were prospectively analyzed. Five other patients, whose high-riding vertebral arteries were incidentally found during the 3-dimensional computerized tomography performance for other cervical pathologic conditions, were also included. The preoperative screw simulation images, convergence angle, and caudal tilting angle for each screw were obtained from each patient. Of 17 subjects, 7 had high-riding vertebral artery unilaterally and 1 had bilaterally. All 12 patients with pathologic atlantoaxial complex, including 2 unilateral and 1 bilateral high-riding vertebral artery, had atlantoaxial transarticular screw fixation. For these 3 patients, the entry point and the trajectory for screw were moved more superiorly and medially as in cases with C2 pedicle screwing. The mean convergence angle and caudal tilt angle obtained during screw simulation for patients with high-riding vertebral arteries was 17.6 and 38 degrees compared with 21 and 53.3 degrees for patients with normal course of vertebral artery. It was possible to insert transarticular screws safely in patients with high-riding vertebral artery guided by preoperative screw insertion simulation program. © 2007 Lippincott Williams & Wilkins, Inc.