Atlantoaxial transarticular screw fixation for a high-riding vertebral artery.
METHODS
The feasibility of inserting a screw for the narrow isthmus with a high-riding vertebral artery was evaluated in patients subjected to posterior atlantoaxial transarticular screw fixation.


OBJECTIVE
To demonstrate the feasibility of inserting bilateral screws and obtaining a stable atlantoaxial complex for patients with a high-riding vertebral artery.


BACKGROUND
Posterior atlantoaxial transarticular screw fixation entails the potential risk of vertebral artery injury, which may be lethal. The risk is much higher for the narrow isthmus caused by a high-riding vertebral artery, and many authors recommend that the procedure should be abandoned if the isthmus is too narrow. On the other hand, bilateral screw fixation is stronger than unilateral screw fixation.


METHODS
For this study 27 consecutive patients who submitted to atlantoaxial transarticular screw fixation were evaluated before surgery for the position of the vertebral artery grooves using computed tomography (CT) reconstruction. Seven of the patients were defined as having a unilateral high-riding vertebral artery. For these patients, bilateral screw insertion through the most posterior and medial part of the isthmus was performed.


RESULTS
No massive bleeding or major complications were encountered in any patients with a high-riding vertebral artery. Postoperative computed tomography reconstruction demonstrated that five of the screws cleared the vertebral artery groove successfully, and two slightly breached it. No screws penetrated into the vertebral artery groove.


CONCLUSIONS
It is possible to insert a screw safely, even into the narrow isthmus with a high-riding vertebral artery, if the surgeon realizes where the screw should be inserted and has the requisite insertion technique. Bilateral screw fixation should provide a high fusion rate.
Neo
Masashi
M
Department of Orthopaedic Surgery, Kyoto University Graduate School of Medicine, Japan. neo@kuhp.kyoto-u.ac.jp
Matsushita
Mutsumi
M
Iwashita
Yasushi
Y
Yasuda
Tadashi
T
Sakamoto
Takeshi
T
Nakamura
Takashi
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D002648:Child; D005240:Feasibility Studies; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D012307:Risk Factors; D013122:Spinal Diseases / Q000601:surgery*; D013123:Spinal Fusion / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014711:Vertebral Artery / Q000033:anatomy & histology / Q000000981:diagnostic imaging