title: Anatomic study of the axis for surgical planning of transarticular screw fixation.
abstract: Transarticular screw fixation has shown increased stability compared with other posterior stabilization techniques. However, there have been few reports on vertebral artery injury related to the screw insertion. The current study measured the parameters of the pedicle and vertebral artery groove of the axis and clarified the accuracy and safety of the transarticular screw fixation. Direct measurements were taken from 98 dry axis vertebrae. The width and height of the pedicle were measured. The mediolateral and anteroposterior dimensions of the vertebral artery groove also were measured. Forty-one percent had asymmetry. In 20% of the specimens, the pedicle was smaller than the diameter of the screw (3.5 mm). The pedicle of the axis has large anatomic variability and asymmetry. Some pedicles were not suitable for atlantoaxial transarticular screw fixation. The risks associated with screw fixation should be prevented by preoperative computed tomography with three-dimensional reconstruction. Screw trajectory reconstruction with coronal and sagittal reconstruction is useful to evaluate the pedicle width and height.
authors.affiliation: Department of Orthopaedic Surgery, Fukushima Medical University, School of Medicine, Fukushima City, Japan. tamaki@fmu.ac.jp
authors.forename: Tamaki
authors.initials: T
authors.lastname: Igarashi
authors.forename: Shinichi
authors.initials: S
authors.lastname: Kikuchi
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Sato
authors.forename: Satoru
authors.initials: S
authors.lastname: Kayama
authors.forename: Koji
authors.initials: K
authors.lastname: Otani
mesh_terms: D001268:Atlanto-Axial Joint / Q000033:anatomy & histology; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000033:anatomy & histology*; D006801:Humans; D007593:Joint Instability / Q000601:surgery; D013123:Spinal Fusion; D014711:Vertebral Artery / Q000033:anatomy & histology*