Morphometric Analysis of Axis Vertebra in Northeastern Brazil

Introduction: The axis is the second cervical vertebra and differs from the others by presenting particular anatomical landmarks. Morphological variations of the axis in different populations have clinical importance, since the lack of anatomical reference may compromise surgical procedures in this region. Objective: To analyze the morphometry of axis vertebra in northeastern Brazil. Methodology: Data collection was performed at the Federal University of Paraiba. Fifty-eight axis were used. Damaged or infantile vertebrae were excluded.Morphometric analysis was performed using a digital caliper and the data were statistically analyzed. Results were considered significant when p<0.05. Results: The width of the pars interarticulares was 9.25±1.68mm and the height was 7.37±1.87mm. The height of the dens of the axis in an anterior view was 16.29±1.82mm and the width was 9.41±0.86mm. The width of the articular face of the dens was 8.27±0.88mm. The anteroposterior length of the vertebral body was 15.29±2.02mm, the width was 16.79±1.68mm, and the height in anterior view was 19.96±2.48mm. The mean height of the vertebral lamina was 10.89±1.64mm and the anteroposterior length was 20.33±2.13mm. Significant difference was observed between right and left sides of anteroposterior length (p=0.012). Conclusion: Axis morphometry was shown for the first time in a specific population from northeastern Brazil. Morphological differences were observed in the present study and differ from others in the literature. These data may serve as guidance for professionals who will perform any procedures in this region, highlighting the importance of anatomical knowledge and its variations.

Motion Preserving Surgery Using O-Arm for Unstable Hangman Fracture

Aim To evaluate clinical outcomes, radiological findings (displacement and angulation), and bony fusion in cases of unstable hangman’s fracture. Introduction Hangman fracture, also known as traumatic spondylolisthesis of axis vertebra, is classically defined as bilateral pars interarticularis fracture of axis vertebra. Opinions vary regarding optimal treatment of unstable hangman’s fractures. Some authors have recommended use of rigid orthosis, whereas others have recommended internal fixation. The peculiar anatomy of the upper cervical spine is highly variable, and presence of surrounding neurovascular structures makes axis pedicle screw fixation even more technically challenging. The advent of intraoperative three-dimensional navigation systems facilitates safe and accurate instrumentation. Materials and Methods This article analyzes patients operated for type II and IIa hangman’s fractures during the period from September 2011 to August 2018 by two neurosurgeons. The patients’ age, sex, mechanism of injury, associated injuries, and neurologic status were noted. The authors retrospectively assessed the clinical outcome, radiological findings (displacement and angulation), and bony fusion. Result Eighteen patients with age ranging from 17 to 81 years, were operated using computed tomography-based (O-arm) navigation. Accuracy of screw insertion, preoperative and postoperative displacement, and angulation of C2 over C3 were evaluated. Bony fusion was assessed in all patients. A total of 92 screws were inserted: 36 screws in C2 pedicle, 34 in C3 lateral mass, 20 in C4 lateral mass, and 2 in C5 lateral mass. Of these 92 screws, 36 C2 pedicle screws were inserted under O-arm guidance. The mean preoperative C2–C3 displacement was 4.5 ± 2.1 mm, and the mean postoperative displacement was 1.8 ± 1.1 mm with a mean reduction of 2.7 ± 1.4 mm. The mean preoperative C2–C3 angulation was 10.2 ± 7.6 degrees and the postoperative angulation was 2.52 ± 4.62 degrees with a mean reduction of 8.2 ± 11.6 degrees. Screw malplacement was seen in two C2 pedicle screws (2/36, 5.5%). All C2 pedicle screw breaches were of grade 2. Excellent anatomical reduction in all cases could be achieved as established by the improvement in morphological parameters of fracture. Conclusion This series using O-arm in unstable hangman fracture demonstrates that intraoperative O-arm-based navigation is a safe, accurate, and effective tool for screw placement in patients with unstable hangman fracture.