Determining Optimal C2 Pedicle Screw Placement and Length in Patients with Axis Traumatic Spondylolisthesis: A Case Series
Authors: Assaad El Hawary M. 
Published: May 2014

Introduction

“Axis traumatic spondylolisthesis” (ATS) and “Hangman's fracture” are terms that describe a specific fracture group, which involves the posterior C2 elements. Wood-Jones first described a C2 vertebra fracture in 1913. He described fractures produced by hanging, and observing that the lesion was produced by a violent cervical traction with abrupt stretching of the head backward, leading to C2 pedicle fractures. Later in 1964, Garber2 described C2 pedicle fractures with a forward dislocation of the C2 body in victims of motor vehicle accidents, called “axis’ traumatic spondylolisthesis.” In 1965, Schneider et al3 described another series of patients with the same fractures, naming them “Hangman's Fracture.” The ATS was referred to as an uncommon and predominantly stable lesion, rarely accompanied by neurological deficit, for which the recommended treatment was cervical traction and rigid immobilization.

Materials and Methods

From June 2008 to April 2010, nine patients with axis traumatic spondylolisthesis with or without C2-3 sub-laxation were operated. All patients were admitted and operated at Dr. Soliman Fakeeh Hospital, Jeddah, Saudi Arabia. There were eight males and one female, with a mean age of 35.7 years. Eight patients had a motor vehicle accident and one fell from second floor into the street. Two patients had a previous conservative treatment, and showed signs of pseudarthrosis at the fracture site, with intense pain at the cervical spine region. Three patients had head injury, two of them with multiple cranial fractures and the third was submitted for surgical treatment for a ruptured cervical disc. Three patients had dislocation of C2-C3, which was not satisfactorily reduced with conservative treatment. None of the patients showed neurological deficit.

Results

The mean follow-up period was 6 months (range, 3-9 months). All nine patients had good postoperative improvement with satisfactory fracture consolidation, and asymptomatic on follow-up. There were no intra or postoperative complications, except one patient who developed pneumonia on postoperative day 3, which resolved in 7 days of antibiotic treatment. The hospitalization period varied from 7 to 13 days. Only one patient developed frequent neck pain, especially after performing intense physical effort, which improved after rest, use of nonsteroidal analgesics, and simple physiotherapeutic remedies. On immediate plain radiographic evaluation, all patients showed satisfactory and correct alignment of fractured bony ends with C2-C3 reduction. Six months after surgery, all patients undertook a CT scan where good healing of the fractures with intact pedicle cortices. There were a total of 18 pedicles inserted in all patients. The mean pedicle screw length was 16.5 mm (range: 16-17 mm), and the mean medial and rostral inclinations measured were 34.7 degrees (range: 28-41 degrees) and 38.6 degrees (range: 28-41 degrees), respectively.

Conclusion

There were many explicit limitations in our study, such as the small number of patients, the single-center, single-surgeon, retrospective design, very short follow-up (was as short as 3 months), lack of standardized outcomes measures, and lack of standardized criteria to assess fusion status. Nonetheless, based on the frequent observations of the bony anatomic variations and the lines of fractures brought about by trauma, the classic 20-degree inclinations in both trajectories previously suggested should be reconsidered. However, fixed angles of angulations cannot be generalized. As a consequence, we conclude that accurate preoperative planning could be obtained with the use of 3D reconstructed CT images that can preoperatively predict the best screw length needed for the procedure, depending on the size of the patient's axis vertebra, and the best angulations for the safety of the neighboring neurovascular structures, Hence, it is important to understand the patient's individual anatomy, as this is the ultimate guide to proper placement despite understanding the angles. Anatomic landmarks can therefore be well seen and demarcated through the use of intraoperative fluoroscopy or image guided navigation techniques. Disclosure of Interest None declared