What's New in the Treatment of the Cervical Spine
Trends in the treatment of the cervical spine include the evaluation of new technology as well as a focus on the understanding of old concepts and postulates. The results of randomized controlled trials of cervical arthroplasty are now available, and this procedure appears promising.
To safely perform many of the complex surgical procedures that involve the use of screw fixation, an understanding of the surgical anatomy of the cervical spine is essential. Osseous and vascular anomalies in the cervical spine that place the vertebral artery at risk during surgery have been identified. The vertebral artery normally enters the spine at C6 and ascends in the foramen transversarium until C2, where it turns, first laterally and then cranially, and ascends into the C1 foramen transversarium. It then loops medially, lying on the superior surface of the C1 arch. Approximately 15 mm from the midline, it turns anteriorly, enters the spinal canal, and passes through the foramen magnum. In the subaxial spine in a small number of patients, the artery can enter at C7 (or, more commonly, it can become ectatic with age) and can intrude into the vertebral body, placing it at risk during corpectomy. This finding is easily recognized on anteroposterior radiographs or axial computed tomography and magnetic resonance images. The vertebral artery may pass too far rostrally and medially within C2, thinning the pedicle so that C1-C2 transarticular and C2 pedicle screws cannot be placed safely. This occurs in as many as 15% of cases. As an alternative, screw purchase can be obtained in the C2 lamina, thereby avoiding vertebral artery risk. Biomechanical studies comparing this method with other C2 screw constructs have shown similar fixation strength.
Lateral mass fixation into C1 is gaining popularity. Screw position is critical, as rostrally angled screws can penetrate the atlanto-occipital articulation and …
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