Computer navigation in dorsal instrumentation of the cervical spine--an in vitro study

Transarticular C1/2 screws are widely used in posterior cervical spine instrumentation. Pedicle screws in the cervical spine remain uncommon until now. In view of improved biomechanical stability compared to lateral mass screws, pedicle screws could be used, especially for patients with poor bone quality or defects in the anterior column. Nevertheless, there are potential risks of iatrogenic damage to the spinal cord, nerve roots, or the vertebral artery related to both techniques of posterior cervical spine instrumentation. Therefore, the aim of this study was to evaluate whether C1/2 transarticular screws as well as transpedicular screws in C3 and C4 can be applied safely and with high accuracy using a computer-assisted surgery (CAS) system. C1/2 transarticular screws as well as transpedicular screws in the cervical spine can be applied safely and with high accuracy using a CAS system in vitro. Therefore, this technique may be used in the clinical setup due to improved accuracy and reduced radiation dose for the patient and medical staff. Nevertheless, to prevent iatrogenic damage, users should be aware of known sources of possible errors that cause inaccuracies. Small pedicles with a diameter below 4.0 mm may not be suitable for pedicle screws.