An intraoperative 3D image-based navigation error during cervical pedicle screw insertion

A 67-year-old man underwent posterior cervical decompression surgery for ossification of the posterior longitudinal ligament (OPLL) with fixation using cervical pedicle screws (CPSs) guided by intraoperative 3D image-based navigation. Intraoperatively, while creating the screw hole using the navigation probe, the virtual trajectory on the intraoperative navigation screen showed a 10-degree angle discrepancy in the axial plane depending on whether a probing force was or was not applied for making the hole. This was potentially caused by vertebra rotation and a bent probe. Consequently, the CPSs were placed more laterally than the ideal trajectory, which resulted in <2 mm lateral perforation to the foramen transversarium. There were no screw insertion-related perioperative complications. Based on this case, we conclude that navigation error during CPS insertion can occur even with intraoperative 3D image-based navigation. The risk of a bowed navigation probe caused by posterior cervical muscle and vertebra rotation should be considered, even with use of a navigation reference frame.