Three-Dimensional Patient-Specific Guides for Intraoperative Navigation for Cortical Screw Trajectory Pedicle Fixation

Background: Cortical bone trajectory (CBT) technique for pedicle fixation has been proposed and adopted in recent years. This technique involves a mediolateral direction and a caudocephalad path to maximize screw purchase in cortical bone. Various techniques have been proposed to increase the accuracy of screw placement. A novel technique for CBT screw placement using a three-dimensional printed patient-specific drill guide (PSDG) is presented.

Methods: CBT screw fixation combined with posterior lumbar interbody fusion was performed for reduction of an L4-5 spondylolisthesis in a 71-year-old woman. PSDGs (MySpine MC Guides) were designed and printed based on the patient's preoperative computed tomography scan. PSDGs were used intraoperatively to facilitate screw trajectory and placement.

Results: Postoperative imaging performed at 6 weeks and 3 months revealed accurate screw trajectory with excellent reduction of spondylolisthesis. The patient improved clinically with minimal mechanical pain and claudication at 3-month follow-up.

Conclusions: PSDG for CBT screw fixation offers significant benefits, including preoperative planning; improved screw placement accuracy while minimizing cortical breach; reduction of operative time; and lower cost compared with intraoperative computed tomography-based neuronavigation, thus expanding the availability of this technique. Drawbacks include time required for PSDG planning and learning curve for surgeons.