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

Abstract

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. 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. 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. 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.