Cortical Bone Trajectory Screw Placement Accuracy with a Patient-Matched 3-Dimensional Printed Guide in Lumbar Spinal Surgery: A Clinical Study.

Background: Cortical bone trajectory (CBT) screw is an attractive technique in terms of fixation strength and less invasiveness. However, the insertion of a pedicle screw penetrating cortical bone on the ideal trajectory is technically demanding. The use of 3-dimensional (3D) patient-matched guides may facilitate the use of this technique. In this technical note and case series, the use of a patient-matched 3D targeting guide for a circumferential fixation with CBT screws is described.

Methods: Eleven patients with a mean age of 49 years were treated. The MySpine MC (Medacta International SA, Castel San Pietro, Switzerland) technology was used to place CBT screws. A computed tomography (CT) scan-derived 3D model of the patient vertebra was created after the surgeons planned the best custom CBT screw trajectory. Then, scaffolds were printed and used during surgery to guide the screw through the patient pedicle. An intersomatic arthrodesis was also performed.

Results: The images of the planned trajectory were superimposed on the postoperative CT scan, confirming the accuracy of the trajectory. The mean deviation from the planned pedicle midpoint was 0.91 mm; 85.2% of the screws were placed within 2° from the planned trajectory. There were 2 grade A (<2 mm) and no grade B or C perforations. The actual entry point was always within 2 mm from the planned entry point.

Conclusions: This technical note and case series is the first clinical description on the use of a patient-matched guide for posterior CBT screw placement. The use of these devices could also improve placement accuracy and decrease the risk of nerve damage.