Three-Dimensional Patient-Matched Template Guides Are Able to Increase Mean Diameter and Length and to Improve Accuracy of Cortical Bone Trajectory Screws: A 5-Year International Experience.

OBJECTIVE: To analyze whether significant differences exist between free-hand three-dimensional (3D) planning-guided cortical bone trajectory (CBT) screw placement and 3D-printed template-guided CBT screw positioning in terms of accuracy, size of screws, and potential complications. METHODS: In this retrospective study, data of adult patients in whom CBT screws were placed for lumbar degenerative pathologies were extracted from a prospectively collected database and analyzed. Patients in whom screws were placed using free-hand 3D planning-guided technique were compared with patients in whom screws were positioned using customized 3D-printed templates. Size of the screws, accuracy, clinical outcomes, and complications were analyzed. RESULTS: The study evaluated 251 patients (1004 screws). The free-hand 3D planning-guided group included 158 patients (632 screws), and the 3D-printed template-guided group included 93 patients (372 screws). The 3D-printed template-guided group involved screws of larger size from L3 to S1. Differences between the 2 groups in terms of accuracy parameters reached statistical significance (P ≤ 0.05). CONCLUSIONS: With the use of 3D patient-matched template guides, mean diameter and length of CBT screws could be safely increased due to improved accuracy of screw placement. Based on previous evidence regarding CBT biomechanical properties, these advantages could allow increased fixation strength over traditional convergent pedicle screw trajectories. Further biomechanics studies are needed.