New Techniques and MIS: The Cortical Bone Trajectory Screws—Indications and Limits

Cortical bone trajectory (CBT) takes divergent and caudocephalad screw path through the pedicle and differs widely from the traditional transpedicular trajectory. The most important advantage of CBT is to maximize the contact between screw thread and cortical bone. Biomechanical studies have shown greater anchoring ability of CBT compared with that of the traditional trajectory. Furthermore, the entry point for CBT requires less soft tissue dissection; thus, these features make the CBT technique attractive for use as a new minimally invasive method for spinal fusion. Clinical studies using the CBT technique demonstrated similar clinical and radiologic outcomes with lower surgical morbidity compared with those using the traditional technique. Meanwhile, it is notable that this technique is not without specific concerns for clinical use due to its own surgical technique, lack of convergence, and short screw length. The purpose of this paper is to provide an overview of the current literature on CBT, with focus on indications, limits, and surgical pitfalls.