The technique of cortical bone trajectory screw fixation in spine surgery: a comprehensive literature review

Pedicle screw fixation is widely used in spinal fusion procedures and an established treatment for a range of spinal disorders including spinal degenerative disc disease, spondylolisthesis, tumor, and deformity. However, there are some disadvantages associated with traditional screw fixation techniques including extensive paraspinal dissection required, and screw loosening associated with traditional pedicle screw (TPS) fixation. As an alternative technique, both cadaveric and clinical studies have proposed and investigated the feasibility of a novel cortical bone trajectory (CBT) screw fixation technique whereby the screw follows a mediolaterally and caudocranially directed path through the pedicle and maximizes thread contact with the cortical bone surface, providing enhanced screw purchase. Moreover, screw insertion through a medial starting point offers advantage in minimizing muscle dissection. This study is to review the history, development, biomechanical and clinical outcomes for CBT as an alternative technique for pedicle screw fixation.