Short term Results of Lumbar Interbody Fusion using Cortical Bone Trajectory Screw Technique

Presented at SMISS Annual Forum 2018
By D. Choi

Disclosures: D. Choi None


Cortical bone trajectory (CBT) pedicle screw fixation is novel technique, and many biomechanical or anatomical studies, which demonstrate the priority of pullout strength of CBT screws comparing to the conventional pedicle screws, have been reported. Several clinical reports have been published recently in terms of the benefit as well as the complications of the CBT screw method.


We report the clinical and radiological results of the short level lumbar interbody fusion with CBT pedicle screw in the surgery of degenerative lumbar spine.


21 patients with at least 6 months follow-up were enrolled, who were underwent single or two levels lumbar interbody fusion using PLIF or TLIF using CBT screw fixation method between October 2014 and August, 2015. All CBT screws were inserted under intraoperative C-arm fluoroscopic guidance. The medical records and imaging studies were reviewed retrospectively. Mean age of the patients was 63 and the mean follow up period was 12.3 months. The 9 cases were revisional surgery. All patients underwent interbody fusion, and the total number of interbody fusion level was 21. Interbody fusion methods were PLIF, TLIF, or OLIF (16, 12 and 1). A total number of 104 CBT screws were analyzed radiologically.


Average T-score of BMD was -2.0 SD. Preoperatively mean VAS score was 7.5 (SD±1.12), and postoperative mean VAS score was 2.8 (SD±0.93). Mean operation time for the single level fusion and two-level fusion was 209 (SD±45.5) and 267 (SD±35) minutes respectively, and the estimated blood loss was 496ml (SD±150) and 722ml (SD±380). Postoperative CT was conducted immediately after surgery, except for two patients among the 21 patients. In the 96 screws analyzed, 21 screws (21.9%) were not inserted correctly, but there was no case of the violation or compromise of the neural foramen. Postoperative screw loosening was detected in the 3 patients. Posterior displacement of the interbody cage was detected just 4 weeks after surgery, in a case of severe osteoporosis patient. Nevertheless, in most of patients (17/21), favorable surgical results were achieved.


The CBT screw fixation is a good alternative method, especially in the case of osteoporosis, and this technique has several advantages that minimize paraspinal muscle disruption and decrease operation time, as well as that allows to avoid exposure or injury of the adjacent facet joint. However, some limitations and possible disadvantages reside simultaneously.