Comparison of Cortical Bone Trajectory Screw Placement Using the Midline Lumbar Fusion Technique to Traditional Pedicle Screws: A Case-Control Study

Background: Cortical bone trajectory (CBT) screws are an alternative to traditional pedicle screws (PS) for lumbar fixation. The proposed benefits of CBT screws include decreased approach-related morbidity and greater cortical bone contact to prevent screw pullout. Relatively little data is published on this technique. Here, we compare the midline lumbar fusion (MIDLF) approach for CBT screw placement to transforaminal lumbar interbody fusion (TLIF) for traditional PS placement.

Methods: A prospectively maintained institutional database was retrospectively reviewed for all patients undergoing lumbar spinal fusion using CBT screws over the past 5 years. Controls were identified from the same database as patients undergoing lumbar spinal fusion with traditional PS placement and matched based on age, sex, and number of levels fused. Exclusion criteria included prior lumbar instrumentation. The electronic health record was retrospectively reviewed for demographic, perioperative, and postoperative data.

Results: A total of 23 patients who underwent CBT screw placement and 35 controls who received traditional PS were included in the study. The median follow-up time was 52.5 months. The CBT screw group had significantly less mean estimated blood loss than the PS group (186 mL versus 414 mL respectively; P = .008). Both groups experienced significant improvements in preoperative Oswestry Disability Index (ODI) and visual analog scale (VAS) scores for back and leg pain. However, there was no significant difference between the groups in regard to operative time and amount of improvement in VAS pain score or ODI. The CBT group was associated with a significantly shorter mean length of stay (LOS). There were 2 instances of screw pullout in each group.

Conclusions: The MIDLF approach with CBT screw placement is associated with less intraoperative blood loss and shorter LOS than traditional PS placement. There is no difference between the 2 techniques in regard to improvement in pain or disability.