Introduction: 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 five 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 24 patients who underwent CBT screw placement and 22 controls who received traditional PS were identified. The median follow-up time was six months. The CBT screw group had significantly less estimated blood loss per operative level than the pedicle screw group (186 mL vs. 342 mL respectively; p = 0.02). Both groups experienced significant improvements in pre-operative ODI and VAS scores for back and leg pain. However, there was no significant difference between the groups in regard to operative time, length of stay, and amount of improvement in VAS pain score or ODI. There were two instances of screw pullout in each group.
Conclusions: The MIDLF approach with CBT screw placement is associated with less intraoperative blood loss than traditional pedicle screw placement. There is no difference between the two techniques in regard to improvement in pain or disability.
Patient Care: There is little data available on the midline lumbar fusion technique for cortical bone trajectory screw placement. Our research provides additional evidence that this is an effective technique for lumbar fusion. By showing that it is associated with less intra-operative blood loss, it supports the technique's use in patients who are more sensitive to reductions in their blood counts.
Learning Objectives: By the conclusion of this session, participants should be able to:
1) Describe the proposed benefits of the midline lumbar fusion approach for cortical bone trajectory screw placement
2) Compare the outcomes of cortical bone trajectory screw placement to pedicle screw placement