Percutaneous Cortical Screw Fixation as a Method for Posterior Spinal Stabilization

Objective: Novel minimally invasive surgery (MIS) approaches and instrumentation such as cortical screws (CS) have recently become commonplace for treating spinal disease. CS comparability to pedicle screws (PS) with respect to safety and mechanical stability, however, have yet to be deter-mined. To our knowledge, this is the first report to describe a percutaneous CS fixation technique with subsequent open anatomical dissection and describe its feasibility compared to PS fixation. Methods: Fresh frozen cadavers were used for fluoroscopy-guided placement of a total of 20 percutaneous PS and CS. Standard percutaneous PS fixation was performed in cadavers from L1-L5 on one-side followed by CS being placed on the other side. Open anatomical dissection was then performed to confirm placement and compare pedicle breach incidence between PS and CS. Results: Both percutaneous PS and CS were easily placed without difficulty. Dissection revealed no breaches of either construct, and as such no statistical comparison was possible. At one-level however, a CS was seen breaching the posterior-third lateral vertebral body (VB) just under the superior end-plate. Two screw threads exposed were visualized well away from any entering and/or exiting foraminal or paraspinal neurovascular structures. Conclusion: Here, we report a novel study of percutaneous CS insertion with open cadaveric dissection comparing it to PS, incorporating the advantages of both MIS and CS fixation. Although feasible and techni-cally comparable to PS in this report, further study comparing these two techniques and rigorous patient selection for its application are necessary.