LAUSR

Background: Cannulating fenestrated pedicle screws are effective for fixating osteoporotic vertebrae. However, a major limitation is the excessive pressure required to inject a sufficient amount of cement into the vertebral body through the narrow hole of a pedicle screw. We have recently proposed a new cannulating fenestrated pedicle screw with a large hole diameter and a matched inner pin for screw‐strength maintenance. Our purpose was to determine whether the new screw can significantly reduce bone‐cement perfusion pressure during cement augmentation, Methods: Two different methods were used to examine perfusion pressure. Hagen–Poisseuille's flow model in a tube was used to calculate pressure drop in the bone‐cement channel. Experimentally, both Newtonian silicone oil and bone‐cement (polymethyl methacrylate) were tested using a cement pusher through the cannulating screw at a constant rate of 2ml/min. Findings: The internal hollow portion of the screw was the bottleneck of the perfusion, and the new design significantly reduced the perfusion pressure. Specifically, perfusion pressure dropped by 59% (P<0.05) when diameter size was doubled. Interpretation: The new design effectively improved the application of bone‐cement augmentation with the ease of bone‐cement perfusion, thereby enhancing operational safety. HIGHLIGHTSThe internal hollow portion of the cannulating fenestrated pedicle screw was the bottleneck of the perfusion.The new cannulating fenestrated pedicle screw has a large hole diameter and a matched inner pin.The new design significantly reduced the perfusion pressure.