Jendoubi K, Khadri Y, Bendjaballah M, Slimane N
École Nationale Supérieure d'Ingénieurs de Tunis, Tunis, Tunisia.
Laboratoire de Biomécanique, Institut National d'Orthopédie M.T. Kassab, Tunis, Tunisia.
Appl Bionics Biomech. 2018 Jul 26;2018:1460195. doi: 10.1155/2018/1460195. eCollection 2018.
The pedicle screw is a surgical device that has become widely used in spinal fixation and stabilization. Postsurgical complications such as screw loosening due to fatigue loading and screw breakage still need investigations. Clinical parameters such as the screw insertion type and depth, the bone density, and the patient degree of mobility greatly affect the mechanisms of the implant's failure/success.
The current finite element study focused on the prediction of the pedicle screw pullout strength under various conditions such as insertion type, insertion depth, bone quality, and loading mode.
As depicted in this study, the preservation of the pedicle cortex as in the N1 insertion technique greatly enhances the pullout resistance. In addition, the higher the screw-anchoring depth, permitting to gear a maximum number of threads, the better the protection against premature breakouts of pedicle screws.
In agreement with experimental data, the type of insertion in which the first screw thread is placed immediately after the preserved pedicle cortex showed the best pullout resistance for both normal and osteoporotic bone.
椎弓根螺钉是一种已广泛应用于脊柱固定和稳定的外科器械。术后并发症，如因疲劳负荷导致的螺钉松动和螺钉断裂，仍需进一步研究。诸如螺钉植入类型和深度、骨密度以及患者活动程度等临床参数会极大地影响植入物成败的机制。
当前的有限元研究聚焦于预测在各种条件下，如植入类型、植入深度、骨质和加载模式下椎弓根螺钉的拔出强度。
如本研究所示，采用N1植入技术保留椎弓根皮质可极大地增强拔出阻力。此外，螺钉锚固深度越高，能啮合的螺纹数量越多，对椎弓根螺钉过早脱出的保护就越好。
与实验数据一致，对于正常骨和骨质疏松骨，第一种螺纹紧挨着保留的椎弓根皮质放置的植入类型显示出最佳的拔出阻力。
