Department of Orthopaedics and Traumatology, San Raffaele Scientific Institute, Milan, Italy.
Eur Spine J. 2011 May;20 Suppl 1(Suppl 1):S3-7. doi: 10.1007/s00586-011-1746-1. Epub 2011 Mar 15.
Posterior spinal instrumentation is frequently used for the treatment of spine disorders. Importantly, different requirements have to be considered for the optimal use of these systems in various clinical scenarios. In this work, we focused on the role of rods diameter on hardware's stiffness. For this purpose, we established an in vitro model and compared the response to axial load of a posterior stabilization system, characterized by rods of different diameter (4, 5, 6 mm), with that of Dynesys®. Intuitively, the higher the stiffness of the hardware, the lower the load is transferred to the disc. However, the 4 hardware tested showed a different trend in the response to the load regimens: when increasing the load, more flexible systems display a progressive reduction in the percentage of load which is transferred to the disc while more rigid system display the opposite trend. Considering that the load which is transferred, and not by-passed by the hardware, influences the healing of a fracture; the integration of a bone graft or a cage; the fusion process, these data have a relevant impact on clinical practice and highlight features that have to be considered in the choice for the optimal posterior spinal instrumentation.
后路脊柱内固定系统常用于治疗脊柱疾病。重要的是，在各种临床情况下，为了优化这些系统的使用，需要考虑不同的要求。在这项工作中，我们专注于杆直径对硬件刚度的作用。为此，我们建立了一个体外模型，并比较了不同直径（4、5、6 毫米）的杆后路稳定系统对轴向载荷的反应与 Dynesis®的反应。直观地说，硬件的刚度越高，传递到椎间盘的负荷就越低。然而，测试的 4 种硬件在对负荷方案的反应中表现出不同的趋势：当增加负荷时，更灵活的系统显示出转移到椎间盘的负荷百分比逐渐减少，而更刚性的系统则显示出相反的趋势。考虑到传递而不是被硬件绕过的负荷会影响骨折的愈合；骨移植物或笼的整合；融合过程；这些数据对临床实践有相关影响，并突出了在选择最佳后路脊柱内固定装置时需要考虑的特征。
