Department of Orthopaedic Surgery, CAPHRI Care and Public Health Research Institute, Maastricht University Medical Centre, P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands.
J Mater Sci Mater Med. 2017 Aug 21;28(10):148. doi: 10.1007/s10856-017-5953-0.
Loss of sagittal alignment and balance in adult spinal deformity can cause severe pain, disability and progressive neurological deficit. When conservative treatment has failed, spinal fusion using rigid instrumentation is currently the salvage treatment to stop further curve progression. However, fusion surgery is associated with high revision rates due to instrumentation failure and proximal junctional failure, especially if patients also suffer from osteoporosis. To address these drawbacks, a less rigid rod construct is proposed, which is hypothesized to provide a more gradual transition of force and load distribution over spinal segments in comparison to stiff titanium rods. In this study, the effect of variation in rod stiffness on the intradiscal pressure (IDP) of fixed spinal segments during flexion-compression loading was assessed. An ex vivo multisegment (porcine) flexion-compression spine test comparing rigid titanium rods with more flexible polycarbonate-urethane (PCU) rods was used. An increase in peak IDP was found for both the titanium and PCU instrumentation groups as compared to the uninstrumented controls. The peak IDP for the spines instrumented with the PCU rods was significantly lower in comparison to the titanium instrumentation group. These results demonstrated the differences in mechanical load transfer characteristics between PCU and titanium rod constructs when subjected to flexion-compression loading. The concept of stabilization with a less rigid rod may be an alternative to fusion with rigid instrumentation, with the aim of decreasing mechanical stress on the instrumented segments and the possible benefit of a decrease in the incidence of screw pullout.
成人脊柱畸形中矢状位排列和平衡的丧失可导致严重疼痛、残疾和进行性神经功能缺损。当保守治疗失败时，目前使用刚性器械的脊柱融合是阻止进一步曲线进展的挽救治疗方法。然而，由于器械故障和近端交界性失败，融合手术与较高的翻修率相关，尤其是如果患者还患有骨质疏松症。为了解决这些缺点，提出了一种刚性较低的棒状结构，假设与刚性钛棒相比，它能在脊柱节段上提供更渐进的力和负荷分布过渡。在这项研究中，评估了棒状刚度变化对弯曲压缩加载时固定脊柱节段椎间盘内压力（IDP）的影响。使用比较刚性钛棒和更柔韧的聚碳酸酯-氨基甲酸酯（PCU）棒的多节（猪）弯曲压缩脊柱体外测试进行了研究。与未固定的对照组相比，钛和 PCU 器械组的峰值 IDP 均增加。与钛器械组相比，PCU 棒固定的脊柱的峰值 IDP 显著降低。这些结果表明，在经受弯曲压缩加载时，PCU 和钛棒结构之间的机械负载传递特性存在差异。使用刚度较低的棒进行稳定的概念可能是刚性器械融合的替代方法，目的是减少器械节段上的机械应力，并可能减少螺钉拔出的发生率。
