Gloria A, Manto L, De Santis R, Ambrosio L
J Appl Biomater Biomech. 2008 Sep-Dec;6(3):163-9.
Low back pain related to intervertebral disc (IVD) degeneration represents a socio-economic problem which affects quality of life. In order to solve this problem the current gold standard techniques such as spinal arthroplasty and arthrodesis (or fusion) are considered. As for spinal arthroplasty, over the past 40 yrs, IVD prostheses have been designed to maintain the correct IVD spacing and to allow for motion, while providing stability. However, there are many difficulties in incorporating important features such as viscoelastic and shock absorber behavior of natural IVDs in a prosthetic disc design. Moreover, in some cases, the use of IVD prostheses does not represent the ideal solution. Consequently, the aim of this study was to improve the design of alternative devices for spinal fusion, which overcome the problems related to metal ones currently available on the market, such as stress shielding, stress concentration effects and eventual bone corrosive or inflammatory reaction.
Accordingly, a novel polyetherimide (PEI)-based cage reinforced with carbon fibers through filament winding and compression molding technologies was realized.
The characterization through a porcine model has produced very interesting results. The small values obtained from local compression tests have suggested that a reduction in mobility occurred, whereas distributed compression tests on IVDs prosthesized by employing the PEI-based cage reinforced with carbon fibers have highlighted a compressive stiffness of 100 MPa. This stiffness is lower than that of the IVD prosthesized through the titanium cage (146 MPa), and closer to the stiffness of natural porcine IVDs (90 MPa).
Through a suitable composite cage design it is possible to control stress-strain distributions and the mechanical signals to bone, thus avoiding the stress-shielding phenomena, but also corrosion and metal ions release which are typical of the metallic implants.
与椎间盘退变相关的下腰痛是一个影响生活质量的社会经济问题。为了解决这个问题，人们考虑了当前的金标准技术，如脊柱置换术和关节固定术（或融合术）。至于脊柱置换术，在过去40年里，椎间盘假体的设计旨在维持正确的椎间盘间隙并允许活动，同时提供稳定性。然而，在假体椎间盘设计中纳入天然椎间盘的粘弹性和减震等重要特性存在许多困难。此外，在某些情况下，使用椎间盘假体并非理想的解决方案。因此，本研究的目的是改进脊柱融合替代装置的设计，以克服与目前市场上现有金属装置相关的问题，如应力屏蔽、应力集中效应以及最终的骨腐蚀或炎症反应。
据此，通过纤维缠绕和压缩成型技术制备了一种新型的基于聚醚酰亚胺（PEI）并由碳纤维增强的椎间融合器。
通过猪模型进行的表征产生了非常有趣的结果。局部压缩试验得到的小数值表明活动度有所降低，而对采用基于PEI并由碳纤维增强的椎间融合器进行假体置换的椎间盘进行的分布式压缩试验突出显示其压缩刚度为100MPa。这个刚度低于通过钛制椎间融合器假体置换的椎间盘的刚度（146MPa），且更接近天然猪椎间盘的刚度（90MPa）。
通过合适的复合椎间融合器设计，可以控制应力 - 应变分布以及传递至骨骼的机械信号，从而避免应力屏蔽现象，以及金属植入物典型的腐蚀和金属离子释放问题。
