Synthes GmbH, Eimattstrasse 3, CH-4436 Oberdorf BL, Switzerland.
Spine J. 2012 Jul;12(7):603-11. doi: 10.1016/j.spinee.2012.07.009.
Total disc replacement (TDR) is a relatively new reconstructive non-fusion technology for the spine that aims to overcome some of the limitations of fusion technology. The first generation artificial discs were mainly based on well-known material combinations from total hip replacement.
To evaluate the feasibility of PEEK-on-PEEK as a bearing surface material for use in cervical TDR.
In vitro biotribological study including the assessment of different parameters, including the influence of radial clearance, axial load, and angular motion on the wear performance of a PEEK-on-PEEK bearing.
PEEK-on-PEEK bearing couples with ball-and-socket articulation were prepared using standard production methods. Two groups of bearing couples, one with large radial clearances and the other with small radial clearances, were manufactured for testing. Wear tests were performed using a servo-hydraulic wear simulator that allowed controlled motions to be applied in three axes corresponding to flexion-extension, lateral bending, and axial rotation. In addition, a dynamic axial compressive load was applied to simulate the weight of the head. All tests were performed at 37°C (±2°C) in bovine calf serum with a 30 g/l protein concentration. In the first test series, the influence of the radial clearance on the wear behavior was evaluated using the load and motion parameters for cervical TDR as defined in the ISO standard 18192-1. Subsequent tests were performed to check if surface degradation was influenced by thermal effects. Finally, in a third series of tests, the effect of load and motion profiles on wear performance was investigated by applying increased loads and corresponding motion parameters for lumbar TDR as defined in the ISO standard 18192-1.
The measured wear rates for a PEEK-on-PEEK bearing under cervical test conditions were considerably larger than those of similar testing using UHMWPE-on-CoCr and seemed to depend on initial radial clearances. The PEEK bearing surfaces exhibited severe surface degradation for large and small clearances, but the group with smaller clearances seemed to have less severe damage. Thermal effects were not found to play a role in the surface degradation, as the temperature near the bearing surface was measured and found to vary only a few degrees during testing. A change of the wear test parameters to simulate lumbar loading resulted in a considerable wear rate reduction as well as in the preservation of the bearing surfaces.
It was found that a cervical TDR using a PEEK-on-PEEK bearing may be subjected to severe long-term degradation of the bearing surfaces. In this study, the use of PEEK as an articulation material for cervical TDR was found to be sensitive to loading conditions as well as to the initial clearance of the bearing surfaces. Despite the excellent properties of PEEK as an implant material, its use for articulating surfaces for cervical TDR must be critically reviewed.
全椎间盘置换术（TDR）是一种相对较新的脊柱重建非融合技术，旨在克服融合技术的一些局限性。第一代人工椎间盘主要基于全髋关节置换术的知名材料组合。
评估 PEEK-ON-PEEK 作为一种用于颈椎 TDR 的轴承表面材料的可行性。
体外生物摩擦学研究，包括评估不同参数的影响，包括径向间隙、轴向载荷和角运动对 PEEK-ON-PEEK 轴承磨损性能的影响。
使用标准生产方法制备 PEEK-ON-PEEK 球窝关节轴承对。制造了两组轴承对，一组具有较大的径向间隙，另一组具有较小的径向间隙进行测试。使用伺服液压磨损模拟器进行磨损试验，该模拟器允许在三个轴上施加受控运动，对应于屈伸、侧向弯曲和轴向旋转。此外，施加动态轴向压缩载荷以模拟头部重量。所有测试均在牛犊血清中在 37°C（±2°C）下进行，蛋白浓度为 30g/l。在第一个测试系列中，使用 ISO 标准 18192-1 中定义的颈椎 TDR 的载荷和运动参数评估径向间隙对磨损行为的影响。随后的测试用于检查表面降解是否受热效应影响。最后，在第三个测试系列中，通过施加增加的载荷和 ISO 标准 18192-1 中定义的腰椎 TDR 的相应运动参数，研究了载荷和运动曲线对磨损性能的影响。
在颈椎测试条件下，PEEK-ON-PEEK 轴承的测量磨损率明显大于使用 UHMWPE-on-CoCr 进行类似测试的值，并且似乎取决于初始径向间隙。对于较大和较小的间隙，PEEK 轴承表面都出现了严重的表面降解，但间隙较小的组似乎损坏程度较轻。未发现热效应在表面降解中起作用，因为测量了轴承表面附近的温度，发现测试过程中仅变化几度。将磨损测试参数更改为模拟腰椎载荷导致磨损率显着降低，并且保持了轴承表面。
研究发现，使用 PEEK-ON-PEEK 轴承的颈椎 TDR 可能会导致轴承表面的严重长期降解。在这项研究中，发现 PEEK 作为颈椎 TDR 的关节材料对载荷条件以及轴承表面的初始间隙很敏感。尽管 PEEK 作为植入物材料具有优异的性能，但必须对其用于颈椎 TDR 的关节表面的使用进行严格审查。
