Denkena Berend, Reichstein Martin, van der Meer Marijke, Ostermeier Sven, Hurschler Christof
Institute of Production Engineering and Machine Tools, Leibniz Universität Hannover, Germany.
Stud Health Technol Inform. 2008;133:75-82.
A primary cause for revision operations of joint replacements is the implant loosening, due to immune reactions resulting from the agglomeration of polyethylene wear debris. Motivated by the successful application of bioceramic materials in hip joint prostheses, a trend towards the development of hard implant materials has occurred. Nonetheless in the area of total knee arthroplasty (TKA), modern efforts have still utilized polyethylene as the tibial-inlay joint component. The use of bioceramic hard-hard-pairings for total knee arthroplasty has been prevented by the complex kinematics and geometries required. Ceramics cannot cope with non-uniform loads, which suggests the need for new designs appropriate to the material. Furthermore, biomechanical requirements should be considered. A rolling-gliding wear simulator, which reproduces the movements and stresses of the knee joint on specimens of simplified geometry, has therefore been developed. High-precision machining processes for free formed bioceramic surfaces, with suitable grinding and polishing tools which adjust to constantly changing contact conditions, are essential. The goal is to put automated finishing in one clamping with five simultaneous controlled axes into practice. The developed manufacturing technologies will allow the advantageous bioceramic materials to be applied and accepted for more complex joint replacements such as knee prostheses.
关节置换翻修手术的一个主要原因是植入物松动，这是由于聚乙烯磨损碎片聚集引发的免疫反应所致。受生物陶瓷材料在髋关节假体中成功应用的推动，出现了开发硬质植入材料的趋势。尽管如此，在全膝关节置换术（TKA）领域，现代研究仍将聚乙烯用作胫骨镶嵌关节部件。全膝关节置换术中生物陶瓷硬-硬配对的应用因所需的复杂运动学和几何形状而受到阻碍。陶瓷无法应对不均匀载荷，这表明需要适合该材料的新设计。此外，还应考虑生物力学要求。因此，开发了一种滚动-滑动磨损模拟器，该模拟器可在简化几何形状的试样上再现膝关节的运动和应力。采用高精度加工工艺来加工自由成型的生物陶瓷表面，使用适合不断变化的接触条件的磨削和抛光工具至关重要。目标是在一次装夹中通过五个同步控制轴实现自动化精加工。所开发的制造技术将使有利的生物陶瓷材料能够应用于更复杂的关节置换，如膝关节假体，并被接受。
