短碳纤维增强聚醚醚酮内接骨板应用于断骨修复过程的有限元模拟

FEM Simulation of Short Carbon Fibre Reinforced PEEK Internal Bone Plate Application to the Healing Process of Fracture Bones

聚醚醚酮(PEEK)作为内植入材料,具有优良的生物相容性、力学性能和透X光等特点。在国外,用该材料制成的商业化产品,包括椎间融合器、牙冠和心脏瓣膜等,已经得到FDA认可。该材料经过纤维等手段增强后,性能可以任意调整到和植入部位组织或骨力学性能匹配,能制作出所需要的植入件。它有望取代骨科金属材料,成为内植入件的主流材料。在先期完成短碳纤维增强PEEK复合材料内接骨板制备和性能测量的基础上,本文选用具有代表性的不同弹性模量的4种骨板(不锈钢骨板、Ti6A14V骨板、碳/羟磷灰石骨板、C/PEEK骨板),采用有限元软件建立正常骨-骨板-断骨三维有限元模型,对骨修复过程中的3个阶段(断骨修复程度1%、50%、75%)分别进行模拟。结果表明:4种内接骨板在断骨处都会产生应力遮挡的现象。随着骨板弹性模量的增大,紧贴骨板下断骨中应力遮挡率越大,有骨板处和其对面没有骨板处应力遮挡率相差变大,没有骨板处断骨最大应变越大,且该处断骨层出现变薄的现象;在螺钉上产生的最大应力也增大,应力集中更明显,骨板内应力集中也越明显,C/PEEK骨板能明显地降低应力屏蔽。

Polyetheretherketone（PEEK）, well known for its excellent biocompatibility, high mechanical properties and transparency to X-rays, has been acknowledged by FDA as implant material in medical applications. Spinal cages, dental crown, cardiac valves etc. made of this material have been commercialized. There is a growing tendency that the PEEK composites will replace metallic implant materials and become staple materials. PEEK can be further enhanced by adding particles or fibers to increase its physical and mechanical performance for applications that require the match between implant materials and bone tissues. Fabrication and performance tests of injection-molded carbon-reinforced PEEK （C/PEEK） bone plates had been completed in our previous study. This paper built a 3-dimensional FE model of a natural bone, bone plate and fractured bone. The mechanical behavior and C/PEEK bone plates were simulated and compared with other three representative elastic modulus bone plates （stainless steel, Ti6A14v, carbon/hydroxylapatite） in the three healing periods of the fractured bone （1% , 50% and 75% ）. The simulation results show that stress-shielding phenomenon exists in each bone fracture of all the bone plates. With the increase of elastic modulus of a bone plate, the stress-shielding ratio of the site beneath the bone plate increases, and the difference of stress-shielding ratio between the site beneath the plate and the site opposite the plate enlarges. The peek stress in fractured bones, bone plates and screws also increases, the phenomenon of stress concentration gets more obvious, and the thickness of the site opposite the plate in fractured bone becomes thinner. In other words, C/PEEK bone plates can obviously reduce the above stress-shielding effects.