Sobajima Atsushi, Okihara Takumi, Moriyama Shigeaki, Nishimura Naoyuki, Osawa Takako, Miyamae Kazutaka, Haniu Hisao, Aoki Kaoru, Tanaka Manabu, Usui Yuki, Sako Ken-Ichi, Kato Hiroyuki, Saito Naoto
Department of Orthopaedic Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan.
Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama, Okayama 700-0082, Japan.
ACS Biomater Sci Eng. 2020 Dec 14;6(12):7032-7040. doi: 10.1021/acsbiomaterials.0c00916. Epub 2020 Oct 20.
Because ultrahigh-molecular-weight polyethylene (UHMWPE) is susceptible to frictional wear when used in sliding members of artificial joints, it is common practice to use cross-linked UHMWPE instead. However, cross-linked UHMWPE has low impact resistance; implant breakage has been reported in some cases. Hence, sliding members of artificial joints pose a major trade-off between wear resistance and impact resistance, which has not been resolved by any UHMWPE. On the other hand, multiwall carbon nanotubes (MWCNTs) are used in industrial products for reinforcement of polymeric materials but not used as biomaterials because of their unclear safety. In the present study, we attempted to solve this trade-off issue by complexing UHMWPE with MWCNTs. In addition, we assessed the safety of these composites for use in sliding members of artificial joints. The results showed the equivalence of MWCNT/UHMWPE composites to cross-linked UHMWPE in terms of wear resistance and to non-cross-linked UHMWPE in terms of impact resistance. In addition, all MWCNT/UHMWPE composites examined complied with the requirements of biosafety testing in accordance with the ISO10993-series specifications for implantable medical devices. Furthermore, because MWCNTs can occur alone in wear dust, MWCNTs in an amount of about 1.5 times that contained in the dust produced from 50 years of wear (in the worst case) were injected into rat knees, which were monitored for 26 weeks. Although mild inflammatory reactions occurred in the joints, the reactions soon became quiescent. In addition, the MWCNTs did not migrate to other organs. Furthermore, MWCNTs did not exhibit carcinogenicity when injected into the knees of mice genetically modified to spontaneously develop cancer. The MWCNT/UHMWPE composite is a new biomaterial expected to be safe for clinical applications in both total hip arthroplasty and total knee arthroplasty as the first sliding member of artificial joints to have both high wear resistance and high impact resistance.
由于超高分子量聚乙烯（UHMWPE）在人工关节的滑动部件中使用时易受摩擦磨损，因此通常使用交联UHMWPE来替代。然而，交联UHMWPE的抗冲击性较低；在某些情况下已报道有植入物断裂的情况。因此，人工关节的滑动部件在耐磨性和抗冲击性之间存在重大权衡，而任何UHMWPE都未能解决这一问题。另一方面，多壁碳纳米管（MWCNTs）用于工业产品中增强聚合物材料，但由于其安全性不明，未用作生物材料。在本研究中，我们试图通过将UHMWPE与MWCNTs复合来解决这一权衡问题。此外，我们评估了这些复合材料用于人工关节滑动部件的安全性。结果表明，MWCNT/UHMWPE复合材料在耐磨性方面与交联UHMWPE相当，在抗冲击性方面与非交联UHMWPE相当。此外，所有检测的MWCNT/UHMWPE复合材料均符合根据ISO10993系列规范对可植入医疗器械进行的生物安全性测试要求。此外，由于MWCNTs可能单独存在于磨损粉尘中，将约为50年磨损产生的粉尘（在最坏情况下）中所含MWCNTs量1.5倍的MWCNTs注入大鼠膝关节，并对其进行26周监测。尽管关节中出现了轻度炎症反应，但这些反应很快就平息了。此外，MWCNTs未迁移到其他器官。此外，当将MWCNTs注入经基因改造可自发患癌的小鼠膝关节时，未表现出致癌性。MWCNT/UHMWPE复合材料是一种新型生物材料，有望作为人工关节的首个滑动部件，在全髋关节置换术和全膝关节置换术中临床应用安全，兼具高耐磨性和高抗冲击性。
