Muratoglu Orhun K, Bragdon Charles R, O'Connor Daniel O, Perinchief Rebecca S, Jasty Murali, Harris William H
Orthopaedic Biomechanics and Biomaterials Laboratory, Massachusetts General Hospital, Boston, 02114, USA.
Clin Orthop Relat Res. 2002 Nov(404):89-95. doi: 10.1097/00003086-200211000-00015.
Recently, highly cross-linked polyethylenes with high wear and oxidation resistance have been developed. These materials may improve the in vivo performance of polyethylene components used in total knee arthroplasty. To date, the in vitro knee wear testing of these new polyethylenes has been done under conditions of normal gait. However, their critical assessment also must include aggressive in vitro fatigue and wear testing. In the current study, an aggressive in vitro knee wear and device fatigue model simulating a tight posterior cruciate ligament balance during stair climbing was developed and used to assess the performance of one type of highly cross-linked polyethylene tibial knee insert in comparison with conventional polyethylene. The highly cross-linked inserts and one group of conventional inserts were tested after sterilization. One additional group of conventional inserts was subjected to accelerated aging before testing. The articular surfaces of the inserts were inspected visually for surface delamination, cracking, and pitting at regular intervals during the test. The aged conventional polyethylene inserts showed extensive delamination and cracking as early as 50,000 cycles. In contrast, the unaged conventional and highly cross-linked polyethylene inserts did not show any subsurface cracking or delamination at 0.5 million cycles. The appearance and location of delamination that occurred in the aged conventional inserts tested with the current model previously have been observed in vivo with posterior cruciate-sparing design knee arthroplasties with a tight posterior cruciate ligament.
最近，已开发出具有高耐磨性和抗氧化性的高度交联聚乙烯。这些材料可能会改善全膝关节置换术中使用的聚乙烯部件的体内性能。迄今为止，这些新型聚乙烯的体外膝关节磨损测试是在正常步态条件下进行的。然而，对它们的关键评估还必须包括激进的体外疲劳和磨损测试。在当前的研究中，开发了一种激进的体外膝关节磨损和装置疲劳模型，该模型模拟了爬楼梯时后交叉韧带的紧密平衡，并用于评估一种高度交联聚乙烯胫骨膝关节插入物与传统聚乙烯相比的性能。高度交联的插入物和一组传统插入物在灭菌后进行测试。另一组传统插入物在测试前进行加速老化。在测试过程中，定期目视检查插入物的关节表面是否有表面分层、开裂和点蚀。老化的传统聚乙烯插入物早在50,000次循环时就出现了广泛的分层和开裂。相比之下，未老化的传统和高度交联聚乙烯插入物在50万次循环时未出现任何亚表面开裂或分层。在当前模型中测试的老化传统插入物中发生的分层的外观和位置，先前已在体内后交叉韧带保留设计的膝关节置换术中观察到，其具有紧密的后交叉韧带。
