- 學位論文
人工膝關節脛骨連接面之新設計
New Design for Tibial-Implant Interface in Total Knee Arthroplasty
摘要
人工關節的發明被稱為近代醫療界三大重要發明之一，其重要性也僅次於抗生素。在各種人工關節手術中，又以人工膝關節之技術與效果最為成熟，的設計也日趨穩定，往往可用20年左右。中央健康保險局統計在民國98至100年間，台灣全年之全人工膝關節置換約為兩萬例；而加上平均壽命逐年上升，人工膝關節因超過年限而需要再置換的個案也逐年增加，每年約有一千例以上的病患需要再置換。 為達到快速接合脛骨與人工關節之間之接面，目前都使用骨水泥(PMMA)於兩者之連接面，黏合效果非常良好。但也因此造成再置換手術時清除骨水泥及拔除原人工關節困難重重，讓骨科醫師在進行此手術時非常費時，且清除骨水泥時，連帶犠牲相當多的有用的鬆質骨及硬質骨，這樣的流失又更增加病人身體上的消耗。 本研究為減少上述接合面分離的困難，將設計新的接面機構及結構以減少清除骨水泥時之正常骨骼之犠牲，而又兼顧到新接合面骨切面與人工關節之穩定度，結合機構將採相互凹凸面之接合，並集中於週邊之硬質骨上，骨水泥亦集中於週邊。此一設計之假設，在於多個凹凸面所提供之接合力，可與目前之多面接觸作穩定度之比較，並增添二次置換手術時的便利性。 在此研究中，先以繪圖軟體Solidwork和模擬軟體ANSYS來分析舊式人工關節受壓應力時，應力集中位置，從分析證實主要應力多半集中於硬質骨上，與鬆質骨關聯性較低；證實理論後，設計新式人工關節，並以豬骨實驗模組作出力學測試，以取得新設計之接合面穩定度；在此研究中，設置四組置換上新式關節的豬骨模組，進行拉伸試驗，從拉伸實驗結果可得知，硬質骨與骨水泥接合處會承受最大拉力，四個模組於周邊硬質骨-骨水泥間分別承受278.6694 (N)、245.2942 (N)、193.9125 (N)的力，可判斷出硬質骨與骨水泥間可承受拉力約略為其平均的240(N)，而有梯形結構支撐下的模組四為564.5449(N)；再就過去未貼合周邊硬質骨而以梯形結構作支撐的模組來看，脛骨梯形凹槽與骨水泥間承受約略810(N)的力，由此可知梯形結構的重要性。且於二次置換時，新式關節可運用骨水泥不抗剪力的特性快速移除關節，以提升置換方便性，並達到本研究設計目的。
並列摘要
Arthroplasty possibly is one of the three most important inventions in last few decades, and just behind antibiotics for its contributions. In various types of arthroplasties, total knee arthroplasty (TKA) is the most established and reliable procedure. The survivorship can last for up to 20 years. In 2009-2011, there were about twenty thousand TKA performed in Taiwan. Along with progressively lengthen life expectancy, Number of revision of TKR increases annually and there are almost one thousand cases per year. Application of bone cement (PMMA) achieves a faster and better bone implant interface in TKA especially in tibial component. In the other hand, this secured fixed implant caused troublesome in removal of bone implant during revision TKA surgery. Orthopedic surgeons always find difficulties in removing bone cement between bone and implant. It also found that massive trabecular and cortical bone are sacrificed. In this study, for decreasing the degree of difficulty in separation of implant from bony component, a new locking mechanism and implant structure are designed to avoid unnecessary bone loss. The locking mechanism based on plug-in surface in the rim of tibial cutting surface and sit on the peripheral strong cortical bone. The multiple plug-in locations showed provide enough combination forces and should be comparable with present stability design. In our experiment, we use Solidwork and ANSYS to analysis the position of stress concentration. The result shows that stress concentrates on cortical bone rather than cancellous bone. We design a new total knee arthroplasty and made several tensile test. Testing models about tensile forces of the Instron device were obtained in mechanical testing. In this research, we set four pig-knee models which are placed on new type artificial knee joint and have tensile test. Results showed that the maximum fracture force for three of all models happened on the interface between rim of the cortical bone and bone cement. The magnitudes are 278.6694 (N), 245.2942 (N) and 193.9125 (N). The last set had support by trapezoid-shape structure, so its magnitude is 564.5499(N). In terms of the model which doesn’t fit between rim of the cortical bone and bone cement, the force between trapezoid-shape fillister and bone cement is about 810(N). Those data could show the importance of the trapezoid-shape structure. For TKA revision, new design arthroplasty take advantage of the weakness of the bone cement which hardly bearing the shear force to remove arthroplasty rapidly. It also improved the convenience of Revision and achieved the purpose of this research.