人工全膝關節穩定性及裂紋成長之研究

Stability and Crack Propagation Analysis in Total Knee Replacements

林活光(Huo-Kuang Lin)

指導教授 ： 呂東武

國立臺灣大學/工學院/醫學工程學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.00043

摘要

做為治療退化性關節炎的主要方式—人工全膝關節得以有效減輕疼痛及回復患者的運動能力。近來隨著手術技術提升以及設計研發的不斷改良，患者在置換後均有不錯的表現。然而針對功能性動作的回復效果與長期使用而衍生的材料疲勞破壞等議題，仍有改善的空間。一方面，由於手術過程中，必須切除前十字韌帶(ACL)因而改變了膝關節原本的解剖構造，使得置換者在術後回無法完全回復到正常人的表現。另一方面，長久以來對於後十字韌帶(PCL)是否保留存有很大的爭議，現有的設計可分為保留型(CR)與穩定型(PS)，二者於不同的功能性動作表現，經由動態X光技術的運動學分析，卻又互有高下。此外，經過週期性的負載作用，無可避免地將會引發超高分子聚乙烯層(UHMWPE)疲勞破壞問題—磨耗與裂紋生長等現象，嚴動時甚至會造成人工關節的失敗，其發生原因與機制至今仍然缺乏具體而明確的了解。
由於疲勞破壞與關節的運動方式及接觸特性有很大的關聯。其中接觸特性又是取決於關節之間的相對運動方式，故欲了解接觸特性以進行疲勞破壞研究之前必先了解關節的運動學特性。本研究在第一部份嘗試探討韌帶對於兩種型式人工全膝關節被動穩定之表現，以增加關節運動學之理解。第二部份則是藉由功能性動作的資料—上樓梯，做為討論裂紋生長之依據。
而分析所得的結果顯示，PS型的人工關節在未受外的情況下有較小的接觸應力，且在前後平移(A/P translation)及內外扭轉(Int/Ext rotation)兩種自由度方向上有較佳的表現。PS型的穩定效果有很大的部份是來自於關節表面的卡榫設計(cam-spine)，CR型則必須經由PCL的協助才能產生相應的效果。有關裂紋生長的型態，PS及CR型的次表面裂紋最終均發展為扁平圓盤狀，與臨床破壞的型式—點蝕及脫層有所不同，然而真實情況中，並非僅有單一裂紋，是故兩個以上的裂紋彼此之間的交互影響是否才是造成臨床上材料破壞的主要原因，仍有繼續探討的必要。

關鍵字

人工全膝關節 ； 超高分子聚乙烯 ； 穩定性 ； 裂紋 ； 動態X光影像

並列摘要

Total knee arthroplasty (TKA) has been the main choice of treatment for advanced degenerative knee osteoarthritis over the last few decades with excellent long-term survivorship. However, there is still searching for improvement, such as crack propagation, functional range of motion, etc., as well as potential problems that may emerge in the future. Injury or removal of any of the force-bearing structures will inevitably affect the function of the knee, and whether to preserve the posterior cruciate ligament (PCL) remains controversial. Therefore, posterior stabilized (PS) and posterior cruciate retaining (CR) type of TKRs are both available. Previous studies had used several approaching methods to estimate TKRs biomechanic behaviors, but they did not consider kinematics and kinetics which would affect the crack path of ultra-high molecular polyethylene (UHMWPE). Therefore the main purpose of this study was to investigate the relationship of the kinematics, ligamentary force, stress of UHMWPE, and crack propagation patterns between the two types of TKR’s design during functional activities with ligament attached three-dimensional finite element analysis (FEA). The kinematic data during upstairs was obtained from video-fluoroscopy method in vivo. The stability test (anterior-posterior draw test etc.) was performed to validate the accuracy of the model and contact behavior and subsurface crack path of the two types during upstairs were implemented.
The stability test results showed that PS type has higher resistances in anterior-posterior displacement and internal-external rotation. It was influenced by the design of cam-spine to resist the external force and moment. The subsurface crack propagation analysis showed the thin and round shaped crack pattern. With the completed FE model including ligaments and accurate relative kinematic data, the present study showed more reliable and accurate results.

並列關鍵字

Finite element analysis (FEA) ； total knee replacement (TKR) ； stability test ； video-fluoroscopy method ； crack

參考文獻

Abdel-Rahman, E. M. and Hefzy, M. S., 1998. Three-dimensional dynamic behavior of the human knee joint under impact loading. Medical Engineering & Physics 20.

Andriacchi, T. P., Stanwyck, T. S. and Galante, J. O., 1986. Knee biomechanics and total knee replacement. J Arthroplasty 1, 211-219.

Banks, S. A., Markovich, G. D. and Hodge, W. A., 1997. In vivo kinimatics of cruciate-retaining and -substituting knee arthroplaties. Journal of Arthroplasty 12, 297-304.

Bartel, D. L., Bickhell, V. L. and Wright, T. M., 1986. The effect of conformity, thickness and material on stresses in ultra-high molecular weight component for total joint replacement. J. Bone J. Surg. 68(A), 1041-1051.

Benson, L. C., DesJardins, J. D., Harman, M. K. and LaBerge, M., 2002. Effect of stair descent loading on ultra-high molecular weight polyethyiene wear in a force-controlled knee simulator. Proc Inst Mech Eng Part H, J Engng Med 216, 409-418.