人工椎間盤接觸面之設計與分析

Abstract

本研究主要在探討人工椎間盤之接觸面的最佳化設計，人工椎間盤可分為上盤、核心與下盤三個元件，本文即以上盤與核心之接觸面的最佳化設計為主軸。 現今人工椎間盤的研究，以設計出一個可以前彎、後彎與側彎的機構，但對於扭轉的動作並不能有效的提供其活動度。故本研究在人工椎間盤上盤與核心的接觸面改良成橢圓形的機構，以提供人體在扭轉時所需的活動度。 本研究以有限元素法來分析人工椎間盤的接觸面，以應力、應變、變形量與磨耗量為考量，在施以正向壓力與扭轉、前彎等負載，以三個階段來做分析，(1)上盤與核心之接觸面檔板之設計，(2)上盤與核心之接觸面曲率半徑最佳化，(3)在前彎、扭轉時之受力情形下，上盤與核心之接觸面曲率半徑最佳化。 經過分析之後，本研究提供了上盤與核心接觸面的最佳化設計，並且研究其在人體的安全性，並希望未來能夠作植入人體測試，以期達到最適合人體使用之人工椎間盤。

The optimum shape of artificial disc were studied is this research. The artificial disc constructed of superior and inferior cobalt-chromium-molybdenum endplates with a polyethylene articulating bearing. The analysis of the contact face between the upper endplate and the central core was derived in this research. According the former research, the artificial disc was similar to the activities of the real vertebral disc but the angle of rotation was restrained completely. So in this research, we design an ellipse contact face between the upper endplate and the central core for the activities of rotation. Using the finite element analysis for the contact stress, wear and displacement of the contact face between the upper endplate and the central core, we derive an optimum shape for the contact face in three stages. The first stage is the design of the blocking plate of the contact face. The second stage is comparing four kinds of radius of curvature of the contact face. The third stage is comparing two kinds of radius of curvature of the contact face under flexion and rotation. After analysis, we obtain the optimum shape of the artificial disc and prove the safety of the artificial disc is well for human using. However, only after long-term follow-up of clinical experience with the artificial disc is this research could prove the optimum shape of the artificial disc.