新型单髁聚乙烯假体的设计及其稳定性的生物力学研究

目的比较新型单髁聚乙烯假体与临床常用假体的稳定性 ,为新型假体应用于临床提供试验依据。方法试验中使用三种类型的单髁胫骨聚乙烯假体 :光滑型、“井”字型及“三柱”型。三种假体的上表面均为浅碟形，底面的结构各不相同：光滑型假体的底面光滑，无任何立体构型；“井”字型假体是临床使用的假体，其底面带有“井”字形分布的沟槽；“三柱”型假体是新型假体，其底面带有三个短柱，分别位于底面前、内、后三个平衡点。将 18具人体胫骨标本随机分为三组，把三种假体牢固地安装在三组标本的内侧室。将标本安装在 CSS－ 1101生物力学试验机上 ,受力点选在假体的前内侧，循环负荷，分别记录三种假体在循环第 1、 2、 3、 4、 5、 10、 15、 20、 25、 30次时 ,负荷为 147 N和 981 N的前、后微动。结果当负荷为 147 N时 ,“三柱”型假体的前、后微动与“井”字型假体的差异无显著性意义；但是，当负荷为 981 N时 ,“三柱”型假体的前、后微动显著低于“井”字型假体。结论新型“三柱”型假体的稳定性优于临床使用的“井”字型假体。本研究为新型假体应用于临床提供了试验依据。

The design of a new unicompartmental ultra high molecular weight polyethylene prosthesis and the biomechanical study on its stability

Objective To Compare the stability of a newly designed unicompartmental pure polyethylene prosthesis with the currently used ones. Methods Three kinds of unicondylar pure polyethylene prosthesis were investigated. The three kinds of prosthesis have the same shallow dish structure in the superior surface; however, the structures of the undersurface are different. The smooth typed prosthesis has a smooth undersurface, ‘ ＃ ’ shape prosthesis has a under surface with grooves, which is used clinically at present, and the newly designed three peg prosthesis has three pegs anteriorly, posteriorly, and medially. Eighteen tibia specimens were divided into three groups randomly, all prostheses were cemented onto the medial compartment of the tibias. Each specimen was tested in a biomechanical machine(CSS－ 1101). A 147 N and 981 N load was applied anteromedially. The anterior and posterior micromovements were measured for 1,2,3,4,5,10,15,20,25,30 cycles at the load of 147 N and 981 N. Results There was no significant difference between three peg prosthesis and ‘ ＃ ’ shape prosthesis during anterior and posterior micromovements at a load of 147 N. But at a 981 N load , the micromovements of three peg prostheses were significantly lower than that of ‘ ＃ ’ shape prosthesis. Conclusion The stability of the newly designed three peg prosthesis was better than that of ‘ ＃ ’ shape prosthesis currently used clinically.