Department of Mechanical and Materials Engineering, Western University, London, Ontario, Canada.
Bioengineering Laboratory, Roth McFarlane Hand and Upper Limb Centre, Lawson Health Research Institute, St Joseph's Health Care, Western University, Bone and Joint Institute, London, Ontario, Canada.
J Orthop Res. 2020 Aug;38(8):1719-1726. doi: 10.1002/jor.24610. Epub 2020 Mar 2.
Hemiarthroplasty is often preferred to total arthroplasty as it preserves native tissue; however, accelerated wear of the opposing cartilage is problematic. This is thought to be caused by the stiffness mismatch between the implant and cartilage-bone construct. Reducing the stiffness of the implant by changing the material has been hypothesized as a potential solution. This study employs a finite element model to study a concave-convex hemiarthroplasty articulation for various implant materials (cobalt-chrome, pyrolytic carbon, polyether ether ketone, ultra-high-molecular-weight polyethylene, Bionate-55D, Bionate-75D, and Bionate-80A). The effect of the radius of curvature and the degree of flexion-extension was also investigated to ensure any relationships found between materials were generalizable. The implant material had a significant effect (P < .001) for both contact area and maximum contact pressure on the cartilage surface. All of the materials were different from the native state except for Bionate-80A at two of the different flexion angles. Bionate-80A and Bionate-75D, the materials with the lowest stiffnesses, were the closest to the native state for all flexion angles and radii of curvature. No evident difference between materials occurred unless the modulus was below that of Bionate-55D (288 MPa), suggesting that hemiarthroplasty materials need to be less stiff than this material if they are to protect the opposing cartilage. This is clinically significant as the findings suggest that the development of new hemiarthroplasty implants should use materials with stiffnesses much lower than currently available devices.
半关节置换术通常优于全关节置换术，因为它保留了原生组织；然而，对置软骨的加速磨损是一个问题。这被认为是由于植入物和软骨-骨结构之间的刚度不匹配造成的。通过改变材料来降低植入物的刚度已被假设为一种潜在的解决方案。本研究采用有限元模型研究了各种植入物材料（钴铬、热解碳、聚醚醚酮、超高分子量聚乙烯、Bionate-55D、Bionate-75D 和 Bionate-80A）的凹面凸面半关节置换关节。还研究了曲率半径和屈伸程度的影响，以确保在材料之间发现的任何关系都具有普遍性。植入物材料对软骨表面的接触面积和最大接触压力都有显著影响（P < .001）。除了 Bionate-80A 在两个不同的屈伸角度外，所有的材料都与原生状态不同。在所有的屈伸角度和曲率半径下，Bionate-80A 和 Bionate-75D 这两种刚度最低的材料与原生状态最接近。除非模量低于 Bionate-55D（288 MPa），否则材料之间不会出现明显差异，这表明如果半关节置换材料要保护对置软骨，它们的刚度需要低于这种材料。这在临床上是有意义的，因为研究结果表明，新的半关节置换植入物的开发应该使用比现有设备刚度低得多的材料。
