Department of Mechanical Engineering, University of Arkansas, Fayetteville, AR, USA 72701; Center for Advanced Surface Engineering, University of Arkansas, Fayetteville, AR, USA 72701.
Faculty of Mechanical Engineering, Brno University of Technology, Technická 2896/2, 616 69 Brno, Czech Republic.
J Mech Behav Biomed Mater. 2018 Mar;79:314-323. doi: 10.1016/j.jmbbm.2018.01.003. Epub 2018 Jan 6.
The number of revision joint replacements has been increasing substantially over the last few years. Understanding their failure mechanism is extremely important for improving the design and material selection of current implants. This study includes ten retrieved and four new mildly cross-linked ultra-high molecular weight polyethylene (UHMWPE) acetabular liners. Among them, most of the prostheses (n = 5) were reported to be revised and replaced due to aseptic loosening, followed by painful joint (n = 2), dislocation (n = 1), intra articular ossification (n = 1), combination of wear (liner) and osteolysis (stem) (n=1). Surface deviations (wear, material inflation and roughness), oxidative degradation and change of material properties were measured using micro-computed tomography (micro-CT) scan, 3D laser scanning microscopy, raman spectroscopy and nanoindentation, respectively. Prostheses having eccentric worn areas had much higher linear wear rates (228.01 ± 35.51µm/year) compared to that of centrically worn prostheses (96.71 ± 10.83µm/year). Oxidation index (OI) showed similar trends to the surface penetration depth. Among them, sample 10 exhibited the highest OI across the contact area and the rim of the cup liner. It also had the lowest hardness/elasticity ratio. Overall, wear and creep, oxidative degradation and reduced hardness/elasticity ratio all contributed to the premature failure of the UHMWPE acetabular cup liners.
近年来，翻修关节置换的数量大幅增加。了解其失效机制对于改进当前植入物的设计和材料选择至关重要。本研究包括 10 个回收的和 4 个新的轻度交联超高分子量聚乙烯（UHMWPE）髋臼衬垫。其中，大多数假体（n = 5）因无菌性松动而被报告进行了翻修和更换，其次是疼痛关节（n = 2）、脱位（n = 1）、关节内骨化（n = 1）、磨损（衬垫）和溶骨（柄）结合（n=1）。使用微计算机断层扫描（micro-CT）扫描、3D 激光扫描显微镜、拉曼光谱和纳米压痕分别测量表面偏差（磨损、材料膨胀和粗糙度）、氧化降解和材料性能变化。与中心磨损的假体（96.71 ± 10.83µm/year）相比，具有偏心磨损区域的假体具有更高的线性磨损率（228.01 ± 35.51µm/year）。氧化指数（OI）与表面穿透深度显示出相似的趋势。其中，样品 10 在杯衬垫的接触区域和边缘表现出最高的 OI。它的硬度/弹性比也最低。总的来说，磨损和蠕变、氧化降解以及硬度/弹性比的降低都导致了 UHMWPE 髋臼衬垫的过早失效。
