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Breakage of metal hip arthroplasty components: Retrieval and structural analysis.
Bio-Medical Materials and Engineering ( IF 1 ) Pub Date : 2019-04-23 , DOI: 10.3233/bme-191053
Łukasz Łapaj 1 , Waldemar Woźniak 1 , Tomasz Wiśniewski 2 , Justyna Rozwalka 2 , Łukasz Paczesny 3 , Jan Zabrzyński 3 , Piotr Janusz 4 , Jacek Kruczyński 1
Affiliation  

BACKGROUND Breakage of joint arthroplasty components are rare, yet during an implant retrieval program we found several cases. OBJECTIVE In this study we examined the components to determine the causes and mechanisms of breakage of these implants. METHODS From our collection of 849 retrievals we selected 682 cases with metal parts (503 hip, 79 knee arthroplasties) and identified fractured components: seven hip resurfacing implants, five total hip replacement stems, one monopolar femoral head, and one modular revision femoral stem from. Implants were examined using optical and scanning electron microscopy; metallographic sections were prepared and samples of periprosthetic tissues underwent microscopic examination. RESULTS In the resurfacing components breakage occurred in small stems placed in the femoral neck due to necrosis of femoral heads, with no metal flaws detected. Fatigue breakage of femoral stems was caused by presence of material flaws in the CoCrMo alloy, and corrosion. The monopolar head failed in fatigue fracture mechanism, breakage was initiated in an undercut near the taper connection for femoral component. The modular stem from Ti alloy sustained fatigue fracture induced by corrosion caused by debris from previously revised stem; no material flaws were detected in this sample. In most cases periprosthetic tissues had a morphology typical for aseptic loosening. CONCLUSIONS In our series failure was caused by material flaws, presence of stress raisers and localized corrosion. Our findings indicate that sharp edges and other features which can act as stress raisers should be avoided in newly designed implants. Corrosion induced fracture of the modular Ti stem indicates the need for a detailed debridement of periprosthetic tissues during revision arthroplasties.

中文翻译:

金属髋关节置换术部件的断裂:检索和结构分析。

背景技术关节置换术部件的破损很少,但是在植入物修复程序中我们发现了几种情况。目的在这项研究中,我们检查了组件,以确定这些植入物破裂的原因和机理。方法从849份文献中,我们选择了682例金属部件(503髋,79例膝关节置换术)并确定了骨折部位:7例髋关节表面置换植入物,5例全髋关节置换茎,1例单极股骨头和1例模块化翻修股骨茎。使用光学和扫描电子显微镜检查植入物。准备金相切片,并对假体周围组织的样品进行显微镜检查。结果由于股骨头坏死,在股骨颈中的小茎干中发生了表面修复部件的断裂,没有发现金属缺陷。股骨柄疲劳断裂是由于CoCrMo合金中存在材料缺陷和腐蚀引起的。单极头的疲劳断裂机制失败,断裂发生在股骨组件锥形连接附近的底切中。钛合金制成的模块化阀杆由于先前修改过的阀杆的碎屑引起的腐蚀而持续疲劳断裂;在该样品中未检测到材料缺陷。在大多数情况下,假体周围组织具有无菌性松动的典型形态。结论在我们的系列中,故障是由材料缺陷,应力产生器的存在和局部腐蚀引起的。我们的发现表明,在新设计的植入物中应避免使用锋利的边缘和其他可能引起应力增加的特征。
更新日期:2019-11-01
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