3D real time studying fatigue microcrack formation in cemented femur construct

3D 实时研究骨水泥股骨结构中疲劳微裂纹的形成

• 批准号: 7407487
• 负责人: GANG QI
• 金额: $ 6.84万
• 依托单位: UNIVERSITY OF MEMPHIS
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-05 至 2009-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7407487
• 关键词: Acoustics; Arthroplasty; Bone Cements; Cadaver; Condition; Correlation Studies; Decompression Sickness; Devices; Event; Failure; Fatigue; Femur; Hip region structure; Investigation; Location; Measures; Mechanics; Mentors; Modeling; Play; Process; Reporting; Research; Role; Shear Strength; Signal Transduction; Source; Specimen; Stress; Structure; Techniques; Testing; Time; Time Study; Work; density; novel strategies; stem

DESCRIPTION (provided by applicant): Failure of cemented total hip arthroplasty (THA) often occurs when microcracks coalesce into a clinically observable failure. Considerable researches have focused on reducing stress risers in the devices' stem, on failures at the cement interfaces, and on failure in the cement mantle. However, it is not clear what role of progressive microcrack formation play in fatigue failure of a cemented femur stem construct. Our recent studies revealed that the acoustic signatures of model construct permit categorization of the fatigue induced microcracks into two types. Most Type I microcracks are identifiable under SEM with high signal energy. Type II microcracks are associated with low signal energy. The formation, accumulation, and distribution of Type I microcracks correlate with specimen failure whereas Type II microcracks seems to have a counter-correlation with failure. The next step forward in this avenue of investigation is to further study the correlation between these microcracks and material strength, and fatigue failure mechanisms. To achieve this objective, we will use newly developed acoustic emission microcrack source location technique in following steps. (1) We will characterize microcracks in bone cement and investigate their effects on the flexural strength of the cement. (2) We will characterize microcracks generated at the stem-cement interface and investigate their effects on the shear strength of the construct. (3) We will characterize microcracks generated in fatigue tests of cemented femur stem construct using cadaver specimens and correlate their presence with SEM observations. We will use quantitative indicators to assess the formation and progression of microcracks under various fatigue loading conditions. We will measure the onset time, distribution, density, and progression of these microcracks. The accomplishment of this objective will enhance our understanding of femur construct fatigue failure mechanism and open novel approaches to the studies of THA loosening. In the proposed work, we will test the following hypothesis: Two types of microcracks initiate in the cemented femoral stem constructs of total hip arthroplasty before clinically observable failure occurs. Type I microcracks directly contribute to the loosening of a femur stem constructs. Type II microcracks function as energy absorbers and thereby retard the loosening process.

描述(申请人提供)：骨水泥全髋关节置换术(THA)的失败通常发生在微裂纹结合成临床可观察到的失败时。相当多的研究集中在减少装置杆部的应力冒口、水泥界面的故障和水泥套的故障上。然而，目前尚不清楚进行性微裂纹的形成在骨水泥股骨假体的疲劳失效中所起的作用。 我们最近的研究表明，模型结构的声学特征允许将疲劳引起的微裂纹分为两种类型。大多数I型微裂纹在高信号能量的扫描电子显微镜下都能被识别。II型微裂纹与低信号能量有关。形成、积累和 I型微裂纹的分布与试件的失效有关，而II型微裂纹的分布似乎与失效呈负相关。 下一步的研究方向是进一步研究这些微裂纹与材料强度之间的关系，以及疲劳破坏机理。为了实现这一目标，我们将在以下步骤中使用新开发的声发射微裂源定位技术。(1)对骨水泥中的微裂纹进行表征，并研究其对骨水泥抗折强度的影响。(2)我们将表征茎-水泥界面上产生的微裂纹，并研究它们对结构抗剪强度的影响。(3)我们将利用身体标本对骨水泥股骨假体的疲劳试验中产生的微裂纹进行表征，并将其存在与扫描电子显微镜观察相关联。我们将使用定量指标来评估不同疲劳载荷条件下微裂纹的形成和发展。我们将测量这些微裂纹的起始时间、分布、密度和发展。这一目标的实现将增进我们对 股骨构建疲劳破坏机制，开辟研究全髋关节松动的新途径。在拟议的工作中，我们将检验以下假设： 在临床可观察到的失败发生之前，两种类型的微裂纹开始于全髋关节置换术的骨水泥股骨柄结构。I型微裂纹直接导致股骨假体的松动。II型微裂纹起到了能量吸收的作用，从而延缓了松动过程。