构建Cam型髋关节撞击综合征有限元模型及力学分析

Finite element modeling and mechanical analysis for Cam-type femoroacetabular impingement

背景:Cam型髋关节撞击综合征可使关节承受力学过载并最终导致髋关节骨关节炎,然而其诱发骨关节炎的相关力学机制仍不清楚。目的:运用三维有限元的方法,分析Cam型髋关节撞击综合征的关节内力学环境,进一步了解其病理力学特点。方法:采用正常髋关节CT数据,利用Mimics和Hypermesh软件准确构建正常髋关节和Cam型髋关节撞击综合征三维有限元模型。在LS-DYNA软件中,模拟坐下、起立时的力学加载条件,对正常髋关节和Cam型髋关节撞击综合征髋关节的软骨接触力学进行分析。结果与结论:基于CT数据准确构建了包含关节软骨的正常髋关节和Cam型髋关节撞击综合征髋关节三维有限元力学分析模型。坐下、起立加载过程中,正常髋关节在最大屈髋位时峰值接触压力分别为4.43,4.59 MPa;而Cam型髋关节撞击综合征髋关节分别为14.96,14.86 MPa,髋臼缘前上方出现过高压力和应力集中。提示髋臼软骨过高的接触压力可能是Cam型髋关节撞击综合征导致骨关节炎的力学机制。

BACKGROUND：Cam-type femoroacetabular impingement can impose elevated mechanical loading in the hip, and may eventual y result in hip osteoarthritis, while mechanical mechanism on how this deformity leads to osteoarthritis is stil unclear. 〈br〉 OBJECTIVE：To analyze intra-articular mechanical environment of Cam-type femoroacetabular impingement in hip joint using three-dimensional finite element method, and to further understand the features of pathological mechanics. 〈br〉 METHODThree-dimensional geometry models of normal and Cam-type femoroacetabular impingement joints were constructed using Mimics and Hypermesh software with the CT data of normal hip joint. These hip models were imported into LS-DYNA analysis system, then dynamic loads and motions for standing up and sitting down were applied to al joint models. Intra-articular cartilage contact pressures and stresses were analyzed in normal hip joint and hip joint with Cam-type femoroacetabular impingement. 〈br〉 RESULTS AND CONCLUSION：Based on CT data, models of normal hip joint and hip joint with Cam-type femoroacetabular impingement including articular cartilage for three-dimensional finite element analysis were accurately constructed. Peak contact pressures were 4.43 and 4.59 MPa at the anterosuperior region of the acetabular rim during sitting down and standing up. The peaks of Cam-type femoroacetabular impingement hip joint were 14.96 and 14.86 MPa. Peak pressures and stress concentration were found at the anterosuperior area of acetabular rim. High contact pressure at the acetabular cartilage may be the mechanical mechanism of osteoarthritis induced by Cam-type femoroacetabular impingement.