National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, China.
Institute for Surgical Technology and Biomechanics, University of Bern, Bern, Switzerland.
Adv Exp Med Biol. 2018;1093:157-168. doi: 10.1007/978-981-13-1396-7_13.
Modern computerized planning tools for periacetabular osteotomy (PAO) use either morphology-based or biomechanics-based methods. The latter rely on estimation of peak contact pressures and contact areas using either patient-specific or constant thickness cartilage models. We performed a finite element analysis investigating the optimal reorientation of the acetabulum in PAO surgery based on simulated joint contact pressures and contact areas using patient-specific cartilage model. Furthermore we investigated the influences of using patient-specific cartilage model or constant thickness cartilage model on the biomechanical simulation results. Ten specimens with hip dysplasia were used in this study. Image data were available from CT arthrography studies. Bone models were reconstructed. Mesh models for the patient-specific cartilage were defined and subsequently loaded under previously reported boundary and loading conditions. Peak contact pressures and contact areas were estimated in the original position. Afterward we used validated preoperative planning software to change the acetabular inclination by an increment of 5° and measured the lateral center-edge angle (LCE) at each reorientation position. The position with the largest contact area and the lowest peak contact pressure was defined as the optimal position. In order to investigate the influence of using patient-specific cartilage model or constant thickness cartilage model on the biomechanical simulation results, the same procedure was repeated with the same bone models but with a cartilage mesh of constant thickness. Comparison of the peak contact pressures and the contact areas between these two different cartilage models showed that good correlation between these two cartilage models for peak contact pressures (r = 0.634 ∈[0.6, 0.8], p < 0.001) and contact areas (r = 0.872 > 0.8, p < 0.001). For both cartilage models, the largest contact areas and the lowest peak pressures were found at the same position. Our study is the first study comparing peak contact pressures and contact areas between patient-specific and constant thickness cartilage models during PAO planning. Good correlation for these two models was detected. Computer-assisted planning with FE modeling using constant thickness cartilage models might be a promising PAO planning tool when a conventional CT is available.
现代髋臼周围截骨术（PAO）的计算机化规划工具采用基于形态学或基于生物力学的方法。后者依赖于使用患者特异性或恒定厚度软骨模型来估计峰值接触压力和接触面积。我们进行了一项有限元分析，研究了基于患者特异性软骨模型模拟关节接触压力和接触面积的髋臼在 PAO 手术中的最佳重新定位。此外，我们还研究了使用患者特异性软骨模型或恒定厚度软骨模型对生物力学模拟结果的影响。本研究使用了 10 个髋关节发育不良的标本。从 CT 关节造影研究中获得了图像数据。重建了骨模型。定义了患者特异性软骨的网格模型，并在之前报道的边界和加载条件下对其进行加载。在原始位置估计了峰值接触压力和接触面积。然后，我们使用经过验证的术前规划软件将髋臼倾斜度增加 5°，并在每个重新定位位置测量外侧中心边缘角（LCE）。接触面积最大和峰值接触压力最低的位置定义为最佳位置。为了研究使用患者特异性软骨模型或恒定厚度软骨模型对生物力学模拟结果的影响，我们使用相同的骨模型但使用恒定厚度的软骨网格重复了相同的过程。对这两种不同软骨模型的峰值接触压力和接触面积进行比较，结果表明这两种软骨模型的峰值接触压力（r = 0.634 [0.6, 0.8]，p < 0.001）和接触面积（r = 0.872 > 0.8，p < 0.001）之间具有良好的相关性。对于这两种软骨模型，最大的接触面积和最低的峰值压力都出现在相同的位置。本研究是首次比较 PAO 规划中患者特异性和恒定厚度软骨模型的峰值接触压力和接触面积的研究。这两种模型之间检测到了良好的相关性。当有常规 CT 时，使用基于有限元模型的恒定厚度软骨模型的计算机辅助规划可能是一种很有前途的 PAO 规划工具。
