Liu Li, Ecker Timo Michael, Schumann Steffen, Siebenrock Klaus-Arno, Zheng Guoyan
Institute for Surgical Technology and Biomechanics, University of Bern, CH-3014, Bern, Switzerland.
Department of Orthopaedic Surgery, Inselspital, Bern, Switzerland.
PLoS One. 2016 Jan 5;11(1):e0146452. doi: 10.1371/journal.pone.0146452. eCollection 2016.
Modern computerized planning tools for periacetabular osteotomy (PAO) use either morphology-based or biomechanics-based methods. The latter relies 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. Afterwards we used a 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.
现代用于髋臼周围截骨术（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。后者依靠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，基于使用患者特异性软骨模型模拟的关节接触压力和接触面积，研究PAO手术中髋臼的最佳重新定向。此外，我们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。影像数据来自CT关节造影研究。重建了骨骼模型。定义了患者特异性软骨的网格模型，并随后在先前报道的边界和加载条件下加载。在原始位置估计峰值接触压力和接触面积。之后，我们使用经过验证的术前规划软件，将髋臼倾斜度以5°的增量进行改变，并在每个重新定向位置测量外侧中心边缘角（LCE）。将接触面积最大且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，对相同的骨骼模型重复相同的步骤，但使用恒定厚度的软骨网格。比较这两种不同软骨模型之间的峰值接触压力和接触面积表明，这两种软骨模型在峰值接触压力（r = 0.634 ∈ [0.6, 0.8]，p < 0.001）和接触面积（r = 0.872 > 0.8，p < 0.001）方面具有良好的相关性。对于这两种软骨模型，在相同位置发现了最大接触面积和最低峰值压力。我们的研究是第一项在PAO规划期间比较患者特异性和恒定厚度软骨模型之间的峰值接触压力和接触面积的研究。检测到这两种模型具有良好的相关性。当有常规CT可用时，使用恒定厚度软骨模型的有限元建模计算机辅助规划可能是一种有前景的PAO规划工具。
