Lee Chia-Fone, Chen Jyh-Horng, Chou Yuan-Fang, Hsu Lee-Ping, Chen Peir-Rong, Liu Tien-Chen
Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan.
Laryngoscope. 2007 Apr;117(4):725-30. doi: 10.1097/mlg.0b013e318031f0e7.
The purpose of this study was to determine, using finite element analysis, the optimal graft thickness for cartilage myringoplasty in patients with different sizes of tympanic membrane (TM) perforations.
We developed a cartilage plate-TM-coupled model using high-resolution computed tomography and finite element analysis. The geometric models of the perforated TM were generated using Patran and ANSYS software.
Three different sizes of TM perforations (15%, 55%, and 85%, representing small, medium, and large perforations, respectively) were created in the pars tensa. A cartilage plate was used to repair the eardrum perforation, and the new TM-cartilage coupled complex was loaded into our three-dimensional biomechanical model for analysis. The frequency-amplitude responses for different cartilage thicknesses were compared with those for natural TM.
Our results show that, first, in cases with 85% perforation, the frequency-amplitude responses that were most similar to natural TM at lower frequencies were for graft thicknesses of 0.2 mm and for 0.1 mm at higher frequencies. Second, in cases with 55% posterior perforation of the TM, assessment of the predicted vibration amplitude of different thicknesses of the cartilage plate showed that a cartilage plate of less than 0.2 mm had a frequency response function similar to that of a natural TM in umbo and stapes footplate displacement. Finally, for a central perforation involving 15% of the TM, a cartilage plate of less than 1.0 mm showed a frequency response function similar to that of TM in umbo and stapes-footplate displacement.
On the basis of our biomechanical analysis, the optimal thickness of a cartilage graft for myringoplasty appears to be 0.1 to 0.2 mm for medium and large TM perforations. For small perforations, a cartilage of less than 1.0 mm is a good compromise between mechanical stability and low acoustic transfer loss.
本研究旨在通过有限元分析确定不同鼓膜（TM）穿孔大小患者进行软骨鼓膜成形术的最佳移植物厚度。
我们使用高分辨率计算机断层扫描和有限元分析开发了一个软骨板 - TM耦合模型。使用Patran和ANSYS软件生成穿孔TM的几何模型。
在紧张部制造三种不同大小的TM穿孔（分别为15%、55%和85%，代表小、中、大穿孔）。使用软骨板修复鼓膜穿孔，并将新的TM - 软骨耦合复合体加载到我们的三维生物力学模型中进行分析。将不同软骨厚度的频率 - 振幅响应与天然TM的进行比较。
我们的结果表明，首先，在穿孔率为85%的情况下，在较低频率下与天然TM最相似的频率 - 振幅响应对应的移植物厚度为0.2 mm，在较高频率下为0.1 mm。其次，在TM后穿孔率为55%的情况下，对不同厚度软骨板预测振动幅度的评估表明，厚度小于0.2 mm的软骨板在鼓膜脐部和镫骨足板位移方面的频率响应函数与天然TM相似。最后，对于涉及TM 15%的中央穿孔，厚度小于1.0 mm的软骨板在鼓膜脐部和镫骨足板位移方面的频率响应函数与TM相似。
基于我们的生物力学分析，对于中、大TM穿孔，鼓膜成形术软骨移植物的最佳厚度似乎为0.1至0.2 mm。对于小穿孔，厚度小于1.0 mm的软骨在机械稳定性和低声学传输损失之间是一个很好的折衷选择。
