Casha Aaron R, Manché Alexander, Gatt Ruben, Duca Edward, Gauci Marilyn, Schembri-Wismayer Pierre, Camilleri-Podesta Marie-Therese, Grima Joseph N
Department of Cardiothoracic Surgery, Mater Dei Hospital, Msida, Malta Department of Anatomy, University of Malta, Msida, Malta
Department of Cardiothoracic Surgery, Mater Dei Hospital, Msida, Malta.
Interact Cardiovasc Thorac Surg. 2014 Oct;19(4):617-21. doi: 10.1093/icvts/ivu184. Epub 2014 Jun 25.
Biomechanical modelling of the forces acting on a median sternotomy can explain the mechanism of sternotomy dehiscence, leading to improved closure techniques.
Chest wall forces on 40 kPa coughing were measured using a novel finite element analysis (FEA) ellipsoid chest model, based on average measurements of eight adult male thoracic computerized tomography (CT) scans, with Pearson's correlation coefficient used to assess the anatomical accuracy. Another FEA model was constructed representing the barrel chest of chronic obstructive pulmonary disease (COPD) patients. Six, seven and eight trans-sternal and figure-of-eight closures were tested against both FEA models.
Comparison between chest wall measurements from CT data and the normal ellipsoid FEA model showed an accurate fit (P < 0.001, correlation coefficients: coronal r = 0.998, sagittal r = 0.991). Coughing caused rotational moments of 92 Nm, pivoting at the suprasternal notch for the normal FEA model, rising to 118 Nm in the COPD model (t-test, P < 0.001). The threshold for dehiscence was 84 Nm with a six-sternal-wire closure, 107 Nm with seven wires, 127 Nm with eight wires and 71 Nm for three figure-of-eights.
The normal rib cage closely fits the ellipsoid FEA model. Lateral chest wall forces were significantly higher in the barrel-shaped chest. Rotational moments generated by forces acting on a six-sternal-wire closure at the suprasternal notch were sufficient to cause lateral distraction pivoting at the top of the manubrium. The six-sternal-wire closure may be successfully enhanced by the addition of one or two extra wires at the lower end of the sternotomy, depending on chest wall shape.
对正中开胸手术中所受作用力进行生物力学建模，可解释胸骨切开术裂开的机制，从而改进缝合技术。
基于对8例成年男性胸部计算机断层扫描（CT）的平均测量数据，使用一种新型有限元分析（FEA）椭球体胸部模型测量40 kPa咳嗽时胸壁的受力情况，并用Pearson相关系数评估解剖学准确性。构建另一个FEA模型来代表慢性阻塞性肺疾病（COPD）患者的桶状胸。针对这两个FEA模型测试了六种、七种和八种胸骨贯穿缝合及8字缝合。
CT数据测量的胸壁与正常椭球体FEA模型之间的比较显示拟合良好（P < 0.001，相关系数：冠状面r = 0.998，矢状面r = 0.991）。对于正常FEA模型，咳嗽会在胸骨上切迹处产生92 Nm的旋转力矩，在COPD模型中该力矩增至118 Nm（t检验，P < 0.001）。六种钢丝缝合时裂开阈值为84 Nm，七种钢丝为107 Nm，八种钢丝为127 Nm，三个8字缝合为71 Nm。
正常胸廓与椭球体FEA模型紧密贴合。桶状胸中胸壁侧向力明显更高。作用于胸骨上切迹处六种钢丝缝合的力所产生的旋转力矩足以导致在胸骨柄顶部发生侧向撑开。根据胸壁形状，在胸骨切开术下端额外添加一或两根钢丝可能成功增强六种钢丝缝合的效果。
