Cheng Lei, Hannaford Blake
a Department of Mechanical Engineering , University of Washington , Box 352600, Seattle , WA 98195 , USA.
b Department of Electrical Engineering , University of Washington , Box 352500, Seattle , WA 98195 , USA.
Comput Methods Biomech Biomed Engin. 2016;19(1):31-40. doi: 10.1080/10255842.2014.981166. Epub 2014 Nov 19.
Minimizing tissue damage and maintaining grasp stability are essential considerations in surgical grasper design. Most past and current research analyzing graspers used for tissue manipulation in minimally invasive surgery is based on in vitro experiments. Most previous work assessed tissue injury and grasp security by visual inspection; only a few studies have quantified it. The goal of the present work is to develop a methodology with which to compute tissue damage magnitude and grasp quality that is appropriate for a wide range of grasper-tissue interaction. Using finite element analysis (FEA), four graspers with varying radii of curvature and four graspers with different tooth sizes were analyzed while squeezing and pulling liver tissue. All graspers were treated as surgical steel with linear elastic material properties. Nonlinear material properties of tissue used in the FEA as well as damage evaluation were derived from previously reported in vivo experiments. Computed peak stress, integrated stress, and tissue damage were compared. Applied displacement is vertical and then horizontal to the tissue surface to represent grasp and retraction. A close examination of the contact status of each node within the grasper-tissue interaction surface was carried out to investigate grasp stability. The results indicate less tissue damage with increasing radius of curvature. A smooth wave pattern reduced tissue damage at the cost of inducing higher percentage of slipping area. This methodology may be useful for researchers to develop and test various designs of graspers. Also it could improve surgical simulator performance by reflecting more realistic tissue material properties and predicting tissue damage for the student.
在手术抓钳设计中，尽量减少组织损伤并保持抓持稳定性是至关重要的考虑因素。过去和当前大多数分析用于微创手术中组织操作的抓钳的研究都是基于体外实验。以前的大多数工作通过目视检查来评估组织损伤和抓持安全性；只有少数研究对其进行了量化。本研究的目的是开发一种方法，用于计算适用于广泛的抓钳 - 组织相互作用的组织损伤程度和抓持质量。使用有限元分析（FEA），在挤压和拉伸肝脏组织时，对四种不同曲率半径的抓钳和四种不同齿尺寸的抓钳进行了分析。所有抓钳都被视为具有线性弹性材料特性的手术用钢。有限元分析中使用的组织的非线性材料特性以及损伤评估均来自先前报道的体内实验。比较了计算得到的峰值应力、积分应力和组织损伤。施加的位移垂直于然后平行于组织表面，以表示抓持和回缩。对抓钳 - 组织相互作用表面内每个节点的接触状态进行了仔细检查，以研究抓持稳定性。结果表明，随着曲率半径的增加，组织损伤减少。平滑的波形以诱导更高百分比的滑动面积为代价减少了组织损伤。这种方法可能有助于研究人员开发和测试各种抓钳设计。此外，它可以通过反映更真实的组织材料特性并为学生预测组织损伤来提高手术模拟器的性能。
