Analyzing the effect of undermining on suture forces during simulated skin flap surgeries with a three-dimensional finite element method

Skin flaps are common procedures used by surgeons to cover an excised area during the reconstruction of a defect. It is often a challenging task for a surgeon to come up with the most optimal design for a patient. In this paper, we set up a simulation system based on the finite element method for one of the most common flap types — the rhomboid flap. Instead of using the standard 2D planar patch, we constructed a 3D patch with multiple layers. This allowed us to investigate the impact of different undermining areas and depths. We compared the suture forces for each case and identified vertices with the largest suture force. The shape of the final suture line is also visualized for each case, which is an important clue when deciding on the most optimal skin flap orientation according to medical textbooks. We found that under the optimal undermining setup, the maximum suture force is around 0.7 N for top of the undermined layer and 1.0 N for bottom of the undermined layer. When measuring difference in final suture line shape, the maximum normalized Hausdorff distance is 0.099, which suggests that different undermining region can have significant impact on the shape of the suture line, especially in the tail region. After analyzing the suture force plots, we provided recommendations on the most optimal undermining region for rhomboid flaps.

皮瓣是外科医生在缺损重建过程中用于覆盖切除区域的常用手术方法。对于外科医生来说，为患者设计出最优方案往往是一项具有挑战性的任务。在本文中，我们针对最常见的皮瓣类型之一——菱形皮瓣，基于有限元方法建立了一个模拟系统。我们没有使用标准的二维平面贴片，而是构建了一个多层的三维贴片。这使我们能够研究不同潜行分离区域和深度的影响。我们比较了每种情况下的缝合力，并确定了缝合力最大的顶点。每种情况下最终缝合线的形状也进行了可视化呈现，这是根据医学教科书确定最优皮瓣方向的一个重要线索。我们发现，在最优的潜行分离设置下，潜行分离层顶部的最大缝合力约为0.7牛，底部约为1.0牛。在测量最终缝合线形状的差异时，最大归一化豪斯多夫距离为0.099，这表明不同的潜行分离区域会对缝合线的形状产生显著影响，尤其是在尾部区域。在分析缝合力图之后，我们针对菱形皮瓣的最优潜行分离区域提出了建议。