P084 MESH USE IN THE UNITED STATES: MESH TYPES AND THEIR INDICATIONS

Aim Synthetic non-absorbable mesh repair is considered standard of care for most hernias in the United States (US). The introduction of biologic absorbable mesh in the 2000’s has changed this practice and now novel synthetic absorbable and hybrid meshes are available. We aim to describe US trends of mesh use. Material and Methods We surveyed the Abdominal Core Health Quality Collaborative database for all repairs using mesh from 2012 to 2021. Mesh types and indications were analysed. Results Among 47,555 patients who underwent hernia repair with mesh, the majority were with synthetic non-absorbable meshes (96%). Absorbable mesh was placed in 2,039 (4%) patients and included biologic absorbable (893, 44%), synthetic absorbable (1,070, 52%), and hybrid (76, 4%) meshes. Synthetic non-absorbable mesh use was significantly predominant in all wound classes, including dirty/contaminated wounds (P < 0.01) [Figure 1]. Over time, we noted a trend toward lower incidence of absorbable and hybrid mesh use, from 18% to 2% (P < 0.01). Interestingly, we noted a relative increase in annual incidence of absorbable and hybrid mesh use in clean wounds, from 20% to 63% (P < 0.01) [Figure 2]. Figure 1Mesh type used in each wound classFigure 2Absorbable mesh use in clean vs. not clean wounds. Conclusions In the United States, synthetic non-absorbable meshes are commonly used during hernia repairs in dirty and contaminated fields. At the same time, there is a significant increase in the use of absorbable and hybrid meshes in the repair of hernias with clean wound classification. The costs and long-term outcomes of such surgeon choices have yet to be validated.

A Class of Novel Tetrahedron Elements with Curved Surfaces for Three-Dimensional Solid Mechanics Problems with Curved Boundaries

Linear tetrahedral elements with four nodes (Te4) are currently the simplest and most widely used ones in the finite element (FE) developed for solving three-dimensional (3D) mechanics problems. However, the standard Te4 element cannot be used to simulate accurately the 3D problems with curved boundaries because of the flat surfaces. In this paper, we develop a set of new elements having curved surfaces to properly simulate the curved boundaries. At the same time, additional nodes are put on the curved boundaries to improve the accuracy of the approximation. These novel elements are defined as five-noded, six-noded, and seven-noded tetrahedron elements (Te5, Te6, and Te7) according to the number of the nodes in one element. Based on the Te4 FE mesh, a hybrid mesh can be conveniently built for 3D problems with curved boundaries, in which the standard Te4 elements are used for the interior elements, and Te5, Te6, and Te7 elements are used for the curved boundary elements. Compared with the standard FEM using Te4 elements, our hybrid mesh can significantly improve the accuracy of the solutions at the curved boundaries. Several solid mechanics problems are studied using the hybrid meshes to validate the effectiveness of the present new elements.

FESOM-C v.2: coastal dynamics on hybrid unstructured meshes

We describe FESOM-C, the coastal branch of the Finite-volumE Sea ice – Ocean Model (FESOM2), which shares with FESOM2 many numerical aspects, in particular its finite-volume cell-vertex discretization. Its dynamical core differs in the implementation of time stepping, the use of a terrain-following vertical coordinate, and the formulation for hybrid meshes composed of triangles and quads. The first two distinctions were critical for coding FESOM-C as an independent branch. The hybrid mesh capability improves numerical efficiency, since quadrilateral cells have fewer edges than triangular cells. They do not suffer from spurious inertial modes of the triangular cell-vertex discretization and need less dissipation. The hybrid mesh capability allows one to use quasi-quadrilateral unstructured meshes, with triangular cells included only to join quadrilateral patches of different resolution or instead of strongly deformed quadrilateral cells. The description of the model numerical part is complemented by test cases illustrating the model performance.