Finite element simulation of human trachea: Normal vs. surgically treated and scaffold implanted cases

Abstract

Trachea experiences mechanical loads under physiological conditions. Surgery and tissue engineering change its mechanical conditions and may cause remodeling or damage. Here, we mechanically simulated one healthy trachea (from a 53-year-old brain-dead man) and as two examples, evaluated the impacts of surgery and scaffold implantation. Before patient's death, CT-scanning was performed at two respiratory pressures (0 and + 40 cm H2O for constructing 3D tracheal geometry at zero-stress state and model validation, respectively). After harvesting trachea, MRI, mechanical testing and hyperelastic modeling of tracheal tissues (cartilage, smooth muscle, and connective tissue) were performed. We simulated tracheal deformation and stress distribution under three conditions, including normal, 30%-resection of tracheal length and anastomosis (surgery) or its substitution with a cylindrical scaffold. In all models, the greatest stresses were produced in cartilaginous rings. Surgery-related extension reduced the physiologic cross-sectional deformability and increased stress levels in response to respiratory pressures, compared to normal trachea. For instance, maximum von-Mises stress in normal and operated trachea reached 355 kPa and 3.228 MPa, respectively. Scaffold was less deformable than normal trachea, though stress levels in both models were relatively close. This study provides an insight into the mechanics of human trachea and the impacts of surgery or scaffold implantation.