Functional biomimetic design of 3D printed polyether-ether-ketone flexible chest wall reconstruction implants for restoration of the respiration

The lack of deformability of rigid chest wall reconstruction (CWR) implants presents a challenge in reducing postoperative respiratory function in patients with large chest wall defects. Flexible poly-ether-ether-ketone (PEEK) CWR implants, consisting of rib components with elliptical cross-section and costal cartilage components featuring wavy structures, were developed with adjustable design parameters that allow quantitative restoration of respiratory function. During the design process, the equivalent elastic moduli of the rib and costal cartilage components were parametrically adjusted in a validated finite element (FE) model of the chest wall to maximise chest wall deformation during respiration, while considering mechanical safety as the boundary condition. The optimal equivalent elastic moduli were then translated into design parameters for the rib and costal cartilage components, based on a database relating the equivalent elastic modulus to the design parameters of the components with elliptical cross-section and wavy structures. The flexible PEEK CWR implant increased the difference in chest circumference during respiration by 12.2% compared to rigid PEEK implant in a clinical case-based study. This study presents a strategy to address the reduced respiratory function in 3D printed CWR implants, providing a pathway for quantitative restoration of respiratory function through parameterised optimisation.