Simulation-based evaluation of stretching behavior of NiTi wire-knitted implants for reconstructive plastic surgery

A comprehensive study of the mechanical response of a titanium nickelide (TiNi) wire-knitted implant was conducted through tensile testing and finite element simulation using the Bergström-Boyce hyperelastic model calibrated via MCalibration and solved in ANSYS. The elongation-load curves for both the ribbon tissue scaffold (RTS) and the composite samples consisting of a RTS with biological tissues sprouted therein (RTS/bio-tissue) demonstrated nonlinear superelastic behavior. Under longitudinal tension, the biological tissue and the RTS exhibited similar deformation patterns. An evaluation of the biomechanical compatibility between soft tissues and the knitted metallic scaffold revealed the closest correspondence for the 40-µm thick RTS with muscle tissue, and for the 60-µm thick RTS with skin. However, it was noted that the contact areas of the metal knitted loops have the potential to cause damage to biological tissue. A microscopic examination of the connective tissue integrated with the RTS indicated successful incorporation of the implant into the rat abdominal wall under physiological loads, with no observed damage to the host tissue. Both microscopic analysis and low-cycle tensile tests confirmed that the RTS, once implanted, exhibited a relative elongation of less than 16%. This value represents the ultimate longitudinal elongation threshold identified during the pre-operative quantitative assessment of biomechanical compatibility between the RTS and biological tissues.