Tendons are biological structures that connect muscles to bones and are fundamental in transmitting the load generated by the muscles to the bones to achieve body motion. Due to injuries and ageing, tendon diseases represent a major clinical challenge. Natural healing of the tendons is slow, responds poorly to treatment, and often requires invasive surgical procedures followed by long-term rehabilitation. Furthermore, full restoration of the original function of the tendon is almost impossible to achieve.
Recently, it has been demonstrated that tendons show auxetic behaviour. An auxetic material is one that exhibits a negative Poisson’s ratio. While normal materials shrink in the perpendicular direction when stretched, an auxetic material enlarges in that direction. Similarly, during compression, instead of expanding orthogonally to the load, it collapses in all directions. Different auxetic geometries exhibit this behaviour through various mechanisms.
In this work, we propose mimicking tendon mechanics using auxetic 3D metamaterials. A finite element analysis (FEA) will be used to simulate the mechanical response of various auxetic geometries under tensile and compressive loading, focusing on parameters such as the elastic modulus, stress distribution, and Poisson’s ratio. Simulated results will be compared to the mechanical behaviour of native tendons reported in the literature to evaluate their biomechanical fidelity. Polylactic acid (PLA) is selected as the base material due to its biocompatibility, ease of 3D printing, and suitability for short-term applications, although its long-term load-bearing capacity may be limited. Due to these limitations, we decided to also investigate polycaprolactone (PCL) due to its capability to sustain large deformations without showing plastic deformation and ultra-high-molecular-weight polyethylene (UHMWPE), which is a well-known biomaterial widely used in the prosthesis field for its durability and mechanical properties.
The findings of this study may support the development of tendon-mimetic scaffolds for tissue engineering and drug screening. By accurately replicating tendon behaviour, such models could reduce the reliance on animal testing and contribute to more physiologically relevant platforms for studying tendon-related diseases.
