[Mechanical study of polyurethane elastomer and Medpor as the material of artificial auricular scaffold]

By comparing the mechanics of human auricular cartilage, polyurethane elastic material, and high density polyethylene material (Medpor), to produce theoretical proof on choosing optimal artificial auricular scaffold materials.

The experimental materials were divided into 3 groups with 6 samples in each: the auricular cartilage group (group A), the polyurethane elastic material group (group B), and the Medpor group (group C). With an Instron5967 mechanical testing machine, compression and tensile testing were performed to respectively measure values of compression parameters (including yield stress, yield load, elastic modulus, yield compressibility, compressibility within 2 MPa, and compression stress within 10% strain) and values of tensile parameters (including yield stress, yield load, elastic modulus, yield elongation, elongation within 2 MPa, tensile stress within 1% strain) for comparison.

Compression testing: no obvious yield points were observed in the whole process in samples of group B, while obvious yield points were observed in samples of groups A and C. There was no significant difference between groups A and C with respect to yield stress and yield load ( P>0.05); while the yield compressibility in group C was significantly lower than that in group A ( P<0.05) and the elastic modulus in group C was significantly higher than that in group A ( P<0.05). There was a significant difference with respect to compressibility within 2 MPa of materials among the 3 groups ( P<0.05), the high, medium, and low values go to groups B, A, and C respectively. The compression stress within 10% strain in group C was significantly higher than that in groups A and B ( P<0.05), and there was no significant difference between that in groups A and B ( P>0.05). Tensile testing: the materials in group B had extremely high tensile strength. The yield stress in groups A and B was significantly higher than that in group C ( P<0.05), and the elastic modulus and tensile stress within 1% strain were significantly lower than those in group C ( P<0.05); but no significant difference was found between those in groups A and B ( P>0.05). There was no significant difference with respect to yield load among the 3 groups ( P>0.05); but there was significant difference with respect to yield elongation among the 3 groups ( P<0.05), and the high, medium, and low values go to groups B, A, and C respectively. The elongation within 2 MPa in group B was significantly higher than that in groups A and C ( P<0.05), and there was no significant difference between that in groups A and C ( P>0.05).

Compared with the Medpor, the polyurethane elastic material is a more ideal artificial auricular scaffold material.