Comparison of the mechanical behaviors of biological tissues subjected to uniaxial tensile testing: pig, calf and ostrich pericardium sutured with Gore-Tex

The purpose of this study was to compare the mechanical behavior of calf pericardium, pig pericardium and ostrich pericardium when subjected to tensile testing. Tensile stress was applied to 108 tissue samples, 36 of each type of tissue, until rupture. Groups of three adjacent strips measuring 12×2 cm2 were cut longitudinally. Each group consisted of an unsutured center sample, or control, and the two contiguous samples, that on the right sutured with Gore-Tex at a 90° angle with respect to the longitudinal axis and that on the left sewn with the same suture material at 45° angle. The sutured samples showed a statistically significant loss of resistance (p<0.001) when compared with the corresponding unsutured tissue. The mean stresses at rupture for sutured ostrich pericardium were 21.81 and 20.81 MPa in the samples sewn at 45° and 90°, respectively, higher than those corresponding to unsutured calf and pig pericardium, 14.0 and 11.49 MPa, respectively, at rupture. The analysis of the stress/strain curve shows a smaller difference between sutured and unsutured ostrich pericardium than those observed in the other two biomaterials. These results demonstrate that, in addition to its greater resistance, ostrich pericardium also presents a less pronounced interaction with the suture material. Its capacity to absorb the shearing stress produced by the suture is greater. This report also confirms that the method of selection using paired samples ensures their homogeneity and makes it possible to predict the behavior of a sample by determining that of the other half of the pair.