Consistent quasistatic and acoustic elasticity determination of poly-L-lactide-based rapid-prototyped tissue engineering scaffolds.

This paper is concerned with reliable and physically sound elasticity determination of rapid-prototyped tissue engineering scaffolds made of poly-L-lactide (PLLA), with and without small portions of tricalcium phosphate (TCP) inclusions. At the level of overall scaffolds, that is, that of several millimeters, multiple uniaxial loading-unloading (quasistatic) tests were performed, giving access to the scaffolds' Young's moduli, through stress-strain characteristics during unloading. In addition, acoustic tests with 0.05 MHz frequency delivered an independent access to elastic properties, in terms of the normal components of the scaffolds' stiffness tensors. The latter strongly correlate, in a linear fashion, with the Young's moduli from the unloading tests, revealing porosity independence of Poisson's ratio. The magnitude of the latter is in full agreement with literature data on polymers. Both of these facts underline that both ultrasound tests and quasistatic unloading tests reliably provide the elastic properties of tissue engineering scaffolds.