Elasticity modulus of rabbit middle ear ossicles determined by a novel micro-indentation technique

For the purpose of creating a finite element model of the middle ear, the ossicles can be modelled as rigid bodies or as linear elastic materials. The general elasticity parameters used are usually measured on larger bones like the femur. In order to obtain a highly realistic model, the actual elastic modulus (Young's modulus) of the ossicles themselves is needed. We developed a novel 2-needle indentation method of determining the Young's modulus of small samples based on Sneddon's solution. We introduce the second needle in such a way that small specimens can be clamped between the two needles and a symmetry plane is obtained, so that geometry-dependent sample deformations are avoided. A finite element calculated correction factor is used to compensate for the small thickness of the samples. The system was tested on several materials with known parameters in order to validate the technique, and was then used to determine the elasticity parameters of incus and malleus in rabbit. No significant differences between measurement locations were found, and we found an average Young's modulus of 16+/-3 GPa.