Biomechanical Engineering in Choice of Different Stiffness Material

Abstract

It is generally believed that the modulus of elasticity is a major criterion to anticipate the success of an implant material. Often, this elasticity is only partially addressed, since the geometrical data are omitted. For axial and bending stiffness the cross section’s area and area moment of inertia must also be taken into consideration. An additional criterion in respect to the bony anchorage of vertebral cages is being presented, which is the induced lateral strain ε_q = ν · ε. This strain must be sufficiently similar in order to prevent detrimental micromotion. A unique and ideal material stiffness out of the available biomaterials cannot be formulated. But a set of additional criteria for a successful bony anchorage can be listed, such as friction behavior at the interface or material with a potential for stimulating bone ingrowth. The evaluation of stiffness cannot avoid the necessity to carry out numerical analysis, experimental tests with preferably human specimen or careful clinical observations.