Mechanical and Biomechanical Testing of Spinal Implants

Abstract

Mechanical and biomechanical testing provides crucial information about the safety, effectiveness and function of spinal implants. Mainly static and dynamic tests are carried out. While mechanical tests may be carried out according to testing standards or in some cases to individual testing procedures, biomechanical tests should be conducted according to published recommendations or in case of dynamic testing, as individual test procedures. In order to allow for direct comparison between testing laboratories, it should be strived for standardised testing. However, as standardised loading often simplifies the in vivo occurring conditions, more physiological testing can be carried out additionally and may become the next improved testing standard. Mechanical testing focuses mainly on the safety issue, while effectiveness and function of an implant can be tested in a biomechanical setup. Each type of implant generally requires specific mechanical and biomechanical tests depending on its design, material, indication and function. In general, mechanical testing can be subdivided in static and dynamic fatigue testing as well as special types of testing such as wear or corrosion testing. Biomechanical testing concentrates on quasi-static and short-term dynamic testing mostly in interaction with biological tissue.