[A simplified procedure for mechanical testing of lumbar spinal fixation implants]

On the basis of the current ASTM and ISO standard proposals, a simplified test procedure for spinal fixation implants has been developed. It comprises static and dynamic tests aimed at evaluating the stiffness and strength of various different internal implants. Different methods of mounting the pedicle screws to the test device are shown to significantly affect the characteristic values and failure mechanisms of the implants. The feasibility of the procedure was investigated by comparing 7 different internal fixation implants. The reproducible results revealed general differences associated with the material, dimensions and design, which latter in particular correlated with the specific failure mechanisms. For longer-term in situ duration, testing of these implants should be expanded to include an analysis of wear and corrosion properties.