Evaluation of different loading conditions prescribed by standards for the fatigue testing of spinal fixators

The pre-clinical assessment of the long time performances of devices for spinal surgery has peculiar difficulties due to the very complex site of implant: experimental set-ups and procedures prescribed by international standards necessarily represent simplified models of the lumbar tract, thus leading to results that must be carefully evaluated. The purpose of the work is to shed light on the real state of stress arising in the components of a spinal fixator when tested according to different experimental procedures comparing it to the one acting after a virtual implant in a physiological FE model of the lumbar spine.