Integration of shape memory alloy into a pedicle screw for increasing the pullout strength

By the increasing number of spinal fusions with posterior instrumentation and an ageing population, there will be a rising rate of revision operations. Most commonly there are used bone cement in addition to crews or screws with larger diameters. A new concept for increasing the pullout strength out of the trabecular bone structure is seen in the usage of shape memory alloys (SMA) as active elements inside the implant. Therefore a prototype of a pedicle screw with integrated nitinol sheets was developed. The pullout strength of this screw was measured with and without inserted SMA.