Christie McComb1, Barrie Condon1, David Allan2
1Department of Clinical Physics, Institute of Neurological Sciences, Southern General Hospital, Glasgow, UK; 2Queen Elizabeth National Spinal Injuries Unit, Southern General Hospital, Glasgow, UK
The purpose of this study was to assess the translational and rotational forces acting on an orthopaedic implant called the Posterior Fixator in 1.5T and 3T MRI systems. The forces were measured using existing methods, and assessed using guidelines produced by the ASTM. The results showed that the forces acting on the constituent components of the implant were substantial and, based on the ASTM guidelines, would be considered unsafe in both MR systems. However, when the rigid fixation of the implant in bone and the counterbalancing effect of the configuration of the assembled implant are taken into account, the forces are considered unlikely to result in implant migration or rotation.