Many unstable fractures and fracture dislocations of the lower thoracic and the lumbar spine are treated operatively. Internal fixation is mostly done via a posterior approach, anchoring the screws in the pedicles of the vertebrae. In the Traumatology Section of the Department of Surgery, Graz University, three different implantation systems have been employed in recent years. Sixty of all the patients operated on were available for follow-up an average of 36 months after operation. We compared them with respect to type of implant, paying special attention to any loss of reduction.