Biomechanical testing of new and old fixation devices for vertical shear fractures of the pelvis.

Malgaigne fractures of the pelvis have been treated with many different methods of fixation. We developed a plate for use on the anterior aspect of the sacroiliac (SI) joint using information obtained from cadaveric dissections and computed tomography (CT) scans of male (50) and female (50) pelvises. We tested each of six pelvises in the Instron, with five different fixation systems. Our results showed that the weakest system was the anterior quadrilateral frame plus two symphyseal plates. When comparing three posterior screws with the SI joint plate, the difference was not statistically significant. However, in both of these systems, a second symphyseal plate added to the overall stability.