Posterior stabilization of pelvic fractures by use of threaded compression rods. Case reports and mechanical testing.

Threaded compression rods were placed between the posterior-superior spines as a means of posterior stabilization of pelvic fractures. To document the increase in sacroiliac stability afforded by this technique, biomechanical testing was performed. Malgaigne-type fractures with sacroiliac disruptions were created in four cadaver pelvises. The fractures were stabilized with anterior frames of the Slatis or Pittsburgh type and subjected to longitudinal and torsional loading patterns on an Instron machine. The anterior fixation was then augmented with threaded compression rods placed between the posterior-superior spines to compress the disrupted sacroiliac joints, and repeat testing was conducted. Anterior frames alone were found to provide little stabilization of the disrupted sacroiliac joints with either longitudinal or torsional loading. Markedly improved stabilization in both loading modes was achieved with posterior augmentation. Two typical cases are presented to demonstrate that posterior stabilization is as efficacious in clinical practice as in the biomechanics laboratory.