A rod designed to be implanted transversely through the sacrum to connect to bone screws implanted in the ilium on both sides of the sacrum. It is a component of an implant assembly intended for posterior pelvic stabilization to treat unilateral/bilateral unstable pelvic ring injuries. It is made of metal with holes at each end to allow connection to each bone screw and is intended to be implanted posterior to (i.e., not across) the sacroiliac joint.