Magnetic Resonance Imaging for the Evaluation of Ligamentous Injury in the Pelvis: A Prospective Case-Controlled Study

Objectives:Management of external rotation pelvic ring disruptions is based on which ligaments are disrupted within the pelvis. We hypothesized that magnetic resonance imaging (MRI) can evaluate the ligaments of the pelvic ring and differentiate injured from uninjured pelves.Design:Prospective cohort study.Setting:Level I trauma center.Patients:Twenty-one patients with 25 acute external rotation injuries of the hemipelvis; control group of 26 patients without pelvic ring injury.Intervention:All patients underwent the same MRI protocol reviewed by 1 musculoskeletal radiologist.Main Outcome Measures:Integrity of 5 structures: sacrospinous, sacrotuberous, anterior sacroiliac, and posterior sacroiliac ligaments and pelvic floor musculature.Results:Visualization of sacrospinous, sacrotuberous, anterior sacroiliac, and posterior sacroiliac ligaments, and pelvic floor musculature was possible for 91%, 100%, 98%, 91%, and 100%, respectively, of all studied structures. No injuries were identified in control group patients in contrast to ligament injury observed with all injured pelves (0% versus 100%; P < 0.0001). Observed relationship of ligament injury to pelvic injury type generally agreed with the Young-Burgess classification system, with the important exception that patients with anterior-posterior compression type II injuries had damage to the sacrospinous ligament in only 50% of the cases.Conclusions:Ligamentous anatomy and injury about the pelvic ring appears to be easily evaluated with MRI, arguing that there may be a role for this imaging modality in managing these cases. Tearing of the sacrospinous ligament is variable among anterior-posterior compression type II injuries, arguing that the injury pattern can be subdivided into those with and without sacrospinous ligament tears.