Session I - Pelvis

The Treatment of Minimally Displaced Fractures of the Sacrum with Immediate Weight Bearing. Is There A Role for Prophylactic Iliosacral Screw Fixation?

Mark C. Reilly, MD; William K. Accousti, MD; Michael S. Sirkin, MD; Fred Behrens, MD; Susan G. Merrit, PA-C, New Jersey Medical School, Newark, NJ

Purpose: To review the results of a prospectively established protocol for the nonoperative management of minimally displaced sacral fractures with immediate weight bearing and to determine risk factors for fracture displacement.

Methods: Over a period of 28 months, 477 patients with pelvic ring injuries were seen at a level 1 trauma center. After an initial anterior-posterior pelvis radiograph, all patients were evaluated with inlet and outlet views as well as computed tomography scan of the pelvis. Unstable posterior pelvic ring injuries were treated with open reduction internal fixation, as were dislocations of the symphysis pubis. All patients with fractures of the sacrum and less than 10 mm of initial displacement on every film were treated with a prospectively established treatment protocol. All patients were mobilized without restricted weight bearing other than that imposed for associated injuries. Prior to discharge from acute hospitalization, repeat pelvic plain films were obtained to assess interval displacement. Serial radiographs were obtained, and patients were followed until fracture union. Patients were allowed to discontinue use of ambulatory aids on their own, and progressive resistance muscle strengthening was begun at 6 weeks. Initial and healed radiographs were compared to document any displacement.

Results: 73 fractures of the sacrum were followed to union. Fractures were classified as anterior-posterior compression (APC) (9%) or lateral compression (LC) (91%) injuries.(61-B1.2,61-B2.1). All sacral fractures had less than 10 mm of initial cranial displacement; 63% of fractures of the sacrum were impacted, and 11% were associated with multiple sites of anterior pelvic ring injury. The average age at the time of injury was 60.4 years, and the average follow-up was 4 months (range 2 to 13 months). All patients healed without intervention. No patient with a LC fracture suffered fracture displacement during healing. Two patients with APC fractures displaced (9 and 12 mm cranial) prior to healing their sacral fractures. Both were external rotation injuries to the hemipelvis and had symphysis disruptions in addition to fractures of the rami.

Discussion: Iliosacral screw placement has become the standard means of internal fixation for displaced fractures of the sacrum. Some authors have advocated screw fixation for minimally displaced fractures of the sacrum in order to prevent fracture displacement during the mobilization of polytraumatized patients. There remains, however, no information regarding the likelihood that such fractures might displace.

Conclusion: In this study, minimally displaced fractures of the sacrum were seen to be associated with either an internal or external rotation deformity to the hemipelvis. No patient with an internal rotation (LC pattern) developed fracture displacement during healing; 30% of patients with an external rotation (APC pattern) to the sacrum demonstrated cranial displacement and subsequent malunion. Most minimally displaced fractures of the sacrum may be safely managed nonoperatively with early weight bearing. Routine use of iliosacral screw fixation is not necessary but may be considered in the case of external rotation injuries with multiple sites of anterior pelvic ring disruption.