Percutaneous stabilization of U-shaped sacral fractures using iliosacral screws: technique and early results.

PURPOSE: To present the technique and early results of percutaneous stabilization of U-shaped sacral fractures with attention to neurologic recovery and maintenance of fracture reduction of the sacrum.

DESIGN: Retrospective clinical study.

SETTING: Level I trauma center.

PATIENTS: During a thirty-eight-month period, 442 patients with pelvic ring disruptions were treated at a Level I trauma center. Thirteen (2.9 percent) of these patients had displaced U-shaped sacral fractures treated with percutaneous stabilization.

INTERVENTION: Fracture stabilization was accomplished using fluoroscopically guided iliosacral screws inserted percutaneously with the patient positioned supine. Neurodiagnostic monitoring was not used during screw insertions. This technique was limited to patients with sacral kyphotic deformities, which allowed in situ fixation. Sacral neurologic decompression was not performed.

MAIN OUTCOME MEASUREMENTS: Fracture healing and the stability of fixation were assessed on inlet and outlet radiographs and a lateral sacral view. Detailed neurologic examinations were performed at injury and at follow-up.

RESULTS: The sacral fractures were classified based on plain pelvic radiographs and computed tomography scans and included one Type 1, eight Type 2, and four Type 3 fracture patterns. Twenty-five fully threaded cancellous 7.0-millimeter cannulated screws were used. Eleven patients had bilateral screw fixations; one patient had unilateral double screw fixation; and one patient had unilateral single screw fixation. Operative time for screw insertion averaged forty-eight minutes, with 2.1 minutes of fluoroscopy per screw. Accurate screw insertions without neuroforaminal or sacral spinal canal violations were confirmed in all patients with postoperative pelvic plain radiographs and computed tomography scans. A paradoxical inlet view of the upper sacral segments on the injury anteroposterior pelvis was seen in twelve of thirteen patients (92.3 percent), and the diagnosis was confirmed with the lateral sacral view in all thirteen (100 percent) patients. Preoperatively, sacral kyphosis averaged 29 degrees, whereas postoperative sacral kyphosis averaged 28 degrees. Screw disengagement occurred without a change in position of the sacral fracture in the only patient treated with a single unilateral screw. All fractures healed clinically and radiographically. Of the nine patients with preoperative neurologic abnormalities, two (22 percent) patients had residual neurologic deficits. Both patients had associated multiple level lumbar burst fractures, which required decompression and instrumented stabilization.

CONCLUSIONS: These sacral fractures are rare and occur after significant spinal axial loading. A paradoxic inlet view of the upper sacrum on the anteroposterior plain pelvic radiograph heralds the diagnosis. Delayed diagnosis is avoided by a high clinical suspicion, early lateral sacral radiographs, and pelvic computed tomography scans. Surgical stabilization may assist in early mobilization of the patient from recumbency and prevents progressive deformity with associated nerve root injury. Percutaneous fixation diminishes potential blood loss and operative times, yet still allows subsequent sacral decompression of the local neural elements using open techniques when necessary. Early percutaneous iliosacral screw fixation is effective treatment for these injuries.