Zone III fractures of the sacrum. A case report.

STUDY DESIGN

Case reports.

OBJECTIVES

To define the radiologic characteristics, management, and results of Zone III fractures of the sacrum.

SUMMARY OF BACKGROUND DATA

Zone III fractures of the sacrum are rare. There are few case reports of longitudinal fractures of the sacrum involving Zone III.

METHOD

The authors report eight (four transverse, four longitudinal) Zone III fractures of the sacrum. Seven patients were treated surgically by posterior sacral decompression with or without transiliac bar fixation, and one neurologically intact patient with undisplaced longitudinal fracture was treated conservatively.

RESULTS

Two neurologically compromised patients had return of normal bladder and rectal function, and another had bladder recovery only. The rest continued to show neurogenic bladder and required intermittent self-catheterization. The patient with bilateral foot drop had partial motor recovery and did not require an ankle-foot orthosis.

CONCLUSIONS

These fractures may be difficult to diagnose in polytraumatized patients and require a high index of suspicion. The longitudinal fractures may not be apparent on anteroposterior radiographs, and computed tomography scan may be necessary for establishing the diagnosis. The transverse fractures may show a characteristic step ladder sign on anteroposterior radiographs when the fracture is displaced severely. Proper lateral radiographs often are difficult to obtain, particularly in obese polytraumatized patients. Routine computed tomography scan may overlook the diagnosis. Therefore 2- to 3-mm computed tomography cuts are recommended, which may show double neural foramina in presence of significant anteroposterior displacement and overriding of the fracture fragments. Sagittal computed tomography reconstructions are useful in evaluating the transverse fractures. Posterior sacral decompression is safe and probably promotes nerve root recovery. Longitudinal fractures may be stabilized satisfactorily by transiliac rod fixation.