Figure 1. Axial computed tomography (CT) showing displaced sacral fracture.
Figure 2. Coronal view of the displaced sacral fracture.
A 22-year-old woman presents to the emergency room with severe pain in the pelvis after a motorcycle accident. She was the passenger when she was thrown from the motorcycle and landed approximately 15 feet away on the pavement. She was wearing a helmet and denies loss of consciousness. On physical examination she is hemodynamically stable and has pain to palpation over the posterior lower back and when pressing on the anterior superior iliac spines. Motor and sensation are intact in the lower extremities. Axial and coronal computed tomography (CT) images were ordered and show a displaced sacral fracture (Figures 1 and 2, respectively).
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The sacrum connects the lumbar spine to the pelvic ring with support of strong lumbosacral and iliolumbar ligaments. Sacral fractures can range from nondisplaced fractures that are difficult to see on radiograph to severe displaced fractures with neurovascular injury.1,2
A careful physical examination is crucial when diagnosing sacral fractures because up to 30% are missed on initial presentation.1 Any patient who sustains a fall and complains of peripelvic pain and lower buttock pain should be worked up for a sacral fracture.1,2
Radiographs are the initial study of choice but may miss nondisplaced to minimally displaced unstable fractures. Computed tomography is the study of choice in patients with severe pain and difficulty ambulating.1 Magnetic resonance imaging (MRI) is useful for diagnosing sacral insufficiency fractures in elderly patients with peripelvic pain and little to no history of injury.1,2
When evaluating sacral fractures, it is important to recognize or rule out the following1,2:
- An unstable pelvic ring injury
- A lumbosacral facet injury
- A lumbosacral dislocation
- Neurologic injury
The patient in this case sustained an open book-type sacral fracture with disruption of the pelvic ring. The pelvic ring was reduced and the sacral fracture fixed with a screw placed percutaneously with fluoroscopic guidance.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopaedics for Physician Assistants.
1. Mehta S, Auerbach JD, Born CT, Chin KR. Sacral fractures. J Am Acad Orthop Surg. 2006;14(12):656-665. doi:10.5435/00124635-200611000-00009
2. Vaccaro AR, Kim DH, Brodke DS, et al. Diagnosis and management of sacral spine fractures. Instr Course Lect. 2004;53:375-385. doi:10.2106/00004623-200401000-00027