Gregory Emmett Wilde MD, Presenter: Stockholder, Zimmer Holdings, Inc Stockholder, Johnson & Johnson Stockholder, Novartis AG Stockholder, GlaxoSmithKline plc Stockholder, Pfizer Inc

Theodore T. Miller MD, Abstract Co-Author: Stockholder, Johnson & Johnson

Robert Schneider MD, Abstract Co-Author: Research Consultant, Johnson & Johnson

Federico Girardi MD, Abstract Co-Author: Nothing to Disclose

To describe the occurrence and pattern of sacral fractures following lumbosacral fusion.

A search of computed tomography (CT), nuclear medicine, and magnetic resonance imaging (MRI) radiology reports from the past 5 years at a single institution revealed a total of 23 patients with sacral fractures following lumbosacral fusion. Clinical records for these patients were reviewed for history of osteoporosis, diabetes, smoking, obesity, recent steroid or bisphosphonate use, time interval after surgery, and symptomatology at the time of fracture. Operative reports were reviewed for length of spinal fusion, type of hardware, approach, and underlying preoperative diagnosis. Two radiologists reviewed all imaging records to determine the pattern of sacral fracture.

All 23 sacral fractures were horizontal, all involved the screw tracts, and all exited through the posterosuperior portions of the sacral alae. The fractures occurred within 3 months of fusion in 19 of 23 patients. 11 of 23 patients had preoperative DXA studies. Of these 11 patients, only two had T scores consistent with osteoporosis. 6 of 23 patients were obese (BMI>30), and 6 of 23 patients were overweight (BMI 25-30). 6 of 23 patients had a history of smoking, 5 of 23 had recent bisphosphonate use, 3 of 23 had recent steroid use, and 3 of 23 had a history of diabetes. 19 of 23 patients had symptoms of lower back pain and/or lower extremity pain at the time of fracture. 17 of 23 fusions were long fusions (> 4 vertebrae). 17 fractures were diagnosed by CT, 5 fractures by MRI, and 1 by bone scan. 10 of 23 fractures healed nonoperatively with bedrest and/or parathyroid hormone therapy, whereas 13 patients required transiliac screws.

Sacral fractures after lumbosacral fusion have a characteristic transverse pattern through the sacral screw tracts, differing from the configuration of traditional sacral insufficiency fractures. The majority of these fractures occur within 3 months after surgery. Since few of the patients had osteoporosis and the majority of patients had long fusions, the fractures may be related to stress risers in the sacrum from the hardware.

Sacral fractures following lumbosacral fusion are a cause of patient morbidity and hardware failure.

Wilde, G, Miller, T, Schneider, R, Girardi, F, Sacral Fractures after Lumbosacral Fusion: A Characteristic Fracture Pattern.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9006278.html