Sacral insufficiency fractures are a common, but often underdiagnosed source of low back pain in the elderly osteoporotic patient. Fractures of the pelvis are a consequence of undue stress onto a weakened bone. Osteoporosis is the most common cause of fractures of the pelvis. Major or minor trauma is another cause; however, spontaneous sacral insufficiency fractures are also common. The incidence of sacral insufficiency fractures comprises of approximately 1% to 2% of pathologic fractures involving the spine and pelvis. However, these fractures are often misdiagnosed and unrecognized. Risks of sacral insufficiency fractures are very similar to that of vertebral compression fractures.
The treatment of sacral insufficiency fractures can either be noninterventional, interventional, or surgical. Unstable fractures, especially with associated cauda equina syndrome, may require closed manipulation or open reduction and internal fixation procedures. Open reduction procedures as compared to percutaneous reduction have increased risks, especially infection.
Conventionally, treatment in the past has been mainly bed rest, opiate analgesic management, using a walker with partial weight-bearing and early mobilization, and lumbosacral or pelvic corsets.
Deep venous thromboses and pulmonary emboli, reduced muscle strength with prolonged recovery, postural hypotension and impaired cardiac function, atelectasis and pneumonia. Skin breakdown and pressure ulcers, constipation and fecal impaction, depression and intellectual regression are known complications of prolonged periods of inactivity.
The overall 1-year mortality rate associated with pelvic insufficiency fractures is 14.3% and 50% of affected patients will not return to their prior level of function.
Although initial clinical improvement may occur rapidly, compete resolution of symptoms may not occur for up to 9 to 12 months.
Despite a favorable natural history, more aggressive treatments may benefit certain patients who are incapacitated by painful sacral insufficiency fractures.
Chronic symptoms and disability related to osteoporotic insufficiency fractures are believed to be due to fracture nonunion, micromotion, or resultant deformity related to the anemic attempts of the weakened bone to heal. The percutaneous injection of polymethylmethacrylate (PMMA) into fractured vertebral bodies (vertebroplasty) has been safely performed to successfully treat painful osteoporotic compression fractures. A natural extension in the application of vertebroplasty is the percutaneous injection of synthetic bone cement into the fractured sacrum (sacroplasty) to treat persistent symptoms and disability. Sacroplasty was first reported in 2001 as treatment of symptomatic sacral metastatic lesions, and subsequent reports have documented its safe and effective performance.
Once suspicion of a sacral insufficiency fracture is suspected, then appropriate imaging is necessary. Some patient may already have had normal spinal or pelvic radiographs.
The gold standard, which yields the highest sensitivity and specificity, is a magnetic resonance imaging (MRI). If a patient has a pacemaker or other condition that precludes obtaining an MRI, a computed tomography (CT) is necessary to compliment the bone scan. CT scans are more sensitive; however, nondisplaced fractures without reactive sclerosis may be missed.
Fractures of the sacrum are best shown on coronal ...
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