To review, this is a 56 year-old female with acute atraumatic back pain.
Questions and Answers: 1) What history and/or physical exam findings would warrant x-ray imaging in this patient?
Attempts should be made to minimize imaging in patients presenting with atraumatic back pain. In fact, the guidelines from the American College of Physicians state, "clinicians should not routinely obtain imaging or other diagnostic tests in patients with nonspecific low back pain and reserve imaging for patients with severe or progressive neurologic deficits or when serious underlying conditions are suspected on the basis of history and physical examination" Early imaging (prior to 6 weeks into course of back pain) imaging is associated with increased invasive procedures but no improvement in short term or long term outcome. This may be because many patients have asymptomatic spinal pathology; 22-67% of asymptomatic adults have herniated discs on MRI, while 21% of asymptomatic adults have spinal stenosis on MRI.
However, there are history and physical exam findings that increase the likelihood of finding true spinal pathology. Any patient with back pain and new and true neurological deficit should eventually get an MRI. Saddle anesthesia, weakness that crosses multiple dermatomes, or bowel or bladder incontinence warrant emergent MRI for evaluation of cord compression or cauda equina. Patients with infectious risks or findings, such as history of intravenous drug use, immunosuppression, fever, or elevated inflammatory markers, may also need an MRI for evaluation of spinal infection and impending cord compression.
If a patient has none of the above symptoms but has a history of cancer, or high concern for cancer based on risk factors and exam findings (smoking, weight loss, cachexia), radiographs should be obtained for evaluation of pathologic fracture.
And finally, patients with high risk for fracture should also get radiographs. Patients with significant trauma, older age, and corticosteroid use had increased likelihood ratios for fracture of 3.42-12.85, 3.69-9.39, and 3.97-48.50 respectively. A known history of osteoporosis is also associated with increased fracture risk, but generally only in minor trauma.
This patient had a history of osteoporosis, but no other "red flags" warranting imaging.
2) What is the injury shown on the radiographs?
This radiograph shows a clear compression fracture of the L1 vertebrae with involvement of both the anterior and posterior aspects of the vertebral body. For thoracic and vertebral fractures, the "lines of Denis" are used to assess for stability (anterior, middle, and posterior). If a fracture disrupts more than 2 lines of Denis it is considered an unstable fracture.
As you can see in the above image, this fracture involves the anterior and middle lines of Denis and is therefore likely unstable. This fracture is either a severe compression fracture or a burst fracture. A burst fracture would show vertebral body widening on the AP view, but the visualization is limited on this patients AP radiographic study.
3) What are the next steps in diagnosis and management?
Fractures involving more than 1 column of stability (anterior, middle, posterior) are considered to be unstable fractures and require further imaging, log-roll precautions, and specialist input. Depending on the type of fracture, this may be either an MRI to assess for ligament stability and spinal involvement or CT for evaluation of bony fragments.
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Downie A et al. Red flags to screen for malignancy and fracture in patients with low back pain: systematic review. BMJ 2013;347-f7095.
Jensen MC et al. Magnetic resonance imaging of the lumbar spine in people without back pain. N Engl J Med 1994;331-369.
Williams CM et al. Red flags to screen for vertebral fracture in patients presenting with low-bac pain. Cochrane Database Syst Rev 2013;1:CD008643.