Dec 7, 2011

Low Back Pain: When is Medical Imaging Necessary?

By:  Tom Walters, DPT, OCS, CSCS

Are you now or have you experienced low back pain (LBP) in the past?  I would feel fairly confident in betting that the majority of people reading this article would answer “yes”.  In fact, a recent article from the Journal of Sports & Orthopaedic Physical Therapy stated that 25% of Americans reported having LBP for at least one full day in the last three months.1  LBP is the most frequent problem managed by physical therapists and accounts for 2% of all physician office visits. 1  In 2005, approximately 85.9 billion was spent in the United States alone to manage this disorder. 1  These facts raise many questions about how LBP is managed within our healthcare system and leads one to wonder if there might be a better way.

Diagnostic imaging (MRI, CT scan, X-ray) is often a major part of the clinical examination and is commonly used to determine the most appropriate course of treatment for many disorders.  LBP is no different as many individuals suffering from this complaint undergo imaging studies such as MRIs and X-rays.  Being that these tests can be very expensive and expose the patient to varying amounts of radiation, one must ask, when are these tests appropriate.  In 2007, The American College of Physicians and The American Pain Society published guidelines related to the appropriate use of diagnostic imaging.  These guidelines stated:
  1. Clinicians should not routinely obtain imaging or other diagnostic tests in patients with nonspecific low back pain. 
  2. Clinicians should perform diagnostic imaging and testing for patients with low back pain when severe or progressive neurologic deficits are present or when serious underlying conditions are suspected. 
  3. Clinicians should evaluate patients with persistent low back pain and signs and symptoms of radiculopathy or spinal stenosis with MRI (preferred) or CT scan, only if they are candidates for surgery or epidural steroid injection.
Even with these guidelines, medical imaging continues to be ordered inappropriately.  The Journal of the American College of Radiology recently published an article that reported that 26% of all medical images ordered secondary to LBP were inappropriate. 
So, what’s the big deal, you might ask.  Well, besides exposure to potentially harmful doses of radiation and the costs associated with excessive ordering of medical imaging, these tests can be detrimental in other ways.  In cases where medical imaging was not necessary, but was ordered anyway, studies have shown that simply knowing the results of such a test can negatively affect a patient’s recovery.  In one study by Ash and colleagues, 246 patients with LBP and/or sciatica underwent MRIs and were randomly split in to two groups.  The first group received the results of the MRI, whereas, the second did not.  At a 1-year follow-up, both groups showed similar clinical outcomes, but the group that had received the results of the MRI demonstrated significantly lower values of self-rated general health.  As a physical therapist, I see this in action on a daily basis.  Patients are constantly concerned about the results of their diagnostic imaging studies and often have a difficult time getting past these findings.  In these cases, much of the physical therapist’s duty is to explain to the patient that the results of a diagnostic imaging study do not predict the level of severity of a problem or describe which tissue is causing the symptoms.

Take home message:  Medical imaging is without a doubt a valuable tool in the diagnosis of low back pain, when ordered appropriately.  However, when ordered inappropriately, diagnostic imaging can become a burden on the healthcare system and can negatively affect an individual’s perception of their overall health.  The results of such tests must be taken with a grain of salt, as imaging findings do not determine the extent of pain or physical limitation that an individual may experience.  The results of medical imaging represent a single point in time and in no way predict permanent impairment or disability.

1.  Flynn T, Smith B, Chou R. Appropriate Use of Diagnostic Imaging in Low Back Pain: A Reminder That Unnecessary Imaging May Do as Much Harm as Good. Journal of Orthopaedic & Sports Physical Therapy. 2011;41:838-846.

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