We all know that saying, “A picture is worth a thousand words,” but when it comes to x-rays and MRIs for low back pain we have to ask: is it?
Radiographic imaging of the spine (that is to say x-rays and MRIs) is often used by doctors as a diagnostic tool. And it makes sense: even the untrained eye can easily pick out DJD, arthritis, and disc herniations; patients often come in saying something along the lines of, “Doc, I don’t even know what I’m looking at and I can tell you something isn’t right. It looks different right there!” But the truth is that studies as early as the mid 80’s have been highlighting the fact that x-rays and MRIs are inconsistent amongst patients with low back and leg pain, pointing out that the correlation is “poor”, “limited”, or “inconclusive”.
To understand why this happens, we need to first understand that arthritis and DJD (degenerative disc disease) are normal parts of the aging process. We all get some form of arthritis in our bodies, and arthritics changes start as early as our 30’s—sometimes even in our 20’s for those of us who had particularly active youths (young competitive athletes, for example). Therefore, when we see arthritis on an x-ray, we have to consider not just whether or not it is present, but how much of a change there is and compare that to the patient’s age and pain level to look for a correlation.
Second, we simply don’t take MRIs of healthy, asymptomatic people. This means we have no idea how many people are out functioning completely normally with undiagnosed disc bulges and small herniations. Some researchers suspect that there is a higher incidence of asymptomatic disc changes that we know.
However, this doesn’t mean that x-rays and MRIs have no place in the diagnosing of low back and leg pain. There are times when it is very important to assess the structures involved in a patient’s pain and healing, and imaging helps us hone in on exactly what parts of a patient’s body might be playing a part in their pain (and therefore in their treatment plan).
But understanding the limitations of radiographic imaging (high prevalence of “normal” amounts of arthritis and low correlation between amount/size of issues and amount/severity of pain) is all part of the decision-making process for providers determining when to order images.
So next time you’re considering whether or not you need to ask your doctor about an x-ray, or reading through an MRI result, remember that when it comes to radiographic imaging of the low back pain, there’s more than meets the eye.