A lot of Americans experience low back pain- it's estimated anywhere from over half of the population up to 2/3s of Americans experience chronic low back pain. As a healthcare provider, chronic low back pain is a common diagnosis seen in a physical therapy setting. When you go to the doctor with complaints of back pain, some may order imaging, because how else will you figure out what is wrong?
First step with imaging is an x-ray. X-rays show bones and alignment. X-rays are used to determine fractures, and possible degeneration (arthritis) mainly. You cannot specifically identify soft tissue structures on x-rays like muscles, ligaments, tendons, cartilage, etc- that's not what x-rays are designed for! So with low back pain, an x-ray may show a fracture to a vertebrae (not so common, most common in the elderly population who lack bone density), alignment of the spine (loss or exaggeration of spinal curves, individual vertebrae positioning) and space between vertebrae (disc height).
The most common diagnosis from x-rays regarding back pain are something along the lines of "Degenerative Disc Disease" or DDD, arthritis, osteoarthritis, bone spurs. AKA - aging. Degeneration of the spine is more common the older we get- we age on the outside AND the inside, that's normal!
The next step regarding imaging would be to get an MRI. MRIs are used to observe soft tissue structures, such as muscle, tendon, ligament, etc. This is generally where you would get a diagnosis of bulging disc, pinched nerves, etc. You can have these diagnoses without symptoms. I herniated a disc in my spine at age 17, diagnosed via MRI. I had an MRI 2 years ago, which showed degenerative changes at the sight of that previous injury- but I haven't had that pain in years, I was getting the MRI for other complaints of pain.
It should be noted that the American College of Physicians and the American Pain Society released guidelines stating unless low back pain is persistent and severe in nature, and accompanied by severe neurological symptoms, imaging is not beneficial. Everyone's anatomy is completely unique, so any "abnormal findings" doesn't necessarily mean that they're wrong and need to be fixed or that you're "broken".
Studies have shown that findings from MRIs on low backs do not correlate with the severity of symptoms or disability. They have also found that many individuals who are asymptomatic aka don't have back pain, have degeneration, bulging discs, etc. Studies monitoring the presence of a bulging or herniated disc (please don't say "slipped", a disc cannot slip!) have found that half of these resolve and reabsorbed back into the body.
And imaging is open to interpretation of the individuals reading it. An interesting study in 2016 had a volunteer undergo 10 different MRIs, from 10 different locations, read by 10 different radiologists. 49 findings were reported, with not one of them being consistent across all 10 reports. One finding was listed in 9/10 reports. 16 of the findings were unique. Interesting.
So what should I do if I have back pain? Conservative management of symptoms. Go see a healthcare professional who specializes in movement- like a PT. You should NOT stop moving, but activities should be modified. those who have chronic back pain (lasting 6 months or more), consider evaluating other factors such as lifestyle (nutrition, hydration, stress, etc) in addition to physical treatment. If you do have imaging done, remember it's just a piece to the puzzle.
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