If you are over 40 years old and you’ve had X-rays of your spine, you might be convinced that any back pain you have is coming from those joints. That’s because as we age, signs of degeneration are abundant. Bone spurs grow around the joints, the joint cartilage thickens and reduces movement, and overgrowth of the joint margins blocks motion.
But the truth is, there are just as many people with degenerative changes seen on X-ray who don’t have any back pain. How is that possible? Scientists don’t really know. But they’ve been studying the relationship between low back pain and facet (spinal) joint degeneration for years.
There’s some evidence that lumbar facets could cause low back pain. The anatomical structures in that area have a lot of nerves that could get irritated and send painful messages up the spinal cord to the brain. Arthritic changes are most common in the lumbar spine, especially at the L4-L5 level.
But a study of 188 middle-aged (and older) adults didn’t show a statistically significant relationship between facet osteoarthritis and low back pain. The researchers compared self-reported back pain among this group with degenerative changes observed on multidetector CT scans of the low back.
They found an increasing incidence of facet joint changes as people got older. About one-quarter of the group who were 40 years old or younger had facet joint changes. This compared with two-thirds of the group 70 years old and older. But there were no degenerative or arthritic changes that predicted low back pain. And that is a major finding to support the idea that degenerative changes and arthritis of the facet joints are not responsible for low back pain.
The take home message for physicians looking at X-rays is: don’t assume that even the worst of degenerative changes observed on imaging studies has any clinical meaning. That patient’s back pain may not be coming from the facet joint(s) despite appearances otherwise.
The one sticking point to this message comes from the knowledge that some patients get relief from facet joint blocks. The surgeon injects a numbing agent and steroid into the facet joint area, providing pain relief for the patient. This treatment suggests some involvement at the facet joint. But whether that’s really a placebo (the patient expects the treatment to work, so it does) or some other factor remains to be proven.
Ongoing research is needed to end the debate and get down to the bottom of low back pain. The results of this study just adds one more piece to the puzzle.