The strange case of scoliosis and back pain

This article is an abridged excerpt from the e-book “The Complete Guide to Low Back Pain“, by Paul Ingraham.

Scoliosis is right out of the X-files of musculoskeletal medicine: an unexplained anatomical defect that gets multiplied over the many joints of the spine, producing an overall sideways curvature that is much greater than the glitch in any one joint. It often starts in childhood, but it can strike at any age. It can stay subtle and stable for a lifetime, or it can progress relentlessly to extremes of deformity, or almost anything between.

And yet it’s not clear that it causes back pain! Or not as much as most people think. And it is virtually immune to treatment in any case.

The nature of scoliosis

Sometimes scoliosis has an obvious trigger, like the spine being pulled out of shape by the powerful spasms caused by some diseases, or as a reaction to a serious spinal injury (as it did in my wife). Scoliosis can even be induced! It happened to almost everyone who ever had ribs removed (eek!) to treat the consequences of tuberculosis (Loynes). It’s almost like the spine is trying to squirm away from trouble.

But most scoliosis just comes out of the blue, and then often keeps coming (primary idiopathic degenerative scoliosis). Not only is this as weird as snake sneakers, it’s actually common. Spines do this lateral warping thing rather a lot. People with a little of it are simply everywhere: at least one out of three older women, maybe even half of them… and certainly at least one human of any kind in every full train car, busy coffee shop, or classroom (McAviney).

Severe cases are not common, but hard data on them is just as scarce as the patients. Horrifically spiralling spines have been staples of cabinets of medical curiosities for centuries, but that is an exotic fate, and most medical professionals will never see anyone like that.

Nearly everything about why spines do this thing remains a mystery, and a fine example of how primitive musculoskeletal health science still is. Delving into the nature of scoliosis is beyond the scope of this document, or apparently any document. (One of the only modern papers I know of that is ostensibly about the causes of scoliosis is Shakil 2014… if you can call about three paragraphs words of uninspired speculation a “focus.”) But the condition can at least give us an interesting perspective on the uncertain relationship between spinal structure and pain.

An illustration of extreme scoliosis, from a 1903 text on obstetrics by Cameron. Scoliosis this severe is life threatening & has basically nothing to do with common back pain or this book… but I can’t write about scoliosis without showing a vintage image of an extremely deformed spine for “colour.” It’s in my contract, I think.

Does scoliosis even cause back pain?

The answer seems obvious, but it isn’t actually.

It seems that scoliosis must surely increase the stress on spinal tissues — how can it not? And maybe that can add up to a problem over time. Perhaps 60% of scoliotic teens have back pain, and if the scoliosis worse, so is the pain (Théroux). Other data suggests that pain in scoliosis patients is quite bit less common than 60%, maybe only 30% over a lifetime (Wong) — plenty of painful scoliosis, but even more that’s painless.

The link between back pain and scoliosis so murky that legendary spine expert Dr. Alf Nachemson wrote, in 1979:

From available long-term follow-up studies of untreated scoliosis, there seems to be minimal risk of disabling back pain in adult patients who have lumbar curves.

And nothing’s really changed, because the world of back pain research moves like molasses: in 2021, Yuan et al pointed out that there is “no consensus as to whether non-specific low back pain in scoliosis patients is related to scoliosis per se or is just a normal symptom that could happen in anyone.” Still.

If we still can’t agree on that, it’s unlikely that scoliosis is all that painful. If it was, there would be a consensus!

Modern evidence certainly does show some risk, but it’s just not the slam dunk of a link most people think it has to be. The pain is notably not clearly worse than other kinds of back pain (a bit different, causing more groin and thigh pain, see Gremeaux). There are so many other factors in back pain that are not “stress on spinal tissues,” and back pain in the scoliotic is indeed clearly linked to the same squishy factors (insomnia, depression) that contribute to any kind of back pain. So the scoliosis may not actually be the main problem in the scoliotic patients who do have pain.

It is particularly silly to blame severe chronic low back pain on a minor scoliosis, but this happens more or less constantly. If you have minor scoliosis, good luck getting out of a massage appointment without being told “well, there’s your problem.” Even when there is minor scoliosis and pain, the main clinical question there should be why is minor scoliosis a problem? Because it usually isn’t. So there’s probably something else going on.

Six examples of moderate scoliosis. The top centre case might just qualify as severe, but scoliosis can actually get crazy worse. Notice how the x-rays show the degree of curvature more vividly that the photos.

The predictably weak-sauce science of treating mild to moderate scoliosis

Just as scoliosis is unjustly blamed for much more back pain than it probably causes, many therapists also bizarrely claim to be able to cure scoliosis — to straighten the twisted spine.

Scoliosis is clearly one factor in back pain, and so it would sure be lovely if spinal curvatures could be ironed out like wrinkles in a shirt. Alas, there is just no scientific evidence that scoliosis can be significantly helped by any therapy. (Surgery can undoubtedly be the lesser-of-evils option in more serious cases, but it’s out of the question for mild to moderate cases.)

Most studies of therapy for scoliosis go like this: forty-two subjects with moderate (6–12˚) scoliosis were treated by chiropractors for a full year, resulting in “no discernible effect” (Lantz).

At best, they go like this: an anti-scoliosis exercise regimen for 34 patients produced slow and modest results, perhaps better-than-nothing, but not at all impressive, and also not actually “proven” (Negrini). (There are a handful of similar studies, but that is a long way from proof.)

A 2007 paper in the journal Spine reviewed all the science so far on treating scoliosis (spinal curvature) without surgery (Everett). Not much had changed by 2020: Schoutens et al published an inconclusive “garbage in, garbage out” review of particularly sparse evidence for common scoliosis treatments, concluding rather desperately that nothing could be recommended based on the barely-there evidence and “basic clinical research at any level would be helpful” (Schoutens).

Across the board, the evidence is either discouraging, or just of such poor quality that no real conclusions can be drawn.

And so everything that healthcare professionals think they know about treating scoliosis is an untested belief. And if you think the research is weak sauce — and it is — you should see how sketchy the untested beliefs of clinicians can be!