The Natural History of Low Back Pain: A Function of Directional Preference?

May 29, 2014

It is widely accepted that the natural history of low back pain (LBP) is highly favorable, yet we have little understanding as to why so many recover on their own. Is it merely the “tincture of time” that permits LBP to just “run its course”, like the common cold? Or is there something specific about the underlying LBP-generators themselves that allows them to recover so frequently, even without formal treatment? And after recovery, why do episodes so often recur and then recover again, and again?

Consider that multiple studies report that the pain generator of 70-89% of acute LBP has a mechanical characteristic called a “directional preference” (DP). That means that one direction of bending/loading the spine consistently improves the generator by centralizing or even abolishing the pain while the opposite direction consistently worsens it.  The pain source has therefore been described as “rapidly reversible” depending on the direction of spinal bending.  DP is routinely revealed during a standardized mechanical examination known as “Mechanical Diagnosis & Therapy”. Of those with a DP, the great majority improve with lumbar extension testing/movements/positioning while worsening with flexion.

It is also noteworthy that a DP is often present and operative even if it is never tested or identified by this form of mechanical exam.  It often remains undiscovered yet fully operative.

Independent of this MDT form of exam, an unpublished survey a few years ago of 38 primary care docs inquired about any “activity instructions” they give their LBP patients. All 38 responders said they routinely instructed patients to: 1) pursue walking, 2) avoid lifting, and 3) avoid sitting in a slouched position. Further, 75% said they also instructed patients to avoid forward bending and sit-ups and to always sit erectly. Clearly they wanted their patients avoiding lumbar flexion and pursuing erectness.

Likely none of these PCPs were familiar with the notion of DP, despite its prominence in the spine literature. Further, LBP clinical guidelines provide no insight into “good” vs. “poor” activities to pursue. So where did these PCPs learn such uniform instructions?  I would submit they’ve been listening to their patients’ directional likes and dislikes or may have directly learned by monitoring how their own LBP behaved.

My thinking on this is supported by a second survey that asked 349 LBP care-seekers how their pain responded to seventeen common movements, positions, and activities, nine of which clearly required lumbar flexion and the other eight were all upright or erect items.(1) Remarkably, all 349 patients graded all nine flexion items as more aggravating to their LBP than the eight upright items, all of which were graded as more comfortable (p < 0.0001).  That’s an impressive result.

So both patients’ pain experience and PCPs’ activity instructions closely match the DP data produced when the pain-generator is directly mechanically tested using MDT methods.  Further, many studies report that excessive lumbar flexion brings on LBP(5) and then aggravates the pain once started.(2-4, 6-8) Other studies report that being erect, either walking or supported sitting (relative lumbar extension) often decreases the pain.(6, 8)  All these data reflect the mechanics of the underlying condition: most don’t like flexion and prefer more extension.

So when people recover “on their own”, allowing LBP’s natural history to play out, it appears that there may be more than the mere passage of time. As Hippocrates said: “Healing is a matter of time, but it is also a matter of opportunity.” How very true.

A simple skin laceration needs time to heal, but it also needs favorable circumstances: perhaps stitches, or at least a protective bandage and some disinfectant. Alternatively, spending that very same time pulling the cut apart, scratching or tearing at it, or getting it dirty, will greatly prolong or even prevent healing altogether. Such persisting trauma or insult can even create a far worse problem than the original cut.  So time, without the provision of opportunity, is wasteful, even detrimental.

It’s bewildering that this time/opportunity notion is unacknowledged by some spine experts who mistakenly assume that any physical cause of acute LBP will have healed by six weeks so any pain that persists thereafter must be due to some alternative generator independent of the initial healed physical pain source. They ignore the need for an opportunity to heal.

So why is the natural history of LBP so favorable? Realistically, just like the skin cut, lasting recovery of the underlying disorder needs both time and opportunity. But how does an individual provide this opportunity for recovery when the cause of the pain is unknown?

Human nature may hold the key to these recoveries. Ben Franklin put it this way: “We are first moved by pain, and the whole succeeding course of our lives is but one continuous series of actions with a view to be freed from it.”  We instinctively try to avoid or minimize pain.  Even without specific instructions, our own painful backs quickly teach us that bending, lifting, and prolonged slouched sitting aggravates our problem. So we of course avoid or minimize those activities and positions and learn that our pain is actually reduced by other positions and activities which we then pursue.   We sit taller, we minimize sitting, walk more, and avoid bending and lifting, all with the intent of helping ourselves recover.

In essence, clinical guidelines’ recommendations that patients return to activity as soon as possible obviously encourages spinal movement, walking, and less sitting or lying in bed in flexed positions.  This activity in turn provides a variety of spinal positions and activities that then reveals what each painful back likes and doesn’t like.  Patients quickly learn and naturally modify their day in order to have less pain. Less lumbar flexion and more extension provides the pain-generating pathology the opportunity it needs to recover.

More research is needed to investigate the highly favorable natural history of LBP. The current hypothesis, based on these preliminary data, is that so-called “spontaneous” recoveries are closely tied to the pain generator’s DP with pain easily reversed and abolished by honoring and responding to that DP.

As always, I welcome feedback and questions. Please click on “Like” if this was useful and enlightening, or “Leave a Comment” by clicking on “Comment” below.

1. Donelson R, McIntosh G, Hamilton H. Is it time to rethink the typical course of low back pain? Physical Medicine & Rehabilitation Journal. 2012;4:394–401.

2. Donelson R, Grant W, Kamps C, Medcalf R. Pain response to repeated end-range sagittal spinal motion: a prospective, randomized, multi-centered trial. Spine. 1991;16(6S):206-12.

3. Larsen K, Weidick F, Leboeuf-Yde C. Can passive prone extensions of the back prevent back problems?  A randomized, controlled intervention trial of 314 military conscripts. Spine. 2002;27:2747-52.

4. Long A, Donelson R, Fung T. Does it matter which exercise? A randomized controlled trial of exercise for low back pain. Spine. 2004;29(23):2593-602.

5. Lund T, Labriola M, Christensen K, Bültmann U, Villadsen E. Physical work environment risk factors for long term sickness absence: prospective findings among a cohort of 5357 employees in Denmark. British Medical Journal. 2006;332:449-52.

6. Snook S, Webster B, McGorry R, Fogleman M, McCann K. The reduction of chronic nonspecific low back pain through the control of early morning lumbar flexion: a randomized controlled trial. Spine. 1998;23:2601-7.

7. Spratt K, Weinstein J, Lehmann T, Woody J, Syare H. Efficacy of flexion and extension treatments incorporating braces for low-back pain patients with retrodisplacement, spondylolisthesis, or normal sagittal translation. Spine. 1993;18(13):1839-49.

8. Williams M, Hawley J, McKenzie R, Van Wijmen P. A comparison of the effects of two sitting postures on back and referred pain. Spine. 1991;16(10):1185-91.





2 Responses to “The Natural History of Low Back Pain: A Function of Directional Preference?”

  1. This is the best, simplest, brilliant elucidation of the natural history of back pain … Reading this post I kind of feel like I’ve just read Copernicus on how the solar system works…

    • Hi Andy:
      Thank you for your very generous comments about my blog posting on the natural history of LBP. My content obviously made a lot of sense to you. Spread the word to others to log on to read it.
      All the best and Happy Holidays,

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