1.6%: The normalcy of spinal curves

1.6%. That is the percentage of people who have a perfectly straight spine, one with no lateral deviation whatsoever. Those were the findings of Dr. William P. Bunnell, Professor, and Chairperson, Loma Linda University Medical Center, who in 1992 published his paper; Outcome of Spinal Screening. The study looked at 1000 physically mature high school students. A full 80% of the students had three or more degrees of rotation at one or more levels of the spine. An interview with Dr. Bunnell is posted here.

In our study of 1,000 physically mature high school students–in which we used the Scoliometer as the screening device–we found that only 16 out of 1,000 students (1.6%) had a clinically straight spine. Eighty percent had three or more degrees of rotation at one or more levels of the spine. We also learned that within this population, if “any degree of deformity” (i.e., one degree) is used as the criterion, then 98.4 % of students will be referred. (From Dr. Bunnell’s interview)

With simple math, it would mean that 98.4% of these students had scoliosis of some degree, which contradicts oft-reported figures, such as “Scoliosis affects approximately 2% of the population”, as reported on the American Academy of Orthopaedic Surgeons (AAOS) website. So who is correct? The webpage of the AAOS gives no determining criteria for what degree of curvature constitutes being given the diagnosis of scoliosis. Still, one can assume that it is a spinal curve greater than the 3 degrees cited above, and certainly does not apply to ANY degree of a spinal curvature. (see this link for the article, “Why is 10 degrees considered a scoliosis?”

There are also widely varying opinions on how scoliosis affects pain. Searching GoogleScholar will bring up several articles addressing scoliosis and low back pain. Still, few seem to apply to the more subtle effects that I believe exist when posterior thoracic rib asymmetries impair normal scapular motion. In a paper by Aaron LeBauer (LMBT,SDPT), Robert Brtalik (SDPT), and Katherine Stowe (SDPT) titled, The effect of myofascial release (MFR) on an adult with idiopathic scoliosis, LeBauer discusses the various postural deviations/deformities inherent in scoliosis, as well as presenting a case study on how MFR can be helpful with scoliosis. The point in presenting this paper here is to highlight that the typical, though variable, postural deformities, and deviations inherent in scoliosis are quite often the same as what we are assessing with postural examination. The relative “normalcy” of postural deviations should give one pause when assigning blame for painful conditions.

In treatment, as well as in my Foundations in Myofascial Release Seminars, I encourage thoroughly evaluating what effects an asymmetrical thorax can have on pain and limitations in function. There will be times when you find wild asymmetries that seem to have little connection with pain, while other times, subtle asymmetries seem to impact pain and function profoundly. Don’t jump to conclusions too soon that the asymmetries you see in evaluation connect with the presenting issue, but don’t ignore the obvious either. I commented in-depth about how the “normal” asymmetries that result from these changes can impact issues such as a winged scapula in another blog post. This issue is only one of the dozens of postural asymmetries that we see daily that do not necessarily require “correction” (if that is even possible), which does not imply in any way that our services aren’t helpful with issues of the spine/thorax. Carefully applied manual therapy can be quite useful for these and many other problems.

1.6%…..that is your starting point.

For now,

Walt Fritz, PT

Addendum, 11/14/19

I wrote the above passage several years ago, and while I recognize myself in the article, I see the world differently than I did back then. With an emersion into the world of providing education to SLPs and voice professionals, I see that issues of the normalcy of spinal curves in a different light. If you accept the results of Bunnell’s 1992 study as accurate, how might that potentially impact issues of voice, swallowing, globus, etc.? Imagine the orientation of the spine with even a subtle sub-scoliosis. Move up from the thoracic region and into the cervical spine. If the cervical spine is orientation away from true forward, which by the data presented by Bunnell, it will be in 98.4% of people, how might that impact how the entire hyolaryngeal complex sits as well? If the neck and spine are rotated as a result of the spinal curve, will the larynx follow along or remain in what might be viewed as a “normal” resting position? How might the positioning and appearance of the laryngeal musculature appear? Will the SCM and strap muscles appear normal, or might they appear asymmetrical? Might this asymmetry be seen as part of the problem, be it labeled as a sign of weakness, tightness, or by other pathological descriptors? When one moves in to assess the laryngeal position, might the larynx sit askew and be labeled as problematic? The hyoid rests at the mercy of the musculature with which it interacts; it would be doubtful that an underlying spinal rotation, which impacts musculature symmetry, will leave the hyoid in a nice, happy, neutral alignment. Musculature, hyoid, and laryngeal are primary areas of evaluation for both alignment/symmetry as well as to assess abnormalities in apparent muscle tension, with deviations from the expected norm often viewed as potentially problematic or causative. However, might all of the evaluative markers be simply a by-product of an underlying (normal) spinal rotation? While these markers could be significant, might we be making them more relevant than they are? All of this is speculative, but with reasonable doubts like this, should we be so firm in our evaluation conclusions? Might asymmetry be more an aspect of normalcy and not pathology?

Social media is chock-filled with opinion, backed by anecdotal evidence, of how asymmetry is a (or THE) causative factor behind pain or diminished functional performance. Most are claims that when a person was taken form a posture of asymmetry into one of less asymmetry the problem lessened or resolved. Without a doubt these occurrences happen, but what are the factors involved? No therapeutic intervention is a single factor case study, but a collection of physical interactions, coupled strongly with behavioral and indirect aspects. I worked from a postural/asymmetry model for years and seemed to have success. Nowadays I allowed it to take a backseat to other models, mainly a patient-centered one, and I still seem to get good results. The lesson? It might not be what I think is important or causative and it may not be the modality I’m using, but is probably more due to the therapeutic interaction that I am having with my patient. Therapists claim success with nearly every modality taught and I would guess that there is accuracy in those claims. If asymmetry mattered then any model not addressing it should fail. But that is simply not the case.

1.6% of us have no spinal curve to any degree, leaving the remaining 98.4% of us to deal with the potential ramifications of being curvy…maybe curvy is the new normal. 

Cheers,

Walt Fritz, PT

Foundations in Myofascial Release Seminars

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Author: Walt Fritz