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In chiropractic colleges, there are very few unchallenged theories.  One exception is that most schools teach the well-established model of spinal degeneration as described by Kirkaldy-Willis.  This model of repetitive motion explains how small sprains lead to disc pathology and eventually spondylosis.  A new paper by Wang et al. provides an alternate explanation for the onset of spondylosis.  This model explains why some patients experience significant degeneration without an active lifestyle.

Watch Dr. Steele explain the importance of this new information and how to incorporate it into in your daily chiropractic patient education.

 Kirkaldy-Willis’ model of degeneration is dependent on movement

Kirkaldy-Willis proposed that spinal degeneration begins when repetitive microtraumas initiate small circumferential annular tears. These initial “sprains” may be painful, but only if they involve the highly innervated outer annular lamellae. A weakening of annular fibers allows for diffuse circumferential bulging. Tears that coalesce create “channels,” allowing disc herniation. Continued microtrauma is associated with the separation of the annulus from the vertebral endplate, thereby compromising disc imbibition and nutrition. The disc thins from cumulative stressors and by the loss of its normal viscoelastic properties over time. The average lumbar disc loses slightly less than one percent of its height per year, although some of this shortening is offset by unexplained, concurrent increases in vertebral body height.  Loss of disc height reduces the discs ability to absorb impact, and leads to excessive loading of the facet joints, resulting in degeneration and relative instability. As a concurrent hypertrophic response, the body lays down additional bone in the form of osteophytes on the anterior and lateral vertebral body margins. Posterior vertebral body osteophytes are visualized in only a minority of patients but when present, may cause central or lateral recess stenosis. (1)

Check out this ChiroUp quick video demonstration of Kirkaldy-Willis’ model:

The new concept described by Wang is dependent on immobilization

This new study assesses the effects of short and long-term immobilization of the lumbar disc and facet joints. Spondylosis via immobilization is not a new concept.  Previously, Iatridis (2) and MacLean (3) demonstrated the onset of degeneration via fixation in a rat tail model.  Taylor (4) fortified this concept with posterior fusions performed in immature canines, which resulted in significant compositional changes of the discs.

The present study builds on prior knowledge by triggering degeneration while never inducing damage to the structures investigated.  All structural changes are therefore secondary to fixation and not associated with acute trauma. Wang concluded:

“The mechanical environment set up by immobilization alone is capable of inducing lumbar disc degeneration at both 6 and 26 weeks in sheep. Longer duration immobilization did not advance disc degeneration process beyond of that found with short duration. The present model produces a degenerative disc with intact annulus and without acute injury, more closely representing the scenario common in human disc degeneration. (5)

Understanding the process of degeneration is necessary for your patient education.  Most patients have varying degrees of arthritis.  Some patients stamp ARTHRITIS on their forehead. They blame all of their problems on their “BAD BACK” given to them by their mother or second cousin twice removed!  It is our responsibility to minimize future damage by educating our patients about possible contributors to spondylosis.

ChiroUp provides easily digestible information that can be integrated into your practice today.  The patient education portion of your condition report now includes verbiage reflecting these findings to educate your patients about the importance of movement.

It often takes months for a study to reach publication and up to SEVENTEEN years for that information to fully disseminate into clinical practice! (6) ChiroUp brings you up-to-date chiropractic research on a real-time basis, intended to affect patient care on the same day.

Not yet a subscriber? Start your free trial HERE and see why so many schools and evidence-based DC’s trust ChiroUp to help automate patient education and clinical excellence.




  1. Bertelsman TJ and Steele BC. Lumbar DJD. www.ChiroUP.com Accessed 7/4/18. https://apps.chiroup.com/ConditionProtocol.aspx.
  2. Iatridis JC, Mente PL, Stokes IAF, Aronsson DD, Alini M. Compression-induced changes in intervertebral disc properties in a rat tail model. Spine 1999;24:996.
  1. MacLean JJ, Lee CR, Grad S, Ito K, Alini M, Iatridis JC. Effects of immobilization and dynamic compression on intervertebral disc cell gene expression in vivo. Spine 2003;28:973–81.
  2. Taylor TKF, Ghosh P, Braund KG, Sutherland JM, Sherwood AA. The effect of spinal fusion on intervertebral disc composition: an experimental study. J Surg Res 1976;21:91–104.
  3. Tian Wang, PhD, Matthew H. Pelletier, PhD, Chris Christou, PhD, Rema Oliver, PhD, Ralph J. Mobbs, MD, William R. Walsh, PhD. A novel in vivo large animal model of lumbar spinal joint degeneration. The Spine Journal (2018) https://doi.org/10.1016/j.spinee.2018.05.022
  4. Kanter MH et. al. A Model for Implementing Evidence-Based Practices More Quickly. NEJM Catalyst. February 5, 2017

About the Author

Dr. Brandon Steele

Dr. Brandon Steele


Dr. Steele began his career at The Central Institute for Human Performance. Dr. Steele has trained with experts including Pavel Kolar, Stuart McGill, Brett Winchester, and Clayton Skaggs. He has been certified in Motion Palpation, DNS, ART, and McKenzie Therapy. Dr. Steele lectures extensively on clinical excellence and evidence-based musculoskeletal management. He currently practices in Swansea, IL and serves on the executive board of the ICS.

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