Squashing The Jelly Donut Theory

By Aran Bright

Ever heard of The Jelly Donut Theory of Disc Protrusion?

By user: debivort (Own work) or CC-BY-SA-3.0 via Wikimedia Commons

The Jelly (or jam) Donut Theory suggests that your intervertebral discs behave like jelly donuts. If you flex forward you can squirt (bulge) the “jelly” (nucleus pulposus) out the back of your disc (annulus fibrosus) in disc related injuries. This is the logic used to explain why you shouldn’t flex your spine too much – that flexion pain is most likely disc pain, and extension pain is most likely of facet origin.

Emma Maaranen wrote this detailed description of The Jelly Donut Theory for Focus Bodywork in 2013.

Well, it looks like The Jelly Donut (Theory) might actually be less full of jelly and more full of BS (excrementi bovinus*).

A review of 4 studies on the behaviour of our “jelly donuts” (intervertebral discs) show that old understandings of disc behaviour are basically wrong. Why?

1. Until very recently we couldn’t even see intervertebral discs on imaging (MRI became more common in the 1990s). Most of the theories around disc bulges were created even earlier than the 1960s.

2. The concept of “jelly” is a very poor analogy for the nucleus pulposus, because:

… adopting different postures deforms the nucleus pulposus and therefore, changes the position of the nucleus pulposus but there is no apparent nucleus pulposus migration within the intervertebral disc.

Nazari et al 2012

In other words, the “jelly” changes shape when you move, but it doesn’t move forward or backwards within the disc.

3. One (thesis) study did show “movement” of the nucleus pulposus (but read point 4 to understand why it’s not really moving).

… between group comparisons identified that the asymptomatic subjects also demonstrated significantly greater posterior sagittal plane NP (nucleus pulposus) migration than the DLBP (discogenic lower back pain) subjects.

In other words, the jelly “moved” in healthy, pain-free spines, but barely moved in the painful spines. So the idea the “jelly” squirts out in painful backs is unlikely. Alexander, L 2014

4. With spinal movements it’s not actually the nucleus pulposus that moves but more the disc itself – the annulus fibrosus (the pastry of the donut). A much more thorough investigation of disc movement showed during extension:

NP (nucleus pulposus) margins remained unchanged relative to the vertebral body but moved anteriorly with respect to the IVD (Inter Vertebral Disc)

Kim et al 2017.

So it’s more the case the donut moves around the jelly, at least in healthy spines.

5. It’s very possible that the discs themselves actually bulge anteriorly in flexion and posteriorly in extension.

Anterior and posterior IVD margins moved posteriorly with respect to the vertebral body in extension.

Kim et al 2017

6. The final word actually goes way back to 2000 and this summary of intervertebral disc findings by Edmonston et al (2000):

Lumbar spine position was found to be associated with small measured changes in anterior disc height and nucleus position, however, this response was variable within and between individuals. The theoretical concept of a stereotypical effect of spinal position on the lumbar IVD is challenged by these initial data. Since the health of the disc is often unknown in clinical practice, manual therapy treatment for lumbar spine pain should be based on the symptomatic response to movement and position rather than biomechanical theory.

Discogenic back pain is very real but before you start talking about discs as the cause of your clients’/patients’ back pain, please keep in mind that:

Most low back pain is non-specific (commonly cited as 90%) … In the previously mentioned Australian study (1172 patients with acute low back pain in primary care), fewer than 1% had specific causes for their pain.

Maher et al. published in the Lancet, 2017.

Take Home Message

Be careful when making assumptions around the drivers of pain, especially when it comes to discs and backs. At one time, discogenic pain was the hot new topic in back pain care, and we can still see the echoes of that today. Literature around backs and discs are everywhere, hence why the term “slipped a disc” is a household term (psst … you cannot “slip” a disc). But please understand concepts such as The Jelly Donut Theory were developed before we had the capacity to be able to see inside human bodies while they are moving, at least without some level of torture involved.

Instead, it is much more statistically correct to assume a client’s spine is healthy and functional but they are obviously in pain, and so you need to treat each person with a clean slate and not jump to conclusions.

Listen and let the client tell their story. Then you are helping in a way that is specific to them.

Okay, so who’s up for coffee and a jelly donut?

*Editor’s note: I failed Latin.

References

Maher et al, 2017 Non-specific Low Back, Lancet Vol 389 No. 10070 pp 736-747

Nazari, J. et al 2012 Reality about migration of the nucleus pulposus within the intervertebral disc with changing postures Clinical Biomechanics Vol 27 No 3 pp 213-217

Alexander, L. A., 2014. The effect of position on the lumbar intervertebral disc. Available from: http://openair.rgu.ac.uk

Kim, Y.H., et al 2017 Effects of Cervical Extension on Deformation of Intervertebral Disk and Migration of Nucleus Pulposus PM&R Vol 9 No.4 pp 429-338

Edmonston, S.J., 2000 MRI evaluation of lumbar spine flexion and extension in asymptomatic individuals

Manual Therapy Vol 5 No.3 pp 158-164

About the Author

Aran Bright started his career as a massage therapist in 2002 after graduating from the Australian College of Natural Medicine in Queensland. In 2006, Aran completed his Diploma of Remedial Massage and, in 2007, his Bachelor of Health Science in Musculoskeletal Therapy. Aran graduated from University of Queensland with a Graduate Certificate of Sports Coaching, completed a Certificate IV in Fitness and an Advanced Diploma of Myotherapy. He currently runs his own businesses, Bright Health Training and Brisbane Workplace Massage, with his wife, Sheree.

 

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Comments

  1. What a great article. Makes me think of a time I injured my back (unsure how… woke up and couldn’t walk one day). Various practitioners stated after orthopedic testing that I had a bulged disc but in fact I didn’t. Scared the hell out of me because I thought at the beginning of my career I’d be nursing a chronic injury all my life.
    Food for thought.

  2. Great stuff!
    …I saw determined refusal to stick to a doctor’s diagnosis about necessity of spinal disk surgery for a back pain in my 72YO client, who with persistent care maintained massage-exercise-diet pathway and returned to a soccer field along with his younger mates sometimes later!
    I am very cautious about believing in diagnostic labels as they might submit into dependency. I much prefer to invest into optimal environment, when body can restore perfect balance again.

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