, , , ,

sciatica – coughing, sneezing and straining

Sciatica, disc, model

Sciatica is often worsened by coughing, sneezing and straining. It is a sign that patients complain about in the case of back pain. In some, the act of coughing or sneezing can actually cause a disc herniation.

In a recent study in The European Spine Journal, researchers wanted to find out if the act of coughing, sneezing or straining is important in the assessment of nerve root compression or disc herniation on MRI.

In “A diagnostic study in patients with sciatica establishing the importance of localization of worsening of pain during coughing, sneezing and straining to assess nerve root compression on MRI” 1 they found that the worsening of leg pain with these actions which includes increasing intradiscal pressure 2 has good diagnostic value for nerve root compression and disc herniation with MRI.

The research revealed the importance of asking whether the patient has these symptoms in the history taking.

At Dynamic Disc Designs, our models showcase how compression will extrude the nucleus….helping patient’s understand their pain.

Quote by the famous Karel Lewit:

“The first task for the physician is to show the patient the cause of their pain”.

  1.  Eur Spine J. 2016 May;25(5):1389-92. doi: 10.1007/s00586-016-4393-8. Epub 2016 Feb 2.
  2.  Spine (Phila Pa 1976). 1999 Apr 15;24(8):755-62. New in vivo measurements of pressures in the intervertebral disc in daily life. Wilke HJ1, Neef P, Caimi M, Hoogland T, Claes LE.
, , , , ,

Back pain and radiculopathy – upright mri research

Radiculopathy, upright mri

Back pain and radiculopathy is common….very common. Furthermore, it is very common for patients to explain that it ‘hurts’ more when they are vertical. Then why are we mainly looking at supine MRI for findings? Supine MRI is helpful in ruling out pathology and does offer higher resolution with the 1.5 and 3.0 Tesla…but this magnet power is not necessary to investigate biomechanical problems.

In a recent research paper published in The Journal of Craniovertebral Junction and Spine [full text], these group of researchers looked at seventeen adults (10 asymptomatic and 7 symptomatic) and used the .6 Tesla MRI to evaluate the lumbar spine and pelvis in the seated position.

They looked at the “foramen area, height, mid-disc width, width, thickness of ligamentum flavum, disc (bulge, height, width), vertebral body (height and width), and alignment (lordosis angle, wedge angle, lumbosacral angle).” 1

Some of the important results showed significant foramen narrowing and disc bulge was 48% greater in symptomatic volunteers compared to asymptomatic volunteers. Thickness of ligamentum flavum increased as well.

Overall, the researchers were cautious in their conclusive remarks…like all great researchers. But the bottom line is that we all know that symptoms related to spine are often worse being vertical. It is a bit of a no-brainer to continue to investigate the tissue in its load bearing state.

Yet another reason why Dynamic Disc Designs knew it was inevitable that a dynamic model would be to market. They were the first to pioneer this patient education movement. Be sure you are equipped.

flexible spine model nerves


  1.  Nguyen HS, Doan N, Shabani S, Baisden J, Wolfl a C, Paskoff G, et al. Upright magnetic resonance imaging of the lumbar spine: Back pain and radiculopathy. J Craniovert Jun Spine 2016;7:31-7.
, ,

High Intensity Zone (HIZ) – Posterior Annulus

High Intensity Zone

A high intensity zone should not be overlooked-especially with a symptomatic patient. This is a bright white finding on MRI, most notable on the posterior annulus.

High Intensity Zone

In a recent study in The Journal of Medical Investigation, researchers looked at the pathogenesis of low back pain (with and without leg pain) and described it being caused by annular fissures and disc degeneration. 1 2.

Here are some key point of the research:

  1. They identified that more than two-thirds of the high intensity zones were found in the lower lumbar motion segments with the most at L4-5 followed by L5-1.
  2. They commented that they were unable to determine whether the intensity of the MRI magnet played a role in distinguishing HIZs.
  3. It is important to identify reliable measures to find HIZs.
  4. New treatment strategies are developing for the treatment of HIZ including laser.
  5. HIZs are not only a measure of degeneration but an active inflammatory tissue.

Dynamic Disc Designs develope models to help identify the movements that can stress the posterior annulus. Visit the Professional LxH Model to see an example of a high intensity zone.

High Intensity Zone, HIZ, Lumbar Disc


  1. Rozen D. Discogenic Low Back Pain. Pain Prac. 1: 278-86, 2007
  2. Peng B, Zhang Y, Hou S, Wu W, Fou X : Intradiscal Methylene blue injection for the treatment of chronic discogenic low back pain. Pain. 149 : 124-9 2010
, ,

Dynamic Loading of Intervertebral Disc Maintains Cells

Dynamic, Disc , Modeling, Research

Dynamic Loading of the Intervertebral Disc – Ex vivo culturing and what can we learn?

For decades, the study of the intervertebral disc and the process that leads to degeneration has kept researchers very busy. This quest to fully understand the mechanisms that lead to water loss and proteoglycan content of the nucleus pulposus seems to be in the forebrain of spine investigators in hopes that it will provide clues on how to reverse the degenerative process…or at least prevent it.

Degenerative discs are arguably the most common cause of low back pain 1 with the cost affecting millions of people worldwide 2. The intervertebral disc plays a crucial role in the maintenence of bony vertebral spacing in the spine to allow movement. And when it starts to fail, it compromises the biomechanics. So, the search for regenerative strategies continues and hence the reason for this write-up.

One of the foregoing approaches to studying ways to rebuild human discs is to culture them outside of the body which is called ex vivo (outside life) research. In a recent publication in European Cells and Materials 3 these researchers were able to maintain cell life by loading the disc in a dynamic way. The branch of science that looks at how forces can influence real living tissues is called mechanobiology.

By stimulating the discs with motion, the cells remained alive for 14 days without any blood supply. Interestingly, the cells died when too much force was used whereas using medium cyclic forces maintained their viability. You can read the full text here.

This kind of research is VERY important in the greater understanding of how to keep the most important structure in the spine happy and viable. It also leads the way in revealing how much force is optimal (and the timing of it) for a healthy spine.


  1. Adams MA, Lama P, Zehra U, Dolan P (2015) Why do some intervertebral discs degenerate, when others (in the same spine) do not? Clin Anat 28: 195-204.
  2.  Katz JN (2006) Lumbar disc disorders and low-back pain: Socioeconomic factors and consequences. J Bone Joint Surg Am 88 Suppl 2: 21-24.
  3.  European Cells and Materials Vol. 31 2016 (pages 26-39).

Facet spacing – quantifying the effect of posture on interfacet spacing

facet spacing, joint space width, arthritis

Facet spacing has been long thought and known as an indicator of arthritis…especially when the joint space width is reduced significantly. These zygapophyseal joints (facet joints) are two important joints that lie posterior to the anterior intervertebral disc. As dynamic disc height loss occurs, the facet spacing narrows and leads to mechanical compression to the hyaline cartilage.

Furthermore, when the disc is unstable, the facets aberrantly approximate one another and can cause pain if enough force in delivered to the structures to cause irritation to the nerves that either reside below the hyaline cartilage in the subchondral bone, or the facet capsule and synovial fold.

In 2008, a group of researchers led by Drake published a manuscript in Spine titled : The Influence of Posture and Loading on Interfacet Spacing An Investigation Using Magnetic Resonance Imaging on Porcine Spinal Units and looked inter-facet spacing as it related to posture and load history.

zygapophyseal joints

They concluded that posture played a factor on the injury mechanism of the facet joints. They found that flexion increased the spacing and extension decreased the spacing. Which seems like a reasonable conclusion. They reported a “posture-dependent injury mechanism as repetitive loading and flexed postures independently increased the spacing and twist angle.”

At Dynamic Disc Designs, we are committed to sharing important dynamic spine research that can help the professional in both the work-up and communication of clinical findings to the patient. Understanding the relationship of the dynamic disc to the facet joint in spine pain is paramount when looking at pain generators spatially. Our models help with this sense through a physical dynamic spine model that not only brings the real to life bit also and a fourth dimension of time.

An example of this is demonstrated in our multilevel cervical model. This model showcases a straightening of the lordotic curve which not only slightly increases the posterior aspect of the intervertebral disc but it also demonstrates how each facet joint parallelism alters.  That is, normally there should be symmetrical spacing across both plains of facing joint surfaces, but with a reduced cervical curve, joint facing symmetry becomes angular.  This can generate uneven mechanical pressure within the synovial joints of the neck.

Below is an example of joint plain asymmetry seen in a lumbar facet. As you can see, the top of the joint is ‘tighter’ than the bottom.

Facet Joint Arthritic

Using a dynamic model reveals these geometrical changes in a way that can make sense about new (and old) pain generators.

, ,

Life after death – regeneration of degenerated discs?

regeneration - degenerated disc

Will there be regeneration of degenerated discs?

For decades a degenerated disc was thought to be a slow descent towards spinal dysfunction. However, when searching out terms like “degeneration” in PubMed, for example, the word “regeneration” is starting to show up in the searches along side degeneration.

Recently, at the Engineering in Medicine and Biology Society, 2004. IEMBS ’04. 26th Annual International Conference of the IEEE , Lotz et al. presented a paper (Mechanobiology in Intervertebral Disc Degeneration and Regeneration) explaining that while viewing the disc cells in-vivo they observed a temporal and spatial relationship to disc loading and the potential to influence their behaviour. They stated that by studying these load influences, it could lead to understand disc health and tolerance injury states.

“Our data demonstrates that these cells respond differently to pressure and distortion and survive in the discs mechanical/loading environment…intriguingly setting the stage for disc repair”

Mechanobiology is the study of how mechanics influences biology. Why does exercise help and why does sitting in a chair, without movement, often makes thing worse? Understanding the mechanics will give us insights on how we can influence cells to kick start anabolic behaviour and repair.

In 2004, Setton described  “Information on the mechanisms that govern cell responses to mechanical stimuli in the intervertebral disc are just emerging” in Cell Mechanics and Mechanobiology in the Intervertebral Disc . Back pain is the leading cause of disability wordwide and the second most common cause of physician visits. Therefore it only makes sense to look carefully at the influence of mechanics on the intervertebral disc cells. 

So, the future does look promising…especially when we are learning that the inflow fluid dynamics are greater than the outflow across the endplate.

At Dynamic Disc Designs Corp. we like to stay abreast of the literature, and highlight it, especially when it comes to mechanobiological strategies that can potentially regenerate degenerated discs.




Rim Lesion – Intervertebral Disc Modeling

Rim Lesion

Rim Lesions – Dynamic Modeling

Rim lesions of the intervertebral disc exist in outer periphery of the annulus fibrosus. Researchers have wondered if these outer disc injuries facilitate degeneration. In an article published in the European Spine Journal, Melrose et al. looked to recent advances in annular pathobiology to reveal more of the truth. Their objective was to determine the impact annular rim lesions on the etiology of disc degeneration.

As an introduction, it is well known that the disc plays a crucial role in spinal flexibility and stability to allow movement. The outer fibrous lamellae consist of alternating sheets at 35 and 55 degrees. These alternating sheets prevent rotation from occurring too much with half the fibres coming into tension when the vertebra rotate one way while the remaining go into a slackened state….similar to the plys of a bias tire.

Rim Lesion

Rim Lesion - Annular Fibres

Rim lesions are those injuries that occur around the edge of the disc, at the rim. Rim lesion was originally described by Schmorl and Junghans (1971) as discontinuities in the vertebral attachment to the annulus fibrosus that may arise from an avulsion of the annular bony attachment adjacent cartilaginous end-plate.

To get a clearer picture of what this looks like, below is an image showing a lumbar model with a potential area where a rim lesion may exit.

Rim Lesion

Dynamic Disc with Nuclear Migration – Rim Lesion

Dynamic Disc Designs include rim lesion modeling to help in the better understanding of mechanisms associated with pain and solutions to alleviate it.