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Study Finds Evidence Asymmetrical Postures During Loading Contribute to Disc Failure

disc failure

A microstructural analysis of how healthy discs respond to compression and complex loading postures—specifically those incorporating flexion and facet-constrained shear—found evidence that the required load contributing to disc failure was reduced when complex postures, rather than simple flexion, were utilized in load-bearing situations. In addition, when asymmetric postures were used during lifting, rather than simple compression or flexion, there occurred more infiltration of the nucleus material as it made its way to the annular periphery. The results of the study indicate that asymmetric postures during lifting are more likely to contribute to disc degeneration and lower back pain and should therefore be avoided.

The Study

The study 1 involved 30 motion segments from 10 sheep spines that had no previous signs of disc degeneration. The discs were frozen, thawed, and then rehydrated fully prior to the compression experiments to be in agreement with previous similar experiments and maximize the annular load. Researchers created a bending, twisting, lifting scenario that involved axial rotation, lateral, anterior, and posterior shear, and flexion, adapting the mechanical rig to compress and rotate the disc segments to failure using compressive force.

The typical failure was lower under complex loading conditions than in conditions of simple flexion. Microstructural damage included fractures of the vertebrae and three variations of annular damage, including mid-span direct tearing, non-continuous mid-span tearing, and annular-endplate tearing. Combinations of all three types of damage occurred, as well as circumferential failure, in all 30 discs.

The complex postures utilized in the study lessened the discs abilities to withstand compressive loading and contributed to failures. The complex loading conditions contributed to instances of dual modes of failure, including the circumferential (circuitous tracking of nuclear materials towards the annular periphery) evident in all study samples. This suggests that the lateral parts of the disc may be especially vulnerable during flexion because of shear loading in the area. Circumferential damage was evident in all 30 discs involved in this study, which suggests that it is likely an important type of damage involved in disc failure under complex loading conditions.

Conclusion

Complex postures during load-lifting may contribute to herniation and disc failure. Asymmetrical postures (in addition to flexion) should be avoided during lifting to reduce the likelihood of sustaining a lower back injury.

 

KEYWORDS: complex loading, disc failure, asymmetrical postures during loading, compression and complex loading postures, flexion and facet-constrained shear, disc degeneration, annular damage, disc herniation

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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.
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Degeneration vs. Disc Prolapse

Degeneration

Disc degeneration has been a topic of discussion in its mechanism of back pain for decades.

It is believed to be related but a causal link has been difficult to pin down. Researchers believe it to be related while others still question its role in back pain because of asymptomatic individuals with it as seen in MRI.

In order to continue to reveal the mechanisms related to back pain, a discernment between disc degeneration and prolapse was the topic of this outstanding runner up study in The Spine Journal.

Kanna et al. opened this research paper by stating that the pathogenesis, management, symptom presentation, etiology and prevention of lumbar disc degeneration has been elusive and how it is important to sub-classify and investigate degeneration and prolapse. These researchers wanted to analyze the patterns of degenerative disc disease with chronic low back pain and compare it to acute disc prolapse.

This study was conducted using a prospective MRI imaging approach.

In conclusion they found that back pain and degenerative disc disease (ddd) were radiologically and clinically different when compared to those with back pain and disc prolapse. These researchers found that in those with disc prolapse, there was less degeneration and more endplate disruption. This fits with other findings of endplate failure to be more common with disc herniation. Subjects in this study who had back pain were found to have more numbers of degenerative discs with primarily upper lumbar involvement.

Dynamic Disc Designs develops spine models to help patients understand more clearly their own pain generators….helping to reduce psychosocial factors involved with back pain.

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Dynamic Degenerative Disc Model

Degenerated Disc Model - Dynamic Disc Designs

Coming this fall, a Dynamic Degenerative Disc Model with the ability to show innervation of the nucleus pulposus dynamically.

Dynamic Disc Designs strives to showcase important research in a dynamic platform so spine doctors can effectively educate their patients. This new design includes many new features including:

  1. dynamic two-part disc that is easier to squeeze
  2. neoinnervation into the dynamically mobile and fully visible nucleus pulposus
  3. facetogenic arthropathy narrowing the lateral recess
  4. dynamic disc bulge vs. herniation
  5. degenerative specimen chosen to copy
  6. much much more…

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With these features, spine professionals can quickly demonstrate pain generators and the solutions related to mechanical back pain. Help patients understand how to centralize the nucleus during movements in the teaching of lumbar lordosis with load, for example.

Centralization of pain is an important goal in the treatment/management of back and leg pain as well as neck and arm pain. Patients often think in terms of muscles but the core of the issue is often more central. With this new model, a greater understanding of how the nucleus moves can be a huge benefit as patients can work to minimize annular stress and disruption. If patients understand the mechanical forces responsible for their pain, they are better equipped to work as a team player in the management of back pain. Teaching containment of the nucleus will now be an asset with this new model design.

Degenerated Centralizer

This new Degenerative Centralizer Lumbar Model will change the way doctors and physiotherapists talk to their patients. We expect those that use this model for education will have better outcomes. Pre-orders being accepted now with discount offered to those early on the list.

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Disc Herniation on Earth – Learning from Astronauts

Disc Herniation - Dynamic Disc Designs

Disc herniation on Earth are common.

The most common age of disc herniation presentation is thought to be between 31-40 years and is found more common in people from rural areas, moderate and heavy workers and vehicle drivers on bad roads (https://ispub.com/IJNS/3/1/5615). In a recent narrative review article in the European Spine Journal, a team of powerful researchers looked at why astronauts get disc herniations when they return to Earth. This was in response to National Aeronautics and Space Administration (NASA) showed an increased risk of intervertebral disc (IVD) herniations in US astronauts (research).

In Disc herniations in astronauts: What causes them, and what does it tell us about herniation on earth? the authors looked at the common themes seen here on Earth in the better understanding why people get disc herniations in general.

We have known for quite some time that astronauts often suffer from back pain. Why is that? Simply it is because of hyperhydration and flexion.

Over the course of the day on Earth the spine undergoes an accordion-like height change losing as much as 20 percent of fluid loss. When astronauts are in space, their discs over-inflate. And when they return to Earth and bend forward in flexion, the posterior annulus is under increased stress and is susceptible to rupture. This is in line with some research showing disc morning pressures are a risk factor of disc herniations (research).

On the other hand, when we lie down (or go to space) the discs swell up to recharge the fluid loss to prepare for more load the following day.

Teaching patients about avoiding flexion first thing in the morning when putting on socks, for example, is important in the management of back pain. ddd models help with this conversation.

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Quick Clinical Tip:

Teach patients anterior and posterior structures in the spine. Discs are on the front, the facet joints are on the back. Bending forward compresses the discs. Teach posture tips to maintain neutral posture, especially first thing in the morning to help minimize the risk of disc herniation.

So what can we learn about this research?

It is important to keep the discs balanced with regard to compression and decompression. If discs are over-inflated, they are susceptible to disc herniation injury. On the other hand, if the discs are under-inflated, other problems can develop like degenerated disc disease. Most people fall into the latter category and require more off-loading.

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