Our lumbar models are identical in size and geometry to a real cadaveric specimen. With careful construction of the soft tissues including a flexible intervertebral disc including an annulus fibrosus and a nucleus puplosus,  each model is meticulously hand-crafted to provide the most accurate modeling to help the musculoskeletal practitioner to engage with patients in a convincing way.

Lumbar models have historically been static and immobile, but at Dynamic Disc Designs, we have developed flexible lumbar models to help relay essential movements to the patient related to their pain triggers. Having a patient genuinely understand their body mechanics empowers the patient and improves outcomes.

Patient-centered care must include translational strategies to help a pain sufferer understand their origins. A dynamic lumbar model helps execute efficient and accurate patient education.

Degenerative, Spondylolisthesis model, vertebra model, spondylolisthesis

An in vivo dynamic radiographic imaging study of two sets of subjects (symptomatic and asymptomatic) revealed that some degenerative spondylolisthesis (DS) patients showed a greater range of aberrant motion, creating occult instability, in their mid-range kinematic images than previously exhibited on static imaging studies. The new data could have important clinical and diagnostic implications, as practitioners learn to distinguish between DS patients who might benefit from non-surgical interventions and those who require fusion to treat their condition.

Degenerative Spondylolisthesis model

A degenerated lumbar disc model with a grade 1 spondylolisthesis.

Background

Surgical spinal fusion and decompression with laminectomy are the remedies most often prescribed to patients suffering from lumbar DS, but some patients may be treated with decompression alone and avoid costly and potentially risky surgical procedures. Understanding how lumbar spinal instability contributes to DS can help predict which patients may be at risk of destabilization after laminectomy and thus require surgical fusion. The authors of this study sought to compare static and dynamic clinical radiographs to see if the full spectrum of rotational and translational kinematics were evident in MRI’s of subjects utilizing flexion/extension poses.

The Study

Seven Degenerative Spondylolisthesis patients and seven asymptomatic control subjects were imaged during torso flexion as a tracking system measured and calculated the movement of each vertebra and AP slip. Static, and dynamic radiograph images were obtained and compared. The results showed that the static radiographs did not detect the full spectrum of aberrant motion and underestimated AP slip. In contrast, the continuous dynamic imaging showed that DS patients demonstrated a wide range of aberrant motion with high kinematic heterogeneity that was not visible on the static radiographs.





Implications

The results of this ISSLS bioengineering prize-winning study suggest that the presence or absence of lumbar instability in DS patients should be considered and evaluated prior to prescribing treatment. Mid-range kinematics and AP translation may play an important role in determining the relative effectiveness of decompression and laminectomy with—or without—surgical fusion and might spare a subgroup of lumbar DS patients unnecessary expense, risk, and recovery from procedures that are potentially superfluous (or harmful) to their recovery.

KEYWORDS: Some DS Patients May Not Require Fusion Surgery to Improve, some degenerative spondylolisthesis (DS) patients showed a greater range of aberrant motion, creating occult instability, in their mid-range kinematic images, from non-surgical interventions and those who require fusion, static radiographs did not detect the full spectrum of aberrant motion and underestimated AP slip, kinematics and AP translation may play an important role in determining the relative effectiveness of decompression and laminectomy

 

Lumbar Foramen

 An in vivo study of cross-sectional lumbar foramen dimensions during a weight-lifting activity showed that all levels of the lumbar intervertebral foramen (LIVF) area decreased, except for the L5-S1 segment during lumbar extension, which had consistent measurements of the foramen, height, and width throughout the activity. The results of the study could provide insight into ways to improve the diagnosis or treatment of lumbar foramen stenosis.

Purpose of the Study

Radiculopathy caused by nerve root compression is a common symptom of LIVF stenosis and is often treated surgically, through the implantation of an interspinous device or decompression. Because the LIVF is surrounded by mobile facet joints, its shape undergoes changes during typical daily movement. As it changes shape, it may put pressure on nerve roots or other structures that may cause pain. Complications arising from the changing dynamic anatomy of the LIVF during activity can lead to failed back surgery syndrome, so understanding how movement and weight-bearing affects the LIVF is important to effective treatment and maintenance of back pain.

The Study

An MRI study of 10 healthy subjects (five male, five female) in supine, relaxed positions was conducted, and 3D spine models were constructed based upon the results of the scans. The lumbar spines of the subjects were then imaged during lumbar extension postures of 45 degrees to a maximally-extended position, while the subjects were holding an 8-pound dumbbell in both hands. These scans were also used to create 3D vertebral models of the in-vivo dimensions during activity, and a data analytic design was created to determine the area, height, and width of the L2-S1 vertebral levels during the activity for 45-degree flexion, upright position, and maximal extension.

Results

Researchers found that the LIVF area in L2-L3, L3-L4, and L4-L5 decreased during weight-lifting activity. The LIVF widths also showed a similar decrease, but the heights remained throughout the extension activity. However, the foramen area, height, and width at L5-S1 did not change during the weight-lifting. Overall, the data for all other areas demonstrated a change of approximately 10 percent from 45 degrees flexion to an upright standing posture, and again from upright standing to maximal extension. This information underscores how patients with LIVF stenosis may experience nerve root impingement pain during extension postures and feel relief from that pain during flexion. Understanding the in vivo dynamics of the functioning lumbar spine may help practitioners in the treatment and diagnosis of lumbar foramen stenosis.

 

lumbar spinal stenosis, spinal canal narrowing

A superior view of our Lumbar spinal stenosis model with a dynamic disc bulge and dynamic ligamentum flavum.

KEYWORDS: Lumbar Foramen Dimensions During Activity, in vivo study of cross-sectional lumbar foramen dimensions during a weight-lifting activity, insight into ways to improve the diagnosis or treatment of lumbar foramen stenosis, Radiculopathy caused by nerve root compression, Complications arising from the changing dynamic anatomy of the LIVF during activity, nerve root impingement pain during extension postures

Facet Joints, GAG, Annulus Fibrosus, Torsion

A recent study evaluated the role of facet joints in torsion using four different compressive preload conditions in healthy and degenerated lumbar discs—with, and without facet joints. The study also sought to develop a quantitative relationship between structure and function in tissue and torsion mechanics. The study found that annulus fibrosis GAG content substantially affects the mechanics of disc torsion.

Purpose of the Study

Because there is a large population of lower back pain (LBP) sufferers whose jobs involve excessive loading and rotating the lumbar spine, the authors of this study sought to quantify and understand how the facet joints in healthy and degenerated discs would behave under axial rotation scenarios. They did this by observing in vivo changes in spinal segments during torsional behavior. The intervertebral disc (IVD) is capable of stability and flexibility during most movement, receiving stresses and sharing them with the nearby facet joints and other surrounding structures. The facet joints should protect the disc from overload and degeneration by restricting motions that would cause damage to the spine, but some complex motions that involve axial rotation and bending during heavy loading can increase the chance of micro-damage and disc failure. How well the IVD and facet joints share loads is determined by the mode of loading and posture. Previous studies have demonstrated that up to 25 percent of axial compressive forces may be supported by the facet joints. Between 40 to 65 percent of healthy disc joint rotational and shear forces are also supported by the facet joints. Therefore, it is important to understand how the facet joints in healthy and degenerated discs react during torsion.

Study Design

Researchers obtained and imaged seven human cadaveric lumbar spine segments aged 43 to 80 years-old. The musculature and ligaments were then removed, and the intact facet joints near the discs were subdivided mid-vertebrae prior to the samples being potted in bone cement. The segments were then wrapped in gauze and stored in a phosphate solution until brought to room temperature just before testing. They were then mounted onto a testing machine and secured with screws.

The segments underwent a moderate-to-low preloaded axial compression, followed by axial rotation through the center of the disc. The cycles of compression and rotation were performed for two hours to allow the formation of creep. Ten cycles of cyclic rotation, and the samples were tested under four axial compressive preloads and allowed to recover between each test. The facet joints were then removed, and the samples were tested again, using the same loading configuration. For each round of testing, the researchers recorded the levels of force, rotation angle, displacement, and torque.

Isolating and Imaging Each Disc

Each disc was isolated and imaged after mechanical testing. Researchers measured the disc area, anterior-posterior and lateral width using a custom algorithm. Disc height was measured from the posterior, anterior, left, and right lateral sides, as well as the center. A mathematic formula determined the applied axial stress, and the images were graded and compared with radiographic-based grades.

Conclusion

The results of the tests indicated a strong correlation between creep and axial compressive preload and the loss of disc height. Removing the facet joint had no effect on this phenomenon. The presence of facet joints and an axial compressive preload did have a strong effect on torsional mechanical properties, with torsional stiffness and range decreased 50 to 60 percent for compressive loads after removing the facet joints. Energy absorption decreased about 70 percent during rotation after facetectomy, and disc-joint strain increased 74 percent, compared to only 62 percent in disc strain energy using the same axial compression.

Annulus Fibrosis GAG content in degenerated discs greatly reduced torsion mechanics, while the facet joints are integral in keeping the spine from rotating too far and helping to reduce shear stress and damage to the disc. The relationship between the biochemical-mechanical and compression-torsion levels noted in this study may help to provide for more effective and targeted biological repair methods for degenerating discs of various levels.

 

KEYWORDS: AF GAG Content Alters the Mechanics of Disc Torsion, role of facet joints in torsion, axial rotation scenarios, correlation between creep and axial compressive preload and the loss of disc height, targeted biological repair methods for degenerating discs

Published May 5th, 2o16 in the New England Journal of Medicine 1 is a review paper on herniated lumbar disk. Dr. Deyo opens the manuscript with a case presentation of  41-yr-old man. He develops progressive increasing lower back and leg pain from doing yard work. This involved pulling out large bushes. With a positive straight leg raise at 40 degrees, the most probable diagnosis is herniated lumbar disk.

About two-thirds of adults experience back pain some time in their life. Sciatica is often used to describe the result of a disk herniation as the sciatic nerve is the downstream nerve effected. A more appropriate term is lumbar radiculopathy. This is due to the proximal origin of the issue and the sensory and motor findings that presents along the sciatic nerve distribution.

Herniated Lumbar Disk

To help with patient education of a herniated lumbar disk, accurate modeling of the nucleus pulposus and annulus fibrosus is developed by Dynamic Disc Designs Corp. Now, a patient can understand the geometry and forces involved to create a disk herniation and may think twice about repeating the activity that causes the problem initially. Accurate patient education of herniated lumbar disk to reveal the mechanism of the injury is very helpful in the management of the condition. This is both in onset and rehabilitation as load with flexion causes the nucleus to push posteriorly.

herniated lumbar disk. lumbar, disk

Herniated lumbar intervertebral disk – important for patients to see how this happened

It is important for patients to understand what caused their symptoms as to change future behaviours. It is known that a herniated lumbar disk is caused by hydraulic compression of overloading the spine into a flexion moment as the posterior annulus is compromised causing radial fissures 2. And now, this never before seen event can be shown with a knowledge transfer to the patient in an easily understandable dynamic model to help improve outcomes.

 

  1. Richard A. Deyo, M.D., M.P.H., and Sohail K. Mirza, M.D., M.P.H. Herniated Lumbar Intervertebral Disk. The New England Journal of Medicine. May 5, 2016 1763-72
  2.  Samuel P. Veres, BEng, Peter A. Robertson, MD, Neil D. Broom, PhD The Morphology of Acute Disc Herniation. A Clinically Relevant Model Defining the Role of Flexion. SPINE 2009 Volume 34, Number 21, pp 2288–2296
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.
Disc Protrusion, Pain, sitting, back pain, upright MRI

Disc protrusion is defined by an extension of nuclear material extending beyond the confines of the annulus (if the base of the material is larger than the material protruding). In the flexed position, the nucleus pulposus is driven backwards (posteriorly) into the spinal canal. If there are nerves in the area, related pains can extend down into the leg (or legs) causing sciatica.

MRI is our powertool for looking at disc injuries. It was developed in the early 1980s and primarily used to look for pathological conditions like cancer. And because it was and still is important to keep the patient still, lying down (recumbent) MRI was the standard.

However, when looking for load related pain, lying a patient down is not always the best strategy as often a patient’s symptoms disappear when they are on their backs. So it would seem reasonable to image patients in a vertical or upright position to look closely at the tissues as they are loaded….this only makes sense.

Here is an example of how the diagnosis was seen when the spine was placed in the seated position. This patient only had symptoms while sitting. And you can see why below.

Disc Protrusion with Upright MRI

Standing, Case, Modeling, MRI, Upright

Pain, sitting, back pain, upright MRI

In this case, the patient demonstrates further protrusion with sitting…and the upright MRI clearly shows this difference from standing to sitting. This is why it is important to consider upright MRI when the patient presents with a load dependent complaint. Upright MRI can help with the diagnosis.

All MRI images on this page are property of Medserena Upright MRI Centre.

herniated disc model

No one can truly estimate how many patients walk into chiropractic offices each year complaining of back pain. Chances are that that number soars into the millions…maybe even more.

Although chiropractors certainly treat more than just back problems, surveys show that it is the most common reason for visits, with about 80 percent of all people reporting some back pain during their lifetime, according to the American Chiropractic Association. Furthermore, low back pain can be very costly, accounting for lots of missed work and excessive amounts of money allotted for disability payments.

Vertebrae Model Aids showing nerveYet, if people understood why this back pain is present, chances are they would be likely to change the habits that are the cause. In Canada, the Canadian Chiropractic Association has taken a crack at educating the public about back issues, offering a phone app called Straighten Up Canada, designed to offer tips to improve posture and spinal health. It’s a good start, but can a phone app provide patients (or potential patients) with the info they need to make the right choices when it comes to their musculoskeletal health? Or do they need something more?

Vertebrae Model Aids Visual Learners

Many of us are “visual” learners. While hearing information indeed allows us to absorb facts, actually seeing a visual demonstration often prompts us to gather more complete information and process it in our brains. Visual learners, for example, will retain more if they read a story rather than listen to one.

In learning about chiropractic and its advantages, visual learners are usually offered posters and other drawings in hopes that they’ll understand why they are suffering with back pain. But let’s go one step further. A 3-dimensional, hands-on visual, in most cases, allows for even more retention of information, so offering the patient a vertebrae model rather than just an artist’s rendering of the spine can better help these individuals understand their musculoskeletal problems.

Vertebrae Model AidsThat’s where the Dynamic Disc Designs products enter the picture. 3-D spine models like these, which can be held in one’s hand and manipulated as needed, will provide a clearer picture of the inner workings of the body, even for those who have little or no knowledge of anatomy. A vertebrae model such as the Professional LxH is sophisticated enough to be a teaching tool yet it provides chiropractors with the opportunity to clearly and simply demonstrate to patients a variety of issues involving the spine and back and how to fix them.

A well-made vertebrae model can assist chiropractors in demonstrating the specifics of issues such as dynamic disc bulge, disc herniation, facet inflammation, disc height loss, degenerative disc disease, nerve pinching, stenosis, medial branch innervation, discogenic problems, annular fissures, and more.

A visual demonstration takes less time than a lengthy question-and-answer session, allowing both the doctor and patient an opportunity to save time and stay on schedule. Furthermore, when you’re making a visual demonstration that’s easy to grasp, patients won’t feel as if you’re talking “over their head”, spouting medical jargon that might be hard for the average person to understand.

Doctors who’ve already used DDD spine models note that patients respond positively to them, many having “light bulb” moments when they finally understand why they are experiencing a certain type of pain. And, of course, a good chiropractor knows that patient education is just as important a part of the visit as the adjustment, and a well-educated patient is more apt to follow your suggestions, prompting referrals from satisfied patients and, therefore, helping your practice to grow.

[call_to_action color=”orange” button_text=”Pro LHX” button_url=”https://dynamicdiscdesigns.com/product/professional-lxh-disc-model/”]
Browse our vertebrae model store.
[/call_to_action]