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.

lumbar vertebra

A study of Modic changes in 228 middle-aged male workers found a strong association between LBP frequency and intensity and Modic changes observed on magnetic resonance imagery (MRI) scans. These Modic chances were most likely to be at the L5-S1 spinal level and were more strongly correlated with LBP symptoms when Type 1 lesions were present.

What’s at Stake?

Bone marrow lesions—also known as vertebral endplate changes— that are visible on MRIs are considered evidence of disc degeneration. There are three types of lesions recognized by Modic: Type 1, where fissuring and an increase in the subchondral marrow vascularity is apparent; Type 2, where there is fatty degeneration of the bone marrow; and Type 3, where subchondral bone sclerosis is suspected.

Previous studies seeking to establish a positive correlation between Modic changes and clinical LBP symptoms have been inconclusive due to flawed designs and/or limited subject pools. This cross-sectional study used middle-aged male workers to investigate how or if Modic changes affected the intensity and frequency of sciatica and LBP in its subjects.

The Study

The subjects involved in this study were all male—128 Finnish train engineers, and 69 Finnish paper mill and chemical factory workers—with a mean age of 47 years. The train engineers had worked at their jobs, which involved long hours of standing and approximately five hours per day of subjection to intense, whole-body vibrations, an average of 21 years. The control group of chemical and paper workers claimed a mostly sedentary experience during their working hours and were not exposed to intense vibrations while on the job.

Both groups were assessed prior to the MRI study about the number of prior LBP and leg pain episodes, particularly those with a duration of 14 days or more. They were asked to comment on the pain’s intensity over the past week and over a three-month period before the study. They were also questioned about any history of LBP and whether they were experiencing LBP on the day of the assessment. MRI scans were taken and analyzed by two radiologists with no knowledge of the names or histories of the scanned subjects. Modic changes were identified and sorted into groups based upon the three types, with mixed types (I and I/II, and II and II/III) combined, representing more active and less active degeneration types. Other disc irregularities were noted independently and blinded to the clinical data analysts when observed. Disc herniation was either normal, bulging, protrusion, or extrusion in the notation. Neural compromise was identified as no compromise, nerve root contact, or compression. Stenosis was defined and noted according to Willen et al criteria.

modic changes, vertebra model

Modic changes with basivertebral nerve vertebra.

Results

Though the engineers reported the highest sciatica and 1 week and 3-month pain scores, Modic changes at one or more levels were like those observed in the control group—roughly 56%. In the combined groups, 15 % of the subjects showed Modic Type I changes only, and 32% had Modic II changes at one or more-disc levels. Ten percent showed Type 1 or II changes at the same, or separate levels. The combined subject groups had 178 Modic changes across various lumbar levels, with 30 % experiencing Type I and 66 % Type II. None of the scans showed Type III Modic changes. Eighty percent of all Modic changes were located at L4-5, or L5/S1 levels, and 61% of these changes were described as “extensive,” while 39% were minimal.

There was a positive correlation between the reports of LBP episodes—especially those experienced within the past week and three-month period prior to the study— and observed Modic changes at any level. Modic changes at the L5-S1 levels were positively correlated with previous LBP and/or sciatica, especially where high levels of pain were reported within the past week prior to the study. There was little-to-no correlation between reported pain and Modic changes at higher disc levels or at L4/5.

Type II changes at any level was positively correlated with a higher number of previous LBP, especially episodes occurring during the past week or three-month period prior to the study.

Extensive changes were positively associated with more LBP episodes in the past and higher levels of LBP or sciatica within the past week or three months prior to the study. This was especially true when extensive Modic changes were found at the L5-S1 levels or when minimal changes were noted, but the subject had an extensive history of LBP episodes. The LBP had little correlation with the extent of the Modic changes at upper spinal disc levels or at L4/5.

Conclusion

The results of the study—the first to analyze Modic changes as they relate to specific IVD levels— suggest that there is a positive correlation between Modic changes occurring at the L5-S1 IVD level and that LBP is more likely to be associated with Modic Type 1 lesions at this level than at other levels or with other lesion types. The authors of the study suggest more research—particularly of how Modic changes correlate with pain in a younger subject set—is necessary to verify these findings.

 

 

Dr. Jerome Fryer (CEO of Dynamic Disc Designs Corp):

“Hello everyone. Dr. Jerome Fryer here of Dynamic Disc Designs. I just want to reach out to those customers that have one of my models. There’s been a lot of talk lately on social media regarding how models can be scary. I don’t know how they’re scary. Models are not scary. It really depends on the user and these models are not intended to scare anybody. It’s to teach them their own anatomy, so they can improve their posture and biomechanics to relieve their symptoms. It’s a team player. It’s like a car. You can go out there ram into people or you can drive defensively and respectfully. Anyway, so one thing that’s important when you’re using the model is to relay realistic biomechanics  and use the model in a way that simulates real-time and load.

You want to use it in a way that actually represents the actual tissue. You can talk about all sorts of things, but you can talk about disc height changes as the disc over the course of the day loses a percentage of its height. You can talk about normal loading patterns of the disc as it relates the associated nerves. But, what I would encourage is just to use real-time forces. For example if someone goes to sit down, they change their lumbar angle and they compress their disc. When they sit for a period of time, the disc actually loses further height. You want to show the subtle endplate angle changes as it relates to the facet joint for example, or in the suspected case of disc herniation, you can actually create a disc herniation.

Single-Level Disc Herniation

Model of Single-Level Disc Herniation.

One example is the changing fluid expression over the course of the day. This is an important little graph to help patients understand how first thing in the morning you’ll actually lose their height very quickly in the disc height, so the facets will actually approximate with the changing intradiscal pressure, and then over the course of the day the disc height will slowly reduce. Some people talk about around 4:00 or 5:00 in the evening as the day progresses, my symptoms become pronounced. Then also with first lie down too. You can see there’s a quick change in disc height. Anyways, I just wanted to share with you that it’s how you use the model and you want to use it in ways that are realistic with regards to movement.”

 

 

 

When it comes to managing chronic pain, including lower back pain (LBP), evidence suggests that patients who feel supported through caring, interested practitioners, self-help groups, and a steady stream of helpful information designed to assist them in understanding the source and treatment of their discomfort. These patients are more likely to experience a better treatment outcome and psychological well-being than patients without such systems in place. Educating patients about their condition using on-hand pamphlets, dynamic visual devices, and images can help them to feel empowered and better able to cope with their ailments. Care-givers who take the time to establish a human connection with their LBP patients create a more positive healthcare experience and inspire confidence and improved patient-physician relations. Patients who trust their practitioner report better long-term LBP treatment and maintenance outcomes than those who are unhappy with their care.

Because chronic pain patients face obstacles to efficient and reliable self-management of their conditions, practitioners should endeavor to create an environment conducive to patient empowerment by providing support, easy-to-understand information, and confidence-building support structures that encourage family members, friends, and co-workers to better understand chronic pain and its effect on a patient’s lifestyle and career. By utilizing a combination of educational, biomechanical, psychosocial, and physiological supports, care-givers can help to foster a less-limiting and more proactive approach to the self-management of LBP in their patients.

Barriers to Pain Self-Management

  • Managing chronic pain is time-consuming and requires sustained effort.
  • The discomfort associated with experiencing daily LBP can leave a patient feeling fatigued, discouraged, and unmotivated.
  • Unsupportive clinicians, family members, friends, bosses, and co-workers may leave patients feeling alone, misunderstood, and frustrated with their care.
  • Poor understanding of their condition can make patients fearful, uncertain, or anxious regarding their therapy. They may catastrophize their symptoms or avoid potentially therapeutic exercise because they fear to exacerbate their injury.

Solutions to Patient Self-Empowerment  

  • Educate patients about their condition by using visual aids, dynamic models, and clear language to assist them in differentiating the “self” from the pain.
  • Use cognitive techniques, empathy, active listening, positive motivation, and peer validation to help the patient accept the pain as merely one aspect of a greater self and recognize that the pain need not define or limit life’s potential.
  • Create a supportive, collaborative relationship between the patient, care-giver, family, friends, and co-workers by encouraging open communication and an empathetic response. Provide a safe, therapeutic environment in which healthy, supportive alliances can be formed.

A recent literature review 1 found the most effective chronic pain self-management supports involved effective communication, a clinician-patient relationship that fostered self-discovery, occasional “booster” sessions after an initial course of treatment, and involvement in peer support groups. By practicing person-centric care and taking the time to educate their patients about their condition, practitioners can inspire confidence and empower self-reliance that will assist in the long-term management of chronic pain.

KEYWORDS: self-management strategies for the treatment of chronic lower back pain, managing chronic pain, dynamic visual devices, patient empowerment, improved patient-physician relations

degenerative spondylolisthesis model

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