simulation model

Goal of the Study?

In this disc simulation model article from the BMC Musculoskeletal Disorders open access journal 1 the authors created detailed nonlinear 3D finite element models of the C2-C3 Functional Spine Unit.  The simulation models were tested, verified and then used to predict various biomechanical injuries such as tissue swelling and degeneration.

 

Why are they doing this study?

Spine simulation models, if constructed accurately, can be a very efficient tool to predict the impact of various biomechanical spine loading strains and stresses.  They must mimic as closely as possible real-world conditions.  Also, the range that the models are effective must be established.  Building an accurate simulation model that operates over a wide range of variables is the ultimate goal but it takes many incremental improvements to reach this stage.  This study represents one of these attempts at improving current spine simulation models.

 

What was done?

Three  3D Finite Element (FE) fibre-reinforced C2-C3 functional spinal disc models were developed with Linear Elastic (LE), Hyperelastic (HE) and biphasic Intervertebral Disc (IVD) behaviours. These three models were tested through two different loading modes; cyclic compression and sagittal bending, both flexion and extension.  Measurements included deformed disc height, disc fluid pressure, range of motion and stresses.  The three models were first validated with previous experimental models for compression, flexion and extension loading conditions and then compared to each other with the goal of finding the most robust model.

What did they find?

The two single-phase models; LE and HE failed to accurately describe the long-term intervertebral disc height decrease under cyclic compression loading when compared to other experimental data.  They were both a little closer under extension loads. All three models were accurate in predicting stresses during the flexion loading trials.  Overall the biphasic IVD model was the most robust.  It gave the best results in flexion and compression but was limited in extension loading.  Since this was only a partition spine model, C2-C3 there were issues with the inability to predict load sharing.  Given the inability to accurately predict load sharing the authors believe that a full spine model must be developed.

 

Why do these findings matter?

Cervical injuries and fractures are common in many contact-oriented activities and can be life-altering, as they can cause a permanent loss of neural functions.  Since it is impossible to test these conditions on people, simulation models must be developed.  These mechanical models must be robust and mimic as closely as possible real-world conditions.  The better these models are, the better we are able to test and understand various treatment alternatives.

Low back-related leg pain

Goal of the Study?

Low back-related leg pain is thought to be neuropathic in origin due to compromise of a nerve root(s) and is also commonly known as sciatica. In a study published in the Journal of Clinical Medicine 1 a group of authors looked to see if loading the spine during MRI imaging (axial loaded MRI) would help discern more specificity to the anatomical cause of the low back-related leg pain. These leg pain sufferers will often undergo recumbent MRI while their symptoms are in the vertical or axially loading posture. 

 

Why are they doing this study?

Many cases of sciatica can be challenging to diagnose because of the complexity of the disc mechanics and physiology. There are many nuances of sciatica, and each case can bring its own set of complexities. Learning to determine the source(s) of sciatica more accurately can be helpful in its therapeutic management.

 

What was done?

Ninety patients were recruited for this retrospective observational study. The participant’ ages ranged from 21-89 years and were screened by an orthopedic surgeon to exclude those with hip and knee problems from the study. Participants were asked to fill out a self-evaluation including the visual analog scale along with a pain drawing. Each participant was evaluated by an attending physician and underwent an axial-loaded 1.5T MRI with added weight. As a comparison, each participant.

The investigators looked for these variables:

 Cross-section of the dural sac
 Lumbar spinal stenosis grade with axial loading
 Disk herniation with axial loading
 Size of herniated disc with axial loading
 Size of hyperintensity zone with axial loading
 Ligamentum flavum ‘type’ with axial loading
 Intervertebral foraminal size with axial loading
 Foraminal stenosis
 Degenerative disc classification
 Degenerative facet arthropathy
 Edema of facet joint and effusion with axial loading
 Synovial cyst area with axial loading

 

What did they find?

The authors found that axial-loading subjects played a significant role in extracting findings that would otherwise not be seen with conventional recumbent MRI. Specifically, they found facet joint edema, atypical ligamentum flavum, was associated with low back-related leg pain.

 

Why do these findings matter?

Often, sciatica patients undergo MRI to identify a cause. However, recumbent MRI does not tell the whole picture as patients often report a worsening of symptoms when they are axially loaded. This study helped reveal the changes in the loaded state and can help clinicians make informed decisions about the symptoms patients express in a clinical setting. Understanding that the facets are under more load and the ligamentum flavum can buckle inwards towards the spinal canal can help the clinician understand the anatomy when assessing patients. Notably, the authors summarized that these axial-loaded findings could offer a dynamic picture of the instability contributing to sciatica.

 

At Dynamic Disc Designs we have developed models to help demonstrate load related changes to the spine. We believe that our models not only help the patients understand their symptoms better so they can make the appropriate adjustments to improve their sciatica, but they also help in the context of the education of spine pain in general.

Occupational low back pain

Goal of the Study?

In this Bibliometric Analysis [A bibliometric analysis of occupational low back pain studies from 2000 to 2020] the authors used two bibliometric tools; BibExcel and CiteSpace to examine 4,217 documents related to occupational low back pain (OLBP).  Bibliometric Analysis (BA) is the application of statistical methods and visualization tools to analyze books, articles and other publications.  BA attempts to put the articles into a series of clusters.  These clusters can be based on themes, country of origin, journal name, publication date, research institute, authors and something called co-citation.  Co-citation cluster analysis is the frequency of which two articles are cited together in the same document.  

 

Why are they doing this study?

Bibliometric Analysis of OLBP shows where the studies were done, who was doing the research, which industries dominated the high prevalence of OLBP and what was the research tendency over time.  Using bibliometric analysis can help researchers grasp the research structure and latest trends of OLBP.

 

What was done?

Over 4,000 articles from 2000 to 2020 were fed into the BibExcel and CiteSpace tools.  These articles were all from the subscription-based Web of Science academic database.  Terms related to OLBP were used to identify each article.  These articles were downloaded and fed through the two bibliometric tools identifying various clusters.

 

What did they find?

On a country basis, the BA analysis found that the USA, Canada and UK produced the highest number of contributions to OLBP research in the Web of Science databases.  Ontario’s Institute of Work & Heath was the most prolific institution producing over 70 articles on OLBP.  Other Canadian institutions making the top 10 were the University of Waterloo (#7), University of Toronto (#9) and University of Alberta (#10).  The top 2 contributing journals were the Journal of Occupational Rehabilitation (203 documents) and Spine (200 documents). 
Fifteen major OLBP research theme clusters were identified.  The two most popular ones were Musculoskeletal Disorder (227 documents) and Risk Factors (212 documents).  The two most recent themes were Biopsychosocial Approach and Core Outcome.

 

Why do these findings matter?

Occupational low back pain (OLBP) is regarded as one of the most common work-related musculoskeletal disorders.  OLBP not only has huge direct and indirect economic losses but is also responsible for the decline of quality of life.  Comprehensive bibliometric studies, such as this, provide general insight into aggregate performance in the OLBP field and can help identify further research directions.

lumbar stiffness

Goal of the Study?

In this primary research article1, the authors had two goals: (a) Determine and quantify the relationship between biomechanical and neurophysiology measurements in lower back pain patients and (b) examine if the correlations differ when considered regionally (lumbar back) or segmentally.

 

Why are they doing this study?

To improve our understanding of Lower Back Pain etiology, better non-invasive measurement tools and techniques must be established and quantified. 

 

What was done?

A sample of 132 patients of the Spine Centre of Southern Denmark who had persistent non-specific Lower Back Pain was measured for three different sensitivities: (a) global spinal stiffness (GS) using a VerteTrack Device which applied a rolling weight across the S1 and T12 spine; (b) deep mechanical pressure pain sensitivity threshold (PPT) using pressure algometer which applied bilateral pressure at each lumbar segment and (c) superficial heat pain sensitivity threshold (HPT) using a handheld thermode at the midline of each lumbar segment. 

A series of statistical tests were performed to determine if there were any correlations between these three quantitative sensory metrics: Global Stiffness (GS), Pressure Pain Threshold (PPT) and Heat Pain Threshold (HPT).

 

What did they find?

The correlation coefficients (R) for each pair of these three quantitative sensory metrics; GS, PPT and HPT were calculated and tested for statistical significance. 

  • Correlation between GS and HPT were found to be poor and statistically insignificant (R = 0.23)
  • Correlation between GS and PPT were moderate (R = 0.38) and statistically significant
  • Correlation between HPT and PPT were good (R= 0.53) and statistically significant

Unexpectedly, the correlation between GS and PPT was positive, meaning participants with higher global stiffness had a higher pressure pain threshold. The authors expected the reverse. They based their explanation of this unexpected relationship on the body’s adaptive mechanical protection system. Pain is considered a protective response and a stiffer spine is more resilient to applied forces and therefore can tolerate a higher pain threshold.

The other’s unexpected anomaly was that for the three QST’s measured, no differences were found between the individual lumbar segments. This indicates that patients with persistent LBP are probably less able to perceive lumbar stiffness reliably, perhaps due to “Cortical Smudging”, an overlapping of the cortical homunculus. 

 

Why do these findings matter?

Around four out of five people have lower back pain at some point in their lives. It’s one of the most common reasons people visit healthcare providers. To successfully evaluate both the extent of LBP and the effectiveness of any treatment plan, a reliable metric must first be established. This study is an attempt to use stiffness (GS), heat (HPT) and pressure (PPT) as this critical metric.

 

At Dynamic Disc Designs, we have developed models with varying lumbar stiffness to help in the education of the possible sources of back pain. This new research is important in establishing greater understanding of the causes and solutions of low back pain.

 

 

Disc Degeneration Model

Goal of the Study?

In this primary research article 1, the authors aim to establish an animal model that can be extrapolated to the complex mechanical load of a human intervertebral disc during bending and compression loading.  They hypothesized that a disc herniation could be gradually induced by static complex loading.

 

Why are they doing this study?

Disc bulges or protrusions often pre-exist in patients with acute back pain, suggesting that repeated compressive loads may gradually result in a herniated intervertebral disc.  To the author’s knowledge, this assumption has never been verified using animal models.

 

What was done?

Twenty research rats were randomly divided into four equal groups.  Group #1 was the control; the other 15 rats had an external device implanted in the coccygeal 8-10 vertebrae to bend the spine at a fixed angle.  Group #2 had sham surgery but no compression load, Groups #3 and #4 were subject to a compression load of 1.8 N (0.184 kilogram force) and 4.5 N (0.459 kilogram force) respectively.  After 14 days, an MRI was performed on all 20 rats and a Pfirrmann classification system was used to classify the disc images into 5 categories.  The rats were then euthanized and the C8-10 vertebral body was removed and the Norcross calcification system was used to evaluate the degeneration on a scale of 10 for no degeneration and 2 for severe degeneration.  The dissections were also tested for Gene Expression and various statistical tests were performed.

 

What did they find?

No statistical difference was found between the control group and the sham surgery group, so bending alone seemed to have little or no effect on disc degeneration.  There was a slight difference but it was not significant.  The MRI and histological scores for the intervertebral disc degeneration were significantly higher in the two loaded groups than the sham or no load surgery group.  Group #4, heavily loaded had significantly more disc degeneration than the lightly loaded group.   Both loaded groups had significantly more disorganization in the nucleus pulposus and annulus fibrosus from a histological perspective than the sham surgery group.

 

Why do these findings matter?

Even though the disc structure of rodent tails are biomechanically and compositionally similar to human lumbar there are significant differences.  As such, it is difficult to extrapolate this research to humans in a disc degeneration model comparison.  But if it can be extrapolated, it indicates that a static complex loaded can induce posterior intervertebral disc protrusion when combining bending and compression but not during bending alone.

 

At Dynamic Disc Designs, we believe it can be very helpful to show patients the mechanism of a disc injury to help empower a patient about prevention and the solution strategies to their problems. Our dynamic disc models demonstrate that bending alone does not cause disc herniation but will herniate when compression is combined with flexion.

Education of pain

Goal of the review?

In this review 1 the authors evaluate the effectiveness of advice/education of pain and disability in people with non-specific spinal pain. They also examine to what extent the characteristics of patients and interventions change the treatment effects.

 

Why are they doing this study?

Spinal pain is a leading cause of disability across the world. In Australia, the costs associated with chronic pain are predicted to increase from $139 billion to $215 billion by 2050. Despite the significant impact of chronic pain (spinal pain is the largest contributor), most systematic reviews are outdated and have missed critical studies and new research. Moreover, existing reviews have only looked at advice to stay active without analyzing advice on ergonomic changes or pain neuroscience education. For this reason, there continues to be much uncertainty on the effectiveness of guidance and education for the treatment of non-specific spinal pain.

 

What did they do?

The researchers did a systematic review with meta-analyses of randomized controlled trials. They included studies with participants who had non-specific spinal pain (back or neck) of any duration, interventions that focused on advice, education or information given by a healthcare professional. The review focused on two outcomes: pain and disability (primary) and adverse events (secondary). 

 

What did they find?

In total, they included 27 trials with 7,006 participants. Most of the studies (18 in total) were assessed as being low risk of bias. Low-quality evidence from 18 trials indicated that advice had a negligible effect on pain in the short term. However, the advice provided almost no benefits at other time points. Meta-regression revealed no association between type of advice, duration of pain, location of pain, the intensity of treatment or mode of delivery with treatment effects. Moderate-quality evidence from 19 trials with 2579 participants indicated that advice had a small effect on disability in the short term, compared with no advice or placebo.

 

Why do these findings matter?

The findings suggest that advice provides some short-term improvements in pain and disability, but the effects are small and are not sufficient as the only treatment for patients with spinal pain. 

 

At Dynamic Disc Designs, we believe our models can make a large difference when pain education is delivered. We look forward to future studies using ddd models as part of the patient education of pain.

Goal of the study?

In this study, 1 the objective was to assess the effectiveness of a patient education booklet to overcome barriers to the delivery of recommended care for patients with low back pain. 

 

Why are they doing this study?

Low back pain is the leading cause of disability and a major health cost worldwide. One of the reasons for this is that low back pain tends to be managed without following clinical guidelines. For example, almost half of patients undergo inappropriate imaging, which drives up healthcare costs associated with increased disability. To address the barriers to implementing clinical guidelines, Australian researchers developed a patient education booklet that educates patients and their healthcare providers, reminding practitioners of guidelines and facilitating communication. 

 

What did they do?

The researchers used a cluster-randomized trial design to assess the booklet’s effectiveness with low back pain patients in primary care compared to usual care. They recruited 8 clusters, 4 for the intervention (212 participants) and 4 for the control group (203 participants), with 408 participants in the sample. The practitioners in the intervention group were provided with the booklet and a 30-minute training session. The booklet was then also provided to their patients in the intervention group. The professionals only received a short training session on the study and recruitment procedure in the control group. All consenting patients received usual care but did not get the booklet.

There were two outcomes: 1) The proportion of patients presenting with low back pain who underwent imaging examinations due to low back pain during the first three months of follow-up, and 2) Change in Patient-Reported Outcomes Measurement Information System (20 items physical functioning short form) from baseline to three-month follow-up. 

They used statistical software to analyze between-group differences. 

 

What did they find?

The patient education booklet substantially reduced the proportion of patients with low back pain who underwent imaging at 3 months, but the result was not statistically significant. It was only statistically significant when a physician was the first contacted professional. This was compared to the findings at 12 months, which resulted in an effect that was slightly larger and statistically significant. 

The researchers did not find any differences in the Patient-Reported Outcomes Measurement Information System between baseline and 3 months or 12 months. They did find a change in the number of sick days in the intervention group was less than in the control group at 3 months and 12 months. There were no statistically significant differences between the intervention and control groups in the number of healthcare appointments or patient-reported secondary outcomes.

The use of the booklet had no impact on the patient’s pain, physical functioning, disability, or quality of life compared to usual care.

 

Why do these findings matter?

Patient education often matters, and how and when it is delivered should be optimized for each patient. A custom-tailored approach to each patient should be at the forefront of each clinical encounter. This study using a booklet did not show any changes in a patient’s pain score. Something needs to change in how patient education is delivered.

 

At Dynamic Disc Designs we believe a ‘booklet’ is a dated format and practitioners can improve their patient education through the use of accurate modelling to help patients truly understand and see the causes of their specific symptoms. Fostering the right motivational movement within patients is at the hallmark of what we do. To help in the construct of tackling biomechanical causes while addressing the fears of the unknown.