News for Dynamic Disc Designs which includes updated research and a synthesis of the most updated studies to help efficiently engage with patients and their back and neck pain.

We take an approach that an evidence-based practitioner would take. Carefully dissecting the history of a patients complaints, weaving the mechanical and psychosocial factors and then deliver a rational and tangible approach to relieving the back pain to the patient. Our news helps keep the practitioner abreast of the latest publications related to musculoskeletal health.

At our headquarters, we dedicate weekly hours to comb through the research for those who treat back pain and neck pain and deliver it.

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The Parkinson’s disease pain classification system: results from an international mechanism-based classification approach

Pain Syndromes

Goal of the Study?

In this study, 1, the authors have developed a framework to differentiate Parkinson’s Disease (PD) pain from non-PD-related pain and classify PD-related pain into 3 groups based on already validated mechanistic pain descriptors – nociceptive, neuropathic and nociplastic. 

 

Why are they doing this study?

In Parkinson’s disease (PD), about 20% of patients experience chronic pain at diagnosis. This number climbs to 80% during the course of the disease. PD pain has been divided into three categories: de novo pain related to disease onset and symptoms (PD-related); previous chronic pain aggravated by the disease or treatment (PD-indirectly-related); pain that is neither caused nor aggravated by the disease (PD-unrelated). Moreover, pain is considered PD-related when one of the following applies: when occurring along with the first motor symptoms, when occurring/aggravated during the OFF stage of the disease, when occurring at the same time with choreatic dyskinesia or when improved by dopamine treatment. However, these categories have not been validated or tested, making diagnosing and treating pain in PD. In response to this need, the authors develop a classification system to define and distinguish PD-related pain from non-PD-related pain.

 

What was done?

The authors used an international, cross-sectional, multicenter study. They recruited 159 non-demented PD patients and 37 healthy controls across 4 centers. Using the mechanistic pain descriptors (nociceptive, neuropathic and nociplastic), the authors developed a PD pain classification system (PD-PCS) by including classic pain-related situations of PD into each category. The severity of PD-related pain syndromes was scored by ratings of intensity, frequency and interference with daily living activities. Finally, they did an analysis and validation of their scale.

 

What did they find?

This study provides a unifying system for pain in PD that differentiates between PD and non-PD pain and outlines a treatment-based and mechanistic classification system for PD-related pain. Using this system, the authors found that 77% of patients experienced PD-related pain, with 15% suffering more than one syndrome at the same time. PD-related pain with nociceptive, neuropathic or nociplastic components was diagnosed in 55%, 16% and 22% of participants, respectively. Mixed pain syndromes were mostly found in nociceptive pain combined with nociplastic (12.7%) or neuropathic (9.6%). Pain unrelated to PD was found in 22% of participants, versus only 5% of controls. 

Concerning the PD-PCS, the authors found that pain severity scores significantly correlated with commonly used questionnaires such as the pains’ Brief pain Inventory and McGill Pain questionnaire. They did not find that the PD-PCS scores correlated with a motor score.

Finally, they suggest that the three pain types identified by the PD-PCS are different pain syndromes and reflect different mechanistic backgrounds and, potentially, different treatment approaches.  For example, they found that patients with higher nociceptive pain scores had worse quality of life scores, but this was not found for patients with nociplastic pain. 

 

Why do these findings matter?

Better classification of pain in PD will ensure that PD patients’ pain is treated more effectively and timely, ultimately contributing to better outcomes.

 

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ISSLS Prize in Bioengineering Science 2021: in vivo sagittal motion of the lumbar spine in low back pain patients – a radiological big data study

Sagittal

Goal of the Study?

In this study 1, the authors investigated the flexion-extension range of motion (ROM) and centre of rotation (COR) of lumbar motion segments in a large population, as well as the relationship between lumbar movement and sex, age and intervertebral disc degeneration (IVD).

 

Why are they doing this study?

Research on the in vivo motion of the spine has a long history. However, many of these studies have used non-invasive technologies with inherent limitations impacting their accuracy and precision. Moreover, many studies have included a lower number of subjects, preventing the ability of the data to represent the general population.

The authors argue that radiographic techniques in this study help overcome these limitations as the images allow for better visualization of each vertebra and movement of the lumbar segments. Additionally, the use of a large sample size for this study addresses the issue of representation and is the largest study to date looking at in vivo lumbar motion. 

 

What was done?

The researchers did a retrospective study looking at the radiographs of the lumbar spine in full flexion and extension for 602 patients, with the age and sex documented for each one.  Additionally, they used MRI scans of 354 patients. 

All spinal levels between T12-L1 and L5 – S1 were analyzed, resulting in 3612 lumbar motion segments from the radiographic images. They also examined 2124 images from the MRI scans looking at disc degeneration. ROM and COR were calculated for all lumbosacral segments using the software. They then examined the associations between motion and age, sex, spinal level and disc degeneration.

 

What did they find?

The median ROM in this study was 6.6 °. The researchers found an association between age and ROM, with older individuals, have lower ROMS. They argue these findings clearly demonstrate a relationship between age and lumbar spine flexibility independent of any signs of spinal degeneration. They also found that lower ROMS were associated with disc degeneration. However, they did not find any association between sex and ROM.   

In this study, they did not find an association between the position of the COR and the spinal segment. The most common COR was at the centre of the lower endplate of the IVD or slightly lower. With degeneration, particularly severe degeneration, they found the location of the COR spread randomly around the centre of the intervertebral space.

 

Limitations?

One of the main limitations of this study was the sole focus on the flexion-extension motion of the lumbar spine rather than including information on movements of different areas of the back. 

 

Why do these findings matter?

This study comprises the largest examination of the in vivo lumbar spine in flexion-extension, paying attention to age and spinal degeneration issues. Understanding the relationship between age and spinal mobility provides patients and doctors with information to better treat back pain and instability.

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Pain-related behavior is associated with increased joint innervation, ipsilateral dorsal horn gliosis, and dorsal root ganglia activating transcription factor 3 expression in a rat ankle joint model of osteoarthritis

Innervation

Goal of the Study?

In this study 1, the authors use a rat model to examine the time-course development of pathological joint changes and correlate them with pain-related behaviour in OA. 

Why are they doing this study?

There is a very high incidence of Osteoarthritis (OA) in the elderly population, and it is a leading cause of disability and pain. However, there is a lack of knowledge of OA’s pain mechanisms, particularly the role that neuropathic pain (NP) plays in OA.

OA has been described as a degenerative rather than an inflammatory disease. However, in recent years research has identified the many inflammatory processes that take place in OA.  Existing OA models have shown how this inflammation is supported by overexpression of nerve growth factors causing nociceptive fibres to grow into inflamed joints. This inflammatory process helps explain why there is a poor correlation between radiographic changes and pain levels in OA patients. Moreover, some patients continue to experience pain after a total joint replacement, suggesting that OA can result in neuropathic pain (NP). 

What was done?

The researchers used a rat monoiodoacetate (MIA) model of the ankle joint. MIA results in pathological changes and pain-like behaviour common with those observed in human OA. This model has been used extensively in research and is well validated.

They injected MIA or saline into a total of 126 male rats. For this study, they used the rat ankle joint as it receives most of its nerve supply from the sciatic nerve, which is used most commonly in NP models. From this, they assessed a variety of changes, including pain-related behaviour, hypersensitivity, reaction to cold and heat, changes to normal movement, cartilage degeneration, bone degeneration, and the effects of drug treatments.

What did they find?

 Overall, the study provided a time-course view of the development of pathological changes to the joint and the associated pain-related behaviours. 

The researchers found significant innervation increases at specific periods of time that coincided with mechanical hypersensitivity at 4 weeks and pain in response to cold at 5 weeks. X-ray findings showed significant cartilage and bone degeneration and joint space narrowing at 5 and 10 weeks. 

The study also illustrated changes in sensory and sympathetic innervation of joints in the subchondral bone and synovial membrane at 5 and 10 weeks.  This increased concentration of sensory and sympathetic fibres was associated with pain-related behaviour and similar to those observed in NP models. Furthermore, they found that pain-related behaviour and extensive joint damage were associated with the expression of activating transcription factor 3 (ATF3) in the dorsal root ganglia (DRG), as well as the microglia and astrocyte changes in the dorsal horn. Using various pharmacological treatments to inhibit or block sympathetic fibres and glial could suppress pain-related behaviour. They argue that these findings suggest that multiple factors contribute to OA pain, including inflammatory changes in the joints, supporting the theory of a neuropathic component in OA.

Why do these findings matter?

As pain is the main reason patients seek medical help, effective pain management is critical to improving life quality. Therefore, understanding what causes pain will help in the development of pain management protocols and treatments. 

 

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Association of Cervical Spondylosis with Peripheral Vertigo: A Case-Control Study

Cervical Spondylosis

Goal of the Study?

In this study, 1 the researchers investigated the association of prior cervical spondylosis (CS) diagnosis with peripheral vertigo in Taiwanese patients.

Why are they doing this study?

CS is an age-related condition resulting from deterioration in the spine, with a prevalence rate of more than 50% among those over 40 years old. While not all patients will have clinical signs of disease, symptoms can range from tingling, numbness, pain in the neck or arms, stiffness, headaches, vertigo, and balance loss.  Peripheral vertigo is often observed with CS and is one of the most common reasons patients get medical care.

The authors state that despite the wide prevalence, to date, no population-based studies are looking at the association between CS and peripheral vertigo. 

What was done?

The researchers used a case-control study design, selecting cases of peripheral vertigo and matched controls. They used the data from the Taiwan Longitudinal Health Insurance Database 2005 (LHID2005), which consists of all registration riles and medical claims data for a stratified random sample of 2 million enrollees.

They identified all those ≥ 18 years old who had received a diagnosis of peripheral vertigo between January 1, 2010, and December 31, 2016, which totalled 2,570 patients. These were compared to a control group of 7,710 patients from the same dataset (with 3 controls per one case), matching based on patient demographics such as age, sex, income, geographic location and medical comorbidities associated with increased risk of vertigo. They excluded all patients less than 18 years old and those who had never been diagnosed with peripheral vertigo.

They then used a statistical program to estimate determine the relationship between prior CS occurrence among peripheral vertigo patients versus controls. 

What did they find?

Overall, the researchers found that CS is associated with peripheral vertigo, particularly with those patients aged 45 to 64. This association is consistent with other research and may be caused by a range of issues, including cervical instability, inflammatory cytokine stimulation, and more.  They also found that CS with myelopathy (an injury to the spinal cord due to severe compression) is not associated with peripheral vertigo. 

They did not find any significant differences based on demographics. In particular, they did not find that patients over 64 years of age with CS had a higher risk of peripheral vertigo.

Limitations?

There are a few limitations outline by the authors. First, they state that claims data may not be as precise as information based on a clinical examination, resulting in some misclassification between types of vertigo. Second, there is a lack of data on potential confounding variables such as family history, lifestyle, etc. Finally, the vast majority of the study population are Han Chinese, and therefore the results may not be generalizable to other racial and ethnic groups. 

Cervical Spondylosis

Cervical model

Why do these findings matter?

As peripheral vertigo often occurs with CS, it is important to understand the relationship between the two conditions better to diagnose better and treat patients.  

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The impact of different artificial disc heights during total cervical disc replacement: an in vitro biomechanical study

degenerated, cervical, model, height

Goal of the Study?

In this study 1 the authors explore the impact of cervical implant height on facet joint pressure and range of movement (ROM). They hypothesize that a higher artificial disc would result in greater facet pressure and lower ROM and should not be used in total cervical disc replacement (TDR).

 

Why are they doing this study?

Increasingly, total cervical disc replacement (TDR) is being used in clinical practice as it has the ability to maintain the biomechanical state of the cervical spine, ROM and has an accelerated rehabilitation process. However, there is no clear consensus on how to choose the most appropriate height of prosthesis. Some research suggests that a higher artificial disc is better for relieving neurological deficits. Other research suggests that lower (smaller) implants provide a closer to normal biologic function than higher implants.  To date, there has been no research that reports on the biomechanical impacts of different artificial disc heights on facet joints during TDR.

Dynamic Disc Designs

 

What was done?

This is an in vitro biomechanical study using six fresh-frozen cadaveric cervical spines (C2-C7) with 5mm intervertebral disc height at C5/6. Specimens with flaws, including fractures, deformities, tumours and other injuries, were excluded. Biomechanical testing was done with intact specimens first, and then implants with different heights were inserted. These were broken down into 4 groups: 1. Intact specimen; 2. 5mm insert; 3. 6mm insert; 4. 7mm insert. Facet joint pressure and range of motion (ROM) for each group were recorded.

Cervical Model

 

What did they find?

Overall, the researchers found that a 7mm prosthesis resulted in significantly lower ROM and increased facet joint loading compared with specimens of other implant heights. For example, facet joint pressure at the index level increased by 77% during flexion, 53% during extension and 40% during lateral bending. In comparison, specimens with 5mm implant height had a similar ROM and facet joint pressure as intact specimens. Additionally, they found that facet joint pressures increased with implant heights, with the most significant pressure during flexion for implants of 7mm.

While the authors acknowledge that a higher artificial disc could enlarge the volume of the intervertebral foramen and relieve neurological symptoms, it also has the potential to increase the risk of post-surgical complications such as arthritis and neck pain. Therefore, they suggest that a prosthesis with 2mm height than normal should not be used in TDR.

 

Why do these findings matter?

As TDR is becoming more common in clinical practice, it is critical that patients and their health care professionals chose an appropriately sized artificial disc. This research illustrates the importance of choosing an appropriate artificial disc height to achieve near-normal biomechanical outcomes. In particular, this study provides evidence to support the choice of a smaller implant ( ≥1mm) to achieve almost normal ROM and facet joint loads.

 

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Low back pain in children and adolescents: Real life experience of 106 children

children and back pain

The goal of this study?

The objective of this study 1 examined the causes and risk factors for lower back pain (LBP) in children and adolescents who accessed a specific clinic.

Why are they doing this study?

LBP is common in children and adolescents, with existing research showing the prevalence of LBP ranging from 9%-69%, increasing significantly between 12 and 18. While research shows that LBP causes in children are as diverse as adults, there is much less information on LBP in children and adolescents. 

Who was involved?

The research looked at patients under 18 who came to the researcher’s clinic to address LBP between May 2014 and May 2018.

 

  • A total of 106 children and adolescents, aged between 8 and 17:
  • 55 girls (51.8%) & 51 boys (48.1%)

 

Those excluded included:

  • Anyone with referred pain, infections or anyone with emotional or mental stressors that are causing pain.

What was done?

The researchers used a retrospective study for their design, meaning that all of the patients were already experiencing LBP, and they look back in time to determine why.

 

The researchers looked at a variety of patient data, including:

    • demographic information (age, gender, ethnicity, etc.), 
    • pain severity, which was measured using a visual analog scale (VAS)
    • physical examinations
    • laboratory tests
  • Imaging using X-ray and MRI 
  • Family history
  • Lifestyle, including how much sitting per day, sporting activity
  • Examination for hypermobility and hamstring flexibility

 

Statistical analysis of all the data was done using SPSS (which is stat software) to determine…

What did they find?

The researchers found six different etiologies (causes) for LBP in children and adolescents. Overall, they found that LBP was more common in their adolescent patients than younger children. 

 

The vast majority of patients in this study, 62 (58.4%), had non-specific LBP. These patients had various risk factors, including obesity, poor posture, tight hamstring muscles, hypermobility, family history and immobility. All patients in this group had their symptoms resolved either independently or through the use of rest and analgesic medication. Additionally, all patients in this group were given a home exercise program.

 

The second most common cause was lumbar disc herniation, with 24 patients (22.6%). The causes of this were mostly related to trauma and family history. Treatment for these patients varied from steroid injections, analgesic medication, physiotherapy and three patients with uncontrolled pain required surgery.

 

Inflammatory LBP was the third most common findings, with 6 patients (5.6%). All of these patients were treated with non-steroidal anti-inflammatory drugs, exercise and referred to a pediatric rheumatologist.

 

Among the remaining patients, 5 had spondylolysis-listhesis (a crack or stress fracture in one of the vertebrae, the small bones that make up the spinal column), 5 had scoliosis, and 4 had Scheuermann disease (a childhood disorder where the vertebrae grow unevenly and can result in a humpback). Patients in these categories were treated with various approaches, including analgesics, rest, physiotherapy and exercise.

Why do these findings matter?

Determining the cause of LBP in children and adolescents is important to address pain and mobility issues for young people and because it is a significant risk factor for adulthood. If not diagnosed and treated appropriately, it may become chronic and cause disability in adulthood. 

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Vertebral Osteophyte. Is it related to mechanics?

osteophyte

The patterns of vertebral osteophytosis (or the growth of bony projections from vertebrae) is a common study among researchers. The actual cause of these bony outgrowth projections has been questioned over the years, with some pointing to the abnormal movement patterns of motion segments. Others have questioned this and believe the cause to be related to age and genetics. In a 2014 paper, researchers sought to answer: Is vertebral body osteophytosis a reliable indicator of occupational stress1. A shallow dive into their findings will be shared here.

What we do know from the work of Kumareson et al. 2 and Adams & Roughley 3 is that osteophytosis looks to be linked to degeneration of the intervertebral disc which is defined by an aberrant, cell-mediated response to progressive structural failure. With this structural failure, inevitably, there must be physical stress and thought to influence the cells at the vertebral-disc interface margins to produce bony outgrowths.

Furthermore, others have looked at these bony outgrowths and tried to relate them to aberrant mechanical loading patterns along with physical age and genetics. 4 5 6. Archeologists that study biological remains have used this finding as a tool to measure historical population activity level and lifestyles 7 drawing speculative conclusions on the inter and intra-population differences. Two well documented skeletal population differences demonstrated that the women had more severe osteophytosis than the men and was thought to be caused by heavy lifting that the men did not do during this same time period.

However, other researchers believe that degeneration is not solely related to physical activity and more so related to genetic factors 8, ageing 9, and body mass 10. And with this, one can see the complexities underpinning the causative factors of these bony outgrowths that some call ‘bony spurs’ projecting from vertebrae.

The osteophytes’ anatomical margins are the entheses, which you can see in our Lumbar Spinal Stenosis Model. This is the region where a muscle, tendon or ligament attaches to the bone. It is the interface where force intersects with bony anatomy. This is often represented in the extremities but the same biological process is thought to be at the crux of these anatomical changes.

osteophyte

Osteophyte Projection in our Lumbar Spinal Stenosis Model

What did these researchers investigate?

A group of researchers 1 wanted to see if they could determine whether mechanical factors related to osteophyte formation. They looked at these entheseal margins in the lower and upper extremities and the spine to see if they were correlated. Their logic was to see if the bony osteophytes were similar in all anatomical regions and if so, they could speculate that there was a mechanical influence of the formation of them. They also wanted to see if age played a factor as they explored the relationship between vertebral osteophyte formation and entheseal changes in the extremities.

The samples that were used came from a burial site in Cedynia, Poland. 101 male skeletons were examined and divided into two age groups, 20-40 years old and 41-56 years old. To determine the vertebral osteophyte degree, they used a rating scale developed by Swedborg (1974) to measure the entheseal grade; they used Mysezka & Piontek (2012). The entheseal anatomical sites they measured included the humerus, radius, femur and the tibia.

What they found

Interestingly, the researchers found no significant age differences when comparing the presence and degree of both osteophytosis and enthesopathy in the spine and extremities, respectively. They did find a significant correlation between the lower extremity enthesopathy and the vertebral osteophytosis, however. In other words, if they saw bony spurs in the lower extremities of the specimens, there was a good chance they were going to find vertebral osteophytes of the spine.

 

Does this solve anything regarding whether mechanics plays a role in osteophyte presence?

No. But it does shed light on the possible mechanics. These researchers agreed that other factors, besides physical ones, could be at play and should be considered. In particular, like age, body mass and genetics.

 

Commentary by Jerome Fryer

From a clinical standpoint, we should be mindful of these anatomical changes. Do they cause pain and problems all the time? No. We have seen this time and time again with clinically abnormal imaging findings. However, in the case of vertebral osteophytosis, a projecting osteophyte into the foramen where an exiting nerve root needs room for its vascular geometry for nourishing itself, space is everything. Learning about how to prevent the progressive changes of these types of osteophytes that can encroach on the dorsal root ganglia is important. Ongoing facet arthropathy is an adaptable process, but if adaptation is too great and osteogenesis takes up space where the nerve needs it, pain and disability can present and often, there is no turning back. My hunch is if we can improve the spine’s mechanics and keep an eye on disc height changes over a lifetime, we can keep the spine healthier and avoid spinal conditions like lumbar spinal stenosis. However, this is purely speculative in nature, and much more research on the causes of osteophytosis must occur. JF

 

  1. Anthropol. Anz. 71/4 (2014), pp. 381–389 Notes J. Biol. Clinic. Anthropol. Stuttgart, November 2014 ↩
  2. Kumaresan, S., Yoganandan, N., Pintar, F.A., Maiman, D.J. & Goel, V.K. (2001): Contribution of disc degeneration to osteophyte formation in the cervical spine: a biomechanical investigation. – Journal of Orthopaedic Research 19, 977–984. DOI: 10.1016/S0736-0266(01)00 010-9. ↩
  3. Adams, M.A. & Roughley, P.J. (2006): What is intervertebral disc degeneration, and what causes it? – Spine 31, 2151–2161. DOI: 10.1097/01.brs.0000231761.73859.2c. ↩
  4. Sambrook, P.N., McGregor, A.J. & Spector,T.D. (1999): Genetic influences on cervical and lumbar disc degeneration: magnetic resonance imaging study in twins. – Arthritis and Rheumatism. 42, 366–372. DOI: 10.1002/1529-0131(199902)42:2<366::AIDANR20>3.0.CO;2-6. ↩
  5. Spector, T.D. & McGregor, A.J. (2004): Risk factors for osteoarthritis: genetics. Osteoarthritis and Cartilage 12, 39–44. DOI:org/10.1016/j.joca.2003.09.005. ↩
  6. Knüsel, C., Göggel, S. & Lucy, D. (1997): Comparative degenerative joint disease of the vertebral column in the medieval monastic cemetery of the Gilbertine Priory of St. Andrew, Fishergate, York, England. – American Journal of Physical Anthropology 103, 481–495. DOI: 10.1002/(SICI)1096-8644(199708)103:4<481::AID-AJPA6>3.0.CO;2-Q. ↩
  7. Novak, M. & ˇ Slaus, M. (2011): Vertebral pathologies in two Early Modern Period (16th–19th) century) populations from Croatia. – American Journal of Physical Anthropology 145, 270–281. DOI: 10.1002/ajpa.21491. ↩
  8. Sambrook, P.N., McGregor, A.J. & Spector,T.D. (1999): Genetic influences on cervical and lumbar disc degeneration: magnetic resonance imaging study in twins. – Arthritis and Rheumatism. 42, 366–372. DOI: 10.1002/1529-0131(199902)42:2<366::AIDANR20> 3.0.CO;2-6. , ageing and body mass index. ↩
  9. Snodgrass, J.J. (2004): Sex differences and ageing of the vertebral column. – Journal of Forensic Science 49 (3), 458–463. ↩
  10. Oishi, Y., Shimizu, K., Katoh, T., Nakao, H., Yamaura, M., Furuko, T., Narusawa, K. & Nakamura, T. (2003): Lack of association between lumbar disk degeneration and osteophyte formation in elderly Japanese women with back pain. – Bone 32, 405–411. DOI:10.1016/S8756-3282(03)00031-0. ↩
  11. Anthropol. Anz. 71/4 (2014), pp. 381–389 Notes J. Biol. Clinic. Anthropol. Stuttgart, November 2014 ↩
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