loading

Goal of the Study?

In this preliminary study, 1 the authors compared the effects of loading compression and traction on lumbar disc measurements, particularly the magnitude and distribution pattern of fluid within lumbar discs, in relation to intervertebral disc degeneration.

 

Why are they doing this study?

Intervertebral disc degeneration (IVDD) is associated with many biochemical and morphological changes in the disc that contribute to degeneration and negatively impact normal function. With degeneration, there are changes to the amount of fluid and the distribution pattern of this fluid within the disc. The authors argue that this may provide unique biomarkers that can help with diagnosing and classifying degeneration. The authors hypothesize that using T2- weighted MR images will enable better insight into disc degeneration. It only changes in response to variations in fluid distribution and these potential degeneration biomarkers. 

 

What was done?

A total of 35 volunteers between the ages of 18-65 were recruited: 20 with and 15 without low back pain (LBP). Using a custom MRI compatible loading table, the participants spent 20 minutes in the supine, unloaded position; then they spent 20 minutes loaded in axial compression and then 20 minutes with axial traction. A compressive load equal to 50% of each subjects’ body weight was applied to simulate loading and traction. For lumbar discs, the height, angle, width, mean-T2 and T2 weighted centroid (T2WC) locations were calculated. Disc degeneration was measured using the 5-point scale by Pfirrmann et al.

 

What did they find?

Most of the effect size (ES) differences the authors found in response to loading were seen from compression to traction. They observed small but statistically significant changes with an inferior and posterior shift in L4-5 (ES: 0.4, 0.14) and L5-S1 (ES: 0.25, 0.33) T2 weighted centroid. More degeneration was associated with larger anterior displacement and more superior displacement of the disc T2WC. Moreover, degeneration was not associated with changes in disc width, but with greater degeneration, there were larger decreases in an extension of segmental angles.

From unloaded to compression, they found statistically significant small posterior shifts for the disc T2WC at the L1-2 level (ES: 0.39). They also saw an increase in L5-S1 width (ES: 0.22), an anterior shift in L1-2 T2WC (ES: 0.39), and L3-4 (mean 2.1˚) and L4-5 (1.8˚) extension angle. Additionally, with more degeneration, there were larger inferior movements of the disc T2WC, but not changes in disc width. 

Overall, their findings on compression to traction demonstrated the most significant findings in the lower lumbar levels. They also found a magnitude difference associated with the severity of disc degeneration. This supported their hypothesis that fluid distribution-related measurements illustrating the effects of degeneration and lumbar disc loading.

 

Why do these findings matter?

Biomarkers can help to illustrate how the lumbar spine responds to different loading conditions and can be used to monitor degenerative changes in the lumbar spine.

 


At Dynamic Disc Designs, we appreciate the dynamics of the discs and how professionals can communicate these small changes to patients as it relates to their dynamic symptoms and the solutions of back pain.

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.

 

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
Biomechanical stress and Modic 1

A study 1, in the European Spine Journal, set out to uncover some theories related to low back pain (LBP) and biomechanical stress. It concluded that using weight-bearing MRI scans offer a valuable complement to standard sequences due to them presenting the radiologist with additional (and beneficial) diagnostic information about low back pain.

The Context

For many individuals out there, low back pain (LBP) caused by the degenerative disc disease of the spine is a leading reason for chronic disability and morbidity. Although there is a trend to avoid using this language with patients because of the mood it may create about their own spines. The preferred technique to evaluate a spine’s degenerative changes is an MRI because of its ability to detect water content in the discs. According to recent studies, the MRI signal changes in vertebral endplates, particularly the Modic changes (MC) type I, have been deemed a potential specific cause of LBP. More research is required to understand MC’s exact pathophysiology as the relationship between endplates, disc degeneration, and bone marrow is yet to be quantified.

What did this Study do?

The study’s objective was to evaluate the relationship between endplate modic changes type 1, degenerative disc, and pain level during a lumbar spine’s upright weight-bearing MRI scan. The study used patients with non-specific LBP, in other words, without an exact diagnosis.

The underlying hypothesis of the study was that loading could serve a role in the presentation of symptoms of LBP and Modic Type 1 changes.

What was Used?

The study evaluated 38 patients (20 females and 18 males) that had a general lower back pain diagnosis (non-specific LBP) as well as MRI evidence of Modic Type 1 vertebral changes. The age range of the participants was 27 to 69 years. An MRI unit was used to evaluate patients in a standard and upright weight-bearing position. The study compared the type 1 modic endplate  extend, intervertebral disc height at the involved level, as well as the degree of degeneration at the same intervertebral disc.

A visual analog scale questionnaire was used to assess pain. MedCalc was used for statistical analysis.

The Results

Compared to the supine position, a total of 26 participants showed an increase in the area of Modic 1 changes in the upright position. A reduction in the disc height was also observed in the upright position. A moderate negative correlation was analyzed between the area of Modic I changes and intervertebral disc height. Furthermore, a weak positive correlation was seen between Pfirrmann grade and an increase in the area of Modic type 1 changes.

The clinical evaluation showed that 30 patients reported their LBP worsening in an upright position. A significant correlation was seen between an increase in the Modic Type 1 changes and an increase in VAS values (in the upright position).

What Does It Mean?

The study showed the modifications of Modic 1 changes under loading while offering evidence (through MRI) of increased Modic changes area extent in the upright position. The results also displayed a correlation between an increase in pain and as Modic type 1 increases. It was concluded that upright scans under physiological load may offer a valid complement to standard sequences by offering more diagnostic information for treating pain because of “active discopathy” in the presence of Modic Type 1 changes.

Disc Height loss response

A study 1 in the journal of Ergonomics investigated the likelihood of variability of height loss in the sitting position being impacted by the time of day. The day-to-day variability in asymptomatic participants was also analyzed. The results shared data about height loss changes in the morning and the afternoon.

LBP and Height Loss

Millions of people (ranging from the young to the elderly) suffer from low back pain, or LBP, around the world. Such a condition has physical, psychological, and social implications. Sedentary work (which involves sitting for long periods) has become quite common for students, office workers, and more. Prolonged sitting increases the risk of lumbar disc pathology (which is, in part, associated with loading on the lumbar discs).

Spinal loading is considered as a cause for LBP as it causes spinal tissue shrinkage. Such shrinkage is known as height loss. Studies do show that prolonged sitting can lead to height shrinkage and thus, LBP.

Effects of Time of Day in Height Loss

Certain studies display a significant difference between height loss following loading activity applied during the morning and in the afternoon. Changes in height seem to occur in a ‘fast’ and ‘slow’ phase. The rate of change is higher when individuals wake up in the morning, and then it slows down throughout the day. That’s why, for ergonomic researchers, the influence of time of day is essential to consider when it comes to height loss. Day-to-day variability of height loss response is another factor to observe the influence of activities done during the day.

The Study

The research utilized a test-retest design to assess the effects of time of day on the variability of height loss. A total of fifty asymptomatic participants (25 males and 25 females) were involved. The study only included participants without current neck or back pain.

Take note, the participants were requested to sleep for eight hours (before every test) as well as to avoid vigorous activity for 24 hours before every test.

A seated stadiometer device was used for measuring height loss response.

What was found?

The current study is deemed to be the first of its kind to investigate the effects of time of day on the height loss response variability because of sitting for two consecutive days.

No significant difference in the magnitude of height loss during the morning and the afternoon was observed. Take note, changes higher than 0.886 mm (morning) and 1.128 mm (afternoon) can be attributed to intervention effects.

The study suggested the collection of future data during the morning or in the afternoon. Also, more significant responses are needed to confidently state that height loss responses have been influenced by an intervention.

 

spinal shrinkage

There’s some interesting data shared in a study 1 found in the journal of Physiotherapy Theory and Practice. It looked at the possible reversal of spinal shrinkage through press-ups and spinal loading.

Understanding Spinal Height and LBP

Press-up exercises are commonly recommended by clinicians for preserving spinal health as well as to lower changes of Low back pain (LBP). There’s still a lot of research required in the field of LBP to help millions of people around the globe.

Take note, degenerative lumbar intervertebral disc or IVD conditions are highly prevalent in asymptomatic individuals aged 10 to 29 years. According to past studies, spinal degeneration is associated with spinal height loss and thus, leading to LBP, nerve root compression syndrome, and spinal stenosis.

What was the Objective?

The said study was conducted to investigate whether or not sustained, and repetitive prone press-ups (following spinal loading) could possibly play a role in reversing decreased spinal height. It was also to monitor any possible correlation between spinal height gains and the degree of end range of motion spinal extension.

seated unloading

Seated unloading research in The Spine Journal referenced in this article , Jerome Fryer lead author, owner of Dynamic Disc Designs Corp.

The Study

A Pretest-posttest crossover design was implemented for the current study. A total of 32 participants (20 females and 12 males) were a part of it. The participants (between 20 to 45 years of age) were asymptomatic with no current complaints of spinal related symptoms. They had no history of LBP.

The study involved participants being seated in the stadiometer. They sat for 5 minutes with a 4.5-kg weight placed on each shoulder. The said load was removed for 5 minutes. A stadiometer was used to measure the participant’s spinal height before and after 5 minutes of sustained or repetitive prone press-ups.

This study used Two-by-two repeated-measures ANOVA. This was done to identify any possible significant interactions as well as main effects.

What were the Results?

The results of the study showed that there wasn’t a significant interaction present between sustained vs repetitive press-ups as well as the time before and after each prone press-up strategy and no main effect for strategy (repetitive vs. sustained press-ups).

However, a significant main effect for time (after vs. before press-ups) was observed. Furthermore, no correlation was seen between spinal height changes and the degree of end ROM spinal extension after press-up strategies.

The Limitations

This involved the measurements being taken at different times during the day. Also, the sample size of 32 participants didn’t achieve the projected number of 34.

What does it all mean?

The conclusion offered by this study was that spinal height was increased by repetitive and sustained press-ups following a period of spinal loading.

The study’s conclusion put forth the observation that such strategies could be utilized to aid in recovering spinal height as well as to reduce the effects associated with decreased spinal height due to certain daily activities.

LBP and Disability

A cross-section study 1, in Spine, was conducted to investigate the link low back pain (LBP) and disability had with the structural features of the thoracolumbar fascia. The results shared that a relationship existed between these factors.

The Context

While the Global Burden of Disease Study has researched LBP to be the leading cause of disability in humans, a lot of work needs to be done to fully understand the etiology associated with LBP. More research needs to be done to address all of the factors linked to LBP. Such understanding is crucial because it will help with creating targeted prevention strategies to help millions around the globe.

Previous research has analyzed LBP and disability to be associated with structural abnormalities of the lumbar spine. Furthermore, MRI has shown LBP to be linked to disc protrusion, disc degeneration, nerve root displacement or compression, and high-intensity zone. While more research is still needed, the present results do suggest that the issues of LBP and disability can be addressed by targeting structural factors. Take note, there’s evidence that suggests the thoracolumbar fascia may be linked to LBP. However, few MRI studies have examined such a link.

hypermobility-spine

The Study

The current study had an aim to examine the link present between the lumbar fascia’s length and LBP as well as disability. The study used MRI.

A total of 72 participants (49 females and 23 males) were recruited. They weren’t required to have any history of LBP or current LBP to participate. The MRI was performed, in this study, using a 3.0-T magnetic resonance unit (with the participants in supine position). The study administered the Chronic Pain Grade Questionnaire (CPG) at the time of the MRI.

The study used the Logistic regression analyses for examining any likely associations between fascial length and high pain intensity (or disability).

What did the Results Conclude?

The results of the study concluded that there was a significant association between a shorter length of fascia and high-intensity LBP and/or disability. Such association was after adjusting gender, age, and the body mass index. The association was strengthened after adjustment for the cross-section area (in the paraspinal compartment).

While more studies are required, the current results do suggest that fascia’s structural features likely play a role in disability and LBP.