Low back pain

Goal of the review?

In this paper, 1 the authors provide a research-based overview of the epidemiology, causes, and risk factors. They also describe the clinical presentation and diagnostic criteria, and treatment options for low back pain.

 

Overview

Epidemiology and Socioeconomic burden

The economic impact of lower back pain is widely significant, with estimates of £2.8 billion in the UK and $100 billion in the US. Almost two-thirds of the economic costs from lower back pain stem from indirect costs such as loss of productivity. One study done in 195 countries found low back pain the leading cause of productivity loss in 126 countries. 

Low back pain can be classified as mechanical, neuropathic or nociplastic. Studies have shown that the prevalence of neuropathic pain ranges from 16% and 55% in patients with chronic lower back pain. One systematic review illustrated the prevalence of low back pain to range from 11.9% – 23.3 %, increasing with age and most common in middle-aged to older women.

 

Pathogenesis

There is a multitude of factors and causes of lower back pain. These include disc degeneration, radicular (neuropathic) pain, facet arthropathy, myofascial pain, sacroiliac joint pain, spondyloarthropathies (ankylosing spondylitis and psoriatic arthritis), and nociplastic pain (non-specific low back pain).

Low back pain

Professional LxH Model and the Lumbar Spinal Stenosis Model — helping patients understand their source(s) of low back pain.

 

Brain change, behavioural and genetic factors

Low back pain can be caused by changes in the brain, such as alterations in blood flow and changes to white and grey matter in the brain. Behavioural factors can also play a role. Studies show the role that emotion and emotional experiences can have on low back pain. For example, negative expectations, depression, and anxiety have been shown to predict poor pain outcomes in patients. Finally, there are also genetic factors that contribute to low back pain. Research has illustrated that heritability contributed to 26% lifetime prevalence of low back pain, 36% for functional limitations and 25% to pain intensity.

 

Clinical presentation, diagnosis, and screening

Low back and leg pain can be a manifestation of intervertebral disc herniation. Often, this type of pain will resolve itself in a few weeks. However, some patients can have recurring pain for up to two years. 

A large percentage of back pain is non-specific and resolves without any formal diagnosis. However, most guidelines recommend that patients have a physical exam and that history is taken. Some patients may require a neurological exam or vascular-focused exams to differentiate different types of claudication. Routine imaging is not required for most lower back pain cases. However, CT scan, MRI, and x-ray can be useful depending on the case.

Different screening tools have been developed that assist in preventing and treating low back pain, identifying patients prone to chronic pain, and distinguishing neuropathic from non-neuropathic pain.

 

Prevention and Treatment

Research demonstrates that a combination of exercise, education and ergonomic changes are effective as prevention strategies for lower back pain. These behavioural, non-pharmacological approaches are also used as first-line treatment. This can include clarification-oriented and exposure-based interventions that can help patients self-manage their pain and pain behaviours. 

For patients whose pain persists, pharmacological and procedural options can be explored. The American College of Physicians Guidelines recommends that treatment begins with non-steroidal anti-inflammatory drugs (NSAIDs) and muscle relaxants, tramadol, or duloxetine as second-line treatment and opioids as the last choice. Due to the addictive potential and negative side effects, opioid treatment is not recommended for most patients. 

There are also non-pharmacological interventions for low back pain. Steroid injections in the foramen, between the vertebrae, and in the sacroiliac joints have positive therapeutic effects. Other interventions such as facet joint blocks and radiofrequency are used but have mixed evidence supporting them. Spinal cord stimulation has shown positive outcomes and can be cost-effective, depending on the patient. 

When other interventions have not been successful, surgery may be an option for some patients. Research shows that for herniated nucleus pulposus, surgery can provide relief for a period but does not result in long-term benefits. For patients with lumbar spinal stenosis, decompression surgery can provide substantial improvement compared to a traditional approach.

 

Conclusions

Low back pain is globally prevalent and increasing as lifestyles become more sedentary. Lower back pain is a complex condition with various factors; therefore, diagnosis and treatment can be challenging. Existing research provides important evidence that can be used to develop inter-disciplinary and multimodal approaches to treatment and diagnosis. 

disc herniations, sequestered lumbar disc herniation

Goal of the article?

The goal of this study, 1 is to examine why there is an increasing incidence of disc herniation in young people. 

 

Why are they doing this review?

Disc herniation is often the result of natural degeneration changes accompanied by age as the vertebral discs lose water and become less resilient and less responsive to dynamic shock. However, increasingly, disc herniations are appearing in younger people. The cause of this early degeneration is most likely from inactivity sustained by static compressive loads, as well as other factors such as smoking, obesity, familial predisposition and other factors like prolonged sitting. As this can have long-term implications, understanding causes and potential treatments of early degeneration is critical to minimizing the negative outcomes for individuals and society at large.

 

What was done?

This is a prospective study with a total of 33 young patients, all with extruded lumbar disc herniations managed by conservative or surgical approaches between 2017 and 2018. On average, patients were 25 years old. In addition to age, the researchers asked each patient about smoking, familial predisposition, sporting activity, and occupation. They measured pain using a visual analog scale (VAS) and measured patients’ BMI. All patients had lumbar MRI imaging.

 

Helping patients understand compressive loads with a Dynamic Disc Model

 

What did they find?

The researchers found that 18 patients (8 females and 10 males) had a disc extrusion at the L5-S1 level, 12 patients (8 females and 4 males) had a disc extrusion at the L4 and L5 level, and 3 patients had a disc extrusion at both the L4-L5 and L5-S1 levels. Motor deficits were detected in 4 patients who then required surgical treatment. For these patients, three procedures involved the L4-L5; one had right L5 radiculopathy and motor deficit, while the others were on the left side. 

The remaining 29 patients were treated conservatively with physical therapy and pain medication. They were given information on ergonomics and help with stopping smoking. In follow-up, the VAS scores were reduced, and all patients had lost weight. However, only three patients had quit smoking.

When the researchers looked at occupations, they found that all patients sat during the day and lacked movement. They also found that 61% of the patients were smokers and the mean BMI was 32.5 kg/m2.  Additionally, in line with existing research, this study found that familial predisposition with lumbar disc herniation played a role. 

 

Why do these findings matter?

Understanding factors contributing to early disc degeneration can help patients make lifestyle changes that can postpone pain and mobility issues. 

Disc Nucleus

Goal of the review?

The goal of the article, 1 explores the molecular level of intervertebral disc degeneration. Specifically, the authors examine the correlation between proteolytic enzymes, microvascular formation, or neve fibre ingrowth in the intervertebral disc nucleus. 

 

Why are they doing this review?

To aid in diagnosis and treatment, the authors argue that it is important to understand the molecular level of disc degeneration and the functional changes that accompany degenerative IVD. By measuring the extracellular matrix components, such as collagen in the disc nucleus tissue, the relationship between the degrees of degeneration of the intervertebral disc (IVD) is analyzed. 

 

 

What was done?

They selected 40 patients for the case group, all of whom had degenerative disc nucleus pulposus (NP) and were admitted to the hospital. The inclusion criteria for this group were the presence of lumbar degenerative disease and cervical spondylosis. Additionally, they selected 20 healthy subjects for the control group, with inclusion criteria of cervical vertebra and lumbar vertebra injury caused by trauma. There was no significant difference in demographic characteristics, including age, gender, and other variables. 

The researchers took blood and NP tissue from each participant and stored the samples at 80º. They then carried out H&E staining and immunohistochemical staining to observe cathepsins such as aminopeptidase and vascular endothelial positive cells. Finally, they used statistical software to determine correlations.

 

What did they find?

In the normal group, the researchers found that following H&E staining, chondrocytes were clustered in the cartilage depression, and matrix staining was more uniform. In contrast, the chondrocytes were reduced for the case group, and the nucleus was stained or disappeared. When looking at immunohistochemical staining results, the normal group had little or no expression of aminopeptidase N (APN) and leucine aminopeptidase (LAP). However, in the patient group, APN and LAP were expressed in the degenerative IVD. These are important findings as a positive correlation between APN and LAP and degenerative changes to the IVD. Research shows that degenerative changes in the IVD tissue are associated with neovascularization. The appearance of proteolytic enzymes such as APN in the IVD and the relationship between microvessel formation and nerve in growth in the IV illustrate changes at the molecular level of disc degeneration. Moreover, the NP tissue was immunohistochemically stained with CD31-labeled VEGF, and the endothelial cells were stained singly or in clusters.

 

Why do these findings matter?

Understanding molecular changes to the IVD will help to diagnose better and treat issues related to degenerative IVD.

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.