Centre of Rotation

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 data’s ability to represent the general population.

The authors argue that the use of radiographic techniques in this study helps to overcome these limitations as the images allow for better visualization of each vertebra and movements 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 lumbar spine radiographs 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 COR and the spinal segment’s position. 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 COR location spread randomly around the centre of the intervertebral space.

Limitations?

One of the main limitations of this study was the sole focus on the lumbar spine’s flexion-extension motion 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.

Facet pain

Goal of the Study?

The objective of this study 1, is to determine the prevalence of “pure” lumbar Z joint pain.

 

Why are they doing this study?

The prevalence of lumbar Zygapophysial joint (Z joint) is disputed, with rates ranging from 5% to 45%. The reason for this disparity lies in the use of different criteria for diagnosis. The criteria are focused on relief of pain after a diagnostic block, an injection of numbing medication into 1 or more small joints on each side of the vertebrae. However, these criteria can range from 50% to 80% to complete pain relief after a diagnostic block. Additionally, some diagnostic criteria focus on relief from pain after a single diagnostic block, with no controlled blocks. However, the researchers argue that for diagnostic blocks to be valid, pain must be abolished whenever an active agent is administered, and the use of repeat blocks provides validity.

The authors contend that no research has been able to determine the prevalence of “pure” lumbar Z joint pain, defined as complete relief of pain following a placebo-controlled diagnostic block. 

Facet pain

 

What was done?

All 206 patients for this study came from a private practice where they were referred for back pain. To be eligible, they had to have back pain longer than 3 months, with symptoms compatible with a potential diagnosis of lumbar Z joint pain. Patients with imaging that pointed to tumours or infections were excluded from this study, as were patients who were pregnant or had pain in the lower limbs.

The researchers used two protocols for this study. The first protocol was a placebo-controlled local anesthetic comparative blocks. For this, each patient received a local anesthetic on two occasions and normal saline on one occasion.  For the second protocol, patients could receive the same or a different local anesthetic on two or three occasions and normal saline on one or no occasion. Using saline as a placebo showed whether patients could tell the difference between an active control from a placebo.

Patients were considered to have Z joint pain if they had complete relief of pain three times when a local anesthetic was used, if they had complete relief of pain two times when the anesthetic was used, and if they had no relief, saline (the placebo) was used. 

 

What did they find?

The majority of patients did not report any pain relief from the initial block and therefore did not satisfy the criteria for lumbar Z joint pain. Only patients who had complete relief of pain from their initial block were eligible to continue. 

Of eligible patients, the researchers found that 45% of patients in group 1 and 30% in group 2 did not get relief from the second block. Moreover, 20% of patients in group 1 and 3% in group 3 had no relief from the second block but were completely relieved by the placebo. Results for the two groups combined showed a prevalence rate of “pure” lumbar Z joint pain of 15%. This is much lower compared to when a diagnostic criterion is less stringent. Moreover, they did not find any statistically significant differences between the two groups for gender and age. 

 

Why do these findings matter?

Determining the appropriate diagnostic criteria for lumbar facet pain has important implications for patients who need to have the right diagnosis and treatment for their pain.  

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. 

 

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.  

Dynamic Disc Model

Goal of the Study?

In this study 1, the authors attempt to build a three-dimensional finite element (FE) model to investigate how changes to the nucleus pulposus (NP) under axial compression loads influences bulging in the lumbar disc. 

 

Why are they doing this study?

The intervertebral disc provides cushioning between vertebrae and absorbs pressure on the spine. A disc herniation happens when the annulus fibers are weakened or torn, and the NP pushes through the annulus fibrosus (AF). This bulging can generate pressure on the adjacent nerve roots causing lower back pain (LBP) and may even lead to paralysis. 

Existing research suggests that under the same compression the extent of the bulging differs by area, with the posterior region experiencing the least amount of bulging. Taking this knowledge into consideration, the authors argue that it is important to understand the behaviour of bulging in the disc to prevent severe damage and provide a path to more effective treatment. 

 

What was done?

The researchers created a 3D FEA model that simulates a functional human spinal unit of the lumbar region under axial compression loads. The material properties of the AN and NP are assumed to be linear elastic and the structure of the AF is modeled as a homogeneous material without fibrin. 

To validate the model, the authors looked at the axial and bulging displacements under axial compression load and compared that to existing data. They further validated their model by comparing the distribution of stress in the AF with and without the NP.

 

What did they find?

The researchers found that the condition of the disc (partial removal, full removal or intact) significantly affects how the disc bulges and where. For example, they found that for a disc without an NP the posterior region bulges inward. In contrast, for both an intact NP and with partial removal of the NP, the bulging occurs outward due to increasing pressure at the central part of the AF. 

 

Why do these findings matter?

The findings can help to improve treatment decisions of the degenerative disc and nucleus pulposus.

degenerative disc

Goal of the Review?

In this article, 1, the authors ask the question of whether current manual intervention practice reflects the scientifically proven biomechanical aspects of degenerative disc disease (DDD) or if the field is ignoring the science in an effort to discard the diagnostic label?

 

Why are they doing this study?

The American Academy of Orthopedic Manual Physical Therapists (AAOMPT), released a position paper that opposes the use of the term degenerative disc disease (DDD), saying that the diagnostic label can result in overuse of diagnostic imaging and treatment. They assert that DDD is a common age-related issue, not a disease. 

While the authors agree that diagnostic labels must be well thought out, they argue there are significant physiologic and biomechanical changes that occur as a result of disc degeneration. Therefore, scientific evidence such as imaging findings that illustrate these changes should serve to guide treatment decisions as one aspect of larger clinical reasoning. 

 

Degenerative spondylolisthesis

Degenerative Disc Language Should Be Reframed

 

What was done?

The authors perform a narrative review to examine the literature on DDD. This includes a look at the historical research on disc instability, the role of the disc as a pain generator, a review of the science on the cycle of disc degeneration, as well as the impact of rotation on the degenerated disc. In addition to the biomedical research, they provide an overview on the implications of this research for manual therapy and recommendations for evidence-based treatments.

 

What did they find?

 In response to the literature review, the authors make a few evidence-based recommendations for manual therapy treatment. First, they suggest that traction-based manual interventions should be done in mid-position without side bending or axial rotation. This recommendation is in response to evidence suggesting that forceful rotatory treatments may cause further damage and potentially lead to loss of structural integrity of the disc. 

Next, they argue that current clinical practice of spinal manual therapy may not be paying enough attention to the frequency of early disc degeneration, and resulting instability, in the asymptomatic population. Therefore, they recommend that oscillatory traction-based manual interventions be applied in combination with stabilization exercises and neuromuscular re-education thereby serving to enhance disc rehydration and nutrition, as well as facilitate neuromodulation and reduce muscular reticence. 

 

Why do these findings matter?

Many patients use manual spinal therapy for pain and mobility. Understanding how to implement evidence-based treatments that will benefit, and not harm, patients is critically important for providers and patients.

cervical degenerated herniated spine model

Goal of the Study?

The objective of this study 1 was to establish a three-dimensional finite element (3D-FE) model of the cervical disc and spinal cord to simulate an intervertebral disc compression injury of the spinal cord by controlling the expansion of specific parts of the disc model

herniated disc model

Why are they doing this study?

Cervical spondylotic myelopathy (CSM) is one of the most common spinal cord disorders in people older than 55. It is a degenerative disease that impairs the function of the spinal cord due to progressive and chronic compression. In advanced stages it can cause neurological issues ranging from neck stiffness, arm pain, numbness in the hands to more severe symptoms such as quadriplegia (tetraplegia).

To date, many of the in vivo and in vitro experimental studies focusing on impingement or compression are unable to simulate the sophisticated nature of spinal cord injuries. The authors speculate that computational models are better able to evaluate mechanical forces and spinal cord deformations. In particular, they argue that FE models may provide a way to more accurately simulate disc compression and therefore predict future deterioration and onset of CSM.

What was done?

The researchers developed a 3D FE (finite element) model of the cervical disc and spinal cord. This model was comprised of four distinct materials to represent the white matter, gray matter, pia matter and annulus ground. Cervical disc protrusions were simulated by applying thermal expansion to multiple FE unites to trigger bulging of the cervical disc either directly or indirectly.  

Three models of symmetric cervical disc herniation (median, paramedian and lateral) were created by evenly raising the temperature of corresponding FE units to 30 °C. The asymmetric hernia model was developed by rising the temperature of the paramedian type model gradually from 22 to 30 °C. They then used a linear regression analysis to determine the relationship between the various models and temperature changes.

What did they find?

Overall, the researchers found a correlation between rising temperatures and the gradual increase of severity of disc herniation. In all four models, herniated masses were observed at the region where thermal expansion occurred. In the asymmetric hernia model, the protrusion was more severe on the side with a high temperature increase than on the side with a lower temperature.  

They found that spinal cord compressions resulting from intervertebral disc protrusion were observed in all models, except the lateral type. The greater the cervical cord was compressed by the protruding disc, the larger the area with higher stress. Moreover, as the level of compression increased, the deformation of the spinal cord intensified and the stress was dispersed to the anterior horn and intermediate gray of the grey matter, which could explain the progression of neurological symptoms.  

Why do these findings matter?

A better understanding of the biologic mechanisms of spinal cord damage caused by chronic mechanical stress is required to improve diagnosis, treatment and clinical outcomes. In particular, FE models may provide a way to more accurately simulate disc compression  and herniated discs and therefore predict future deterioration and onset of CSM.

 


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