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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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What’s the Relationship Between MRI Findings & Clinical Symptoms in Patients with Suspected Lumbar Spinal Canal Stenosis?

What's the Relationship Between MRI Findings & Clinical Symptoms in Patients with Suspected Lumbar Spinal Canal Stenosis_

A recent study 1 published in the last legs of 2019 set out to find the correlation between clinical symptoms and MRI findings in patients who are suspected to be suffering from lumbar spinal canal stenosis.

What was the Context?

Lumbar spinal stenosis (LSS) is the most common sign that a patient over the age of 65 will need a spinal surgery. What is LSS? It is a condition that shows decrease in the available space for the vascular and neural components of the lumbar spinal cord.

Within clinical practice, symptomatic LSS comes with different symptoms. This includes: buttock pain, bilateral or unilateral neurological disorder, and pain in the lower extremities.

LSS manifests usually because of less space present for neural and vascular structures of the lumbar spine. The definition of LSS has two aspects: structural abnormalities and clinical manifestations. Both are a result of certain physical abnormalities.

Previous studies have shown that clinical symptoms showing mild to moderate lumbar LSS might exist in less than half of patients.

So in order to define destructive LSS, it’s important that clinical symptoms match up with the imaging results. This is the reason why using clinical findings along with radiological evaluation through magnetic resonance imaging (MRI) is seen as proper standard in diagnosing LSS.

Numerous clinical criteria and imaging are available for the diagnosis of LSS. But despite the availability, coming up for the right diagnosis is a challenging part for radiologists and clinicians.

Therefore, this study aims to assess and understand the relation between clinical symptoms and MRI findings in groups of symptomatic and asymptomatic patients having suspected LSS.

What was the Methodology?

Using a case-control study, there are two groups of 100 symptomatic and asymptomatic individuals involved. Their ages range from 20 to 84 years old.

Both the groups have suspected lumbar spinal canal stenosis. They were all referred to the imaging unit for lumbosacral MRI. Within the study, patients’ clinical symptoms and radiological parameters in MRI were recorded. Afterwards, the researchers evaluated the results of the correlation between clinical symptoms and MRI findings.

What Were the Results?

Throughout the duration of the case-control study, 100 patients in the case group with signs and symptoms of LSS were evaluated.

100 patients in the control group who underwent lumbar MRI were also evaluated throughout the study period. Age ranges of the case group were between 21 to 84 years old. While the age range for the control group was 20 to 84 years old.

Table 1 in the study showed the prevalence of clinical symptoms in patients who did or didn’t have LSS symptoms.

Table 1 Frequency of clinical symptoms in patients with and without LSS

Table 2 shows the quantitative and qualitative radiological features in case and control groups.
Table 2. Quantitative and qualitative radiological features in case and

What Does This Mean?

The most common clinical manifestations of patients in both case and control groups involved:

  • Mechanical low back pain
  • Radicular pain
  • Gluteal pain

There were also no significant relationships between most clinical symptoms with each of the radiological indices separately. The highest significant correlation was observed between radiological indices and neurogenic claudication.

What Was Concluded?

Based on the results of the quantitative criteria of MRI imaging findings, the central spinal canal cross-section and lateral recesses cross-section had the highest specificity and sensitivity for LSS diagnosis in asymptomatic and symptomatic patients with suspected LSS.

The strongest observed correlation? It was between neurogenic claudication and LSS diagnostic radiological markers.

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How Accurate Is Quantifying IVD Strain and Deformity Using DVC-MRI?

Intervertebral disc strain

A research study 1 in the Journal of Biomechanics offered findings regarding the unique potential of DVC-MRI to help assess intervertebral disc strain in patients.

Why Conduct Such a Study?

A common cause of musculoskeletal disorders and disabilities in people is LBP or Low Back Pain. According to statistics, 70-85% of people have experienced LBP in their lifetime.

Take note; physical disruptions can play a role in degeneration and LBP. That is why it is vital to understand the mechanical behavior of IVDs or intervertebral discs further.

There is potential to create better treatment methods if internal deformities and intervertebral disc strain are quantified. Such quantification can help improve the current understanding of progressive mechanical changes in degenerate IVDs.

DVC or Digital Volume Correlation is used for assessing full-field 3D deformities as well as strains from MRIs. This method is deemed to be more sensitive than other techniques. DVC is also regarded as an efficient tool to calculate 3D strains in biological tissues.

Non-invasive strain measurements can be obtained by using DVC with MRIs. However, this combination hasn’t been appropriately used before.

The objective of this study was to quantify the deformation and strain errors associated with DVC-MRI when analyzing IVDs in humans.

What Was the Methodology?

A total of 8, fresh frozen, human cadaveric vertebral body-disc-vertebral body (VB-disc-VB) samples were collected from the L3-L4 and L4-L5 level of four male donors. A clinical MRI scanner was used to scan each sample.

A custom-made rig was designed to enable samples to be imaged within a 9.4T MRI scanner under load.

The current study used three DVC approaches. There was Direct Correlation (DC), Fast Fourier Transform (FFT), and combined FFT+DC.

The team implemented a one-way analysis of variance (ANOVA) with Tukey post hoc tests, Levene’s test, and paired-sample t-tests were used for statistical analysis.

What Did the Study Share?

The results revealed a decrease in random errors with increasing subset size for all three DVC approaches in all directions.

Compared to the DC approach, a reduced level of random errors was observed using the FFT and FFT+DC approaches.

The team designated FFT+DC as the optimal method. Also, a subset size of 56 voxels (2520 micrometers) was shown to be a good compromise between spatial resolution and errors.

It was concluded that the current method is a powerful tool to help accurately quantify the IVDs’ mechanical behavior even with certain limitations. It can also be used for assessing degenerative changes as well as to evaluate mechanical behavior-related changes after surgical procedures.

There’s a lot of potential for this method to help enhance LBP treatment options.

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MRI Displayed Differences in Patterns of Lumbar Disc Degeneration in Degenerative Disc Disease and Disc Prolapse

Lumbar Spinal Stenosis Model

Due to the differences between Degenerative Disc Disease and Disc Prolapse not being well-known, with regards to patterns of Lumbar Disc Degeneration, a study 1 was conducted to find some answers. The study shared results (it suggested) would help with better disc degeneration-related treatments.

Why was it Conducted?

According to the current study, there a lot of inconclusiveness in the field of lumbar disc degeneration. This is particularly true when focusing on lumbar disc degeneration’s pathogenesis, prevention, management, etiology, and symptomatology. DDD (degenerative disc disease) and DP (disc prolapse) are two of the common ailments that affect lumbar discs. While these two ailments do manifest differently (in a clinical sense), numerous studies tend to include both and thus, have led to varying observations.

The current study was conducted to better evaluate the possible link between DP and DDD. The objective was to analyze lumbar disc degeneration patterns in patients with acute DP and those with chronic back pain and DDD.

The Study

This was a prospective, magnetic resonance imaging-based radiological study. Two groups of participants (aged between 20 to 50 years) were studied. Group 1 was made of 91 participants that required a single level microdiscectomy for acute DP. 133 Participants with chronic low back pain and DDD were part of Group 2. The study assessed discs by MRI through Pfirmann grading, Schmorl nodes, Modic changes, and the total end-plate damage score for all the five lumbar discs.

What were the Results?

The study’s results showed there were significant differences between DDD and DP patients with regards to the extent, number, and severity of degeneration. A significantly higher number of degeneration discs were analyzed in DDD patients compared to DP patients. The DDD group also showed a higher incidence of multilevel and pan-lumbar degeneration. The DP patients had lower lumbar degeneration while it was upper lumbar involvement in the DDD group. Modic changes were also observed to be more common in DP patients. Furthermore, both groups showed a positive correlation for the total end-plate damage score with disc degeneration.

What does it Mean?

The results of the study suggested that patients with DP as well as the ones with back pain and DDD were radiologically and clinically different groups. They varied when it came to the severity, pattern, and extent of disc degeneration. Understanding the differences between the two groups of patients could help with future studies when dealing with disc degeneration.

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MRI Study Finds Correlation between Modic Changes and LBP Frequency and Intensity

lumbar vertebra

A study of Modic changes in 228 middle-aged male workers found a strong association between LBP frequency and intensity and Modic changes observed on magnetic resonance imagery (MRI) scans. These Modic chances were most likely to be at the L5-S1 spinal level and were more strongly correlated with LBP symptoms when Type 1 lesions were present.

What’s at Stake?

Bone marrow lesions—also known as vertebral endplate changes— that are visible on MRIs are considered evidence of disc degeneration. There are three types of lesions recognized by Modic: Type 1, where fissuring and an increase in the subchondral marrow vascularity is apparent; Type 2, where there is fatty degeneration of the bone marrow; and Type 3, where subchondral bone sclerosis is suspected.

Previous studies seeking to establish a positive correlation between Modic changes and clinical LBP symptoms have been inconclusive due to flawed designs and/or limited subject pools. This cross-sectional study used middle-aged male workers to investigate how or if Modic changes affected the intensity and frequency of sciatica and LBP in its subjects.

The Study

The subjects involved in this study were all male—128 Finnish train engineers, and 69 Finnish paper mill and chemical factory workers—with a mean age of 47 years. The train engineers had worked at their jobs, which involved long hours of standing and approximately five hours per day of subjection to intense, whole-body vibrations, an average of 21 years. The control group of chemical and paper workers claimed a mostly sedentary experience during their working hours and were not exposed to intense vibrations while on the job.

Both groups were assessed prior to the MRI study about the number of prior LBP and leg pain episodes, particularly those with a duration of 14 days or more. They were asked to comment on the pain’s intensity over the past week and over a three-month period before the study. They were also questioned about any history of LBP and whether they were experiencing LBP on the day of the assessment. MRI scans were taken and analyzed by two radiologists with no knowledge of the names or histories of the scanned subjects. Modic changes were identified and sorted into groups based upon the three types, with mixed types (I and I/II, and II and II/III) combined, representing more active and less active degeneration types. Other disc irregularities were noted independently and blinded to the clinical data analysts when observed. Disc herniation was either normal, bulging, protrusion, or extrusion in the notation. Neural compromise was identified as no compromise, nerve root contact, or compression. Stenosis was defined and noted according to Willen et al criteria.

modic changes, vertebra model

Modic changes with basivertebral nerve vertebra.

Results

Though the engineers reported the highest sciatica and 1 week and 3-month pain scores, Modic changes at one or more levels were like those observed in the control group—roughly 56%. In the combined groups, 15 % of the subjects showed Modic Type I changes only, and 32% had Modic II changes at one or more-disc levels. Ten percent showed Type 1 or II changes at the same, or separate levels. The combined subject groups had 178 Modic changes across various lumbar levels, with 30 % experiencing Type I and 66 % Type II. None of the scans showed Type III Modic changes. Eighty percent of all Modic changes were located at L4-5, or L5/S1 levels, and 61% of these changes were described as “extensive,” while 39% were minimal.

There was a positive correlation between the reports of LBP episodes—especially those experienced within the past week and three-month period prior to the study— and observed Modic changes at any level. Modic changes at the L5-S1 levels were positively correlated with previous LBP and/or sciatica, especially where high levels of pain were reported within the past week prior to the study. There was little-to-no correlation between reported pain and Modic changes at higher disc levels or at L4/5.

Type II changes at any level was positively correlated with a higher number of previous LBP, especially episodes occurring during the past week or three-month period prior to the study.

Extensive changes were positively associated with more LBP episodes in the past and higher levels of LBP or sciatica within the past week or three months prior to the study. This was especially true when extensive Modic changes were found at the L5-S1 levels or when minimal changes were noted, but the subject had an extensive history of LBP episodes. The LBP had little correlation with the extent of the Modic changes at upper spinal disc levels or at L4/5.

Conclusion

The results of the study—the first to analyze Modic changes as they relate to specific IVD levels— suggest that there is a positive correlation between Modic changes occurring at the L5-S1 IVD level and that LBP is more likely to be associated with Modic Type 1 lesions at this level than at other levels or with other lesion types. The authors of the study suggest more research—particularly of how Modic changes correlate with pain in a younger subject set—is necessary to verify these findings.

 

 

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