facet, lumbar spinal stenosis model

A retrospective CT scan and medical record review [ 1. The Prevalence of Asymptomatic Cervical and Lumbar Facet Arthropathy: A Computed Tomography Study] of 50 patients with no history of spinal pathology used a four-point scale to grade the severity of evident arthritis and found that arthritic spinal changes were frequently evident—even in asymptomatic patients. The incidence of these changes corresponded positively with aging and was more prevalent in scans of the lower lumbar spine.

What’s at Stake?

Chronic neck and lower back pain affect between 66 and 84 percent of the U.S. population and is responsible for approximately 87 billion dollars of lost income and medical expenses annually—a figure that is only surpassed by the yearly wage loss and expenditures on diabetes and heart disease.

Diagnosing CNP and LBP is problematic due to the number of possible factors—including dysfunction of the intervertebral discs (IVD’s), facet joints, spinal nerve roots, ligaments, and muscles surrounding the spine— that can contribute to these disorders.

Some studies have indicated that facet arthropathy, rather than nerve root irritation, cause axial neck and back pain. The increase of CNP and chronic LBP in aging populations may be associated with a progressive degeneration of the IVDs that subsequently increases facet joint loading and creates favorable conditions for the development of facet arthritis. Facet joint blocks by injection have been shown to be ineffective in providing symptomatic relief in up to 90 percent of patients diagnosed via CT scan in previous studies. This suggests that scan observations alone may provide prevalent false positive results and therefore cannot be a reliable diagnostic tool.

Disc replacement may alleviate pain and restore spinal fluidity of motion, but the presence of facet joint arthritis is considered a contraindication to this surgical procedure. Understanding more about facet joint arthritis can assist practitioners in developing effective treatment plans for LBP and CBP patients—including the determination of which patients may be ill-suited for IVD replacement. This study of asymptomatic patients was conducted with the aim of understanding the prevalence of facet joint arthritis to help quantify the percentage of patients for whom facet injections are ineffective.

The Study

An approved review of archived CT scans of 100 total non-spinal patients was conducted using scans of 500 cervical facet joints from 50 subjects and 500 lumbar facet joints from an additional 50 subjects. All of the patient subjects’ medical records and scans were previously analyzed and evaluated as spinally asymptomatic for the purpose of this study.

The images were each graded and evaluated by an orthopedic spinal surgeon, neuroradiologist, and trained medical student on an independent basis. An additional three observers with separate clinical backgrounds also conducted a review of the facet joints to ensure no bias existed due to training backgrounds of the first group. The severity of facet joint arthritis symptoms were graded and statistical analysis was applied across different subject age groups. An average of all groups was then calculated using a coefficient.

The Results

Cervical Data

Of the 500 cervical facet joints from 50 patient subjects studied, asymptomatic cervical facet joint arthritis was evident in more than 33 percent of the scans. Nearly 60 percent of these patients showed only mild narrowing of the joint space and irregularities. About half of the subjects over the age of 40 demonstrated signs of arthritic changes. There were fewer “normal” or non-degenerated facet joints in patients in the aging (over 45) subject population. The prevalence of degenerative changes increased at all cervical levels in the aging subjects.

In all age groups, greater changes occurred more prevalently in the caudal spine area. At the C6-C7 spinal level, 78 percent of patients over-40 demonstrated facet joint arthritis. At the C2-C3 level, however, only 29 percent of the patients of the over-40 age group showed arthritic changes.

Lumbar Data

Thirty-seven percent of the patient subjects in the lumbar data group demonstrated asymptomatic lumbar facet joint arthritis, and up to 2/3 of these subjects showed grade 1 changes. As with the cervical data set, the lumbar set demonstrated a positive correlation with aging (over 45) and arthritic changes and degeneration of the facet joints. Caudal levels (L5-S1, for example) were more likely to show increased arthritic degeneration compared to cephalad levels. Only 12 percent of the patients over 50 years old showed changes at the L1-L2 levels, while 54 percent demonstrated these changes at the L5-S1 level.

Lumbar Spinal Stenosis Model

Conclusion

This study found a statistically significant positive correlation between aging and asymptomatic arthritic changes and degeneration of the facet joints of patients over the age of 45. These changes were evident at all spinal levels but were most prevalent in the lumbar facet joints and the C2-C3 and C6-C7 levels of the caudal spine. Approximately one third of the patient population in this study were found to have evident facet joint arthritic changes that were asymptomatic and associated with aging. When considering motion-preserving spinal implants, the age of the patient should be considered, as the treatment may not be as effective in patients over the age of 45, who are more likely to have or develop asymptomatic facet joint arthritis—a contraindication of the implant procedure.

 

 

 

 

Radiculopathy

A study 1 compared different treatment efficacies in two groups of patients with degenerative spinal disease-related buttock pain and found that the group receiving a selective nerve root block had clinically-significant improvement outcomes at post-procedure through 6-weeks, compared to the group that were treated with a facet joint block. This suggests that the cause of spinal-related buttocks pain is most likely radiculopathy, rather than facet joint degeneration.

What’s at Stake?

Many patients with spinal stenosis complain of back pain, buttock pain, or pain radiating from the buttock to the lower legs. As it is assumed that nerve root inflammation can contribute to lumbar and lower leg pain radiating from the spine, a common and frequently effective treatment may involve steroid or procaine injections. Selective nerve root block is used effectively in the treatment of degenerative scoliosis and has been demonstrated to be a successful form of short-and-long-term treatment for the pain. Similarly, a facet joint block has been used as an effective treatment for buttock pain, post-procedural lumbar pain, and morning stiffness associated with spinal degeneration.

Though various treatments have proven effective in alleviating or reducing pain in a percentage of the spinal patients receiving injections and blocks, the exact etiology of spinal-related buttock pain and radiating pain remains unclear. Because of this, uniform diagnostic and treatment guidelines for buttock pain—especially without concurrent radiating lower leg involvement—have been difficult to establish. This study links positive treatment outcomes with a more definitive diagnostic cause of buttock pain and seeks to contribute to the diagnostic and treatment criteria of buttock pain discussion.

The Study

Researchers treated 146 male and female patients presenting with spinal-related buttock pain without lower leg radiation by one of two methods—a) selective nerve root block (76 patients), or b) facet joint block (70 patients). The mean age of patients in both groups was 65 years. Both groups shared similar demographics when it came to age, sex, and health. Each of the patients was evaluated prior to their procedure and on day one, week 2, week 6, and at 12 weeks post-procedure. Their evaluation results were compared by their group injection method, and the results were then analyzed.

Results

On the DAY 1 post-procedure analysis, 7 percent of the patients in the nerve block group (GROUP A) were shown to have experienced an “excellent” response, and 6 percent of those in the facet joint block group (GROUP B) had an “excellent” response. In GROUP A, 46 percent of the patients treated showed a “good” response to the treatment, while only 13 percent of the patients in GROUP B had a “good” response.

At the two-week post-procedure follow up, 11 percent of the GROUP A patients demonstrated an “excellent” response, with only 4 percent of the patients from GROUP B had an “excellent” response. Similarly, 41 percent of the GROUP A patients were classified as having experienced a “good” response, compared with only 20 percent of those in GROUP B.

At the six-week post-procedural follow up, 11 percent of the GROUP A patients were classified in the “excellent” response group, while only 7 percent from GROUP B had this distinction. Forty-one percent of the patients from GROUP A demonstrated a “good” response, and only 20 percent of the GROUP B patients had a “good” response.

At 12-weeks, 47 percent of the GROUP A patients were classified in the “good” response category, and 46 percent of those in GROUP B experienced a “good” response to the treatment.

Conclusion

Researchers in this study sought to identify the cause of buttock pain associated with spinal stenosis. Specifically, they used a retrograde methodology to discover if the buttock pain was radiating pain or caused by facet joint degeneration. They treated two groups of patients using either selective nerve root block or facet joint block, and the data collected and analyzed indicates that the selected nerve root block was more effective through post-treatment follow ups through 6 weeks. The implication of this data suggests that spinal-related buttock pain is most likely caused by radiculopathy, rather than facet joint degeneration.

IVD Problems, Disc Degeneration

A study 1 of how dietary advanced glycation end-products (AGEs) effect the structure and function of intervertebral discs (IVDs) in male and female mice concluded that high dietary AGEs impaired IVD collagen quality, altered annulus fibrosus (AF) organization and changed the biomechanical properties of female IVDs, while having no clinically-significant effect on male mice subjects. The results of the study suggest the importance of targeting AGEs in spinal health assessments and treatments of female patients—particularly those at risk for, or suffering from, Diabetes Mellitus (DM).

What’s at Stake?

Structural disruption and chronic inflammation of the IVD is one of the leading causes of back pain, disability, and lost work wages worldwide. The many contributors to IVD damage and degeneration include DM and obesity, conditions that are increasing rapidly across the globe. Obesity increases the risk of IVD herniation, spinal stenosis, chronic inflammation, and other complications of the spine. It is also associated with an increased risk of cardiovascular disease, stroke mortality, and heart attacks–particularly in women. Since AGE accumulation is known to cause complications in populations with DM, this study investigates the effects of a high AGE diet on the IVD and how sex-differences may play a role in sex-specific IVD changes and disruption.

The Study

The subjects of the study were 21 male and 23 female recently-weaned mice, separated by sex and assigned to two groups. One group received a low-AGE diet (chow), and another group was fed only high AGE chow, which had been subjected to high-temperature heating. Each subject represented a third-generation off-spring of maternal mice fed only the respective diet used in the study groups, to exclude any effects of maternal AGES on the newly-weaned experiment mice.

The high AGE chow was representative of the typical Western human diet, with 80 percent higher AGE values than those of the low AGE chow. An increased AGE content is typically caused by thermally processing (extreme heating) the foods prior to ingesting. Examples of this include microwaving or deep-frying foods.

The feeding study lasted for 6 months, after which time the mice were sacrificed, dissected, and prepared for biomechanical IVD testing through Western blot analysis. Fasting glucose and total serum AGE levels were measured and quantified, and proteins were extracted, buffered, and sonicated. A single freeze-thaw cycle was used prior to biomechanical testing to avoid the process influencing the IVD mechanics. Axial compression-tension and torsional tests were performed on caudal motion segments, and the IVD diameter measurements were taken using a caliper. Assessments of IVD morphology, collagen molecular properties, and fiber orientation were created, measured, compared, and analyzed.

Results

The Western blot data showed a significant accumulation of AGEs accumulation of the IVD problems of the female mice fed the high AGE (H-AGE) diet compared to those fed the low AGE (L-AGE) diet. There were no changes in the IVD AGE levels or serum samples of the male mice in either feeding group. The results indicate that even without the presence of DM or obesity, dietary AGEs are likely to systemically accumulate in the IVDs of female mice—but not in males.

Further, the H-AGE female mice IVDs showed increase stiffness and torque-range, while the date on the L-AGE female mice showed no such correlation, and the male mice IVDs of both feeding groups were unaffected. This indicates that motion segment behaviors of female mouse IVDs—but not male mouse IVDs— are negatively affected by the H-AGE diet.

In addition, the AF organization and collagen fibers of H-AGE diet female mouse IVDs—but not male mouse IVDs— appeared compromised, particularly in the anterior AF. The H-AGE diet also appears to have contributed substantially to AGE accumulation and collagen damage in the AF of the female mice subjects but not the male mice subjects.

Conclusion

The results of this study, combined with previous study literature, suggests that female mice are negatively affected by a H-AGE diet, which appears to increase glycation within the AF collagen matrix and damage collagen and molecules in the IVD. High IVD crosslinking and collagen damage can contribute to biomechanical changes in the IVD and disrupt form and function in the unit. It appears that high AGE diets may increase these risks in female spinal tissues. Future research is needed to investigate ways to promote spinal health through dietary interventions to lower AGE levels, particularly in at-risk populations. This includes patients suffering from obesity and DM, especially females.

 

 

 

 

 

Stuart McGill, ddd spinal models

In an online interview with Bill Morgan, President of Parker University, world-renowned spine researcher and scientist, Stuart McGill, uses dynamic disc models from Dynamic Disc Designs to explain lumbar disc herniations, extrusions, and the mechanisms for lumbar disc injuries and treatments.

When treating spinal injuries, McGill stresses the importance of recognizing that the cause of most disc extrusions and herniations is a combination of factors, occurring over time. The cumulative array of factors may present as an acute condition causing pain, but in most cases, the disruption has not been created by a single loading event.

McGill uses the analogy of cloth to explain how repetitive loading and movement fray the collagen fibers that cover the socket joints, eventually working a hole into the fibers by repetitive stress strains occurring in a back and forth motion.

“The disc is layer upon layer of collagen fibers held together with [a tightly woven lamination matrix]. If you keep moving the disc under load, the hydraulic pressure of the pressurized nucleus slowly starts to work its way through the delamination that forms because of the movement,” he says.

He explains that when the collagen is intact and supple, a person has full range-of-motion without danger of creating tears, but when the spine is stiff and has become adapted to bearing heavy loads, it is in danger of injury.

“The problem comes when you combine the two worlds and confuse the adaptation process,” he says.

“In a modern lifestyle, you might have a person who sits at a computer for eight or more hours in a flexion stressed position which—on its own—may not be that bad. But then they go to the gym for an hour every night and start lifting loads. They’re taking their spine through the range of motion, so cumulatively, the collagen is asked to move, but it’s also pressurized. The nucleus behind gets pressurized and slowly works its way through the delaminated collagen.”

Stuart McGill, Models

Stuart McGill and the many ddd models he uses.

McGill, Dynamic Disc Designs

Professor Stuart McGill and Dynamic Disc Designs endorsement.

Recreating Compression Loading, Disc Bulge, and Proper Thrust Line with our Dynamic Model

Using the disc model, McGill demonstrates how the gel inside the disc remains pressurized under compression, but in cases where the collagen has become delaminated, bending the spine under a load creates a disc bulge.

“This is exactly what we see on dynamic MRI,” he says, manipulating the disc model to demonstrate. “In the laboratory we would inject the nucleus with various radio-opaque markers. We would watch the migration as the bulge would come through. Touch a nerve root and now you would match where the disc bulges with the precise anatomic pathway. If you sit for 20 minutes slouched and your right toe goes on fire, we know it’s the right ring and that’s exactly where the disk bulge is.”

McGill stacks the disc model into a thrust line and squeezes the spine segment to show how proper alignment adapts the movement experience.

“The whole disc is experiencing movement, but there’s no pressure, and nothing comes out to touch the nerve root,” he says.

Empowering the Patient with Simple Posture and Stress Exercise

McGill says his insight is based upon years of experiments studying the exact mechanisms of spinal injury and pain. He recommends using improved posture and stress—lying on the stomach for five minutes with two fists under their chin—to help,” mitigate the dynamics of that very dynamic disc bulge.”

He says the immediate relief provided by this simple exercise can empower a patient with discogenic pain and help alleviate the potential psychological trauma of feeling hopeless at not understanding the source of, or how to mitigate, pain.

intradiscal, endplate

A study 1 on the efficacy of intradiscal biologic therapy, where new cells or genes are implanted into the degenerated disc matrix to reduce inflammation and increase matrix cell production, found that degenerated discs may not have the necessary nutrient transport capabilities to ensure proper disc nutrition during this form of therapy. The authors of the study emphasize the importance of research into the determining factors influencing disc cell nutrient transport in informing targeted treatments and strategies to improve disc nutrition in degenerated discs.

What’s at Stake?

Disc degeneration (DD) is a chronic condition that causes spinal pain in aging adults worldwide. The process of DD involves biomechanical modeling of the entire disc matrix and frequently leads to surgical intervention to remove the offending disc and restore functionality to the spine. For many patients, surgical procedures are unsuccessful, however. A noninvasive treatment that has demonstrated recent promise involves regenerating the DD by injecting it with genes, growth factors, small molecules, or implanted cells. These procedures are intended to reduce inflammation and catabolism and assist in the creation of a new disc matrix. But a cell-rich disc requires increased nutrients, and the cartilage endplate (CEP) of the DD may not have the capacity to deliver these nutrients to the matrix. In this study, researchers examined the effects of CEP transport properties in DD on nutrient diffusion and cell function and survival.

The Study

In order to isolate the variable of how nutrient supply affects the nucleus pulposus (NP) cell function, the researchers involved in this study mimicked the in vivo, diffusion-poor disc environment by creating diffusion chambers with similar parameters to isolate the NP nutrient supply mechanics. The cells of the NP receive nutrients that are diffused through the CEP matrix. Cells at the center of the lumbar discs can be up to 10mm from a capillary, while other cells can be just beside a CEP.

Researchers provided glucose and oxygen to cultured NP cells within the chambers. These nutrients were delivered through diffusion from human CEP’s from the open sides of the chamber. Metabolites were expelled into the culture medium by CEP diffusion. The functioning and survival of the cells require a balance between CEP transport properties and cell density, allowing for the request and supply of nutrients. The researchers reproduced the disc matrix environment and physiologic transport conditions in their CEP tissue cultures and diffusion chambers to monitor the effects of NP cell viability and gene expression across the different conditions of nutrient transport.

Specifically, intact human CEP’s from human cadaveric lumbar spines were used for the study. Full-thickness samples of the CEP’s and surrounding calcified cartilage were frozen and sectioned. The researchers calculated the diffusivity of each full-thickness CEP sample through fluorescence and photo-bleaching and using the Axelrod method. They measured each CEP’s biochemical composition spatially via imaging. They created special maps of the collagen, aggrecan, and mineral-to-matrix ratio of the CEP samples with the highest and lowest diffusivities. They measured CEP thickness with photomicrographs and then determined the average measurement across the five chambers.

Bovine NP cells were used in the study (similar to human NP cells). Post-incubation cell viability was determined using a cytotoxicity assay involving gel-stains and low-magnification imagery. Each L4-L5 donor CEP was analyzed for cell density and the anabolic and catabolic gene expressions were examined after chamber incubation. A regression model of fluorescence intensity was used to determine the NP cell gene expression and distance from the CEP. Spatial fluctuations of the CEP composition were described based upon regression models.

Results

The diffusive transport of nutrients varied widely between the CEP samples, affecting the function, health, and survival potential of the NP cells. In fact, there was a four-fold variation in small solute diffusivity in our human CEP sample array. Those allowing less diffusive transport reduced the supply of nutrients to the NP and shortened the viable distance within the diffusion chambers up to 51 percent with typical cell density. Those permitting poor diffusion seemed to downregulate anabolic and catabolic NP cell gene expression. This may mean that a reduced number of disc cells are capable of being sustained through low nutrient CEP diffusion, and the cell’s ability to retain its matrix homeostatic condition is hindered.

When we increased cell density, there was a reduction in cell viability caused by the CEP transport properties, though increasing cell density should raise nutritional demands and shorten the viable distance.  The CEP’s in our study that exhibited low diffusive transport were unresponsive to doubling the cell density, perhaps because they did not provide enough nutrient diffusion to nurture the cell.

We imaged the CEP’s to identify any differences between those with low or high intradiscal diffusivity. Our data found that those with low-diffusivity (and shortened viable distance) contained more collagen and aggrecan, mineral, and lower cross-link maturity. This could explain the blockage of solute penetration and diffusion. At any rate, there appears to be a strong correlation between NP cell survival or function and the availability and mobility of the nutrient supply in the CEP. Compositional defects with the CEP matrix can inhibit nutrient diffusion and undermine biologic therapies that depend upon an increased supply of nutrients to the cell matrix to succeed.

Summary

Our findings suggest that the composition of CEP can contribute to or detract from the function and viability of NP cells. Deficits within the CEP matrix can cause poor nutrient diffusion and block solute passages. This can cause an abundance of collagen and aggrecan, as well as mineral, and lower cross-link maturity. When cell density is increased, CEP’s developed transport deficits, decreasing the cell’s viability. It appears NP function and survival are dependent on the proper CEP composition, as an imbalance in this makeup can reduce the supply of nutrients to the cells, reducing the success rates of biologic therapies.

 

Facet Tropism - Disc Bulge

A study examining the relationship between facet joint angulation, joint tropism, and Degenerative Spondylolisthesis (DS) found a clinically significant link between DS and facet tropism, as well as observing facet tropism in non-DS disc levels of the study subjects. This supports the theory that tropism may pre-exist and contribute to the development of DS, rather than being a by-product of the condition.

 

What’s at Stake?

DS is a common condition affecting middle-aged and the elderly population—especially women. Frequently occurring at the L4-L5 spinal level, the condition has been associated with a number of potential causes, including facet joint orientation. Patients with DS may have more sagittal-oriented facet joints, which allows anterior gliding of their superior vertebra. When a patient’s left and right facet joints are asymmetrical by a minimum of 8 degrees, the condition is considered to be tropism. The authors of this study compared patients with DS with a control group of patients who had no DS to determine how facet joint angulation and/or the presence of facet tropism might play a role in the development of DS.

 

The Study

A retrospective radiographic study of 45 patients with single-level DS, presenting with lower back pain (LBP), leg pain with or without neurological effects, and neurogenic claudication compared the images of the subjects in Group A with a control group (B) of 45 non-DS patients surgically treated for disc prolapse or stenosis, matched in sex and age. Patients with previous spinal surgery or trauma, tumors, vertebrae or congenital anomalies, degenerative lumbar scoliosis, and isthmic spondylolisthesis, as well as those with flawed imaging, were excluded from the group.

MRI axial images of various disc levels were processed and analyzed with PACS software in order to calculate the facet joint angles. A difference of 8 degrees of angulation was termed facet tropism. An independent and case-blinded observer assessed the images of both groups, and an analysis was conducted as to the orientation of the facet joints at three levels in both groups.

Results

Group A was comprised of 15 male subjects and 30 female subjects between 38 and 79 years of age, with a mean age of 62.2. Of the 45 Group A patients, 8.8 percent (4/45) presented with DS, two of which (50%) had facet tropism at index level. All four of these subjects also presented with facet tropism at an adjacent distal level. A total of 37 patients (82.2 percent) showed DS in the L4-5 level, and of those patients, 14 (37.8 percent) also had facet tropism at index level. Eleven patients (29.7 percent) presented with tropism at adjacent proximal level, and 29.7 percent (11) showed the condition at adjacent distal level. Four subjects had DS at L5-S1 level, and all of thse patients had facet propism at index level. A single patient also had tropism at adjacent L4-5 level, as well.

Twenty of the 45 Group A patients (44.4 percent) demonstrated facet tropism at the level of DS. IN addition, 12 of the patients (26.6 percent) had it at a proximal  level to DS level, and 15 (33.3 percent) at level distal to the DS level. Nineteen of the subjects (42.2 percent) had it at a single level, 9 showed tropism at two levels, and 4 (8.8 percent) had it at all three of the levels examined. In all, 71.1 percent of the patients in Group A had facet tropism at one or more levels.

The numbers in Group B were considerably lower, with 2 patients showing facet tropism at L3-4, 5 at L4-5, and 2 at L5-S1. Five of the subjects had single-level tropism, and 2 had it at two levels. None of the Group B patients had tropism at all three levels. In all, only 15.5 percent of the Group B subjects had facet tropism.

Conclusion

The study confirms the association between facet joint tropism and DS. More notably, the observation of higher numbers of facet joint tropism at adjacent non-DS levels in the DS group suggests that facet tropism could contribute to the development of DS, rather than being a secondary symptom of the condition. Patients presenting with single level DS should be followed up closely to monitor adjacent spinal segments that could become symptomatic in the future.

 

 

 

 

 

ddd models, dynamic disc models

A systematic clinical literature review 1 found evidence that high intensity zones (HIZ) on MRI scans may indicate a potential risk factor in lower back pain (LBP). The review authors suggest further studies are needed to understand the relevance of lumbar biomarkers in imaging to properly diagnose and classify LBP as it relates to HIZ.

What’s at Stake?

Various lumbar phenotypes have been identified and studied in the past to determine their effects on patients suffering from LBP. MRI is a common LBP diagnostic tool used by practitioners treating patients with LBP, but its effectiveness in identifying the sources of LBP has been questioned by researchers over the years. For three decades, the debate over whether and how imaged biomarkers may relate to LBP has remained inconclusive. This extensive literature review was conducted to seek clarity on how HIZ in MRI may indicate a reliable diagnostic tool for clinicians treating patients with LBP.

The Review

A total of 756 studies were scanned for data relating to search terms that were indicative of their usefulness to the researchers involved in this review. Six studies—five comparison studies, and one cross-sectional population-based study—were ultimately chosen for their relevance, and their data was reviewed in the context of an association between HIZ and LBP. The literature chosen was published between 2000 and 2015 and involved studies of symptomatic subjects and asymptomatic controls between the ages of 21 to 50 years of age.

Results

Three of the comparative studies demonstrated a clinically-significant association between HIZ and LBP. In one study, over 32 percent of the patients with LBP exhibited HIZ in at least one disc. Of these patients, 5.3 percent showed multi-segmental HIZs, with 3.9 percent showing HIZs in the adjacent discs. Furthermore, 57.5 percent of the HIZs subjects had symptoms of LBP, while only .02 percent of the patients without HIZs were symptomatic. There was a correlation between higher LBP incidence and HIZs in the lower lumbar spine or with multiple HIZs, but these statistics were considered clinically-insignificant. In another study, 61 percent of patients with HIZs experienced LBP, compared to only 32 percent of those without HIZs. The median rate of HIZs was lower in subjects without LBP than in those who were symptomatic.

While the data studied in this review indicates a higher prevalence of LBP in patients with identifiable HIZs in imaging studies, other studies have found little-to-no evidence of this correlation, indicating the need for further studies and reviews on the nature of HIZs and LBP in symptomatic and asymptomatic patients.

Conclusion

This systematic literature review suggests an association between HIZs and LBP. However, the authors express the need for further study of the LBP pathology and HIZs morphology/topography as they relate to various spinal phenotypes to determine how variant biomarkers on MRI studies may help determine the existence and source of LBP in patients.