Are "patterns" of lumbar disc degeneration associated with low back pain?: new insights based on skipped level disc pathology

Different Load-Induced Alterations in Intervertebral Discs Between Low Back Pain Patients and Controls: A T2-map Study

STUDY DESIGN

Prospective cohort study.

OBJECTIVE

Investigate load-induced effects in lumbar intervertebral discs (IVDs) and differences between low back pain (LBP) patients and controls.

SUMMARY OF BACKGROUND DATA

T2-map values, obtained from quantitative MRI sequences, reflect IVD tissue composition and integrity. Feasibility studies with T2-mapping indicate different load-induced effects in entire IVDs and posterior IVD parts between LBP patients and controls. Larger studies are required to confirm these findings and increase the understanding of specific characteristics distinguishing IVD changes in LBP patients compared with controls.

MATERIALS AND METHODS

Lumbar IVDs of 178 patients (mean age: 43.8 yr; range: 20-60 yr) with >3 months of LBP and 74 controls (mean age: 40.3 yr; range: 20-60 yr) were imaged with T2-map sequence in a 3T scanner in supine position without axial load, immediately followed by a repeated examination, using the same sequence, with axial load. On both examinations, mean T2-map values were obtained from entire IVDs and from central/posterior IVD parts on the three midsagittal slices in 855 patient IVDs and 366 control IVDs. Load-induced effect was compared with Fold-change ratio and adjusted for IVD-degeneration grade.

RESULTS

Loading induced an increase in T2-map values in both patients and controls. Excluding most extreme values, the ranges varied between -15% and +35% in patients and -11% and +36% in controls (first to 99th percentile). Compared with controls, the T2-map value increase in patients was 2% smaller in entire IVDs (Fold-change: 0.98, P =0.031), and for central and posterior IVD parts 3% (Fold-change: 0.98, P =0.005), respectively, 2% (Fold-change: 0.9, P =0.015) smaller.

CONCLUSIONS

This quantitative study confirmed diverse load-induced behaviors between LBP patients and controls, suggesting deviant biomechanical characteristics between IVDs in patients and controls not only attributed to the global grade of degeneration. These findings are an important step in the continuous work of identifying specific IVD phenotypes for LBP patients.

LEVEL OF EVIDENCE

Level II.

Role of End Plate Changes and Paraspinal Muscle Pathology in Lower Back Pain: A Narrative Review

Degenerative changes of the lumbar intervertebral disc are the most significant causes of enduring lower back pain. The possibility of the diagnosis is limited in people with this low back pain. Therefore, it is essential to identify the relevant back pain subgroups. The paraspinal muscles, that is, the muscles that attach to the spine, are necessary for the proper functioning of the spine and the body; insufficiency can result in back pain. Lower back pain disorders are strongly associated with altered function or structure of these paraspinal muscles, especially fibrosis and fatty infiltration. Modic changes are the bone marrow changes of the end plate in the vertebral body seen on MRI. These are strongly related to degeneration of the disc and are common in individuals with back pain symptoms. Articles were selected from Google Scholar using the terms 'Modic changes,' 'end plate changes,' 'paraspinal muscles,' and 'lower back pain. ' This article compiled different studies aiming to enhance the comprehension of biochemical processes resulting in the development of lumbar pain. Search using the keywords 'Modic changes,'' end plate changes lower back pain,' 'paraspinal muscles lower back pain,' and 'Modic changes lower back pain' on Google Scholar yielded 33000, 41000, 49400, and 17,800 results, and 958, 118, 890 and 560 results on Pubmed respectively.

MRI phenotypes of herniated discs associated with adjacent disc degeneration

Adjacent segment degeneration is commonly observed in patients after fusion surgery. Among the associated risk factors is the preoperative presence of adjacent disc degeneration (ADD). The risk factors and other spine phenotypes associated with preoperative ADD is critical to understand the pathological process and better prognosis postsurgery. Current study aims to assess and compare the magnetic resonance imaging (MRI) spinal phenotype of herniated level with and without ADD. Preoperative T2W sagittal lumbar MRI images of 155 lumbar disc herniated patients were analyzed for the presence of ADD (Pfirrmann grade III and above). The herniated disc level was assessed for the presence and absence of vertebral endplate (VEP) defects, Modic changes, and high intensity zone (HIZ). Mean age of patients was 38 ± 2 years, almost 62% were males. ADD was found in 57%, VEP defects were seen in 62% of the herniated level, 24.5% showed Modic changes, 3.8% showed spondylolishthesis, and 15.5% revealed HIZ. Age and other demographic factors did not have any significant effect on the presence of ADD, the patients with extruded and sequestered discs had more ADD (p = 0.02). VEP defects were significantly higher in levels with ADD (p = 0.02). Patients with ADD had significantly VEP defect scores (p = 0.01), Modic score (p = 0.002), HIZ score (0.02), and posterior bulge score (p < 0.001). Findings suggest that affected levels with VEP defects and severe grade of disc herniation have the greater likelihood of having ADD. Once developed this ADD may also affect the other spinal levels, and also can affect postoperative prognosis.

Extracellular Vesicle-Conjugated Functional Matrix Hydrogels Prevent Senescence by Exosomal miR-3594-5p-Targeted HIPK2/p53 Pathway for Disc Regeneration

Nucleus pulposus stem cells (NPSCs) senescence plays a critical role in the progression of intervertebral disc degeneration (IDD). Stem cell-derived extracellular vesicles (EV) alleviate cellular senescence. Whereas, the underlying mechanism remains unclear. Low stability largely limited the administration of EV in vivo. RGD, an arginine-glycine-aspartic acid tripeptide, strongly binds integrins expressed on the EV membranes, allowing RGD to anchor EV and prolong their bioavailability. An RGD-complexed nucleus pulposus matrix hydrogel (RGD-DNP) is developed to enhance the therapeutic effects of small EV (sEV). RGD-DNP prolonged sEV retention in vitro and ex vivo. sEV-RGD-DNP promoted NPSCs migration, decreased the number of SA-β-gal-positive cells, alleviated cell cycle arrest, and reduced p16, p21, and p53 activation. Small RNA-seq showed that miR-3594-5p is enriched in sEV, and targets the homeodomain-interacting protein kinase 2 (HIPK2)/p53 pathway. The HIPK2 knockdown rescues the impaired therapeutic effects of sEV with downregulated miR-3594-5p. RGD-DNP conjugate with lower amounts of sEV achieved similar disc regeneration with free sEV of higher concentrations in DNP. In conclusion, sEV-RGD-DNP increases sEV bioavailability and relieves NPSCs senescence by targeting the HIPK2/p53 pathway, thereby alleviating IDD. This work achieves better regenerative effects with fewer sEV and consolidates the theoretical basis for sEV application for IDD treatment.

The role of co-occurring insomnia and mental distress in the association between lumbar disc degeneration and low back pain related disability

BACKGROUND

Lumbar disc degeneration (LDD) is associated with low back pain (LBP). Although both insomnia and mental distress appear to influence the pain experience, their role in the association between LDD and LBP is uncertain. Our objective was to investigate the role of co-occurring insomnia and mental distress in the association between LDD and LBP-related disability.

METHODS

A total of 1080 individuals who had experienced LBP during the previous year underwent 1.5-T lumbar magnetic resonance imaging, responded to questionnaires, and participated in a clinical examination at the age of 47. Full data was available for 843 individuals. The presence of LBP and LBP-related disability (numerical rating scale, range 0-10) were assessed using a questionnaire. LDD was assessed by a Pfirrmann-based sum score (range 0-15, higher values indicating higher LDD). The role of insomnia (according to the five-item Athens Insomnia Scale) and mental distress (according to the Hopkins Symptom Check List-25) in the association between the LDD sum score and LBP-related disability was analyzed using linear regression with adjustments for sex, smoking, body mass index, education, leisure-time physical activity, occupational physical exposure, Modic changes, and disc herniations.

RESULTS

A positive association between LDD and LBP-related disability was observed among those with absence of both mental distress and insomnia (adjusted B = 0.132, 95% CI = 0.028-0.236, p = 0.013), and among those with either isolated mental distress (B = 0.345 CI = 0.039-0.650, p = 0.028) or isolated insomnia (B = 0.207, CI = 0.040-0.373, p = 0.015). However, among individuals with co-occurring insomnia and mental distress, the association was not significant (B = -0.093, CI = -0.346-0.161, p = 0.470).

CONCLUSIONS

LDD does not associate with LBP-related disability when insomnia and mental distress co-occur. This finding may be useful when planning treatment and rehabilitation that aim to reduce disability among individuals with LDD and LBP. Future prospective research is warranted.

Evaluation of health related quality of life with the use of Oswestry disability index in degenerative discogenic low back pain

Background

Intervertebral disc degeneration (IVD) is a main underlying cause for low back pain (LBP). Oswestry Disability Index (ODI) is a valuable tool used to measure patient’s low back functional outcome. Our aim is to evaluate the relation between clinical assessment of LBP and health related quality of life with the use of ODI and magnetic resonance image (MRI) findings in patients with degenerative prolapsed IVD disease.

Result

There was a significant correlation between Pfirrmann grades and ODI (p < 0.0001) and with type of disc morphology mostly protrusion (p < 0.0001) but insignificant correlation with visual analogue scale (VAS) (p = 0.198) and most of the clinical parameters (p > 0.05). There was a significant correlation between ODI and VAS (p = 0.003). Higher Pfirrmann grades were found at lower lumbosacral levels L4-5 and L5-S1.

Conclusion

Higher Pfirrmann grades correlated with the increased ODI. No association was found between MRI grading in lumbosacral spine with pain intensity and most of the clinical parameters among persons with discogenic LBP. Chronic LBP is widely accepted to be a multifactorial disorder that could not be contained within a single lumbar compartment. Clinician should not depend on MRI findings only in the diagnosis. History from the patient and clinical examination is particularly important to reach the final diagnosis. ODI might be convenient in achieving patient’s confidence and decreasing unnecessary investigations.

TGF-β1-supplemented decellularized annulus fibrosus matrix hydrogels promote annulus fibrosus repair

Annulus fibrosus (AF) repair remains a challenge because of its limited self-healing ability. Endogenous repair strategies combining scaffolds and growth factors show great promise in AF repair. Although the unique and beneficial characteristics of decellularized extracellular matrix (ECM) in tissue repair have been demonstrated, the poor mechanical property of ECM hydrogels largely hinders their applications in tissue regeneration. In the present study, we combined polyethylene glycol diacrylate (PEGDA) and decellularized annulus fibrosus matrix (DAFM) to develop an injectable, photocurable hydrogel for AF repair. We found that the addition of PEGDA markedly improved the mechanical strength of DAFM hydrogels while maintaining their porous structure. Transforming growth factor-β1 (TGF-β1) was further incorporated into PEGDA/DAFM hydrogels, and it could be continuously released from the hydrogel. The in vitro experiments showed that TGF-β1 facilitated the migration of AF cells. Furthermore, PEGDA/DAFM/TGF-β1 hydrogels supported the adhesion, proliferation, and increased ECM production of AF cells. In vivo repair performance of the hydrogels was assessed using a rat AF defect model. The results showed that the implantation of PEGDA/DAFM/TGF-β1 hydrogels effectively sealed the AF defect, prevented nucleus pulposus atrophy, retained disc height, and partially restored the biomechanical properties of disc. In addition, the implanted hydrogel was infiltrated by cells resembling AF cells and well integrated with adjacent AF tissue. In summary, findings from this study indicate that TGF-β1-supplemented DAFM hydrogels hold promise for AF repair.

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Injectable DAFM derived hydrogel with mechanical property matching natural AF and sustained TGF-β1 release was developed.

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DAFM derived hydrogels promote AF cell proliferation, migration and ECM production.

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DAFM derived hydrogels display good integration with host AF tissue.

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DAFM derived hydrogels facilitate AF repair and restore intervertebral disc biomechanics.

MRI grading of spinal stenosis is not associated with the severity of low back pain in patients with lumbar spinal stenosis

Background

Although lumbar spinal stenosis (LSS) often coexists with other degenerative conditions, few studies have fully assessed possible contributing factors for low back pain (LBP) in patients with LSS. The purpose of this study was to identify factors associated with the severity of LBP in patients with LSS.

Methods

The patients with neurogenic claudication caused by LSS, which was confirmed by magnetic resonance imaging (MRI) were included in this cross-sectional study. Data included ratings of LBP, buttock and leg pain, and numbness on a numerical rating scale (NRS), 36-item Short-Form Survey (SF-36) scores, muscle mass measured by bioelectrical impedance analysis, and radiographic measurements including lumbopelvic alignment and slippage. The severity of LSS, endplate defects, Modic endplate changes, intervertebral disc degeneration, and facet joint osteoarthritis were evaluated on MRI. Spearman correlation and multivariate linear regression analyses were used to examine the factors associated with the severity of LBP (NRS score).

Results

A total of 293 patients (135 male and 158 female, average age 72.6 years) were analyzed. LBP was moderately correlated with buttock and leg pain, and buttock and leg numbness. Significant but weak correlations were observed between LBP and body mass index, appendicular and trunk muscle mass, all domains of SF-36, pelvic tilt, total number of endplate defects and Modic endplate changes, and summary score of disc degeneration grading, but not severity or number of spinal stenoses. In the multivariate regression analysis, age, female sex, trunk muscle mass, diabetes, NRS buttock and leg pain, NRS buttock and leg numbness, SF-36 vitality, pelvic tilt, and total number of endplate defects were associated with the severity of LBP.

Conclusions

Trunk muscle mass, lumbopelvic alignment, and endplate defects, but not severity of stenosis are partly associated with severity of LBP, but buttock and leg pain and buttock and leg numbness have strongest relationships with LBP in patients with LSS.

Hyperosmolar expansion medium improves nucleus pulposus cell phenotype

Background

Repopulating the degenerated intervertebral disc (IVD) with tissue‐specific nucleus pulposus cells (NPCs) has already been shown to promote regeneration in various species. Yet the applicability of NPCs as cell‐based therapy has been hampered by the low cell numbers that can be extracted from donor IVDs and their potentially limited regenerative capacity due to their degenerated phenotype. To optimize the expansion conditions, we investigated the effects of increasing culture medium osmolarity during expansion on the phenotype of dog NPCs and their ability to produce a healthy extracellular matrix (ECM) in a 3D culture model.

Methods

Dog NPCs were expanded in expansion medium with a standard osmolarity of 300 mOsm/L or adjusted to 400 or 500 mOsm/L in both normoxic and hypoxic conditions. Following expansion, NPCs were cultured in a 3D culture model in chondrogenic culture medium with a standard osmolarity. Read‐out parameters included cell proliferaton rate, morphology, phenotype and healthy ECM production.

Results

Increasing the expansion medium osmolarity from 300 to 500 mOsm/L resulted in NPCs with a more rounded morphology and a lower cell proliferation rate accompanied by the expression of several healthy NPC and progenitor markers at gene (KRT18, ACAN, COL2, CD73, CD90) and protein (ACAN, PAX1, CD24, TEK, CD73) level. The NPCs expanded at 500 mOsm/L were able to retain most of their phenotypic markers and produce healthy ECM during 3D culture independent of the oxygen level used during expansion.

Conclusions

Altogether, our findings show that increasing medium osmolarity during expansion results in an NPC population with improved phenotype, which could enhance the potential of cell‐based therapies for IVD regeneration.

Prevalence and Definition of Multilevel Lumbar Developmental Spinal Stenosis

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

To define multilevel lumbar developmental spinal stenosis (DSS) using a composite score model and to determine its prevalence.

METHODS

This was a cohort study of 2385 openly recruited subjects with lumbosacral (L1-S1) MRIs. All subjects with previous spinal surgery or spinal deformities were excluded. The anteroposterior (AP) vertebral canal diameter was measured by two independent observers. Any associations between level-specific vertebral canal diameter and subject body habitus were analysed with non-parametric tests. Three or more stenotic levels, equivalent to a composite score of 3 or more, were considered as multilevel DSS. The median values of these subjects' AP canal diameters were used to construct the multilevel DSS values. Receiver operating characteristic analysis was utilized to determine the ability of these cut-off values to screen for DSS by presenting their area under curve, sensitivity and specificity.

RESULTS

Subject body habitus was poorly correlated with AP vertebral canal diameter. Multilevel DSS was identified as L1<19 mm, L2<19 mm, L3<18 mm, L4<18 mm, L5<18 mm, S1<16 mm with 81%-96% sensitivity and 72%-91% specificity. The prevalence of multilevel DSS in this cohort was 7.3%.

CONCLUSIONS

Utilizing a large homogeneous cohort, the prevalence of multilevel DSS is determined. Our cut-offs provide high diagnostic accuracy. Patients with multiple levels that fulfil these criteria may be at-risk of spinal canal compressions at multiple sites.

LEVEL OF EVIDENCE

III.

Anemia was associated with multilevel lumbar disc degeneration in patients with low back pain: a single-center retrospective study

PURPOSE

It has not been determined which factors were related to multilevel lumbar disc degeneration (MLDD). The objective of this study was to determine the prevalence of MLDD among symptomatic patients using the magnetic resonance imaging method. The study also aimed to clarify the associations between MLDD and suspected risk factors through a multivariate model.

METHODS

A total of 530 young and middle-aged patients, suffered from low back pain were retrospectively assessed by 2 independent observers, who used sagittal T2-weighted MR imaging. Subjects were divided into two groups, MLDD group and non-MLDD group, according to the number of degenerated discs. Demographic and radiological data included age, gender, weight, height, body mass index, smoking status, alcohol drinking, lumbar lordosis, presence of hypertension (HT), diabetes mellitus and anemia.

RESULTS

There were 309 men and 221 women with an average age of 37.5  ±  8.5 years. In general, 37.7% of patients were diagnosed with disc degeneration (DD) at more than two levels. Triple level DD was the most common pattern and was more prevalent in women (p <0.05). Using multivariate analyses, age (odds ratio [OR]: 1.14; 95% confidence interval [CI] 1.11-1.18; p <0.001), hypertension (OR: 2.67; 95% CI 1.38-5.16; p = 0.03) and anemia (OR: 3.84; 95% CI 2.03-7.28; p <0.001) were significantly associated with MLDD.

CONCLUSION

Despite the young age of this cohort, MLDD is common among patients with low back pain. A significant independent association exists between age, HT, anemia and multilevel disc degeneration in the lumbar region.

Association of lumbar disc degeneration with low back pain in middle age in the Northern Finland Birth Cohort 1966

Background

Although it has been suggested that lumbar disc degeneration (LDD) is a significant risk factor for low back pain (LBP), its role remains uncertain. Our objective was to clarify the association between LDD and LBP and whether mental distress modifies the association.

Methods

Participants of a birth cohort underwent 1.5-T lumbar magnetic resonance imaging at the age of 47. The association between the sum score of LDD (Pfirrmann classification, range 0–15) and LBP (categorized into “no pain”, “mild-to-moderate pain”, “bothersome-and-frequent pain”) was assessed using logistic regression analysis, with sex, smoking, body mass index, physical activity, occupational exposure, education, and presence of Modic changes and disc herniations as confounders. The modifying role of mental distress (according to the Hopkins Symptom Check List-25 [HSCL-25], the Beck Depression Inventory and the Generalized Anxiety Disorder Scale) in the association was analyzed using linear regression.

Results

Of the study population (n = 1505), 15.2% had bothersome and frequent LBP, and 29.0% had no LBP. A higher LDD sum score increased the odds of belonging to the “mild-to-moderate pain” category (adjusted OR corresponding to an increase of one point in the LDD sum score 1.11, 95% CI 1.04–1.18, P = 0.003) and the “bothersome-and-frequent pain” category (adjusted OR 1.20, 95% CI 1.10–1.31, P < 0.001), relative to the “no pain” category. Mental distress significantly modified the association between LDD and LBP, as a linear positive association was consistently observed among individuals without mental distress according to HSCL-25 (adjusted B 0.16, 95% CI 0.07–0.26, P < 0.001), but not among individuals with higher mental distress.

Conclusions

LDD was significantly associated with both mild-to-moderate and bothersome-and-frequent LBP. However, the co-occurrence of mental distress diminished the association between LDD and LBP bothersomeness. Our results strongly suggest that mental symptoms affect the pain experience.

Notochordal Cell-Based Treatment Strategies and Their Potential in Intervertebral Disc Regeneration

Chronic low back pain is the number one cause of years lived with disability. In about 40% of patients, chronic lower back pain is related to intervertebral disc (IVD) degeneration. The standard-of-care focuses on symptomatic relief, while surgery is the last resort. Emerging therapeutic strategies target the underlying cause of IVD degeneration and increasingly focus on the relatively overlooked notochordal cells (NCs). NCs are derived from the notochord and once the notochord regresses they remain in the core of the developing IVD, the nucleus pulposus. The large vacuolated NCs rapidly decline after birth and are replaced by the smaller nucleus pulposus cells with maturation, ageing, and degeneration. Here, we provide an update on the journey of NCs and discuss the cell markers and tools that can be used to study their fate and regenerative capacity. We review the therapeutic potential of NCs for the treatment of IVD-related lower back pain and outline important future directions in this area. Promising studies indicate that NCs and their secretome exerts regenerative effects, via increased proliferation, extracellular matrix production, and anti-inflammatory effects. Reports on NC-like cells derived from embryonic- or induced pluripotent-stem cells claim to have successfully generated NC-like cells but did not compare them with native NCs for phenotypic markers or in terms of their regenerative capacity. Altogether, this is an emerging and active field of research with exciting possibilities. NC-based studies demonstrate that cues from developmental biology can pave the path for future clinical therapies focused on regenerating the diseased IVD.

Endplate defects, not the severity of spinal stenosis, contribute to low back pain in patients with lumbar spinal stenosis

BACKGROUND CONTEXT

It is controversial whether lumbar spinal stenosis (LSS) itself contributes to low back pain (LBP). Lower truncal skeletal muscle mass, spinopelvic malalignment, intervertebral disc degeneration, and endplate abnormalities are thought to be related to LBP. However, whether these factors cause LBP in patients with LSS is unclear.

PURPOSE

To identify factors associated with LBP in patients with LSS.

STUDY DESIGN/SETTING

Cross-sectional design.

PATIENT SAMPLE

A total of 260 patients (119 men and 141 women, average age 72.8 years) with neurogenic claudication caused by LSS, as confirmed by magnetic resonance imaging (MRI).

OUTCOME MEASURES

Ratings of LBP, buttock and leg pain, and numbness on a numerical rating scale (NRS), 36-Item Short Form Survey (SF-36) scores, muscle mass measured by bioelectrical impedance analysis, and radiographic measurements including slippage and lumbopelvic alignment. The severity of LSS, endplate defects, Modic endplate changes, intervertebral disc degeneration, and facet joint osteoarthritis were assessed on MRI.

METHODS

The presence of LBP was defined as an NRS score ≥3. The demographic data, patient-reported outcomes, and radiological and MRI findings were compared between patients with and without LBP. Multivariate logistic regression analysis was used to identify the factors that were independently associated with the presence of LBP.

RESULTS

There were significant differences between patients with and without LBP for buttock and leg pain and numbness on the NRS, general health on the SF-36, presence of endplate defects, presence of Modic changes, disc degeneration grading, and disc height grading (all p < .05). Multivariate logistic regression analysis showed significant associations between LBP and diabetes (OR 2.43; 95% CI 1.07-5.53), buttock and leg numbness on the NRS (OR 1.34; 95% CI 1.17-1.52), general health on the SF-36 (OR 0.97; 95% CI 0.95-0.99), and the presence of erosive endplate defects (OR 3.04; 95% CI 1.51-6.11) (all p < .05).

CONCLUSIONS

These results suggest that LBP in patients with LSS should be carefully assessed not only for spinal stenosis but also clinical factors and endplate defects.

Texture analysis in the classification of T2 -weighted magnetic resonance images in persons with and without low back pain

Magnetic resonance imaging findings often do not distinguish between people with and without low back pain (LBP). However, there are still a large number of people who undergo magnetic resonance imaging to help determine the etiology of their back pain. Texture analysis shows promise for the classification of tissues that look similar, and machine learning can minimize the number of comparisons. This study aimed to determine if texture features from lumbar spine magnetic resonance imaging differ between people with and without LBP. In total, 14 participants with chronic LBP were matched for age, weight, and gender with 14 healthy volunteers. A custom texture analysis software was used to construct a gray-level co-occurrence matrix with one to four pixels offset in 0° direction for the disc and superior and inferior endplate regions. The Random Forests Algorithm was used to select the most promising classifiers. The linear mixed-effect model analysis was used to compare groups (pain vs. pain-free) at each level controlling for age. The Random Forest Algorithm recommended focusing on intervertebral discs and endplate zones at L4-5 and L5-S1. Differences were observed between groups for L5-S1 superior endplate contrast, homogeneity, and energy (p = .02). Differences were observed for L5-S1 disc contrast and homogeneity (p < .01), as well as for the inferior endplates contrast, homogeneity, and energy (p < .03). Magnetic resonance imaging textural features may have potential in identifying structures that may be the target of further investigations about the reasons for LBP.

Role of CD14-positive cells in inflammatory cytokine and pain-related molecule expression in human degenerated intervertebral discs

Multiple human and animal studies suggest that the upregulation of inflammatory cytokines and other pain-related molecules in degenerated or injured intervertebral discs (IVDs) may cause discogenic low back pain (LBP). We previously reported that macrophages in injured IVD in mice produced inflammatory cytokines, but not other pain-related molecules. CD14 is a monocyte marker expressed mainly by macrophages. The aim of the current study was to evaluate the role of CD14-positive cells in inflammatory cytokine and pain-related molecule expression in human degenerated IVD. IVD samples were harvested from 14 patients, including 10 with lumbar spinal stenosis, four with adult spinal deformity, and one with lumbar disc herniation during spinal interbody fusion surgery. Harvested IVD-derived mononuclear cells were obtained and CD14-positive (+) and CD14-negative (-) cells were separated using CD14 antibody and streptavidin-labeled magnetic beads. Inflammatory cytokines messenger RNA (mRNA) in the CD14(+) and CD14(-) cells, including tumor necrosis factor ɑ (TNFA), in, terleukin-1β (IL1B) and IL6, were determined using quantitative polymerase chain reaction (qPCR) and their expression levels were compared. To evaluate factors controlling the regulation of pain-related molecules mRNA expression, cultured CD14(-) and CD14(+) cells from IVDs were stimulated with recombinant human TNF-ɑ and IL-1β and levels of pain-related molecules, including calcitonin gene-related peptide (CGRP) and nerve growth factor (NGF) were determined using qPCR. Levels of TNFA, IL1B, IL6, and NGF in CD14(+) cells were significantly increased compared with those in CD14(-) cells (TNFA, p = 0.006; IL1B, p = .017; IL6, p = .010; NGF, p = .027). Following TNFA stimulation, NGF levels were significantly increased in CD14(-) and CD14(+) cells (CD14(-), p = .003; CD14(+), p < .001) and CGRP was significantly increased in CD14(-) IVD cells (p = .040). Following IL1B stimulation, NGF levels were significantly increased in CD14(-) cells (p = .004). CD14(+) cells had higher TNFA, IL1B, IL6, and NGF expressions than CD14(-) cells in human degenerated IVDs. Additionally, TNFA stimulation promoted the upregulation of NGF and CGRP in CD14(-) cells. These findings suggested that CD14(+) cells directly and indirectly contributed to inflammatory cytokine and pain-related molecule expression in human degenerated IVD. CD14(+) cells might be important in the pathological mechanism of chronic discogenic LBP in humans.

Prospective Evaluation of Local Sustained Release of Celecoxib in Dogs with Low Back Pain

Back pain affects millions globally and in 40% of the cases is attributed to intervertebral disc degeneration. Oral analgesics are associated with adverse systemic side-effects and insufficient pain relief. Local drug delivery mitigates systemic effects and accomplishes higher local dosing. Clinical efficacy of intradiscally injected celecoxib (CXB)-loaded polyesteramide microspheres (PEAMs) was studied in a randomized prospective double-blinded placebo controlled veterinary study. Client-owned dog patients suffering from back pain were treated with CXB-loaded (n = 20) or unloaded PEAMs ("placebo") (n = 10) and evaluated by clinical examination, gait analysis, owners' questionnaires, and MRI at 6 and 12 weeks follow-up. At 6 and 12 weeks, CXB-treated dogs experienced significantly less pain interference with their daily life activities compared to placebo. The risk ratio for treatment success was 1.90 (95% C.I. 1.24-2.91, p = 0.023) at week 6 and 1.95 (95% C.I. 1.10-3.45, p = 0.036) at week 12. The beneficial effects of CXB-PEAMs were more pronounced for the subpopulation of male dogs and those with no Modic changes in MRI at inclusion in the study; disc protrusion did not affect the outcome. It remains to be determined whether intradiscal injection of CXB-PEAMs, in addition to analgesic properties, has the ability to halt the degenerative process in the long term or restore the disc.

A comprehensive tool box for large animal studies of intervertebral disc degeneration

Preclinical studies involving large animal models aim to recapitulate the clinical situation as much as possible and bridge the gap from benchtop to bedside. To date, studies investigating intervertebral disc (IVD) degeneration and regeneration in large animal models have utilized a wide spectrum of methodologies for outcome evaluation. This paper aims to consolidate available knowledge, expertise, and experience in large animal preclinical models of IVD degeneration to create a comprehensive tool box of anatomical and functional outcomes. Herein, we present a Large Animal IVD Scoring Algorithm based on three scales: macroscopic (gross morphology, imaging, and biomechanics), microscopic (histological, biochemical, and biomolecular analyses), and clinical (neurologic state, mobility, and pain). The proposed algorithm encompasses a stepwise evaluation on all three scales, including spinal pain assessment, and relevant structural and functional components of IVD health and disease. This comprehensive tool box was designed for four commonly used preclinical large animal models (dog, pig, goat, and sheep) in order to facilitate standardization and applicability. Furthermore, it is intended to facilitate comparison across studies while discerning relevant differences between species within the context of outcomes with the goal to enhance veterinary clinical relevance as well. Current major challenges in pre-clinical large animal models for IVD regeneration are highlighted and insights into future directions that may improve the understanding of the underlying pathologies are discussed. As such, the IVD research community can deepen its exploration of the molecular, cellular, structural, and biomechanical changes that occur with IVD degeneration and regeneration, paving the path for clinically relevant therapeutic strategies.

Development of a standardized histopathology scoring system for human intervertebral disc degeneration: an Orthopaedic Research Society Spine Section Initiative

BACKGROUND

Histopathological analysis of intervertebral disc (IVD) tissues is a critical domain of back pain research. Identification, description, and classification of attributes that distinguish abnormal tissues form a basis for probing disease mechanisms and conceiving novel therapies. Unfortunately, lack of standardized methods and nomenclature can limit comparisons of results across studies and prevent organizing information into a clear representation of the hierarchical, spatial, and temporal patterns of IVD degeneration. Thus, the following Orthopaedic Research Society (ORS) Spine Section Initiative aimed to develop a standardized histopathology scoring scheme for human IVD degeneration.

METHODS

Guided by a working group of experts, this prospective process entailed a series of stages that consisted of reviewing and assessing past grading schemes, surveying IVD researchers globally on current practice and recommendations for a new grading system, utilizing expert opinion a taxonomy of histological grading was developed, and validation performed.

RESULTS

A standardized taxonomy was developed, which showed excellent intra-rater reliability for scoring nucleus pulposus (NP), annulus fibrosus (AF), and cartilaginous end plate (CEP) regions (interclass correlation [ICC] > .89). The ability to reliably detect subtle changes varied by IVD region, being poorest in the NP (ICC: .89-.95) where changes at the cellular level were important, vs the AF (ICC: .93-.98), CEP (ICC: .97-.98), and boney end plate (ICC: .96-.99) where matrix and structural changes varied more dramatically with degeneration.

CONCLUSIONS

The proposed grading system incorporates more comprehensive descriptions of degenerative features for all the IVD sub-tissues than prior criteria. While there was excellent reliability, our results reinforce the need for improved training, particularly for novice raters. Future evaluation of the proposed system in real-world settings (eg, at the microscope) will be needed to further refine criteria and more fully evaluate utility. This improved taxonomy could aid in the understanding of IVD degeneration phenotypes and their association with back pain.

The profile of the spinal column in subjects with lumbar developmental spinal stenosis

AIMS

The aim of this study was to determine the differences in spinal imaging characteristics between subjects with or without lumbar developmental spinal stenosis (DSS) in a population-based cohort.

METHODS

This was a radiological analysis of 2,387 participants who underwent L1-S1 MRI. Means and ranges were calculated for age, sex, BMI, and MRI measurements. Anteroposterior (AP) vertebral canal diameters were used to differentiate those with DSS from controls. Other imaging parameters included vertebral body dimensions, spinal canal dimensions, disc degeneration scores, and facet joint orientation. Mann-Whitney U and chi-squared tests were conducted to search for measurement differences between those with DSS and controls. In order to identify possible associations between DSS and MRI parameters, those who were statistically significant in the univariate binary logistic regression were included in a multivariate stepwise logistic regression after adjusting for demographics. Odds ratios (ORs) and 95% confidence intervals (CIs) were reported where appropriate.

RESULTS

Axial AP vertebral canal diameter (p < 0.001), interpedicular distance (p < 0.001), AP dural sac diameter (p < 0.001), lamina angle (p < 0.001), and sagittal mid-vertebral body height (p < 0.001) were significantly different between those identified as having DSS and controls. Narrower interpedicular distance (OR 0.745 (95% CI 0.618 to 0.900); p = 0.002) and AP dural sac diameter (OR 0.506 (95% CI 0.400 to 0.641); p < 0.001) were associated with DSS. Lamina angle (OR 1.127 (95% CI 1.045 to 1.214); p = 0.002) and right facet joint angulation (OR 0.022 (95% CI 0.002 to 0.247); p = 0.002) were also associated with DSS. No association was observed between disc parameters and DSS.

CONCLUSION

From this large-scale cohort, the canal size is found to be independent of body stature. Other than spinal canal dimensions, abnormal orientations of lamina angle and facet joint angulation may also be a result of developmental variations, leading to increased likelihood of DSS. Other skeletal parameters are spared. There was no relationship between DSS and soft tissue changes of the spinal column, which suggests that DSS is a unique result of bony maldevelopment. These findings require validation in other ethnicities and populations. Level of Evidence: I (diagnostic study) Cite this article: Bone Joint J 2021;103-B(4):725-733.

The Natural History of Ossification of Yellow Ligament of the Thoracic Spine on MRI: A Population-Based Cohort Study

PURPOSE

To assess the natural history of ossification of yellow ligament (OYL) in the thoracic spine and determine risk factors for progression based on a longitudinal population-based cohort.

METHODS

A prospective, longitudinal cohort study was performed on a population-based cohort of Southern Chinese volunteers. T2-weighted magnetic resonance imaging (MRI) was used at baseline to identify any OYL and was verified with computed tomography. Follow-up MRI was performed 5 years later. Parameters under study included the size of OYL, levels of involvement, morphology (round, triangular, beak), whether it crossed the midline and any disc degeneration.

RESULTS

A total of 114 (6.1%) individuals were identified to have OYL at baseline out of the 1864 individuals. Size progression occurred predominantly at the lower thoracic region. Majority of the new OYL were also in the lower thoracic spine and was associated with higher body mass index (BMI). Smokers were associated with OYL size progression while patients with higher BMI tended to develop new OYL at follow-up. Progression commonly occurred at the lower thoracic levels and regression occurred mostly at the upper thoracic levels.

CONCLUSIONS

This is the first population-based series addressing the natural history of OYL. Better understanding of the natural history of OYL may provide incentive to introduce preventive measures such as weight reduction and close monitoring for myelopathy development in those at-risk groups for progression. This is especially important for patients with lower thoracic OYL and who are smokers with higher BMI.

LEVEL OF EVIDENCE

1 (prognostic study).

Clinical implications of lumbar developmental spinal stenosis on back pain, radicular leg pain, and disability

AIMS

To study the associations of lumbar developmental spinal stenosis (DSS) with low back pain (LBP), radicular leg pain, and disability.

METHODS

This was a cross-sectional study of 2,206 subjects along with L1-S1 axial and sagittal MRI. Clinical and radiological information regarding their demographics, workload, smoking habits, anteroposterior (AP) vertebral canal diameter, spondylolisthesis, and MRI changes were evaluated. Mann-Whitney U tests and chi-squared tests were conducted to search for differences between subjects with and without DSS. Associations of LBP and radicular pain reported within one month (30 days) and one year (365 days) of the MRI, with clinical and radiological information, were also investigated by utilizing univariate and multivariate logistic regressions.

RESULTS

Subjects with DSS had higher prevalence of radicular leg pain, more pain-related disability, and lower quality of life (all p < 0.05). Subjects with DSS had 1.5 (95% confidence interval (CI) 1.0 to 2.1; p = 0.027) and 1.8 (95% CI 1.3 to 2.6; p = 0.001) times higher odds of having radicular leg pain in the past month and the past year, respectively. However, DSS was not associated with LBP. Although, subjects with a spondylolisthesis had 1.7 (95% CI 1.1 to 2.5; p = 0.011) and 2.0 (95% CI 1.2 to 3.2; p = 0.008) times greater odds to experience LBP in the past month and the past year, respectively.

CONCLUSION

This large-scale study identified DSS as a risk factor of acute and chronic radicular leg pain. DSS was seen in 6.9% of the study cohort and these patients had narrower spinal canals. Subjects with DSS had earlier onset of symptoms, more severe radicular leg pain, which lasted for longer and were more likely to have worse disability and poorer quality of life. In these patients there is an increased likelihood of nerve root compression due to a pre-existing narrowed canal, which is important when planning surgery as patients are likely to require multi-level decompression surgery. Cite this article: Bone Joint J 2021;103-B(1):131-140.

Could compression and traction loading improve the ability of magnetic resonance imaging to identify findings related to low back pain?

BACKGROUND

Diagnostic imaging is routinely used to depict structural abnormalities in people with low back pain (LBP), but most findings are prevalent in people with and without LBP. It has been suggested that LBP is related to changes induced in the spine due to loading. Therefore, new imaging measurements are needed to improve our ability to identify structures relating to LBP.

OBJECTIVES

To investigate the response of the lumbar spine to compression and traction in participants with and without chronic LBP using MRI T₂-mapping.

METHOD

Fifteen participants with chronic LBP were matched for age, weight, and gender with 15 healthy volunteers. All participants underwent MRI under three loading conditions maintained for 20 min each: resting supine, followed by compression and traction, both using 50% body weight. Participants were imaged in the last 5 min of each loading condition. Disc morphometric and fluid-based measurements from T₂-maps were obtained.

RESULTS

Traditional MRI measurements (i.e. disc height, width and mean signal intensity) were not able to capture any differences in the changes measured in response to loading between individuals with and without pain. The location of the T₂ weighted centroid (WC) was able to capture the difference between groups in response to compression in the horizontal (p < 0.01) and vertical direction (p < 0.01), and in response to traction in the vertical direction (p < 0.01). While the location of T₂WC moved anteriorly (Effect Size (ES): 0.44) and inferiorly with compression in those with pain (ES: 0.34), it moved posteriorly (ES: -0.14) and superiorly (ES: -0.05) in the group without pain. In response to traction, the vertical location of T₂WC moved superiorly in both groups but the change was larger in those with pain (ES _Pain = -0.52; ES _{No Pain}: -0.13).

CONCLUSION

The novel measurements of the location of the T₂WC in the intervertebral discs were the only measurements capturing differences in response to loading between those with and without low back pain.

"Old Drugs, New Tricks" - Local controlled drug release systems for treatment of degenerative joint disease

Osteoarthritis (OA) and chronic low back pain (CLBP) caused by intervertebral disc (IVD) degeneration are joint diseases that have become major causes for loss of quality of life worldwide. Despite the unmet need, effective treatments other than invasive, and often ineffective, surgery are lacking. Systemic administration of drugs entails suboptimal local drug exposure in the articular joint and IVD. This review provides an overview of the potency of biomaterial-based drug delivery systems as novel treatment modality, with a focus on the biological effects of drug release systems that have reached translation at the level of in vivo models and relevant ex vivo models. These studies have shown encouraging results of biomaterial-based local delivery of several types of drugs, mostly inhibitors of inflammatory cytokines or other degenerative factors. Prevention of inflammation and degeneration and pain relief was achieved, although mainly in small animal models, with interventions applied at an early disease stage. Less convincing data were obtained with the delivery of regenerative factors. Multidisciplinary efforts towards tackling the discord between in vitro and in vivo release, combined with adaptations in the regulatory landscape may be needed to enhance safe and expeditious introduction of more and more effective controlled release-based treatments with the OA and CLBP patients.

Radiographic cervical spine degenerative findings: a study on a large population from age 18 to 97 years

Purpose

The aims of this study were (1) to determine the prevalence of radiographic cervical disc degeneration in a large population of patients aged from 18 to 97 years; (2) to investigate individually the prevalence and distribution of height loss, osteophyte formation, endplate sclerosis and spondylolisthesis; and (3) to describe the patterns of cervical disc degeneration.

Methods

A retrospective study was performed. Standard lateral cervical spine radiographs in standing, neutral position of 1581 consecutive patients (723 males, 858 females) with an average age of 41.2 ± 18.2 years were evaluated. Cervical disc degeneration was graded from C2/C3 to C6/C7 based on a validated quantitative grading system. The prevalence and distribution of radiographic findings were evaluated and associations with age were investigated.

Results

53.9% of individuals had radiographic disc degeneration and the most affected level was C5/C6. The presence and severity of disc degeneration were found to be significantly associated with age both in male and female subjects. The most frequent and severe occurrences of height loss, osteophyte formation, and endplate sclerosis were at C5/C6, whereas spondylolisthesis was most observed at C4/C5. Age was significantly correlated with radiographic degenerative findings. Contiguous levels degeneration pattern was more likely found than skipped level degeneration. The number of degenerated levels was also associated with age.

Conclusions

The presence and severity of radiographic disc degeneration increased with aging in the cervical spine. Older age was associated with greater number of degenerated disc levels. Furthermore, the correlations between age and the degree of degenerative findings were stronger at C5/C6 and C6/C7 than at other cervical spinal levels.

New combination of IntraSPINE device and posterior lumbar interbody fusion for rare skipped-level lumbar disc herniation: a case report and literature review

Posterior lumbar interbody fusion is an open surgical technique that has been widely used for the treatment of degenerative lumbar disease. However, traditional lumbar spinal fusion, especially long-segment fusion surgery, is associated with several complications. The IntraSPINE (Cousin Biotech, Wervicq-Sud, France) is a new device for non-fusion lumbar spine surgery that is used as an alternative for the treatment of degenerative lumbar disease. Although the designer of the IntraSPINE proposed indications for its use, including combination of the device with lumbar spinal fusion for the treatment of degenerative lumbar disease, use of the IntraSPINE has not been reported in the clinical literature. In the present case, we boldly combined the IntraSPINE device and posterior lumbar interbody fusion for the treatment of skipped-level lumbar disc herniation to explore the indications of the IntraSPINE and report its clinical outcomes.

An in vivo study exploring correlations between early-to-moderate disc degeneration and flexion mobility in the lumbar spine

PURPOSE

Early disc degeneration (DD) has been thought to be associated with loss of spine stability. However, before this can be understood in relation to back pain, it is necessary to know the relationship between DD and intervertebral motion in people without pain. This study aimed to find out if early-to-moderate DD is associated with intervertebral motion in people without back pain.

METHODS

Ten pain-free adults, aged 51-71, received recumbent and weight bearing MRI scans and quantitative fluoroscopy (QF) screenings during recumbent and upright lumbar flexion. Forty individual level and 10 composite (L2-S1) radiographic and MRI DD gradings were recorded and correlated with intervertebral flexion ROM, translation, laxity and motion sharing inequality and variability for both positions.

RESULTS

Kinematic values were similar to previous control studies. DD was evidenced up to moderate levels by both radiographic and MRI grading. Disc height loss correlated slightly, but negatively with flexion during weight bearing flexion (R =  - 0.356, p = 0.0.025). Composite MRI DD and T2 signal loss evidenced similar relationships (R =  - 0.305, R =  - 0.267) but did not reach statistical significance (p = 0.056, p = 0.096). No significant relationships between any other kinematic variables and DD were found.

CONCLUSION

This study found only small, indefinite associations between early-to-moderate DD and intervertebral motion in healthy controls. Motion sharing in the absence of pain was also not related to early DD, consistent with previous control studies. Further research is needed to investigate these relationships in patients.

Significance of the Association between Disc Degeneration Changes on Imaging and Low Back Pain: A Review Article

Low back pain (LBP) is a major health issue resulting in a huge economic burden on the community. It not only increases the medical costs directly, but also raises the disability and loss of productivity in the general population. Symptoms include local pain over the spinal area, pain radiating to the lower leg, stiffness, and muscle tension. LBP is strongly linked with intervertebral disc degeneration that is further associated with the disruption of the complex anatomy of nucleus pulposus, annulus fibrosus, and adjacent supporting structures of the spine. Change in the shape and intensity of nucleus pulposus, decreased disc height, disc herniation, vertebral endplate changes, presence of osteophyte, and posterior high intensity zones are degenerative changes found in imaging studies. Every feature is considered while grading the severity score. Modic changes, DEBIT (disc extension beyond interspace) score, and Pfirrmann criteria are some of the scoring criteria used for evaluating disc degeneration severity. Moreover, the total number and contiguous pattern of affected discs play a crucial role in symptom generation of back pain. Many studies have reported asymptomatic patients. Thus, the correlation between degeneration severity found in imaging study and symptom severity of LBP remain unclear. This review discusses and summarizes the available literature on the significance of the association between the severity of degenerative changes found in imaging study with the presence and intensity of LBP.

Nutrient supply and nucleus pulposus cell function: effects of the transport properties of the cartilage endplate and potential implications for intradiscal biologic therapy

OBJECTIVE

Intradiscal biologic therapy is a promising strategy for managing intervertebral disc degeneration. However, these therapies require a rich nutrient supply, which may be limited by the transport properties of the cartilage endplate (CEP). This study investigated how fluctuations in CEP transport properties impact nutrient diffusion and disc cell survival and function.

DESIGN

Human CEP tissues harvested from six fresh cadaveric lumbar spines (38-66 years old) were placed at the open sides of diffusion chambers. Bovine nucleus pulposus (NP) cells cultured inside the chambers were nourished exclusively by nutrients diffusing through the CEP tissues. After 72 h in culture, depth-dependent NP cell viability and gene expression were measured, and related to CEP transport properties and biochemical composition determined using fluorescence recovery after photobleaching and Fourier transform infrared (FTIR) spectroscopy.

RESULTS

Solute diffusivity varied nearly 4-fold amongst the CEPs studied, and chambers with the least permeable CEPs appeared to have lower aggrecan, collagen-2, and matrix metalloproteinase-2 gene expression, as well as a significantly shorter viable distance from the CEP/nutrient interface. Increasing chamber cell density shortened the viable distance; however, this effect was lost for low-diffusivity CEPs, which suggests that these CEPs may not provide enough nutrient diffusion to satisfy cell demands. Solute diffusivity in the CEP was associated with biochemical composition: low-diffusivity CEPs had greater amounts of collagen and aggrecan, more mineral, and lower cross-link maturity.

CONCLUSIONS

CEP transport properties dramatically affect NP cell survival/function. Degeneration-related CEP matrix changes could hinder the success of biologic therapies that require increased nutrient supply.

Multidimensional vertebral endplate defects are associated with disc degeneration, modic changes, facet joint abnormalities, and pain

The aim of the current study was to investigate the multi-dimensional characteristics of lumbar endplate defects in humans in relation to disc degeneration and other MRI phenotypes as well as their role with pain and disability. A total of 108 subjects were recruited and underwent 3T MRI of the lumbar spine. Structural endplate defects were identified and their dimensions were measured in terms of maximum width and depth, and were then standardized to the actual width of the endplate and depth of the vertebral body, respectively. Both width and depth of all endplate defects in each subject were added separately and scores were assigned on the basis of size from 1 to 3. Combining both scores provided "cumulative endplate defect scores." Disc degeneration scores, Modic changes, disc displacement, HIZ, and facet joint changes were assessed. Subject demographics, pain profile, and Oswestry Disability Index (ODI) were also obtained. Endplate defects were observed in 67.5% of the subjects and in 13.5% of the endplates. All dimensions of endplate defects showed significance with disc degenerative scores, Modic changes, and posterior disc displacement (p < 0.05). Maximum width (p = 0.009) and its standardized value (p = 0.02), and cumulative endplate defect scores (p = 0.004) increased with narrow facet joints. Cumulative endplate defect scores showed a strong positive association with ODI (p < 0.05) compared to disc degenerative scores. Large size endplate defects were strongly associated with degenerative spine changes and more back-related disability. Findings from this study stress the need to assess endplate findings from a multi-dimensional perspective, whose role may have clinical utility. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Inhibiting tumor necrosis factor-alpha at time of induced intervertebral disc injury limits long-term pain and degeneration in a rat model

Background

Painful intervertebral disc (IVD) degeneration has tremendous societal costs and few effective therapies. Intradiscal tumor necrosis factor‐alpha (TNFα) is commonly associated with low back pain, but the direct relationship remains unclear.

Purpose

Treatment strategies for low back pain require improved understanding of the complex relationships between pain, intradiscal pro‐inflammatory cytokines, and structural IVD degeneration. A rat in vivo lumbar IVD puncture model was used to 1) determine the role of TNFα in initiating painful IVD degeneration, and 2) identify statistical relationships between painful behavior, IVD degeneration, and intradiscal pro‐inflammatory cytokine expression.

Methods

Lumbar IVDs were punctured anteriorly and injected with TNFα, anti‐TNFα, or saline and compared with sham and naive controls. Hindpaw mechanical hyperalgesia was assayed weekly to determine pain over time. 6‐weeks post‐surgery, animals were sacrificed, and IVD degeneration, IVD height, and intradiscal TNFα and interleukin‐1 beta (IL‐1β) expressions were assayed.

Results

Intradiscal TNFα injection increased pain and IVD degeneration whereas anti‐TNFα alleviated pain to sham level. Multivariate step‐wise linear regression identified pain threshold was predicted by IVD degeneration and intradiscal TNFα expression. Pain threshold was also linearly associated with IVD height loss and IL‐1β.

Discussion

The significant associations between IVD degeneration, height loss, inflammation, and painful behavior highlight the multifactorial nature of painful IVD degeneration and the challenges to diagnose and treat a specific underlying factor. We concluded that TNFα is an initiator of painful IVD degeneration and its early inhibition can mitigate pain and degeneration. Intradiscal TNFα inhibition following IVD injury may warrant investigation for its potential to alter downstream painful IVD degeneration processes.

Do Older Adults and Those Recovered from Low Back Injury Share Common Muscle Activation Adaptations?

Theoretical models suggest trunk muscle activation compensates for spinal systems impairments. The purpose of this study was to determine if two populations (older adults and those recovered from a lower back injury (rLBI)) with spinal system impairments have similar muscle activation patterns to each other, but differ from controls. Trunk electromyograms collected from 12 older adults, 16 rLBI, and 19 controls during two dynamic tasks showed that older adults and rLBI had higher activation amplitudes, sustained temporal and more synergistic activation relative to controls. However, differences found between older adults and rLBI suggest that spinal system impairments differed between groups or that recent pain (rLBI) uniquely influenced muscle activation. This sheds light on our understanding of the relationship between spinal system impairments and muscle activation.

The UTE Disc Sign on MRI: A Novel Imaging Biomarker Associated With Degenerative Spine Changes, Low Back Pain, and Disability

STUDY DESIGN

Cross-sectional.

OBJECTIVE

To assess the distribution of the ultra-short time-to-echo (UTE) disc sign (UDS) and its association with disc degeneration, other magnetic resonance imaging (MRI) phenotypes, pain, and disability profiles.

SUMMARY OF BACKGROUND DATA

Disc degeneration has been conventionally assessed by T2-weighted (T2W) signal intensity on MRI; however, its clinical utility has been questionable. UTE MRI assesses short T2 components. The authors have identified a new imaging biomarker on UTE-the UDS.

METHODS

One hundred eight subjects were recruited. T2W MRI assessed disc degeneration and other phenotypes, and T1-rho MRI values represented quantitative proteoglycan disc profiles of L1-S1. UDS was detected on UTE (i.e., hyper-/hypointense disc band). A UDS score (cumulative number of UDS levels) and T2W summated lumbar degenerated scores (cumulative disc degeneration score) were assessed. Subject demographics, chronic low back pain (LBP), and disability profiles (Oswestry Disability Index: ODI) were obtained.

RESULTS

UDS was noted in 39.8% subjects, 61.4% occurred at the lower lumbar spine and 39.5% had multilevel UDS. UDS subjects had significantly greater severity and extent of disc degeneration, and Modic changes (P < 0.05). By disc levels, a higher prevalence of disc degeneration/displacement, Modic changes, and spondylolisthesis were noted in UDS discs than non-UDS discs (P < 0.05). T1-rho values were also lower in UDS discs (P = 0.022). The majority of UDS could not be detected on T2W. The UDS score significantly correlated with worse ODI scores (r = 0.311; P = 0.001), whereas T2W cumulative disc degeneration score did not (r = 0.13; P = 0.19). LBP subjects exhibited more multilevel UDS (P < 0.015) but not on T2W MRI (P = 0.53). The UDS score was significantly related to LBP (P = 0.009), whereas T2W cumulative disc degeneration score was not (P = 0.127).

CONCLUSION

This is the first study to report "UDS" in humans. UDS is a novel imaging biomarker that is highly associated with degenerative spine changes, chronic LBP, and disability than conventional T2W MRI.

LEVEL OF EVIDENCE

2.

Association between intervertebral disc degeneration and the Oswestry Disability Index

BACKGROUND

Low back pain and lumbar intervertebral disc degeneration (IDD) are common findings. Valid data on correlation between clinical pain scores and grades of IDD are not available.

OBJECTIVE

To investigate the correlation of intervertebral disc degeneration (IDD) at lumbar levels L4/5 and L5/S1 and the Oswestry Disability Index (ODI).

METHODS

The lumbar discs L4/5 and L5/S1 of 591 patients were evaluated according to the 5-point (Grade I to Grade V) grading system as published by Pfirrmann et al. Functional status was assessed using the Oswestry Disability Index. Spearman's coefficient of rank correlation was used for statistical analysis (p < 0.05).

RESULTS

The majority of patients revealed lumbar discs with Pfirrmann grade II to grade IV changes (93.3% at level L4/5; 89.8% at level L5/S1), while a relatively low percentage of lumbar discs presented with grade I (level L4/5: 1.5%; level L5/S1: 2.0%) or grade V (level L4/5: 5.1%; level L5/S1: 8.1%) changes, respectively. Patients' ODI scores ranged between 0 and 91.11% (arithmetic mean of 32.77% ± 17.02%). The largest group of patients (48.39%) had moderate functional disability (ODI score between 21 and 40%). There was a weak, but statistically significant positive correlation between IDD and ODI for both evaluated lumbar levels.

CONCLUSIONS

Increased lumbar IDD in MRI goes along with an increased ODI. Thus, MRI is a strong indicator of a patient's clinical appearance. However, low back pain cannot be explained by imaging alone. Clinical correlation is imperative for an adequate diagnostic advance in patients with low back pain.

No Transfer of Pressure to Adjacent Discs During Human Low-Pressure Controlled Discography: A Prospective Clinical Study

Background

A substantial part of low back pain (LBP) originates from degeneration of the intervertebral disc. To confirm the diagnosis of discogenic pain, provocation discography seems the best available tool. However, provocation discography is also considered to be a controversial and subjective test because the patient's personal pain response is the most crucial for the result of the test. Recently, an in vivo porcine study and a study in nine human subjects showed passing of pressure to the adjacent discs during discography. This could mean that the concordant pain the patient describes originates from an adjacent disc. The object of this study is to assess if during human lumbar pressure-controlled provocation discography there is pressure transmission to adjacent discs.

Methods

Consecutive patients between age 18 and 65 years with intractable low back pain and at least 50% preserved height of the suspected painful disc were included. Exclusion criteria were prior lumbar surgery of the suspected level, use of anticoagulants, pregnancy, local infection, and iodine allergy. An arterial blood pressure monitoring system simultaneously assessed the pressure in the adjacent discs while low-speed flow, pressure-controlled discography was performed.

Results

In 50 patients with a positive discography, the average intradiscal peak pressure was 15.1 psi (SD = 11.1). In 48 procedures, no pressure rise in the adjacent discs was found. A small pressure rise (1.1 psi) in the adjacent disc during discography was recorded in two patients.

Conclusions

Pressure rise in adjacent discs does not seem to occur during low-speed flow pressure-controlled lumbar provocation discography. False-positive pain reactions caused by potentially painful adjacent discs are therefore unlikely during pressure-controlled discography.

The association of lumbar intervertebral disc calcification on plain radiographs with the UTE Disc Sign on MRI

PURPOSE

The pathogenesis and the clinical impact of disc calcification are not well known. Utilizing ultra-short time-to-echo (UTE) magnetic resonance imaging, the UTE Disc Sign (UDS) (i.e., hypo/hyper-intense disc band) was developed and found to be more significantly related to pain and disability than the conventional T2-weighted (T2W) MRI. It has been hypothesized that the UDS may represent mineralized deposits in the disc. The following study addressed the relationship between disc calcification on plain radiographs to that of the UDS on MRI.

METHODS

A cross-sectional study was performed on 106 Southern Chinese subjects (50% male; mean age 52.3 years). Standing lateral plain radiographs as well as T2W and UTE MRI of L1-S1 (n = 530 discs) were performed of all subjects. Lateral radiographs were used to localize disc calcification of the lumbar spine, T2W MRI was utilized to assess disc degeneration based on a defined grading scheme, and the UTE MRI was implemented to detect the UDS (hyper- or hypo-intense band across a disc). Disc degeneration and UDS scores were summed to represent cumulative scores. Subject demographics and disability profiles (Oswestry Disability Index: ODI) were obtained.

RESULTS

Disc calcification on plain radiographs was observed in 33.9% of subjects (55.5% males; mean age 54.3 years), whereas UDS was noted in 40.5% of subjects (51.1% males; mean age 55.0 years). Of these subjects, 66.6% calcification and 74.4% UDS occurred at the three lowest lumbar levels, while multilevel calcification and UDS involved 19.4 and 39.5%, respectively. 72.2% of subjects with plain radiographic disc calcification had corresponding UDS on UTE MRI (p < 0.001). Multilevel disc calcification on plain radiographs was associated with multilevel UDS (71.4%, p < 0.001). Both the number of calcified disc levels on plain radiographs and the number of UDS levels were also significantly and positively correlated with each other (r = 0.58, p < 0.001). Subjects with disc calcification and positive UDS as well as individuals with increased disc degeneration scores on T2 W MRI were significantly older (p < 0.05). The cumulative UDS score on UTE MRI significantly correlated with worse ODI scores (r = 0.31; p = 0.001), whereas cumulative disc calcification scores on plain radiographs did not (r = 0.15; p = 0.19).

CONCLUSIONS

This is the first study to compare the UDS on UTE MRI with disc calcification on plain radiographs. Disc calcification was correlated with the UDS on UTE, suggesting that the UDS may represent disc calcification. However, UTE MRI appears to be a more sensitive imaging modality in identifying subtle and unique disc changes that may not be revealed on plain radiographs or conventional MRI. This disconnect may rationalize the significant correlation of UTE with disability in comparison with the conventional imaging, further stressing its potential clinical importance.

Progression, incidence, and risk factors for intervertebral disc degeneration in a longitudinal population-based cohort: the Wakayama Spine Study

OBJECTIVE

The present study examined the progression, incidence, and risk factors for intervertebral disc degeneration (DD) throughout the lumbar spine using magnetic resonance imaging (MRI) in a large population-based cohort.

METHODS

We followed up 617 subjects for more than 4 years as part of the Wakayama Spine Study. 1) "Progression of DD" in each of the entire, upper (L1/2 to L3/4) and lower (L4/5 and L5/S1) lumbar spine was defined as Pfirrmann grade progression at follow-up in at least one disc in the affected region. 2) "Incidence of DD" in each of these regions was defined if all discs were grade 3 or lower (white disc) at baseline, and at least one disc had progressed to grade 4 or higher (black disc) at follow-up. Logistic regression analyses were used to determine the risk factors for progression and incidence of DD.

RESULTS

DD progression and incidence in the entire lumbar spine were 52.0% and 31.6% in men, and 60.4% and 44.7% in women, respectively. Women was associated with DD progression in the upper lumbar spine (odds ratio [OR] = 1.68, 95% confidence interval [CI] = 1.18-2.42). Aging was associated with the incidence of DD in each region (entire: OR = 1.14, CI = 1.06-1.14; upper: OR = 1.10, CI = 1.05-1.15; lower: OR = 1.11, CI = 1.05-1.19). Diabetes mellitus (DM) was associated with the incidence of DD in the upper lumbar spine (OR = 6.83, CI = 1.07-133.7).

CONCLUSION

This 4-year longitudinal study is the first to demonstrate DD progression and incidence in the lumbar spine and their risk factors in a large population-based cohort.

Radiographic indices for lumbar developmental spinal stenosis

Background

Patients with developmental spinal stenosis (DSS) are susceptible to developing symptomatic stenosis due to pre-existing narrowed spinal canals. DSS has been previously defined by MRI via the axial anteroposterior (AP) bony spinal canal diameter. However, MRI is hardly a cost-efficient tool for screening patients. X-rays are superior due to its availability and cost, but currently, there is no definition of DSS based on plain radiographs. Thus, the aim of this study is to develop radiographic indices for diagnosing DSS.

Methods

This was a prospective cohort of 148 subjects consisting of patients undergoing surgery for lumbar spinal stenosis (patient group) and asymptomatic subjects recruited openly from the general population (control group). Ethics approval was obtained from the local institutional review board. All subjects underwent MRI for diagnosing DSS and radiographs for measuring parameters used for creating the indices. All measurements were performed by two independent investigators, blinded to patient details. Intra- and interobserver reliability analyses were conducted, and only parameters with near perfect intraclass correlation underwent receiver operating characteristic (ROC) analysis to determine the cutoff values for diagnosing DSS using radiographs.

Results

Imaging parameters from a total of 66 subjects from the patient group and 82 asymptomatic subjects in the control group were used for analysis. ROC analysis suggested sagittal vertebral body width to pedicle width ratio (SBW:PW) as having the strongest sensitivity and specificity for diagnosing DSS. Cutoff indices for SBW:PW were level-specific: L1 (2.0), L2 (2.0), L3 (2.2), L4 (2.2), L5 (2.5), and S1 (2.8).

Conclusions

This is the first study to define DSS on plain radiographs based on comparisons between a clinically relevant patient group and a control group. Individuals with DSS can be identified by a simple radiograph using a screening tool allowing for better cost-saving means for clinical diagnosis or research purposes.

Classification of Schmorl's nodes of the lumbar spine and association with disc degeneration: a large-scale population-based MRI study

OBJECTIVE

Schmorl's nodes (SN) are highly associated with lumbar disc degeneration (DD). However, SN present with different morphologies/topographies that may be associated with varying degrees of DD. This study proposed a classification of SN to determine their morphological/topographical prevalence and association with the severity of DD.

METHODS

Sagittal T2-weighted MRIs were assessed to identify SN and additional imaging findings from L1-S1 in 2,449 individuals. SN characteristics were classified by six criteria: disc level; endplate involvement; shape; size; location of endplate zone; and the presence of marrow changes. Hierarchical clustering was performed to identify distinct SN characteristics with endplate patterns.

RESULTS

Good to excellent observer classification reliability was noted. SN most commonly presented at the L1 and L2 disc levels, and entailed one-third of the endplate, predominantly the middle zone. Round shape (39.2%) was the most common SN shape. Four specific SN and endplate linkage patterns were identified. 8.3% of identified SN (n = 960) were "Atypical SN". Multivariable regression showed that "Typical SN" and "Atypical SN", depending on levels, were associated with an adjusted 2- to 4-fold and a 5- to 13-fold higher risk of increased severity of DD, respectively (p < 0.05).

CONCLUSIONS

This is the first large-scale magnetic resonance imaging (MRI) study to propose a novel SN classification. Specific SN-types were identified, which were associated with more severe DD. This study further broadens our understanding of the role of SN and degrees of DD, further expanding on the SN phenotyping that can be internationally adopted for utility assessment.

Two subtypes of intervertebral disc degeneration distinguished by large-scale population-based study

BACKGROUND CONTEXT

Lumbar disc degeneration (LDD) is a major cause of low back pain, and is a common and disabling condition worldwide. It has been defined and measured by multiple spine magnetic resonance imaging (MRI) features, but the heterogeneity among them has never been fully addressed.

PURPOSE

This study examined the intercorrelations, risk factor associations, and single nucleotide polymorphism (SNP) heritabilities of lumbar disc MRI features in a large-scale sample to classify the different intervertebral disc phenotypes associated with LDD.

STUDY DESIGN

A cross-sectional study was conducted consisting of 2,943 volunteers of Southern Chinese origin (mean age: 41.1 years; range: 15-55 years; 59.6% women).

OUTCOME MEASURES

The outcome measures were MRI phenotypic spinal patterns and their risk factor profiles in relation to developmental or degenerative origins of disc degeneration.

METHODS

Sagittal T2-weighted MRI of the lumbar spine from L1 to S1 was assessed. The MRI features of lumbar intervertebral disc changes, such as disc signal intensity loss and disc bulges or extrusions, as well as additional imaging phenotypes of end plate changes, high-intensity zones, and bone marrow changes, were evaluated. Blood samples were taken for genotyping using the HumanOmni-ZhongHua-8 BeadChip. Subject demographics, environmental, and lifestyle factors were assessed by questionnaires. Multivariate statistical techniques were used for phenotype evaluation. Polychoric correlations and local regression statistical analyses were performed. The genetic components contributed by common SNPs were estimated by comparing genetic correlations and phenotypic correlations using the Genome-Wide Complex Trait Analysis (GCTA) tool.

RESULTS

The study noted that lumbar disc MRI features separated into two groups with differential patterns of risk factor associations. A subset of lumbar disc abnormalities, including end plate changes but also upper lumbar disc bulging and signal intensity loss, may have a developmental origin. Subsequent degenerative changes, typically affecting the lower lumbar discs, then emerge as individuals age and are associated with body mass index.

CONCLUSIONS

This is the first large-scale study to identify two distinct patterns of lumbar disc alterations, noting degenerative changes and a possible developmental component affecting the lumbar spine. This new classification provides a starting point for a more homogeneous phenotype definition, which may provide greater statistical power and precision in future genetic and epidemiologic studies. In addition, such insights may have direct clinical implications in the prevention, therapeutics, and prognostics of patients with disc degeneration.

Do mechanical strain and TNF-α interact to amplify pro-inflammatory cytokine production in human annulus fibrosus cells?

During intervertebral disc (IVD) injury and degeneration, annulus fibrosus (AF) cells experience large mechanical strains in a pro-inflammatory milieu. We hypothesized that TNF-α, an initiator of IVD inflammation, modifies AF cell mechanobiology via cytoskeletal changes, and interacts with mechanical strain to enhance pro-inflammatory cytokine production. Human AF cells (N=5, Thompson grades 2-4) were stretched uniaxially on collagen-I coated chambers to 0%, 5% (physiological) or 15% (pathologic) strains at 0.5Hz for 24h under hypoxic conditions with or without TNF-α (10ng/mL). AF cells were treated with anti-TNF-α and anti-IL-6. ELISA assessed IL-1β, IL-6, and IL-8 production and immunocytochemistry measured F-actin, vinculin and α-tubulin in AF cells. TNF-α significantly increased AF cell pro-inflammatory cytokine production compared to basal conditions (IL-1β:2.0±1.4-84.0±77.3, IL-6:10.6±9.9-280.9±214.1, IL-8:23.9±26.0-5125.1±4170.8pg/ml for basal and TNF-α treatment, respectively) as expected, but mechanical strain did not. Pathologic strain in combination with TNF-α increased IL-1β, and IL-8 but not IL-6 production of AF cells. TNF-α treatment altered F-actin and α-tubulin in AF cells, suggestive of altered cytoskeletal stiffness. Anti-TNF-α (infliximab) significantly inhibited pro-inflammatory cytokine production while anti-IL-6 (atlizumab) did not. In conclusion, TNF-α altered AF cell mechanobiology with cytoskeletal remodeling that potentially sensitized AF cells to mechanical strain and increased TNF-α-induced pro-inflammatory cytokine production. Results suggest an interaction between TNF-α and mechanical strain and future mechanistic studies are required to validate these observations.

Risk factors for lumbar intervertebral disc height narrowing: a population-based longitudinal study in the elderly

BACKGROUND

The progression of disc degeneration is generally believed to be associated with low back pain and/or degenerative lumbar diseases, especially in the elderly. The purpose of this study was to quantitatively evaluate changes in lumbar disc height using radiographic measurements and to investigate risk factors for development of disc height narrowing of the elderly.

METHODS

From 1997 to 2007, 197 village inhabitants at least 65 years-old who participated in baseline examinations and more than four follow-up examinations conducted every second year were chosen as subjects for this study. Using lateral lumbar spine radiographs of each subject, L1-L2 to L5-S1 disc heights were measured. The subjects were divided into two groups according to the rate of change in disc height: mildly decreased (≤20 % decrease) and severely decreased (>20 % decrease). A stepwise multiple logistic regression analysis was used to select those factors significantly associated with disc height narrowing.

RESULTS

Disc height at each intervertebral disc (IVD) level decreased gradually over ten years (p < 0.01, an average 5.8 % decrease of all disc levels). There was no significant difference in the rate of change in disc height among the IVD levels. Female gender, radiographic knee osteoarthritis and low back pain at baseline were associated with increased risk for disc height narrowing.

CONCLUSIONS

We conducted the first population-based cohort study of the elderly that quantitatively evaluated lumbar disc height using radiographic measurements. The risk factors identified in this study would contribute to a further understanding the pathology of disc degeneration.

Phenotype profiling of Modic changes of the lumbar spine and its association with other MRI phenotypes: a large-scale population-based study

BACKGROUND CONTEXT

Modic changes (MC) are associated with low back pain. They represent vertebral endplate and adjacent vertebral marrow changes on magnetic resonance imaging (MRI), classified into three types. Because of small sample sizes, patient cohorts, and limited phenotype assessment, the morphology and involvement of MC and their association with other spinal phenotypes remain speculative.

PURPOSE

We addressed and proposed a phenotypic profiling of MC and their relationship with lumbar MRI phenotypes in a large-scale population-based study.

STUDY DESIGN/SETTING

A cross-sectional study of the Hong Kong Disc Degeneration Cohort.

PATIENT SAMPLE

The study population consisted of 1,546 Southern Chinese volunteers.

OUTCOME MEASURES

Topographical and morphological dimensions of MC, presence of disc degeneration (DD) and displacement, and Schmorl nodes were evaluated.

METHODS

Axial T1-weighted and sagittal T2-weighted MRIs (3T) were assessed.

RESULTS

Females were 62.4% (mean age, 49 years). The overall prevalence of MC was 21.9% (6.3% Type I and 15.5% Type II). Of all MC, 76% were located at the two lowest lumbar levels. Modic changes at the two lowest lumbar levels were more commonly located laterally (p<.001), less commonly anteriorly (p<.001), and were more extensive horizontally (p=.006) but not in vertical height compared with the upper levels. Type I MC were less common in the anterior part (p=.022), larger in size (height p=.004), and affected more likely the whole horizontal plane (p=.016) than Type II MC. Modic changes were associated with disc displacement, Schmorl nodes, and DD at the affected level (all p<.001), and the strength of association increased with the size of the lesion. Type I MC were associated more strongly with disc displacement (p=.008) and DD (p=.022) than Type II MC.

CONCLUSIONS

Our large-scale MRI study is the first to definitely note that MC were size- and type-dependently significantly associated with disc pathology and endplate abnormalities. Our phenotype profiling of MC may have clinical utility.

Magnetic resonance imaging-based interpretation of degenerative changes in the lower lumbar segments and therapeutic consequences

Intervertebral disc degeneration and facet joint osteoarthritis of the lumbar spine are, among others, well known as a cause of low back and lower extremity pain. Together with their secondary disorders they set a big burden on health care systems and economics worldwide. Despite modern imaging modalities, such as magnetic resonance imaging, for a large proportion of patients with low back pain (LBP) it remains difficult to provide a specific diagnosis. The fact that nearly all the lumbar structures are possible sources of LBP, may serve as a possible explanation. Furthermore, our clinical experience confirms, that imaging alone is not a sufficient approach explaining LBP. Here, the Oswestry Disability Index, as the most commonly used measure to quantify disability for LBP, may serve as an easy-to-apply questionnaire to evaluate the patient’s ability to cope with everyday life. For therapeutic purposes, among the different options, the lumbar facet joint intra-articular injection of corticosteroids in combination with an anaesthetic solution is one of the most frequently performed interventional procedures. Although widely used the clinical benefit of intra-articular steroid injections remains controversial. Therefore, prior to therapy, standardized diagnostic algorithms for an accurate assessment, classification and correlation of degenerative changes of the lumbar spine are needed.

Low Back Pain: A Biomechanical Rationale Based on "Patterns" of Disc Degeneration

STUDY DESIGN

A nonlinear finite element study of a lumbar spine with different "patterns" of multilevel intervertebral disc degeneration.

OBJECTIVE

To determine how different patterns of multilevel disc degeneration influence the biomechanical behavior of the lumbar spine.

SUMMARY OF BACKGROUND DATA

Because of the complex etiology of low back pain, it is often difficult to identify the specific factors that contribute to the symptoms of a particular patient. Disc degeneration is associated with the development of low back pain, but its presence is not always synonymous with symptoms. However, studies have suggested that "patterns" of disc degeneration may provide insight into such pain generation rather than the overall presence of degenerative changes. Specifically, individuals with contiguous multilevel disc degeneration have been shown to exhibit higher presence and severity of low back pain than patients with skipped-level disc degeneration (i.e., healthy discs located in between degenerated discs).

METHODS

In this study, the biomechanical differences between these patterns were analyzed using a nonlinear finite element model of the lumbar spine. Thirteen separate "patterns" of disc degeneration were evaluated using the model and simulated under normal physiological loading conditions in each of the primary modes of spinal motion.

RESULTS

The results showed that stresses and forces of the surrounding ligaments, facets, and pedicles at certain vertebral levels of the spine were generally lower in skipped-level disc degeneration cases than in the contiguous multilevel disc degenerations cases even when the skipped level contained more degenerated discs.

CONCLUSION

To our knowledge, this is the first study to illustrate the biomechanics of specific patterns of disc degeneration of the lumbar spine. Using a multilevel disc degeneration model, our study provides insights as to why various patterns of disc degeneration throughout the lumbar spine may affect motion and soft tissue structures as well that may have bearing in the clinical pathway of pain generation.

LEVEL OF EVIDENCE

N/A.

Current trends in biologics delivery to restore intervertebral disc anabolism

Low back pain is generally attributed to intervertebral disc (IVD) degeneration. This is a multifactorial disease induced by genetic and environmental factors and that progresses with aging. Disc degeneration is characterized by a limited ability of IVD cells to produce functional matrix while producing abnormal amounts of matrix-degrading enzymes. The prolonged imbalance between anabolism and catabolism in degenerative discs alters their composition and hydration. In turn, this results in increased angiogenesis and the loss of the disc's ability to maintain its aneural condition. Inflammation in the IVD, in particular the presence of pro-inflammatory cytokines, was found to favor innervation and also sensitization of the nociceptive pathways, thereby exacerbating degenerative symptoms. In this review, we discuss anti-inflammatory approaches to encounter disc catabolism, potential treatments to lower discogenic pain and pro-anabolic approaches in the form of protein delivery, gene therapy and cell delivery, to trigger regeneration in the IVD.