Prevalence and pattern of lumbar magnetic resonance imaging changes in a population study of one thousand forty-three individuals

Identification of novel nucleus pulposus markers: Interspecies variations and implications for cell-based therapiesfor intervertebral disc degeneration

Mesenchymal stem-cell based therapies have been proposed as novel treatments for intervertebral disc degeneration, a prevalent and disabling condition associated with back pain. The development of these treatment strategies, however, has been hindered by the incomplete understanding of the human nucleus pulposus phenotype and by an inaccurate interpretation and translation of animal to human research. This review summarises recent work characterising the nucleus pulposus phenotype in different animal models and in humans and integrates their findings with the anatomical and physiological differences between these species. Understanding this phenotype is paramount to guarantee that implanted cells restore the native functions of the intervertebral disc. Cite this article: Bone Joint Res 2013;2:169-78.

Anterior Limbus Vertebra and Intervertebral Disk Degeneration in Japanese Collegiate Gymnasts

Background:

Magnetic resonance imaging (MRI) studies have shown that gymnasts have a high prevalence of radiological abnormalities, such as intervertebral disk degeneration (IDD) and anterior limbus vertebra (ALV). These 2 abnormalities may coexist at the same spinal level. However, the relationship between IDD and ALV remains unclear.

Hypothesis:

A significant relationship exists between IDD and ALV in Japanese collegiate gymnasts.

Study Design:

Case-control study.

Methods:

A total of 104 Japanese collegiate gymnasts (70 men and 34 women; age, 19.7 ± 1.0 years) with 11.8 ± 3.6 years of sporting experience participated. T1- and T2-weighted MRIs were used to evaluate ALV and IDD.

Results:

The prevalence among the gymnasts of IDD and ALV was 40.4% (42/104) and 20.2% (21/104), respectively. The prevalence of IDD was significantly higher in gymnasts with ALV than those without ALV, as determined using the chi-square test. Logistic regression analysis demonstrated a significant association between IDD and ALV (adjusted odds ratio [OR], 6.60; 95% confidence interval [CI], 2.14-20.35). IDD was further grouped by whether it was present in the upper lumbar region (L1-2, L2-3, and L3-4 disks) or in the lower lumbar region (L4-5 and L5-S1 disks). Upper IDD had a greater association with ALV (adjusted OR, 33.17; 95% CI, 7.09-155.25) than did lower IDD (adjusted OR, 6.71; 95% CI, 1.57-28.73).

Conclusion:

In Japanese collegiate gymnasts, ALV is a predictor of IDD, especially in the upper lumbar region.

Clinical Relevance:

Information regarding ALV is important to prevent IDD in Japanese collegiate gymnasts.

Intervertebral disc decompression following endplate damage: implications for disc degeneration depend on spinal level and age

STUDY DESIGN

Mechanical and morphological studies on cadaveric spines.

OBJECTIVE

To explain how spinal level and age influence disc degeneration arising from endplate fracture.

SUMMARY OF BACKGROUND DATA

Disc degeneration can be initiated by damage to a vertebral body endplate, but it is unclear why endplate lesions, and patterns of disc degeneration, vary so much with spinal level and age.

METHODS

One hundred seventy-four cadaveric motion segments, from T7-T8 to L5-S1 and aged 19 to 96 years, were subjected to controlled compressive overload to damage a vertebral body. Stress profilometry was performed before and after damage to quantify changes in intradiscal pressure, and compressive stresses in the annulus. Eighty-six of the undamaged vertebral bodies were then sectioned in the midsagittal plane, and the thickness of the central bony endplate was measured from microradiographs. Regression analysis was used to compare the relative influences of spinal level, age, disc degeneration, and sex on results obtained.

RESULTS

Compressive overload caused endplate fracture at an average force of 3.4 kN, and reduced motion segment height by an average 1.88 mm. Pressure loss in the adjacent nucleus pulposus decreased from 93% at T8-T9 to 38% at L4-L5 (R = 22%, P < 0.001), and increased with age (R = 19%, P < 0.001), especially in male specimens. Stress concentrations in the posterior annulus increased after endplate fracture, with the effect being greatest at upper spinal levels (R = 7%, P < 0.001). Endplate thickness increased by approximately 50% between T11 and L5 (R = 21%, P < 0.001).

CONCLUSION

Endplate fracture creates abnormal stress distributions in the adjacent intervertebral disc, increasing the risk of internal disruption and degeneration. Effects are greatly reduced in the lower lumbar spine, and in young specimens, primarily because of differences in nucleus volume, and materials properties, respectively. Disc degeneration between L4 and S1 may often be unrelated to endplate fracture.

LEVEL OF EVIDENCE

N/A.

Comparison of apparent diffusion coefficient and T2 relaxation time variation patterns in assessment of age and disc level related intervertebral disc changes

PURPOSE

To compare the variation patterns of ADC and T2 values in different age and intervertebral disc (IVD) levels, thus to identify their sensitivities in assessing age and disc level related IVDs changes.

MATERIALS AND METHODS

The T2 and ADC values were recorded from 345 IVDs of 69 volunteers. Kendall's correlation analysis was used to identify the relationship between age and T2/ADC mean values respectively. The one-way analysis of variance (ANOVA) with post hoc analysis was then applied to test the differences of T2 and ADC values among different IVD levels and age groups, followed by linear regression analysis between age (<45 and >45 years) and T2/ADC mean values. This study was approved by the Ethics Committee of the Chinese Academy of Medical Sciences and the Peking Union Medical College Hospital.

RESULTS

Significant negative correlation was observed between age and T2/ADC mean values. The T2 and ADC values showed significant differences among IVD levels and among age groups except for T2 values in age group 1 (25-34 years) and group 2 (35-44 years), and for ADC values at L1-2 level. Both T2 and ADC values showed significant differences between young (age<45 years) and elderly group (age>45 years) at each IVD level. A linear relationship was observed between age and T2/ADC mean values in the elderly group as well as in the young group for the ADC mean values, while no such tendency was identified in the young group for the T2 mean values.

CONCLUSIONS

ADC values may be a more sensitive parameter than T2 in assessing age and disc level related intervertebral disc changes.

Association between low-back pain and lumbar spine bone density: a population-based cross-sectional study

OBJECT

The authors undertook this study to investigate the relationships between low-back pain (LBP) and spinal bone density. Low-back pain is a major health issue and contributes to increases in medical and economic costs. Epidemiological studies have identified individual, sociodemographic, psychosocial, and occupational risk factors for LBP. However, there have been limited studies addressing the relationships between LBP and spinal bone density.

METHODS

Data were obtained from the population-based Fourth Korea National Health and Nutrition Examination Survey (K-NHANES IV, 2009). From 10,533 K-NHANES participants, the authors identified 7144 (3099 men and 4045 women) 21 years of age or older who underwent dual-energy x-ray absorptiometry and anthropometric measurements for inclusion in this study. Low-back pain patients were defined as those who had been diagnosed with LBP by a medical doctor. Chi-square tests, t-tests, and multivariable logistic regression analyses were used to examine the relationships between LBP and spinal bone density.

RESULTS

The total prevalence of LBP in the patient sample was 17.1%. More females (21.0%) reported LBP than males (12.1%). A number of sociodemographic and medical factors-sex, age, place of residence, occupation, education, hypertension, diabetes mellitus, and depression-were all associated with LBP, while LBP was not associated with income or exercise levels. Regression analyses indicated that higher lumbar spine T-scores (OR 1.11, 95% CI 1.02-1.20) were associated with LBP.

CONCLUSIONS

Higher bone density in the lumbar spine is associated with LBP, independent of confounding factors such as sociodemographic status, education, and medical-psychiatric disorders. Cause and effect relationship between higher bone density and LBP, such as degenerative changes in spine, requires further investigation.

Can pathoanatomical pathways of degeneration in lumbar motion segments be identified by clustering MRI findings

Background

Magnetic Resonance Imaging (MRI) is the gold standard for detailed visualisation of spinal pathological and degenerative processes, but the prevailing view is that such imaging findings have little or no clinical relevance for low back pain. This is because these findings appear to have little association with treatment effects in clinical populations, and mostly a weak association with the presence of pain in the general population.

However, almost all research into these associations is based on the examination of individual MRI findings, despite its being very common for multiple MRI findings to coexist. Therefore, this proof-of-concept study investigated the capacity of a multivariable statistical method to identify clusters of MRI findings and for those clusters to be grouped into pathways of vertebral degeneration.

Methods

This study is a secondary analysis of data from 631 patients, from an outpatient spine clinic, who had been screened for inclusion in a randomised controlled trial. The available data created a total sample pool of 3,155 vertebral motion segments. The mean age of the cohort was 42 years (SD 10.8, range 18–73) and 54% were women.

MRI images were quantitatively coded by an experienced musculoskeletal research radiologist using a detailed and standardised research MRI evaluation protocol that has demonstrated high reproducibility. Comprehensive MRI findings descriptive of the disco-vertebral component of lumbar vertebrae were clustered using Latent Class Analysis. Two pairs of researchers, each containing an experienced MRI researcher, then independently categorised the clusters into hypothetical pathoanatomic pathways based on the known histological changes of discovertebral degeneration.

Results

Twelve clusters of MRI findings were identified, described and grouped into five different hypothetical pathways of degeneration that appear to have face validity.

Conclusions

This study has shown that Latent Class Analysis can be used to identify clusters of MRI findings from people with LBP and that those clusters can be grouped into degenerative pathways that are biologically plausible. If these clusters of MRI findings are reproducible in other datasets of similar patients, they may form a stable platform to investigate the relationship between degenerative pathways and clinically important characteristics such as pain and activity limitation.

Coupling of small leucine-rich proteoglycans to hypoxic survival of a progenitor cell-like subpopulation in Rhesus Macaque intervertebral disc

Degeneration of the intervertebral disc (IVD) is a major spinal disorder that associates with neck and back pain. Recent studies of clinical samples and animal models for IVD degeneration have identified cells with multi-potency in the IVD. However, IVD tissue-specific progenitor cells and their niche components are not clear, although degenerated IVD-derived cells possess in vitro characteristics of mesenchymal stromal cell (MSCs). Here, we firstly identified the tissue-specific intervertebral disc progenitor cells (DPCs) from healthy Rhesus monkey and report the niche components modulated the survival of DPCs under hypoxia. DPCs possess clonogenicity, multipotency and retain differentiation potential after extended expansion in vitro and in vivo. In particular, the nucleus pulposus-derived DPCs are sensitive to low oxygen tension and undergo apoptosis under hypoxic conditions due to their inability to induce/stabilize hypoxia-inducible factors (HIF). The presence of small leucine-rich proteoglycans (SLRP), biglycan or decorin, can reduce the susceptibility of DPCs to hypoxia-induced apoptosis via promoting the activation/stabilization of HIF-1α and HIF-2α. As IVD is avascular, we propose SLRPs are niche components of DPCs in IVD homeostasis, providing new insights in progenitor cell biology and niche factors under a hypoxic microenvironment.

Disk degeneration and low back pain: are they fat-related conditions?

Low back pain (LBP) is the world's most debilitating condition. Disk degeneration has been regarded as a strong determinant associated with LBP. Overweight and obesity are public health concerns that affect every population worldwide and whose prevalence continues to rise. Studies have indicated strong associations between overweight/obesity and disk degeneration as well as with LBP. This broad narrative review article addresses the various mechanisms that may be involved leading to disk degeneration and/or LBP in the setting of overweight/obesity. In particular, our goal is to raise awareness of the role of fat cells and their involvement via altered metabolism or the release of adipokines as well as other pathways that may lead to the development of disk degeneration and LBP. Understanding the role of fat in this process may aid in the development of novel biological therapies and technologies to halt the progression or regenerate the disk. Moreover, with genetic advancements and the appreciation of genetic epidemiology, a more personalized approach to spine care may have to consider the role of fat in any preventative, therapeutic, and/or prognosis modalities toward the disk and LBP.

Neurological examination of the peripheral nervous system to diagnose lumbar spinal disc herniation with suspected radiculopathy: a systematic review and meta-analysis

BACKGROUND CONTEXT

Disc herniation is a common low back pain (LBP) disorder, and several clinical test procedures are routinely employed in its diagnosis. The neurological examination that assesses sensory neuron and motor responses has historically played a role in the differential diagnosis of disc herniation, particularly when radiculopathy is suspected; however, the diagnostic ability of this examination has not been explicitly investigated.

PURPOSE

To review the scientific literature to evaluate the diagnostic accuracy of the neurological examination to detect lumbar disc herniation with suspected radiculopathy.

STUDY DESIGN

A systematic review and meta-analysis of the literature.

METHODS

Six major electronic databases were searched with no date or language restrictions for relevant articles up until March 2011. All diagnostic studies investigating neurological impairments in LBP patients because of lumbar disc herniation were assessed for possible inclusion. Retrieved studies were individually evaluated and assessed for quality using the Quality Assessment of Diagnostic Accuracy Studies tool, and where appropriate, a meta-analysis was performed.

RESULTS

A total of 14 studies that investigated three standard neurological examination components, sensory, motor, and reflexes, met the study criteria and were included. Eight distinct meta-analyses were performed that compared the findings of the neurological examination with the reference standard results from surgery, radiology (magnetic resonance imaging, computed tomography, and myelography), and radiological findings at specific lumbar levels of disc herniation. Pooled data for sensory testing demonstrated low diagnostic sensitivity for surgically (0.40) and radiologically (0.32) confirmed disc herniation, and identification of a specific level of disc herniation (0.35), with moderate specificity achieved for all the three reference standards (0.59, 0.72, and 0.64, respectively). Motor testing for paresis demonstrated similarly low pooled diagnostic sensitivities (0.22 and 0.40) and moderate specificity values (0.79 and 0.62) for surgically and radiologically determined disc herniation, whereas motor testing for muscle atrophy resulted in a pooled sensitivity of 0.31 and the specificity was 0.76 for surgically determined disc herniation. For reflex testing, the pooled sensitivities for surgically and radiologically confirmed levels of disc herniation were 0.29 and 0.25, whereas the specificity values were 0.78 and 0.75, respectively. The pooled positive likelihood ratios for all neurological examination components ranged between 1.02 and 1.26.

CONCLUSIONS

This systematic review and meta-analysis demonstrate that neurological testing procedures have limited overall diagnostic accuracy in detecting disc herniation with suspected radiculopathy. Pooled diagnostic accuracy values of the tests were poor, whereby all tests demonstrated low sensitivity, moderate specificity, and limited diagnostic accuracy independent of the disc herniation reference standard or the specific level of herniation. The lack of a standardized classification criterion for disc herniation, the variable psychometric properties of the testing procedures, and the complex pathoetiology of lumbar disc herniation with radiculopathy are suggested as possible reasons for these findings.

Mechanisms of intervertebral disk degeneration/injury and pain: a review

Degeneration of the intervertebral disk and its treatments are currently intensely investigated topics. Back pain is a condition whose chronic and debilitating nature combined with its prevalence make it a major health issue of substantial socioeconomic importance. Although researchers, and even sometimes clinicians, focus on the degenerated disk as the problem, to most patients, pain is the factor that limits their function and impacts their well-being. The purpose of this review is to delineate the changes associated with disk degeneration and to outline mechanisms by which they could be the source of back pain. Although the healthy disk is only innervated in the external layer of its annulus fibrosus, adjacent structures are plentiful with nociceptive receptors. Stimulation of such structures as a consequence of processes initiated by disk degeneration is explored. The concept of discogenic pain and possible mechanisms such as neoinnervation and solute transport are discussed. Finally, how such pain mechanisms may relate to current and proposed treatment strategies is discussed.

Cell signaling pathways related to pain receptors in the degenerated disk

Many of the causes of low back pain are still unknown; sufficient evidence indicates that both degenerative and mechanical change within the intervertebral disk (IVD) is a relevant factor. This article reviews intracellular signaling pathways related to pain receptors in the degenerated IVD. Several reports have demonstrated the number of nerve fibers in the IVD was increased in degenerated disks. In recent years, some groups have reported that an increase in nerve fibers is associated with the presence of inflammatory mediators and/or neurotrophins in the IVD. Cell signaling events, which are regulated by inflammatory mediators and neurotrophins, must be identified to clarify the mechanism underlying low back pain. Major intracellular signaling pathways (nuclear factor kappa β, mitogen-activated protein kinases, and Wnts) potentially play vital roles in mediating the molecular events responsible for the initiation and progression of IVD degeneration. These signaling pathways may represent therapeutic targets for the treatment of IVD degeneration and its associated back pain.

Spinal manipulation under anesthesia: a narrative review of the literature and commentary

As exhibited throughout the medical literature over many decades, there is a lack of uniformity in the manner in which spine pain patients have historically qualified for and received manipulation under anesthesia (MUA). Also, for different professions that treat the same types of spinal conditions via the same means, fundamental MUA decision points vary within the published protocols of different professional associations. The more recent chiropractic literature communicates that the evidence to support the efficacy of MUA of the spine remains largely anecdotal. In addition, it has been reported that the types of spinal conditions most suitable for MUA are without clear-cut consensus, with various indications for MUA of the low back resting wholly upon the opinions and experiences of MUA practitioners. This article will provide a narrative review of the MUA literature, followed by a commentary about the current lack of high quality research evidence, the anecdotal and consensus basis of existing clinical protocols, as well as related professional, ethical and legal concerns for the chiropractic practitioner. The limitations of the current medical literature related to MUA via conscious/deep sedation need to be recognized and used as a guide to clinical experience when giving consideration to this procedure. More research, in the form of controlled clinical trials, must be undertaken if this procedure is to remain a potential treatment option for chronic spine pain patients in the chiropractic clinical practice.

Biomechanical and rheological characterization of mild intervertebral disc degeneration in a large animal model

Biomechanical properties of healthy and degenerated nucleus pulposus (NP) are thought to be important for future regenerative strategies for intervertebral disc (IVD) repair. However, which properties are pivotal as design criteria when developing NP replacement materials is ill understood. Therefore, we determined and compared segmental biomechanics and NP viscoelastic properties in normal and mildly degenerated discs. In eight goats, three lumbar IVDs were chemically degenerated using chondroitinase ABC (CABC), confirmed with radiography and MRI after euthanasia 12 weeks post-operative. Neutral zone (NZ) stiffness and range of motion (ROM) were determined sagitally, laterally, and rotationally for each spinal motion segment (SMS) using a mechanical testing device. NPs were isolated for oscillatory shear experiments; elastic and viscous shear moduli followed from the ratio between shear stress and strain. Water content was quantified by weighing before and after freeze-drying. Disc height on radiographs and signal intensity on MRI decreased (6% and 22%, respectively, p < 0.01) after CABC treatment, confirming that chemical degeneration provides a good model of disc degeneration. Furthermore, CABC-injected IVDs had significantly lower NZ stiffness and larger ROM in lateral bending (LB) and axial rotation (AR) than controls. Rheometry consistently revealed significantly lower (10-12%) viscoelastic moduli after mild degeneration within goats, though the inter-animal differences were relatively large (complex modulus ∼12 to 41 kPa). Relative water content in the NP was unaffected by CABC, remaining at ∼75%. These observations suggest that viscoelastic properties have a marginal influence on mechanical behavior of the whole SMS. Therefore, when developing replacement materials the focus should be on other design criteria, such as biochemical cues and swelling pressure.

Dynamic and static overloading induce early degenerative processes in caprine lumbar intervertebral discs

Mechanical overloading of the spine is associated with low back pain and intervertebral disc (IVD) degeneration. How excessive loading elicits degenerative changes in the IVD is poorly understood. Comprehensive knowledge of the interaction between mechanical loading, cell responses and changes in the extracellular matrix of the disc is needed in order to successfully intervene in this process. The purpose of the current study was to investigate whether dynamic and static overloading affect caprine lumbar discs differently and what mechanisms lead to mechanically induced IVD degeneration. Lumbar caprine IVDs (n = 175) were cultured 7, 14 and 21 days under simulated-physiological loading (control), high dynamic or high static loading. Axial deformation and stiffness were continuously measured. Cell viability, cell density, and gene expression were assessed in the nucleus, inner- and outer annulus. The extracellular matrix (ECM) was analyzed for water, glycosaminoglycan and collagen content. IVD height loss and changes in axial deformation were gradual with dynamic and acute with static overloading. Dynamic overloading caused cell death in all IVD regions, whereas static overloading mostly affected the outer annulus. IVDs expression of catabolic and inflammation-related genes was up-regulated directly, whereas loss of water and glycosaminoglycan were significant only after 21 days. Static and dynamic overloading both induced pathological changes to caprine lumbar IVDs within 21 days. The mechanism by which they inflict biomechanical, cellular, and extracellular changes to the nucleus and annulus differed. The described cascades provide leads for the development of new pharmacological and rehabilitative therapies to halt the progression of DDD.

Ultrashort time-to-echo MRI of the cartilaginous endplate: technique and association with intervertebral disc degeneration

INTRODUCTION

The purpose of this study was to report the feasibility of the ultrashort time-to-echo (UTE) MRI technique to assess cartilaginous endplate (CEP) defects in humans in vivo and to assess their relationship with intervertebral disc (IVD) degeneration.

METHODS

Nine volunteer subjects (mean age = 43.9 years; range = 22-61 years) were recruited, representing 54 IVDs and 108 CEPs. The subjects underwent T2-weighted and UTE MRI to assess for the presence and severity of IVD degeneration, and for the presence of CEP defects, respectively, from T12 to S1. IVD degeneration was graded according to the Schneiderman et al. classification on T2-weighted MRI. CEP defects were defined on UTE MRI as discontinuity of high signal over four consecutive images and were independently assessed by two observers.

RESULTS

Thirty-seven out of 108 (34.3%) CEPs had defects, which mainly occurred at T12/L1, L1/L2 and L4/L5 (P = 0.008). Multivariate logistic regression revealed that lower body mass index (P = 0.009) and younger (P = 0.034) individuals had a decreased likelihood of having CEP defects. A statistically significant association was found to exist between the presence of CEP defects and IVD degeneration (P = 0.036). A higher prevalence of degenerated IVDs with CEP defects was found at L4/5 and L5/S1, while degenerated IVDs with no CEP defects were found throughout the whole lumbar region. Mean IVD degeneration scores of the L4/5 and L5/S1 levels with CEP defects were higher in comparison with those with no CEP defects.

CONCLUSIONS

Our study demonstrates the feasibility of using UTE MRI in humans in vivo to assess the integrity of the CEP. A statistically significant association was found to exist between the presence of CEP defects and IVD degeneration. In the lower lumbar region, more severe degeneration was found to occur in the IVDs with CEP defects than in those without defects.

Body mass index is associated with lumbar disc degeneration in young Finnish males: subsample of Northern Finland birth cohort study 1986

BACKGROUND

The role of environmental factors in lumbar intervertebral disc degeneration (DD) in young adults is largely unknown. Therefore, we investigated whether body mass index (BMI), smoking, and physical activity are associated with lumbar DD among young adults.

METHODS

The Oulu Back Study (OBS) is a subpopulation of the 1986 Northern Finland Birth Cohort (NFBC 1986) and it originally included 2,969 children. The OBS subjects received a postal questionnaire, and those who responded (N = 1,987) were invited to the physical examination. The participants (N = 874) were invited to lumbar MRI study. A total of 558 young adults (325 females and 233 males) underwent MRI that used a 1.5-T scanner at the mean age of 21. Each lumbar intervertebral disc was graded as normal (0), mildly (1), moderately (2), or severely (3) degenerated. We calculated a sum score of the lumbar DD, and analyzed the associations between environmental risk factors (smoking, physical activity and weight-related factors assessed at 16 and 19 years) and DD using ordinal logistic regression, the results being expressed as cumulative odds ratios (COR). All analyses were stratified by gender.

RESULTS

Of the 558 subjects, 256 (46%) had no DD, 117 (21%) had sum score of one, 93 (17%) sum score of two, and 92 (17%) sum score of three or higher. In the multivariate ordinal logistic regression model, BMI at 16 years (highest vs. lowest quartile) was associated with DD sum score among males (COR 2.35; 95% CI 1.19-4.65) but not among females (COR 1.29; 95% CI 0.72-2.32). Smoking of at least four pack-years was associated with DD among males, but not among females (COR 2.41; 95% CI 0.99-5.86 and 1.59; 95% 0.67-3.76, respectively). Self-reported physical activity was not associated with DD.

CONCLUSIONS

High BMI at 16 years was associated with lumbar DD at 21 years among young males but not among females. High pack-years of smoking showed a comparable association in males, while physical activity had no association with DD in either gender. These results suggest that environmental factors are associated with DD among young males.

Intervertebral disc viability after burst fractures of the thoracic and lumbar spine treated with pedicle screw fixation and direct end-plate restoration

BACKGROUND CONTEXT

Controversies persist for the best treatment of burst fractures of the thoracolumbar spine. Anterior corpectomy and discectomy followed by reconstruction with intervertebral cage and posterior fixation, for example, are based mainly on the widespread assumption that intervertebral discs involved in burst-type fractures, typically, do not survive the traumatic event and will degenerate irrevocably.

PURPOSE

To evaluate whether intervertebral discs, located adjacent to traumatic burst fractures and treated with pedicle screw fixation and direct end-plate restoration, survive the traumatic event or irrevocably progress to severe disc degeneration.

STUDY DESIGN

Prospective trial.

PATIENT SAMPLE

Twenty adult patients with traumatic burst fractures of the thoracolumbar spine and treated with pedicle screw fixation and direct end-plate reduction were included.

OUTCOME MEASURES

Disc degeneration according to the Pfirrmann classification.

METHODS

Magnetic resonance imaging scans were obtained preoperatively, 1 month after surgery and 1 month after pedicle screw removal 12 to 18 months after index surgery. Degeneration of the intervertebral discs adjacent to the fracture was assessed using the Pfirrmann classification. Grade 1/2/3 was defined as mild-to-moderate degeneration of the intervertebral disc (MDID), whereas Grade 4/5 was defined as severe-to-endstage degeneration of the intervertebral disc (SDID). Repeated measure analysis was performed to detect significant differences between MDID and SDID scores.

RESULTS

A total of 19 patients (38 discs) were fully documented and available for study. All discs showed MDID preoperatively, and while five discs (13%) progressed to SDID at 12 to 18 months posttrauma, the other discs did not show progression of degeneration.

CONCLUSIONS

Intervertebral discs adjacent to traumatic burst fractures treated with pedicle screw instrumentation and direct end-plate restoration do not routinely seem to progress to severe degeneration at 12 to 18 months postinjury.

Genetic polymorphisms associated with intervertebral disc degeneration

BACKGROUND CONTEXT

Disc degeneration (DD) is a multifaceted chronic process that alters the structure and function of the intervertebral discs and can lead to painful conditions. The pathophysiology of degeneration is not well understood, but previous studies suggest that certain genetic polymorphisms may be important contributing factors leading to an increased risk of DD.

PURPOSE

To review the genetic factors in DD with a focus on polymorphisms and their putative role in the pathophysiology of degeneration. Elucidating the genetic components that are associated with degeneration could provide insights into the mechanism of the process. Furthermore, defining these relationships and eventually using them in a clinical setting may allow an identification and early intervention for those who are at a high risk for painful DD.

STUDY DESIGN

Literature review.

METHODS

This literature review focused on the studies concerning genetic polymorphisms and their associations with DD.

RESULTS

Genetic polymorphisms in 20 genes have been analyzed in association with DD, including vitamin D receptor, growth differentiation factor 5 (GDF5), aggrecan, collagen Types I, IX, and XI, fibronectin, hyaluronan and proteoglycan link protein 1 (HAPLN1), thrombospondin, cartilage intermediate layer protein (CILP), asporin, MMP1, 2, and 3, parkinson protein 2, E3 ubiquitin protein ligase (PARK2), proteosome subunit β type 9 (PSMB9), tissue inhibitor of metalloproteinase (TIMP), cyclooxygenase-2 (COX2), and IL1α, IL1β, and IL6. Each genetic polymorphism codes for a protein that has a functional role in the pathogenesis of DD.

CONCLUSIONS

There are known associations between several genetic polymorphisms and DD. Of the 20 genes analyzed, polymorphisms in vitamin D receptor, aggrecan, Type IX collagen, asporin, MMP3, IL1, and IL6 show the most promise as functional variants. Genetic studies are crucial for understanding the mechanism of the degeneration. This genetic information could eventually be used as a predictive model for determining a patient's risk for symptomatic DD.

Association of abdominal obesity with lumbar disc degeneration--a magnetic resonance imaging study

Purpose

To evaluate whether midsagittal (abdominal) obesity in magnetic resonance imaging (MRI), waist circumference (WC) and body fat percentage are associated with lumbar disc degeneration in early adulthood.

Methods

We obtained the lumbar MRI (1.5-T scanner) of 325 females and 233 males at a mean age of 21 years. Lumbar disc degeneration was evaluated using Pfirrmann classification. We analysed the associations of MRI measures of obesity (abdominal diameter (AD), sagittal diameter (SAD), ventral subcutaneous thickness (VST), and dorsal subcutaneous thickness (DST)), WC and body fat percentage with disc degeneration sum scores using ordinal logistic regression.

Results

A total of 155 (48%) females and 147 (63%) males had disc degeneration. AD and SAD were associated with a disc degeneration sum score of ≥3 compared to disc degeneration sum score of 0–2 (OR 1.67; 95% confidence interval (CI) 1.20–2.33 and OR 1.40; 95% CI 1.12–1.75, respectively) among males, but we found no association among females. WC was also associated with disc degeneration among males (OR 1.03 per one cm; 95% CI 1.00–1.05), but not among females.

Conclusion

Measures of abdominal obesity in MRI and waist circumference were associated with disc degeneration among 21-year-old males.

Effect of a synthetic link N peptide nanofiber scaffold on the matrix deposition of aggrecan and type II collagen in rabbit notochordal cells

Self-assembling peptide nanofiber scaffolds have been studied extensively as biological materials for 3-dimensional cell culture and repairing tissue defects in animals. However, few studies have applied peptide nanofiber scaffolds in the tissue engineering of intervertebral discs (IVDs). In this study, a novel functionalized peptide scaffold was specifically designed for IVD tissue engineering, and notochordal cells (NCs) as an alternative cell source for IVD degeneration were selected to investigate the bioactive scaffold material. The novel RADA16-Link N self-assembling peptide scaffold material was designed by direct coupling to a bioactive motif link N. The link N nanofiber scaffold (LN-NS) material was obtained by mixing pure RADA16-I and RADA16-Link N (1:1) designer peptide solutions. Although live/dead cell assays showed that LN-NS and RADA16-I scaffold materials were both biocompatible with NCs, the LN-NS material significantly promoted NC adhesion compared with that of the pure RADA16-I SAP scaffold material. The depositions of aggrecan and type II collagen, which are significant markers for IVD cells, were remarkably increased. Furthermore, the results indicated that the link N motif, the matrix analog of the nucleus pulposus, significantly promoted the accumulation of other extracellular matrices in vitro. We conclude that the novel LN-NS material is a promising biological scaffold material, and may have a broad range of applications in IVD tissue engineering.

Challenges and strategies in the repair of ruptured annulus fibrosus

Lumbar discectomy is the surgical procedure most frequently performed for patients suffering from low back pain and sciatica. Disc herniation as a consequence of degenerative or traumatic processes is commonly encountered as the underlying cause for the painful condition. While discectomy provides favourable outcome in a majority of cases, there are conditions where unmet requirements exist in terms of treatment, such as large disc protrusions with minimal disc degeneration; in these cases, the high rate of recurrent disc herniation after discectomy is a prevalent problem. An effective biological annular repair could improve the surgical outcome in patients with contained disc herniations but otherwise minor degenerative changes. An attractive approach is a tissue-engineered implant that will enable/stimulate the repair of the ruptured annulus. The strategy is to develop three-dimensional scaffolds and activate them by seeding cells or by incorporating molecular signals that enable new matrix synthesis at the defect site, while the biomaterial provides immediate closure of the defect and maintains the mechanical properties of the disc. This review is structured into (1) introduction, (2) clinical problems, current treatment options and needs, (3) biomechanical demands, (4) cellular and extracellular components, (5) biomaterials for delivery, scaffolding and support, (6) pre-clinical models for evaluation of newly developed cell- and material-based therapies, and (7) conclusions. This article highlights that an interdisciplinary approach is necessary for successful development of new clinical methods for annulus fibrosus repair. This will benefit from a close collaboration between research groups with expertise in all areas addressed in this review.

Annulus fissures are mechanically and chemically conducive to the ingrowth of nerves and blood vessels

STUDY DESIGN

Mechanical and biochemical analyses of cadaveric and surgically removed discs.

OBJECTIVE

To test the hypothesis that fissures in the annulus of degenerated human discs are mechanically and chemically conducive to the ingrowth of nerves and blood vessels.

SUMMARY OF BACKGROUND DATA

Discogenic back pain is closely associated with fissures in the annulus fibrosus, and with the ingrowth of nerves and blood vessels.

METHODS

Three complementary studies were performed. First, 15 cadaveric discs that contained a major annulus fissure were subjected to 1 kN compression, while a miniature pressure transducer was pulled through the disc to obtain distributions of matrix compressive stress perpendicular to the fissure axis. Second, Safranin O staining was used to evaluate focal loss of proteoglycans from within annulus fissures in 25 surgically removed disc samples. Third, in 21 cadaveric discs, proteoglycans (sulfated glycosaminoglycans [sGAGs]) and water concentration were measured biochemically in disrupted regions of annulus containing 1 or more fissures, and in adjacent intact regions.

RESULTS

Reductions in compressive stress within annulus fissures averaged 36% to 46%, and could have been greater at the fissure axis. Stress reductions were greater in degenerated discs, and were inversely related to nucleus pressure (R(2) = 47%; P = 0.005). Safranin O stain intensity indicated that proteoglycan concentration was typically reduced by 40% at a distance of 600 μm from the fissure axis, and the width of the proteoglycan-depleted zone increased with age (P < 0.006; R(2) = 0.29) and with general proteoglycan loss (P < 0.001; R(2) = 0.32). Disrupted regions of annulus contained 36% to 54% less proteoglycans than adjacent intact regions from the same discs, although water content was reduced only slightly.

CONCLUSION

Annulus fissures provide a low-pressure microenvironment that allows focal proteoglycan loss, leaving a matrix that is conducive to nerve and blood vessel ingrowth.

The natural history of degeneration of the lumbar and cervical spines: a systematic review

STUDY DESIGN

Systematic review.

OBJECTIVE

To determine the population risk of radiographical degeneration in the lumbar and cervical spine as well as the risk of adjacent segment pathology (ASP) among patients who receive and do not receive (but were eligible for) fusion for lumbar or cervical degeneration.

SUMMARY OF BACKGROUND DATA

The etiology of ASP remains unclear. It has been suggested that ASP results because of a biomechanical stress transfer from the fusion. It has also been suggested that ASP is a continuation of natural arthritic disease. We sought to examine the literature and compare the rates of spinal degeneration without fusion and the rates of adjacent segment degeneration. Similarities or differences may yield insight into the etiology of ASP.

METHODS

A systematic review of the English language literature was undertaken for articles published between 1990 and March 15, 2012. Electronic databases and reference lists of key articles were searched to identify articles reporting prevalence and/or incidence of radiographical spinal degeneration (de novo degeneration) or radiographical adjacent segment pathology (RASP) (degeneration after fusion). Two independent reviewers assessed the level of evidence and the overall quality of the literature using the Grades of Recommendation Assessment, Development and Evaluation criteria. Disagreements were resolved by consensus.

RESULTS

We identified 15 studies from our search strategy that met the inclusion criteria from a total of 235 possible studies. Various definitions of radiographical spinal degeneration were used across the studies. For the population risk of radiographical lumbar and cervical spine degeneration, the cumulative incidence ranged from 12.7% to 51.5% during a 5- to 25-year period across 3 studies. One study of the cervical spine reported that there was a baseline prevalence of disc degeneration of 21.7% and, in their follow-up study, reported that 47.9% of individuals had evidence of progression of degeneration during a mean 5.8-year follow-up. The rate of progression per 100 person-years showed an age- and sex-specific trend, with females progressing at a faster rate than males through the 50s, males progressing faster than females during the 60s and 70s, with rates becoming identical in the 80s. Regarding age-specific risk, the prevalence of lumbar degeneration increased with age across 2 studies. For RASP following fusion, the cumulative incidence ranged from 6.3% to 44.4% during 6 to 12.6 years of follow-up across the 7 studies; the risk of cervical RASP was higher than that of lumbar despite the shorter mean follow-up periods.

CONCLUSION

RASP may occur at a higher rate than natural history and suggests that another factor (such as biomechanical effect of fusion) may accelerate pathologic changes.

CONSENSUS STATEMENT

ASP may occur at a higher rate than natural spinal degeneration and suggests that another factor (such as biomechanical effect of fusion) may accelerate pathologic changes. Strength of Statement: Weak.

Low back pain prevalence and associated factors in Iranian population: findings from the national health survey

Background. There are very few studies that had a sample size sufficient to explore the association between factors related to low back pain in a representative sample of the Iranian population. Objective. To examine the relationship between sociodemographic factors, smoking, obesity, and low back pain in Iranian people. Methods. We used Iranian adults respondents (n = 25307) from the National Health Survey. Adjusted odds ratios and 95% confidence intervals were estimated by using logistic regression. Results. The prevalence of low back pain was found in 29.3% of the studied sample. High age, female sex, being married, obesity, low-economic index, being smoker, in a rural residence, and low educational attainment, all increased the odds of low back pain. Conclusions. Our findings add to the evidence on the importance of obesity in relation to low back pain. These results can be used as a basis to reinforce health programs to prevent obesity.

A longitudinal study for incidence of low back pain and radiological changes of lumbar spine in asymptomatic Japanese military young adults

INTRODUCTION

The relation between radiological abnormalities on lumbar spine and low back pain (LBP) has been debated, presumably because of potential biases related to heterogeneity in selection of the subjects, radiological abnormalities at entry, or its cross-sectional observation in nature. Therefore, the aim of this study of a selected population of asymptomatic Japanese Self Defense Forces (JSDF) young adults male with normal lumbar radiographs was to investigate the incidence of newly developed lumbar degenerative changes at middle age and to study their association to LBP.

SUBJECTS AND METHODS

In 1990, 84 JSDF male military servicemen aged 18 years, without a history of LBP and radiological abnormal findings, were enrolled. After 20 years, 84 subjects were underwent repeated X-ray and completed questionnaires on current LBP and lifestyle factors.

RESULTS

The prevalence of LBP was demonstrated 59 %, with 85 % of them showing mild pain. Analysis of lumbar radiographs revealed that 48 % had normal findings and 52 % had degenerative changes. The association between LBP and life style factors was not demonstrated. Lumbar spine in subjects with LBP was more degenerated than in those without. Although disc space narrowing and LBP did not achieve a statistical significance, a significant correlation existed between vertebral osteophyte and LBP in univariate and multivariate analysis (OR 3.0; 95 % CI 1.227-7.333).

DISCUSSION AND CONCLUSIONS

This longitudinal study demonstrated the significant association between vertebral osteophyte and incidence of mild LBP in initially asymptomatic and radiologically normal subjects. These data provide the additional information concerning the pathology of LBP, but further study is needed to clarify the clinical relevance.

Degenerative joint disease of the spine

Degenerative changes are the manifestations of metabolic disturbances in the matrix of intervertebral disks and zygapophysial joints. Genetic factors and physical loading contribute, but the strongest correlation is with age. Degenerative changes lack any significant correlation with spinal pain. Therefore, they do not constitute a diagnosis. Internal disk disruption is a distinctive condition that is independent of degeneration and age. Its biophysical and morphologic features correlate with back pain, as do its manifestations on magnetic resonance imaging.

Modulation of in vitro microenvironment facilitates synovium-derived stem cell-based nucleus pulposus tissue regeneration

STUDY DESIGN

Two experiments were conducted. Experiment 1 evaluated the effect of 3 kinds of decellularized extracellular matrices (DECMs) deposited by synovium-derived stem cells (SDSCs) and/or nucleus pulposus cells (NPCs) on SDSC expansion and NP lineage differentiation. Experiment 2 evaluated the effect of DECM deposited by SDSCs on NPC expansion and redifferentiation capacity. In both experiments, hypoxia was evaluated in DECM preparation and pellet culture.

OBJECTIVE

Modulating the in vitro microenvironment facilitates SDSC-based NP tissue regeneration.

SUMMARY OF BACKGROUND DATA

Autologous cell therapy is a promising approach for NP regeneration. Current in vitro expansion in monolayer results in cell dedifferentiation.

METHODS

In Experiment 1, passage 3 SDSCs were expanded for 1 passage on DECM deposited by NPCs, SDSCs, or NPCs combined with SDSCs (50:50); DECM was prepared under either normoxia (21% O2) or hypoxia (5% O2). Expanded SDSCs were then cultured in a serum-free chondrogenic medium in hypoxia for 14 days. In Experiment 2, passage 2 NPCs were expanded for 1 passage on DECM deposited by SDSCs; DECM was prepared under either normoxia or hypoxia. Expanded NPCs were cultured in a serum-free chondrogenic medium under either hypoxia or normoxia for 14 days. Cell expansion on plastic flasks served as a control in both experiments. Fourteen-day pellets were evaluated for chondrogenesis using histology, immunostaining, biochemistry, and real-time polymerase chain reaction.

RESULTS

DECM deposited by NPCs combined with SDSCs effectively enhanced expanded SDSC viability and guided SDSC differentiation toward an NP lineage; this effect is comparable with DECM deposited by SDSCs but higher than that deposited by NPCs. DECM prepared under normoxia favored SDSC viability and NP lineage differentiation whereas DECM prepared under hypoxia benefited NPC viability and redifferentiation. Low oxygen in a pellet culture system enhanced NPC viability and redifferentiation.

CONCLUSION

The in vitro microenvironment can be modulated by low oxygen and tissue-specific cell-based DECM to facilitate NP tissue regeneration.

Intervertebral disc degeneration: evidence for two distinct phenotypes

We review the evidence that there are two types of disc degeneration. 'Endplate-driven' disc degeneration involves endplate defects and inwards collapse of the annulus, has a high heritability, mostly affects discs in the upper lumbar and thoracic spine, often starts to develop before age 30 years, usually leads to moderate back pain, and is associated with compressive injuries such as a fall on the buttocks. 'Annulus-driven' disc degeneration involves a radial fissure and/or a disc prolapse, has a low heritability, mostly affects discs in the lower lumbar spine, develops progressively after age 30 years, usually leads to severe back pain and sciatica, and is associated with repetitive bending and lifting. The structural defects which initiate the two processes both act to decompress the disc nucleus, making it less likely that the other defect could occur subsequently, and in this sense the two disc degeneration phenotypes can be viewed as distinct.

The relationship between concave angle of vertebral endplate and lumbar intervertebral disc degeneration

STUDY DESIGN

A retrospective study of magnetic resonance imaging of the lower lumbar spine.

OBJECTIVE

To describe the characteristics of the concave angle of vertebral endplate (CAVE) and study the association between CAVE and lumbar intervertebral disc degeneration (IVDD).

SUMMARY OF BACKGROUND DATA

The vertebral endplate is responsible for transferring stress between disc and vertebral body, and its concavity is important in dispersing compression stress. However, the characteristics of CAVE and the relationship between CAVE and IVDD have not been investigated.

METHODS

Magnetic resonance images of the lower lumbar spine in 511 patients with low back pain were examined by 2 experienced spine surgeons. The grades of IVDD and lumbar disc herniation (LDH) were evaluated, several parameters including CAVE, height, and the sagittal diameter of vertebral body were measured, and the association between IVDD or LDH and CAVE was analyzed.

RESULTS

At L3-L4, L4-L5, and L5-S1, CAVE was smaller in the upper endplate (i.e., the inferior endplate of the superior vertebra) than in the lower endplate (i.e., the superior endplate of the inferior vertebra). There was no male/female difference in the size of CAVE in any of the segments. According to partial correlation analysis, CAVE was moderately related to IVDD, but no association between CAVE and LDH was found.

CONCLUSION

When lumbar IVDD occurs, the CAVE increases and the endplate tends to flatten. The degree of flattening is related to the severity of the degeneration.

The association of lumbar intervertebral disc degeneration on magnetic resonance imaging with body mass index in overweight and obese adults: a population-based study

OBJECTIVE

To investigate the association of being overweight or obese with the presence, extent, and severity of lumbar disc degeneration on magnetic resonance imaging (MRI) in adults.

METHODS

A population-based cross-sectional study of 2,599 southern Chinese volunteers was conducted. Subjects underwent radiographic and clinical assessment, and weight and height were measured. Sagittal T2-weighted MRIs of the lumbar spine were obtained. The presence, extent, and severity of disc degeneration and additional radiographic and clinical parameters were assessed. Asian-modified body mass index (BMI) (kg/m(2) ) categories were used. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

The study included 1,040 men and 1,559 women (mean age 41.9 years). Disc degeneration was noted in 1,890 subjects (72.7%). BMI was significantly higher in subjects with disc degeneration (mean 23.3 kg/m(2) ) than in subjects without degeneration (mean 21.7 kg/m(2) ) (P < 0.001). A significant increase in the number of degenerated levels (P < 0.001), global severity of disc degeneration (P < 0.001), and end-stage disc degeneration with disc space narrowing (P < 0.001) was noted with elevated BMI, in particular in overweight and obese subjects. In the adjusted multivariate logistic regression model, there was a positive linear trend (r(2) = 0.99) between BMI and the overall presence of disc degeneration in overweight (OR 1.30 [95% CI 1.03-1.62]) and obese (OR 1.79 [95% CI 1.17-2.74]) subjects. End-stage disc degeneration with disc space narrowing was significantly more pronounced in obese subjects (adjusted OR 1.72 [95% CI 1.23-2.41] [reference normal weight]).

CONCLUSION

Our findings, in one of the largest studies to systematically assess lumbar disc degeneration on MRI, indicated a significant association between the presence, extent, and global severity of disc degeneration with weight in overweight and obese adults.

Association of modic changes, Schmorl's nodes, spondylolytic defects, high-intensity zone lesions, disc herniations, and radial tears with low back symptom severity among young Finnish adults

STUDY DESIGN

A cross-sectional magnetic resonance imaging (MRI) study.

OBJECTIVE

We investigated the association among Modic changes, Schmorl's nodes, spondylolytic defects, high-intensity zone lesions, radial tears, herniations, and low back symptom severity.

SUMMARY OF BACKGROUND DATA

Disc degeneration is associated with low back pain in early adulthood, but the associations between other MRI findings and low back pain are not well known.

METHODS

Questionnaire data and MRI scans (1.5-T) were available for 554 subjects derived from a birth cohort at 21 years of age. Data on low back pain and back-related functional limitations at 18, 19, and 21 years of age were used for clustering of subjects, using latent class analysis. We used logistic regression with adjustment for the degree of disc degeneration to evaluate the associations between specific imaging findings and low back symptom severity.

RESULTS

The prevalence of herniations was 20%, Schmorl's nodes 17%, radial tears 9.9%, high-intensity zone lesions 3.2%, spondylolytic defects 5.8%, and Modic changes 0.7%. Latent class analysis produced 5 clusters: "Always Painful" (n = 65) meant painful at all time points and "Recent Onset Pain" (n = 56) meant increasing symptom severity, whereas subjects in the "Moderately Painful" (n = 73), "Minor Pain" (n = 193), and "No Pain" (n = 167) clusters had fewer symptoms. Compared with the "No Pain" cluster, Schmorl's nodes were more likely to occur in the "Always Painful" cluster (P = 0.017) and herniations in the 3 most painful clusters (P < 0.001). Herniations were associated with low back symptom severity (odds ratio, 2.5; 95% confidence interval, 1.4-4.4). Schmorl's nodes and radial tears were associated with symptoms in crude analyses only, whereas high-intensity zone lesions and spondylolytic defects occurred in similar frequencies in all clusters.

CONCLUSION

Herniations were most likely in the subjects with recent onset or persistent (3-yr period) low back symptoms, although they were also detected in subjects with no symptoms. The clinical relevance of herniations on MRI remains to be evaluated in the context of symptoms.

Initiation and progression of mechanical damage in the intervertebral disc under cyclic loading using continuum damage mechanics methodology: A finite element study

It is difficult to study the breakdown of disc tissue over several years of exposure to bending and lifting by experimental methods. There is also no finite element model that elucidates the failure mechanism due to repetitive loading of the lumbar motion segment. The aim of this study was to refine an already validated poro-elastic finite element model of lumbar motion segment to investigate the initiation and progression of mechanical damage in the disc under simple and complex cyclic loading conditions. Continuum damage mechanics methodology was incorporated into the finite element model to track the damage accumulation in the annulus in response to the repetitive loading. The analyses showed that the damage initiated at the posterior inner annulus adjacent to the endplates and propagated outwards towards its periphery under all loading conditions simulated. The damage accumulated preferentially in the posterior region of the annulus. The analyses also showed that the disc failure is unlikely to happen with repetitive bending in the absence of compressive load. Compressive cyclic loading with low peak load magnitude also did not create the failure of the disc. The finite element model results were consistent with the experimental and clinical observations in terms of the region of failure, magnitude of applied loads and the number of load cycles survived.

Factores de riesgo para la recurrencia de hernia de disco lumbar

OBJETIVO: La recurrencia de hernia del disco lumbar es un padecimiento que implica algunas dificultades en relación con el diagnóstico y tratamiento. Es importante tratar de identificar los factores que puedan influir en la presentación de la recurrencia. MÉTODOS: Se revisaron los casos de pacientes operados por hernia de disco lumbar recurrente entre los años de 2006 y 2008, buscando identificar los factores que tuvieran relación con dicha patología, y también se revisaron los casos de pacientes operados por hernia de disco lumbar en forma primaria. RESULTADOS: Se analizaron los casos de 20 pacientes con hernia discal lumbar recurrente y de 27 con hernia discal lumbar operados en forma primaria. Para los pacientes con recurrencia, se encontró que el 95% de ellos presentaban algún grado de obesidad, determinado por la Fórmula de Quetelet basada en el Índice de Masa Corporal; se observó también que el 75% de los casos tenían protrusión, con resultados excelentes en 35%, y buenos en 55%, el 10% presentó molestias residuales de forma grave. Para los pacientes con hernia primaria se estudiaron 27 casos, en los que se observó que el 92% de ellos se operaron antes de los 6 meses de iniciado el cuadro, 38% tuvieron resultados excelentes, 40% buenos y el 19% malos resultados. Al estudiar las variables, con el índice de Pearson, se encontró relación de la recurrencia con tabaquismo, trabajo, diabetes e hipertensión, y nivel de estudios, no con la obesidad. CONCLUSIONES: es destacable que dos de los factores relacionados son susceptibles de modificación antes del evento quirúrgico o posteriormente a este, lo cual puede beneficiar el desenlace del mismo.

An Association Study of Interleukin 18 Receptor Genes (IL18R1 and IL18RAP) in Lumbar Disc Degeneration

Objectives:

To examine association of candidate genetic variants in structural, inflammatory, matrix modifying, vitamin D receptor genes and variants associated with osteoarthritis, with surgical candidates and surgical patients with lumbar disc degeneration (LDD), in light of their previously reported susceptibility for LDD.

Methods:

Genotyping of 146 Norwegian LDD patients and 188 Norwegian controls was performed for 20 single-nucleotide polymorphisms (SNPs) from collagen, aggrecan, interleukin, VDR, MMP3 and COX2 genes and 7 SNPs from osteoarthritic genes.

Results:

The neighboring genes IL18R1 and IL18RAP polymorphisms (rs2287037 and rs1420100), showed a statistically non-significant risk for developing LDD (OR 1.36 [95 % CI 0.99 – 1.87]; p=0.06 and OR 1.33 [95 % CI 0.98-1.81]; p=0.07). Homozygosity of these risk alleles was associated with LDD (p=0.023 and p=0.027). The non-risk alleles at these SNPs were situated on a haplotype negatively associated with LDD (p=0.008). Carriage of at least one non-risk allele at both loci also reduces the risk of developing LDD (OR 0.51 [95 % CI 0.33-0.80]; p=0.003).

Conclusion:

Our findings support the polygenic nature of LDD and suggest that variation in interleukin 18 receptor genes could affect the risk of severe LDD and associated low back pain.

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

STUDY DESIGN

A cross-sectional, population-based cohort study.

OBJECTIVE

The objective of this study was to evaluate the clinical relevance of skipped level disc degeneration (SLDD) to that of contiguous, multilevel disc degeneration (CMDD) of the lumbar spine. The study also aimed to identify patterns of SLDD, its classification, prevalence, and clinical relevance.

SUMMARY OF BACKGROUND DATA

The association of disc degeneration on magnetic resonance imaging with low back pain (LBP) remains questionable. The occurrence of SLDD of the lumbar spine has recently been noted. To date, patterns of disc degeneration have been overlooked in the association with low back symptoms.

METHODS

A population-based radiographic and clinical study of 3099 Southern Chinese patients. Individuals with multilevel disc degeneration of the lumbar spine on sagittal T2-weighted magnetic resonance imaging (N = 1457) were stratified to SLDD (n = 301; 20.7%) or CMDD (n = 1156; 79.3%) groups. SLDD was further classified into 5 types by the relative location of nondegenerated normal disc(s) to degenerated disc levels. Subject demographics, presence of LBP, pain intensity, and functional disability were assessed.

RESULTS

In the multivariate analyses, CMDD increased the likelihood of historical LBP (odds ratio [OR]: 1.39; 95% confidence interval [CI]: 1.00-1.93; P = 0.047) and pain severity (OR: 1.83; 95% CI: 1.23-2.73; P = 0.003) in comparison with SLDD. A significant increasing trend of number of levels with disc degeneration, overall disc degeneration severity, and presence of disc bulges/extrusions was noted from SLDD type I (least severe) to SLDD type V (most severe) (P < 0.05). A higher prevalence of LBP and a higher pain intensity were observed in SLDD classification type V. Functional disability scores did not differ between CMDD and SLDD, nor within SLDD classification types (P > 0.05).

CONCLUSION

Our large-scale study is the first to describe novel variants of SLDD types and their clinical relevance. More important, LBP and severity of pain were more pronounced in individuals with CMDD rather than those with SLDD. Our study suggests that subjects with a similar degree but different patterns of multilevel disc degeneration do differ with respect to low back symptoms. This finding may provide new evidence with regard to the mechanism of LBP.

Biomechanical behavior of a biomimetic artificial intervertebral disc

STUDY DESIGN

The biomechanical behavior of a biomimetic artificial intervertebral disc (AID) was characterized in vitro in axial compression and compared with natural disc behavior.

OBJECTIVE

To evaluate the strength and durability of a novel biomimetic AID and to demonstrate whether its axial deformation behavior is similar to that of a natural disc.

SUMMARY OF BACKGROUND DATA

Current clinically used AIDs have reasonable success rates. However, because of their nonphysiological design, spinal mechanics are altered. To avoid long-term complications, a novel biomimetic AID, with a nucleus-annulus structure and osmotic swelling properties has been developed.

METHODS

Eighteen AIDs in total were tested in axial compression. Six were loaded monotonically to determine strength. Six were tested in fatigue (600-6000 N). Another 6 were used to characterize the axial creep and dynamic behavior (0.01-10 Hz). Creep and dynamic response were also determined for 4 AIDs after fatigue loading.

RESULTS

The AIDs remained intact up to 15 kN and 10 million cycles. The creep and dynamic behavior were similar to the natural disc behavior, except for hysteresis, which was 20% to 30% higher. After fatigue, creep decreased from 4% to 1%, stiffness increased 2-fold, and hysteresis was reduced to that for a normal disc.

CONCLUSION

A strong and durable AID design was introduced. Compared with current clinical articulating AIDs, this biomimetic AID introduces the natural disc annulus-nucleus structure, resulting in axial behavior closer to that of the natural disc.

Simulated-physiological loading conditions preserve biological and mechanical properties of caprine lumbar intervertebral discs in ex vivo culture

Low-back pain (LBP) is a common medical complaint and associated with high societal costs. Degeneration of the intervertebral disc (IVD) is assumed to be an important causal factor of LBP. IVDs are continuously mechanically loaded and both positive and negative effects have been attributed to different loading conditions.

In order to study mechanical loading effects, degeneration-associated processes and/or potential regenerative therapies in IVDs, it is imperative to maintain the IVDs' structural integrity. While in vivo models provide comprehensive insight in IVD biology, an accompanying organ culture model can focus on a single factor, such as loading and may serve as a prescreening model to reduce life animal testing. In the current study we examined the feasibility of organ culture of caprine lumbar discs, with the hypothesis that a simulated-physiological load will optimally preserve IVD properties.

Lumbar caprine IVDs (n = 175) were cultured in a bioreactor up to 21 days either without load, low dynamic load (LDL), or with simulated-physiological load (SPL). IVD stiffness was calculated from measurements of IVD loading and displacement. IVD nucleus, inner- and outer annulus were assessed for cell viability, cell density and gene expression. The extracellular matrix (ECM) was analyzed for water, glycosaminoglycan and total collagen content.

IVD biomechanical properties did not change significantly with loading conditions. With SPL, cell viability, cell density and gene expression were preserved up to 21 days. Both unloaded and LDL resulted in decreased cell viability, cell density and significant changes in gene expression, yet no differences in ECM content were observed in any group.

In conclusion, simulated-physiological loading preserved the native properties of caprine IVDs during a 21-day culture period. The characterization of caprine IVD response to culture in the LDCS under SPL conditions paves the way for controlled analysis of degeneration- and regeneration-associated processes in the future.

Regenerative potential of TGFβ3 + Dex and notochordal cell conditioned media on degenerated human intervertebral disc cells

Injection of soluble cell signaling factors into degenerated intervertebral discs (IVDs) offers a minimally invasive treatment that could limit the processes of degeneration by stimulating native matrix repair. This study evaluated the regenerative capacity of degenerated nucleus pulposus (NP) cells obtained from patients undergoing anterior interbody fusions by measuring metabolic activity, DNA content, glycosaminoglycan (GAG) content, and cellular phenotype using qRT-PCR profiling with a custom array of 42 genes. NP cells were cultured in alginate for 7 days with 4 treatment groups: transforming growth factor beta 3 (TGFβ3) + dexamethasone (Dex), soluble factors released from notochordal cells (NCs) cultured in alginate (NCA), soluble factors released from NCs in their native tissue environment (NCT), and basal media. TGFβ3 + Dex stimulated degenerated human NP cells to proliferate and exhibit an anti-catabolic gene expression profile (with a decrease in ADAMTS5 and MMP1 compared to basal, and an increase in SOX9, decrease in ADAMTS5, MMP1, collagen I and collagen III compared to day 0), while NCA stimulated the greatest GAG per cell. We conclude that degenerated human NP cells exhibit regenerative potential, and that an optimal treatment will likely require treatments, such as TGFβ3 + Dex, which were able to increase cell metabolism and reduce catabolism, as well as treatments with factors found in NC conditioned medium, that were able to produce high amounts of GAG per cell. Additional studies to optimize NC culture conditions are required to determine if NC conditioned medium can be made with the capacity to enhance NP cell proliferation and metabolism.

Non-specific low back pain

Non-specific low back pain has become a major public health problem worldwide. The lifetime prevalence of low back pain is reported to be as high as 84%, and the prevalence of chronic low back pain is about 23%, with 11-12% of the population being disabled by low back pain. Mechanical factors, such as lifting and carrying, probably do not have a major pathogenic role, but genetic constitution is important. History taking and clinical examination are included in most diagnostic guidelines, but the use of clinical imaging for diagnosis should be restricted. The mechanism of action of many treatments is unclear, and effect sizes of most treatments are low. Both patient preferences and clinical evidence should be taken into account for pain management, but generally self-management, with appropriate support, is recommended and surgery and overtreatment should be avoided.

The thoracic and lumbar spine in severe juvenile idiopathic arthritis: magnetic resonance imaging analysis in 50 children

OBJECTIVE

To determine the prevalence of vertebral fractures as a complication of juvenile idiopathic arthritis (JIA).

STUDY DESIGN

This cross-sectional study evaluated the prevalence and characteristics of spinal abnormalities in 50 children (aged 7.0-18.7 years) with treatment-resistant JIA by magnetic resonance imaging. Vertebral deformities, endplate irregularities, intervertebral disc involvement, spinal canal, neural foramina, and back muscles were analyzed and correlated with clinical characteristics and bone mineral density.

RESULTS

Magnetic resonance imaging revealed various abnormalities in 31 patients (62%). Vertebral compression was seen in 28%, disc degeneration in 46%, protrusions in 14%, prolapses in 4%, endplate changes in 26%, and anterior vertebral corner lesions in 16%. Two patients (4%) had mild spinal canal narrowing without medullar involvement; none had neural root compression. Six patients (12%) had mild back muscle atrophy. No correlation was observed between spinal fractures or other vertebral changes and disease activity or duration, pain or bone mineral density; patients with spinal fractures tended to have a higher recent glucocorticoid exposure (P=.086).

CONCLUSION

Children with severe JIA have a high prevalence of compression fractures and other vertebral, endplate, and disc abnormalities in the thoracic and lumbar spine.

Incidental vertebral lesions

Incidental vertebral lesions on imaging of the spine are commonly encountered in clinical practice. Contributing factors include the aging population, the increasing prevalence of back pain, and increased usage of MR imaging. Additionally, refinements in CT and MR imaging have increased the number of demonstrable lesions. The management of incidental findings varies among practitioners and commonly depends more on practice style than on data or guidelines. In this article we review incidental findings within the vertebral column and review management of these lesions, based on available Class III data.

Discussion paper: what happened to the 'bio' in the bio-psycho-social model of low back pain?

PURPOSE

Over 20 years ago the term non-specific low back pain became popular to convey the limitations of our knowledge of the pathological source of most people's low back pain. Knowledge of underlying pathology has advanced little since then, despite limited improvements in outcomes for patients with low back pain.

METHODS

This paper discusses potential misunderstandings related to diagnostic studies in the field of low back pain and argues that future diagnostic studies should include and investigate pathological sources of low back pain.

RESULTS

Six potential misunderstandings are discussed. (1) Until diagnosis is shown to improve outcomes it is not worth investigating; (2) without a gold standard it is not possible to investigate diagnosis of low back pain; (3) the presence of pathology in some people without low back pain means it is not important; (4) dismissal of the ability to diagnose low back pain in clinical guidelines is supported by the same level of evidence as recommendations for therapy; (5) suggesting use of a diagnostic test in research is misinterpreted as endorsing its use in current clinical practice; (6) we seem to have forgotten the 'bio' in biopsychosocial low back pain.

CONCLUSIONS

We believe the misunderstandings presented in this paper partly explain the lack of investigation into pathology as an important component of the low back pain experience. A better understanding of the biological component of low back pain in relation, and in addition, to psychosocial factors is important for a more rational approach to management of low back pain.

Does lumbar disc degeneration on magnetic resonance imaging associate with low back symptom severity in young Finnish adults?

STUDY DESIGN

A cross-sectional magnetic resonance imaging study with questionnaires on low back pain (LBP) and functional limitations.

OBJECTIVE

To investigate the association between lumbar intervertebral disc degeneration (DD) and low back symptom severity among young Finnish adults.

SUMMARY OF BACKGROUND DATA

Both LBP and lumbar DD are common already in adolescence, but very little is known of their association in young adults.

METHODS

Young adults belonging to a birth cohort (n=874) were invited to lumbar magnetic resonance imaging using a 1.5-T scanner. Data on LBP and functional limitations at the ages of 18, 19, and 21 years were used to cluster the subjects with respect to low back symptoms using latent class analysis. The prevalence and 95% confidence intervals of DD at 21 years and the sum score of DD at all lumbar levels were compared between the clusters. The contribution of DD and other imaging findings (herniations, anular tears, Modic changes, spondylolytic defects) to symptom severity was analyzed with logistic regression analysis.

RESULTS

Latent class analysis produced five clusters from the 554 subjects, ranging from a cluster where subjects (n=65) had been painful at all time points to an asymptomatic cluster (n=168). DD was more prevalent in the three most symptomatic clusters compared to the two least symptomatic ones. Similar findings were obtained for the DD sum scores. Lumbar DD was related to symptom severity independently of other degenerative findings. Moreover, moderately degenerated discs were more likely than mildly degenerated discs to be associated with the most severe low back symptoms.

CONCLUSION

Intervertebral DD was associated with low back symptom severity among young adults, suggesting that the symptoms may have a discogenic origin at this age. However, DD was also found in one-third of asymptomatic subjects.

Genetic susceptibility of intervertebral disc degeneration among young Finnish adults

BACKGROUND

Disc degeneration (DD) is a common condition that progresses with aging. Although the events leading to DD are not well understood, a significant genetic influence has been found. This study was undertaken to assess the association between relevant candidate gene polymorphisms and moderate DD in a well-defined and characterized cohort of young adults. Focusing on young age can be valuable in determining genetic predisposition to DD.

METHODS

We investigated the associations of existing candidate genes for DD among 538 young adults with a mean age of 19 belonging to the 1986 Northern Finland Birth Cohort. Nineteen single nucleotide polymorphisms (SNP) in 16 genes were genotyped. We evaluated lumbar DD using the modified Pfirrmann classification and a 1.5-T magnetic resonance scanner for imaging.

RESULTS

Of the 538 individuals studied, 46% had no degeneration, while 54% had DD and 51% of these had moderate DD. The risk of DD was significantly higher in subjects with an allele G of IL6 SNPs rs1800795 (OR 1.45, 95% CI 1.07-1.96) and rs1800797 (OR 1.37, 95% CI 1.02-1.85) in the additive inheritance model. The role of IL6 was further supported by the haplotype analysis, which resulted in an association between the GGG haplotype (SNPs rs1800797, rs1800796 and rs1800795) and DD with an OR of 1.51 (95% CI 1.11-2.04). In addition, we observed an association between DD and two other polymorphisms, SKT rs16924573 (OR 0.27 95% CI 0.07-0.96) and CILP rs2073711 in women (OR 2.04, 95% CI 1.07-3.89).

CONCLUSION

Our results indicate that IL6, SKT and CILP are involved in the etiology of DD among young adults.

Acute disc herniation in the elderly

BACKGROUND

Acute disc prolapse in young adults has been studied extensively. However, little is known about acute disc prolapse in the elderly.

OBJECTIVE

We aimed to define the features of acute disc prolapse in the elderly.

DESIGN, SETTING AND PATIENTS

Elderly (≥ 65 years) patients who had lumbar or thoracic discectomy for acute (< 3 months) disc prolapse in our unit between July 2004 and March 2010 were identified. For comparison, we used a 'young' (25-45 years) patient cohort with acute thoracic or lumbar disc prolapse. Data collected included age, symptom onset, preoperative signs and spinal level.

RESULTS

During the study period, 390 patients had discectomy, of which 59.7% were 'young' and 7.4% 'elderly'. The young and elderly patients had significantly different distributions of prolapsed disc levels. In the young, 97% of all disc protrusions were at L4/5 or L5/S1, but < 50% were at these levels in the elderly. In the elderly, about 10% of disc protrusions were thoracic.

CONCLUSIONS

Acute disc prolapse is rare in the elderly and primarily affects the upper lumbar and lower thoracic spine.

Assessment of association between low back pain and paraspinal muscle atrophy using opposed-phase magnetic resonance imaging: a population-based study among young adults

STUDY DESIGN

A cross-sectional imaging study of young adults.

OBJECTIVE

To evaluate whether severity of low back symptoms predicts atrophy in the paraspinal muscles of young adults.

SUMMARY OF BACKGROUND DATA

Although an increased fat content of the lumbar muscles has been observed among adults with chronic LBP, there is limited knowledge of this association in younger populations.

METHODS

The population-based study sample consisted of 554 subjects (321 females and 233 males) from the 1986 Northern Finland Birth Cohort. Latent Class Analysis (LCA) was used to cluster the subjects according to the low back symptoms and functional limitations at 18, 19, and 21 years. The mean age of the subjects at the time of the MRI (magnetic resonance imaging) was 21 years (range, 20-23). Muscle atrophy was evaluated by assessing the fat content of the paraspinal muscles using Opposed-Phase MRI. The cross-sectional areas (CSAs) of the erector spinae and multifidus muscles were also measured.

RESULTS

LCA analysis produced five clusters differing in symptoms, ranging from a cluster (n = 65) in which subjects had high likelihood of symptoms and functional limitations at all time points, to a cluster (n = 165) with no pain ever. The fat content of the multifidus muscles was significantly higher among women than men (14.0% vs. 5.3%, P < 0.001), but it was not significantly associated with symptom severity. The CSA of both erector spinae and multifidus muscles were significantly larger among men than women (P < 0.001 in all of the muscles), but were not associated with pain severity.

CONCLUSION

Low back symptoms and functional limitations over a 3-year period were not associated with increased fat content or a reduction in the cross-sectional area of lumbar paraspinal muscles among young adults.