Lumbar disc degeneration: epidemiology and genetic influences

Low-back pain

Low-back pain is one of the most common painful conditions experienced by humans throughout their life. Some occupational risk factors (namely, heavy manual material handling) may also contribute to the development of low-back pain: due to the high prevalence of both low-back pain and manual material handling in the adult working population, it has been estimated that low-back pain is probably the most common occupational disorder worldwide. Lifetime prevalence of low-back pain has been reported to be as high as 84%, depending on the case definition used, and no age group is spared, even children. Although low-back pain is not a lethal condition, it was estimated at the third rank among all diseases by disability-adjusted life-years in 2010 in the USA, after ischemic heart disease and chronic obstructive pulmonary disease, and at the first rank by years lived with disability. It also ranked high (13th) globally for the same year, in disability-adjusted life-years. Low-back pain is currently classified as nonspecific/specific as to putative cause and as acute (lasting less than 6 weeks), subacute (6-12 weeks), or chronic (more than 12 weeks) according to duration of symptoms. The distinction between nonspecific/specific and acute/subacute/chronic low-back pain is useful not only for epidemiologic studies, but also (mainly) for choosing the appropriate strategy for the diagnosis and treatment of the disorder. Workplace risk factors for low-back pain include manual lifting and whole-body vibration exposure. This chapter will provide an overview of modern concepts of low-back pain (in general) and will then outline some distinctive features of work-related low-back pain.

Population average T2 MRI maps reveal quantitative regional transformations in the degenerating rabbit intervertebral disc that vary by lumbar level

Magnetic resonance imaging (MRI) with T2-weighting is routinely performed to assess intervertebral disc degeneration. Standard clinical evaluations of MR images are qualitative, however, and do not focus on region-specific alterations in the disc. Utilizing a rabbit needle puncture model, T2 mapping was performed on injured discs to develop a quantitative description of the degenerative process following puncture. To do so, an 18G needle was inserted into four discs per rabbit (L3/L4 to L6/L7) and T2 maps were generated pre- and 4 weeks post-injury. Individual T2 maps were normalized to a disc-specific coordinate system and then averaged for pre- and post-injury population composite T2 maps. We also developed a method to automatically segment the nucleus pulposus by fitting the NP region of the T2 maps with modified 2-D and 3-D Gaussian distribution functions. Puncture injury produced alterations in MR signal intensity in a region-specific manner mirroring human degeneration. Population average T2 maps provided a quantitative representation of the injury response, and identified deviations of individual degenerate discs from the pre-injury population. We found that the response to standardized injury was modest at lower lumbar levels, likely as a result of increased disc dimensions. These tools will be valuable for the quantitative characterization of disc degeneration in future clinical and pre-clinical studies.

The association between lumbar spine radiographic features and low back pain: a systematic review and meta-analysis

BACKGROUND/PURPOSE

Low back pain (LBP) is a prevalent musculoskeletal condition and represents a substantial socioeconomic burden. Plain film radiography is a commonly used imaging technique. Radiographic features (RFs) such as disc space narrowing, osteophytes, spondylosis, endplate sclerosis, spondylolisthesis, and facet joint osteoarthritis have all been debated as potential pain generators in the lumbar spine. The aim of this study is to (1) determine the association between LBP and lumbar spine RFs in both community- and occupation-based groups and (2) to determine if there are differences in these associations between these two groups.

METHODS

A systematic electronic search of PubMed, EMBASE, CINAHL, and Cochrane was conducted with keywords related to LBP and lumbar spine RFs. The search was restricted from inception of each respective database to April 2014. Inclusion criteria consisted of observational studies of adults (≥18 years) with and without nonspecific LBP. Studies were excluded if they investigated LBP related to infection, malignancy, or rheumatologic nature or were conducted in cadavers. Quality assessment was conducted with the Item Bank for Assessment of Risk of Bias and Precision for Observational Studies of Interventions or Exposures. Random effect models were used for all pooled analyses with associations represented by odds ratios (OR) and 95% confidence intervals (95% CIs). Statistical heterogeneity was assessed with I(2), with significant heterogeneity represented as >50%.

RESULTS

Overall, 28 (22 community-based and six occupation-based) studies met the eligibility criteria consisting of 26,107 subjects. A significant, positive association was found between disc space narrowing and LBP, which did not differ (p = 0.22) in both community- and occupation-based studies [OR = 1.47 (95% CI: 1.36-1.58)] and [OR = 1.76 (95% CI: 1.34-2.33)], respectively. No significant statistical heterogeneity was present in either estimate (I(2) = 0.0%). A significant association was found between spondylolisthesis and LBP in occupation-based studies [OR = 2.21 (95% CI: 1.44-3.39)] that differed significantly (p < 0.01) from community-based studies [OR = 1.12 (95% CI: 1.03-1.23)]. These individual estimates were also homogeneous (I(2) = 0.0%). The association between other radiographic features was modest (i.e., spondylosis and osteophytes) or non-significant (i.e., endplate sclerosis and facet joint). Quality of included studies varied, with the majority demonstrating good quality.

CONCLUSION

A significant association was found between disc space narrowing in both community- and occupational-based populations without significant differences between the associations. A significant strong association was found between spondylolisthesis and LBP among the occupational group but was weakly associated in the community-based group, which supports that spondylolisthesis may contribute a specific cause for LBP.

Genetic and functional studies of the intervertebral disc: a novel murine intervertebral disc model

Intervertebral disc (IVD) homeostasis is mediated through a combination of micro-environmental and biomechanical factors, all of which are subject to genetic influences. The aim of this study is to develop and characterize a genetically tractable, ex vivo organ culture model that can be used to further elucidate mechanisms of intervertebral disc disease. Specifically, we demonstrate that IVD disc explants (1) maintain their native phenotype in prolonged culture, (2) are responsive to exogenous stimuli, and (3) that relevant homeostatic regulatory mechanisms can be modulated through ex-vivo genetic recombination. We present a novel technique for isolation of murine IVD explants with demonstration of explant viability (CMFDA/propidium iodide staining), disc anatomy (H&E), maintenance of extracellular matrix (ECM) (Alcian Blue staining), and native expression profile (qRT-PCR) as well as ex vivo genetic recombination (mT/mG reporter mice; AdCre) following 14 days of culture in DMEM media containing 10% fetal bovine serum, 1% L-glutamine, and 1% penicillin/streptomycin. IVD explants maintained their micro-anatomic integrity, ECM proteoglycan content, viability, and gene expression profile consistent with a homeostatic drive in culture. Treatment of genetically engineered explants with cre-expressing adenovirus efficaciously induced ex vivo genetic recombination in a variety of genetically engineered mouse models. Exogenous administration of IL-1ß and TGF-ß3 resulted in predicted catabolic and anabolic responses, respectively. Genetic recombination of TGFBR1^fl/fl explants resulted in constitutively active TGF-ß signaling that matched that of exogenously administered TGF-ß3. Our results illustrate the utility of the murine intervertebral disc explant to investigate mechanisms of intervertebral disc degeneration.

Lumbar disc herniation in a patient with congenital vertebral body anomaly: a case report

Lumbar disc herniation is characterized with low back and leg pain resulting from the degenerated lumbar disc compressing the spinal nerve root. The etiology of degenerative spine is related to age, smoking, microtrauma, obesity, disorders of familial collagen structure, occupational and sports-related physical activity. However, disc herniations induced by congenital lumbar vertebral anomalies are rarely seen. Vertebral fusion defect is one of the causes of congenital anomalies. The pathogenesis of embryological corpus vertebral fusion anomaly is not fully known. In this paper, a 30-year-old patient who had the complaints of low back and right leg pain after falling from a height is presented. She had right L5-S1 disc herniation that had developed on the basis of S1 vertebra corpus fusion anomaly in Lumbar computed tomography. This case has been discussed in the light of literature based on evaluations of Lumbar Computed Tomography (CT) and Magnetic Resonance Imaging (MRI). This case is unique in that it is the first case with development of lumbar disc herniation associated with S1 vertebral corpus fusion anomaly. Congenital malformations with unusual clinical presentation after trauma should be evaluated through advanced radiological imaging techniques.

The dose-response relationship between cumulative lifting load and lumbar disk degeneration based on magnetic resonance imaging findings

BACKGROUND

Lumbar disk degeneration (LDD) has been related to heavy physical loading. However, the quantification of the exposure has been controversial, and the dose-response relationship with the LDD has not been established.

OBJECTIVE

The purpose of this study was to investigate the dose-response relationship between lifetime cumulative lifting load and LDD.

DESIGN

This was a cross-sectional study.

METHODS

Every participant received assessments with a questionnaire, magnetic resonance imaging (MRI) of the lumbar spine, and estimation of lumbar disk compression load. The MRI assessments included assessment of disk dehydration, annulus tear, disk height narrowing, bulging, protrusion, extrusion, sequestration, degenerative and spondylolytic spondylolisthesis, foramina narrowing, and nerve root compression on each lumbar disk level. The compression load was predicted using a biomechanical software system.

RESULTS

A total of 553 participants were recruited in this study and categorized into tertiles by cumulative lifting load (ie, <4.0 × 10(5), 4.0 × 10(5) to 8.9 × 10(6), and ≥8.9 × 10(6) Nh). The risk of LDD increased with cumulative lifting load. The best dose-response relationships were found at the L5-S1 disk level, in which high cumulative lifting load was associated with elevated odds ratios of 2.5 (95% confidence interval [95% CI]=1.5, 4.1) for dehydration and 4.1 (95% CI=1.9, 10.1) for disk height narrowing compared with low lifting load. Participants exposed to intermediate lifting load had an increased odds ratio of 2.1 (95% CI=1.3, 3.3) for bulging compared with low lifting load. The tests for trend were significant.

LIMITATIONS

There is no "gold standard" assessment tool for measuring the lumbar compression load.

CONCLUSIONS

The results suggest a dose-response relationship between cumulative lifting load and LDD.

ISSLS Prize winner: Long-term follow-up suggests spinal fusion is associated with increased adjacent segment disc degeneration but without influence on clinical outcome: results of a combined follow-up from 4 randomized controlled trials

STUDY DESIGN

Cross-sectional analysis of long-term follow-up (LTFU) data from 4 randomized controlled trials of operative versus nonoperative treatment for chronic low back pain.

OBJECTIVE

To examine the influence of spinal fusion on adjacent segment disc space height as an indicator of disc degeneration at LTFU.

SUMMARY OF BACKGROUND DATA

There is ongoing debate as to whether adjacent segment disc degeneration results from the increased mechanical stress of fusion.

METHODS

Plain standing lateral radiographs were obtained at LTFU (mean, 13 ± 4 yr postrandomization) in 229 of 464 (49%) patients randomized to surgery and 140 of 303 (46%), to nonoperative care. Disc space height and posteroanterior displacement were measured for each lumbar segment using a validated computer-assisted distortion compensated roentgen analysis technique. Values were reported in units of standard deviations above or below age and sex-adjusted normal values. Patient-rated outcomes included the Oswestry Disability Index and pain scales.

RESULTS

Radiographs were usable in 355 of 369 (96%) patients (259 fusion and 96 nonoperative treatment). Both treatment groups showed significantly lower values for disc space height of the adjacent segment than norm values. There was a significant difference between treatment groups for the disc space height of the cranial adjacent segment (in both as-treated and intention-to-treat analyses). The mean treatment effect of fusion on adjacent segment disc space height was -0.44 SDs (95% CI, -0.77 to -0.11; P = 0.01; as-treated analysis); there was no group difference for posteroanterior displacement (0.18 SDs, 95% confidence interval, -0.28 to 0.64, P = 0.45). Adjacent level disc space height and posteroanterior displacement were not correlated with Oswestry Disability Index or pain scores at LTFU (r = 0.010-0.05; P > 0.33).

CONCLUSION

Fusion was associated with lower disc space height at the adjacent segment after an average of 13 years of FU. The reduced disc space height had no influence on patient self-rated outcomes (pain or disability).

LEVEL OF EVIDENCE

2.

The high prevalence of symptomatic degenerative lumbar osteoarthritis in Chinese adults: a population-based study

STUDY DESIGN

A population-based study.

OBJECTIVE

To study the prevalence and features of symptomatic degenerative lumbar osteoarthritis in adults.

SUMMARY OF BACKGROUND DATA

Lumbar osteoarthritis adversely affects individuals and is a heavy burden. There are limited data on the prevalence of lumbar osteoarthritis.

METHODS

A representative, multistage sample of adults was collected. Symptomatic degenerative lumbar osteoarthritis was diagnosed by clinical symptoms, physical examinations, and imaging examinations. Personal information was obtained by face-to-face interview. Information included the place of residence, age, sex, income, type of medical insurance, education level, body mass index, habits of smoking and drinking, type of work, working posture, duration of the same working posture during the day, mode of transportation, exposure to vibration, and daily amount of sleep. Crude and adjusted prevalence was calculated. The features of populations were analyzed by multivariable logistic regression in total and subgroup populations.

RESULTS

The study included 3859 adults. The crude and adjusted prevalence of lumbar osteoarthritis was 9.02% and 8.90%, respectively. There was no significant difference in the prevalence of lumbar osteoarthritis between urban, suburban, and rural populations (7.66%, 9.97%, and 9.44%) (P = 0.100). The prevalence of lumbar osteoarthritis was higher in females (10.05%) than in males (9.1%, P = 0.021). The prevalence of lumbar osteoarthritis increased with increasing age. Obese people (body mass index >28 kg/m), those engaged in physical work, those who maintained the same work posture for 1 to 1.9 hours per day, those who were exposed to vibration during daily work, and those who got less than 7 hours of sleep per day had a higher prevalence. These features differed by subgroup.

CONCLUSION

This study established epidemiological baseline data for degenerative lumbar osteoarthritis in adults, especially for people younger than 45 years. Lumbar osteoarthritis is epidemic in Beijing and will become a more severe problem in aging society. Different populations have different features that require targeted interventions.

Long-term Outcomes of 2-Level Total Disc Replacement Using ProDisc-L: Nine- to 10-Year Follow-up

STUDY DESIGN

A prospective clinical data analysis.

OBJECTIVE

To determine the long-term clinical success of 2-level total disc replacement (TDR) in patients with degenerative disc disease.

SUMMARY OF BACKGROUND DATA

Early successful clinical results of 2-level TDR have been reported. Few studies exist that have described this procedure's durability in the long term.

METHODS

Fifteen patients underwent 2-level lumbar TDR with the ProDisc-L as part of a randomized trial, 13 of whom were available for follow-up. The patients were assessed preoperatively and at 2 years, 5 years, and more than 9 years postoperatively using visual Oswestry Disability Index. At the last follow-up visit, 2 additional questions were asked: satisfaction with surgery and willingness to undergo the same treatment. Finally, clinical success was assessed using a previously described definition.

RESULTS

Mean follow-up time was 9.6 years (range, 9.2-10.3 yr). Postoperatively there was a significant improvement in Oswestry Disability Index score from baseline (70.0 vs. 15.7 at 2 yr, P = 0.002) that remained unchanged during the period of follow-up (19.8 at 5 yr, P = 0.003 and 12.9 at 9-10 yr, P = 0.002). Ninety-two percent of patients were "satisfied" or "somewhat satisfied" with treatment and the same number would undergo treatment again. Eighty-five percent of patients achieved clinical success.

CONCLUSION

This prospective study demonstrates the durable clinical success of 2-level lumbar TDR as assessed at more than 9 years postoperatively.

LEVEL OF EVIDENCE

4.

Human L3L4 intervertebral disc mean 3D shape, modes of variation, and their relationship to degeneration

Intervertebral disc mechanics are affected by both disc shape and disc degeneration, which in turn each affect the other; disc mechanics additionally have a role in the etiology of disc degeneration. Finite element analysis (FEA) is a favored tool to investigate these relationships, but limited data for intervertebral disc 3D shape has forced the use of simplified or single-subject geometries, with the effect of inter-individual shape variation investigated only in specialized studies. Similarly, most data on disc shape variation with degeneration is based on 2D mid-sagittal images, which incompletely define 3D shape changes. Therefore, the objective of this study was to quantify inter-individual disc shape variation in 3D, classify this variation into independently-occurring modes using a statistical shape model, and identify correlations between disc shape and degeneration. Three-dimensional disc shapes were obtained from MRI of 13 human male cadaver L3L4 discs. An average disc shape and four major modes of shape variation (representing 90% of the variance) were identified. The first mode represented disc axial area and was significantly correlated to degeneration (R(2)=0.44), indicating larger axial area in degenerate discs. Disc height variation occurred in three distinct modes, each also involving non-height variation. The statistical shape model provides an average L3L4 disc shape for FEA that is fully defined in 3D, and makes it convenient to generate a set of shapes with which to represent aggregate inter-individual variation. Degeneration grade-specific shapes can also be generated. To facilitate application, the model is included in this paper׳s supplemental content.

Back pain and its consequences among Polish Air Force pilots flying high performance aircraft

OBJECTIVES

Back pain in Air Force fast jet pilots has been studied by several air forces and found to be relatively common. The objective of the study was to determine the prevalence and degree of the pain intensity in the cervical, thoracic and lumbar spine, subjective risk factors and their effect on the pilots' performance while flying high maneuver aircrafts and the consequences for cognitive deficiencies.

MATERIAL AND METHODS

The study was designed as a retrospective, anonymous questionnaire survey, collecting data on the age, aircraft type, flying hours, pain characteristics, physical activity, etc. The study was participated by 94 pilots aged 28-45 years (mean age: 35.9 ± 3.3 years), actively flying fast jet aircrafts Su-22, Mig-29 and F-16. The estimates regarding the level of the subjective back pain were established using visual analogue scales (VAS).

RESULTS

The values of the Cochran and Cox T-test for heterogeneous variances are as follows: for the total number of flying hours: F = 2.53, p = 0.0145, for the pilot's age: F = 3.15, p = 0.003, and for the BMI factor F = 2.73, p = 0.008.

CONCLUSIONS

Our questionnaire survey showed a significant problem regarding spinal conditions in high performance aircraft pilots. The determination of the risk factors may lead to solving this problem and help eliminate the effect of the unfavorable environment on piloting jet aircrafts. Experiencing back pain during the flight might influence the mission performance and flight safety. The costs of pilots education are enormous and inability to fly, or even disability, leads to considerable economic loss. More research on specific prevention strategies is warranted in order to improve the in-flight working environment of fighter pilots.

Investigating the role of DNA damage in tobacco smoking-induced spine degeneration

BACKGROUND CONTEXT

Tobacco smoking is a key risk factor for spine degeneration. However, the underlying mechanism by which smoking induces degeneration is not known. Recent studies implicate DNA damage as a cause of spine and intervertebral disc degeneration. Because tobacco smoke contains many genotoxins, we hypothesized that tobacco smoking promotes spine degeneration by inducing cellular DNA damage.

PURPOSE

To determine if DNA damage plays a causal role in smoking-induced spine degeneration.

STUDY DESIGN

To compare the effect of chronic tobacco smoke inhalation on intervertebral disc and vertebral bone in normal and DNA repair-deficient mice to determine the contribution of DNA damage to degenerative changes.

METHODS

Two-month-old wild-type (C57BL/6) and DNA repair-deficient Ercc1(-/Δ) mice were exposed to tobacco smoke by direct inhalation (4 cigarettes/day, 5 days/week for 7 weeks) to model first-hand smoking in humans. Total disc proteoglycan (PG) content (1,9-dimethylmethylene blue assay), PG synthesis ((35)S-sulfate incorporation assay), aggrecan proteolysis (immunoblotting analysis), and vertebral bone morphology (microcomputed tomography) were measured.

RESULTS

Exposure of wild-type mice to tobacco smoke led to a 19% increase in vertebral porosity and a 61% decrease in trabecular bone volume. Intervertebral discs of smoke-exposed animals also showed a 2.6-fold decrease in GAG content and an 8.1-fold decrease in new PG synthesis. These smoking-induced degenerative changes were similar but not worse in Ercc1(-/Δ) mice.

CONCLUSIONS

Short-term exposure to high levels of primary tobacco smoke inhalation promotes degeneration of vertebral bone and discs. Disc degeneration is primarily driven by reduced synthesis of proteoglycans needed for vertebral cushioning. Degeneration was not exacerbated in congenic DNA repair-deficient mice, indicating that DNA damage per se does not have a significant causal role in driving smoke-induced spine degeneration.

Prevalence and distribution of intervertebral disc degeneration over the entire spine in a population-based cohort: the Wakayama Spine Study

OBJECTIVES

The purposes of this study were to investigate the prevalence and distribution of intervertebral disc degeneration (DD) over the entire spine using magnetic resonance imaging (MRI), and to examine the factors and symptoms potentially associated with DD.

DESIGN

This study included 975 participants (324 men, mean age of 67.2 years; 651 women, mean age of 66.0 years) with an age range of 21-97 years in the Wakayama Spine Study. DD on MRI was classified into Pfirrmann's system (grades 4 and 5 indicating DD). We assessed the prevalence of DD at each level in the cervical, thoracic, and lumbar regions and the entire spine, and examined DD-associated factors and symptoms.

RESULTS

The prevalence of DD over the entire spine was 71% in men and 77% in women aged <50 years, and >90% in both men and women aged >50 years. The prevalence of an intervertebral space with DD was highest at C5/6 (men: 51.5%, women: 46%), T6/7 (men: 32.4%, women: 37.7%), and L4/5 (men: 69.1%, women: 75.8%). Age and obesity were associated with the presence of DD in all regions. Low back pain was associated with the presence of DD in the lumbar region.

CONCLUSION

The current study established the baseline data of DD over the entire spine in a large population of elderly individuals. These data provide the foundation for elucidating the causes and mechanisms of DD.

Joint laxity negatively correlates with lumbar disc degeneration in young adults

STUDY DESIGN

Cross-sectional study of preselected cohort of patients with neck pain.

OBJECTIVE

To determine the association between joint laxity and lumbar disc degeneration in young adults.

SUMMARY OF BACKGROUND DATA

Joint laxity is known to be closely related with orthopedic injuries and disease; however, studies about the relationship between spinal disorder and joint laxity are lacking.

METHODS

Patients aged 30 to 40 years, seen at the outpatient clinic of our hospital for the evaluation of neck pain, who had magnetic resonance imaging of the cervical spine with routine inclusion of T2-weighted sagittal plane of the whole spine were included in the study. The Beighton and Horan criteria was used for the assessment of joint laxity. Logistic regression analysis was performed to estimate the odds ratio for lumbar disc degeneration in patients with joint laxity, and other variables including age, sex, body mass index, physical workload, neck pain (visual analogue scale score), and related disability (neck disability index score), and sagittal alignment.

RESULTS

A total of 101 patients were enrolled in the study: 34 patients with joint laxity and 67 patients without joint laxity. There were no differences in age, body mass index, physical workload, neck pain (visual analogue scale score), and neck disability index score between the 2 groups, but there was a significant difference in sex ratio (P < 0.001). Patients with joint laxity showed increased lumbar lordosis (P = 0.004) and increased sacral slope (P = 0.003) but without significant difference in pelvic incidence (P = 0.084). In univariate analysis, presence of joint laxity (Beighton score ≥4) as well as positive results of thumb (P = 0.016) and elbow (P = 0.047) tests were significantly associated with decreased risk for lumbar disc degeneration. Presence of joint laxity remained significant after multivariate adjustment for sex and lumbar lordosis (odds ratio = 0.373, P = 0.040).

CONCLUSION

Increased joint laxity was closely associated with lower prevalence of lumbar disc degeneration in young adults, and the increased lumbar lordosis associated with joint laxity might explain the decreased risk of lumbar disc degeneration.

LEVEL OF EVIDENCE

2.

A statistical model for intervertebral disc degeneration: determination of the optimal T2 cut-off values

PURPOSE

The aim of this study was to investigate the possibility of quantitative classification in intervertebral disc degeneration using spin-spin relaxation time (T2) cut-off values with regard to morphological classifications.

METHODS

Lumbar magnetic resonance (MR) imaging was performed on 21 subjects (a total of 104 lumbar disks). The T2 relaxation time was measured in the nucleus pulposus using a sagittal multi-echo spin-echo sequence. The morphological classification of disc degeneration was assessed independently by three experienced neuroradiologists according to the Pfirrmann and Schneiderman classifications. Receiver operating characteristic analysis was performed among grades to determine T2 cut-off values in each classification. Intra- and interobserver differences were calculated using kappa statistics.

RESULTS

Moderate overall interobserver agreement was found between observers in both the Pfirrmann and Schneiderman classification schemes (kappa 0.46 and 0.51), while intraobserver reliability was substantial to almost perfect. The interobserver reliability was only fair in Pfirrmann grades III and IV (kappa 0.33 and 0.36), but the T2 cut-off values still indicated a significant difference between grades (p<0.05).

CONCLUSIONS

Interobserver agreement of MR evaluation in patients with intervertebral disc degeneration was only fair to moderate on the classification of more severe disc degeneration in the Pfirrmann and Schneiderman schemes. Based on our results, quantitative T2 cut-off values seem to be a more reliable method to define the degree of disc degeneration, which may help staging intervertebral disc degeneration (IVDD) even if the interobserver reliability is low.

Association study between the polymorphisms of the fat mass- and obesity-associated gene with the risk of intervertebral disc degeneration in the Han Chinese population

OBJECTIVE

Insights gained from studies suggest that genetic factors are major contributors to the onset and progression of intervertebral disc degeneration (IVDD). The aim of this study is to investigate whether fat mass- and obesity-associated (FTO) gene polymorphisms are related to the disease in Han Chinese People.

METHODS

118 IVDD cases and 113 healthy subjects were enrolled in this study. Forty-four single nucleotide polymorphisms (SNP) in the FTO gene were tested and analyzed by the VeraCode GoldenGate Genotyping Assay.

RESULTS

A novel SNP rs11076008 was identified in the association analysis between the genotype and the phenotype. There was statistical significance in the expression of SNP rs11076008 in an allelic frequency distribution (p=0.003) and genotype (p=0.014) using the method of multi-test correction.

CONCLUSION

SNP rs11076008 of the FTO gene is associated with IVDD and may play an important role in developing IVDD in Han Chinese People. Our findings provide valuable information regarding the genetic etiology of IVDD in the investigated cohort.

Disc height and sagittal alignment in operated and non-operated levels in the lumbar spine at long-term follow-up: a case-control study

Purpose:

To compare lumbar disc degeneration at 9-year follow-up in patients with chronic low back pain who had instrumented lumbar fusion or no fusion.

Material and methodology:

The main outcomes were disc height and sagittal alignment measured by Distortion Compensated Roentgen Analysis (DCRA). Secondary outcome included the Oswestry Disability Index and VAS back pain.

Results:

Forty-eight patients with baseline and 9-year radiographs from L2- S1 were included. Twenty-three had lumbar fusion and 25 had no fusion. Disc height was reduced at all levels independent of fusion. No difference in disc height and sagittal alignment was observed between patients fused and not fused. There were weak correlations, ranging from 0.04 to 0.36, between clinical and radiological parameters.

Conclusion:

Lumbar disc degeneration increased at all measured levels independent of fusion and correlated poorly with clinical outcome.

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.

Lumbar Disc Degeneration in Osteoporotic Men: Prevalence and Assessment of the Relation with Presence of Vertebral Fracture

Objective.

The relationship between osteoarthritis (OA) and osteoporosis (OP) remains controversial. An inverse relationship between spine OA and the presence of prevalent vertebral fractures has been shown in osteoporotic women. Our objective was to assess this relationship in osteoporotic men.

Methods.

All the patients had OP based on densitometric data and were aged ≥ 65 years. Spine radiographs were performed according to a standardized procedure. Vertebral fractures were assessed from T4 to L4 by a semiquantitative method. Disc degenerative changes were assessed by the presence and severity of osteophytes and disc narrowing at levels T12–L1 to L5–S1. Logistic regression was used to study the relationship between the presence of vertebral fracture and lumbar disc degeneration.

Results.

The study included 261 osteoporotic men. The prevalence of vertebral fractures was 26.4% (69/261). At least 1 osteophyte was found in 91.6% (239/261) of patients, and at least 1 disc space narrowing in 63.5% (165/260). The prevalence of at least 1 osteophyte and/or at least 1 disc space narrowing was similar in patients with and those without vertebral fracture. No relationship was found between the presence and/or the severity of osteophytes and disc narrowings and the presence of prevalent vertebral radiographic fractures.

Conclusion.

In osteoporotic men, the prevalence of lumbar spine degeneration is high. There is no relationship between lumbar disc degeneration and the presence of vertebral fracture in osteoporotic men.

Investigation of the relationship between chromobox homolog 8 and nucleus pulposus cells degeneration in rat intervertebral disc

Here, we aimed to investigate the expression of chromobox homolog 8 (CBX8) in nucleus pulposus (NP) cells from rat intervertebral disc (IVD) and its function in DNA damage and repair. NP cells were isolated from healthy rat IVD for immunohistochemistry staining. Small interfering RNA (siRNA) of CBX8 was applied for gene silencing, and reverse transcriptase-polymerase chain reaction (RT-PCR) was performed to determine mRNA levels of CBX8, type II collagen, and proteoglycans. Cell proliferation and cell cycle were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, colony-forming assay, and flow cytometry. Hydrogen peroxide (H2O2) was added to simulate DNA oxidative damage, and expression of CBX8 was examined using RT-PCR and Western blot. After five passages, mRNA levels of type II collagen and proteoglycans decreased but that of CBX8 increased. When CBX8 was silenced by siRNA, the expressions of CBX8, type II collagen and proteoglycans declined, and the cell growth was inhibited. Besides, cell cycle was slowed down as most cells were arrest in G0/G1 phase. Furthermore, CBX8 expression went up responding to DNA oxidative damage caused by H2O2. The data indicated that CBX8 plays important roles in cell proliferation and DNA damage. Cell proliferation and cell cycle were stimulated by CBX8, which may be associated with INK4A-ARF pathway. Moreover, CBX8 plays a role in DNA damage which made it a potential gene therapy target for treatment of disc degeneration.

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.

Intervertebral disc regeneration: from the degenerative cascade to molecular therapy and tissue engineering

Low back pain is one of the major health problems in industrialized countries, as a leading source of disability in the working population. Intervertebral disc degeneration has been identified as its main cause, being a progressive process mainly characterized by alteration of extracellular matrix composition and water content. Many factors are involved in the degenerative cascade, such as anabolism/catabolism imbalance, reduction of nutrition supply and progressive cell loss. Currently available treatments are symptomatic, and surgical procedures consisting of disc removal are often necessary. Recent advances in our understanding of intervertebral disc biology led to an increased interest in the development of novel biological treatments aimed at disc regeneration. Growth factors, gene therapy, stem cell transplantation and biomaterials-based tissue engineering might support intervertebral disc regeneration by overcoming the limitation of the self-renewal mechanism. The aim of this paper is to overview the literature discussing the current status of our knowledge from the degenerative cascade of the intervertebral disc to the latest molecular, cell-based therapies and tissue-engineering strategies for disc regeneration.

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.

Morphometrics and lesions of vertebral end plates are associated with lumbar disc degeneration: evidence from cadaveric spines

BACKGROUND

Prior studies have suggested that vertebral end plate morphometrics and lesions may play a role in disc degeneration. However, most prior end plate studies have been based on radiographic images, and findings of associations between end plate morphometrics (measurements of size and shape) and disc degeneration remain controversial. The present study investigated the prevalence of vertebral end plate lesions and determined end plate morphometrics through direct measurements of cadaveric spines, and it examined the association of these factors with disc degeneration.

METHODS

We studied 600 vertebral end plates and 313 intervertebral discs from the cadaveric lumbosacral spines of seventy-six men (mean age, fifty-one years). Discography was performed to evaluate disc degeneration as indicated by disruption of the anulus fibrosus. The shape of the vertebral end plate and the presence of any lesions were visually evaluated. Lesions were rated as absent, small to moderate, or large. In addition, each end plate was digitized to quantify its area, circularity, and concavity. The association of end plate morphometrics and lesions with disc degeneration was examined.

RESULTS

Vertebral end plate lesions were found in 72% (fifty-five) of the seventy-six lumbar spines and in 32.8% (197) of the 600 end plates. The presence of end plate lesions was associated with disc degeneration, with larger lesions being associated with more severe disc degeneration (odds ratio, 2.31 for small to moderate lesions [p < 0.01] and 3.54 for large lesions [p < 0.001]). Greater end plate area was also associated with more severe disc degeneration (odds ratio, 1.2 per cm2 [p < 0.05]).

CONCLUSIONS

Vertebral end plate lesions were common and were associated with adjacent disc degeneration, with greater lesion size being associated with more severe disc degeneration. End plate morphometrics, particularly greater end plate size, may also play a role in the pathogenesis of disc degeneration.

Low back pain and lumbar spine osteoarthritis: how are they related?

Lumbar spine osteoarthritis (OA) is very common, with estimates of prevalence ranging from 40-85 %. The process of degeneration of the spine has commonly been classified as OA (disc space narrowing together with vertebral osteophyte formation); however, anatomically, the facet joint is the only synovial joint in the spine that has a similar pathological degenerative process to appendicular joints. Low back pain (LBP) is also a common condition, with nearly 80 % of Americans experiencing at least one episode of LBP in their lifetime. The complex relationship between spine radiographs and LBP has many clinical and research challenges. Specific conservative treatments for spine degeneration have not been established; there has, however, been recent interest in use of exercise therapy, because of some moderate benefits in treating chronic LBP. An understanding of the relationship between spine degeneration and LBP may be improved with further population-based research in the areas of genetics, biomarkers, and pain pathways.

Evidence for juvenile disc herniation in a homo erectus boy skeleton

STUDY DESIGN

An analysis and differential diagnosis of bony alterations in the lower lumbar vertebrae of a Homo erectus boy skeleton.

OBJECTIVE

To analyze low back problems during early human evolution.

SUMMARY OF BACKGROUND DATA

Back problems in modern humans are often attributed to our upright, bipedal locomotion that is thought to place huge mechanical stresses on the vertebral column. However, little is known of this situation during the course of human evolution.

METHODS

We analyzed the lower lumbar spine of the most complete early hominid skeleton, the 1.5-million-year-old Homo erectus boy KNM-WT 15000 from Nariokotome, Kenya, who died at an age of approximately 8 years. We use bony alterations as indirect evidence for disc disease in the absence of soft tissue.

RESULTS

We describe an extensive osteophytic anterior curved remodeling of the left superior articular process of L5 and formation of a new joint at the underside of the left pedicle of L4. This indicates collisional facet joint subluxation, most likely as the result of juvenile traumatic disc herniation.

CONCLUSIONS

This indirect evidence of possible juvenile disc herniation in a Homo erectus boy skeleton represents the earliest known case of this typical human ailment that is intricately linked to upright bipedalism. The extensive bony remodeling of the articular processes of L4 and L5 suggests that the disc herniation occurred several months before his death. Disabling backache and recurrent sciatica might have, at least, temporarily restricted his daily activities, which indicates advanced social care and nursing in early Homo. We hypothesize that the early Homo intervertebral discs were more vulnerable to injury compared with modern humans because of a relatively small vertebral cross-sectional area.

Posterior Transpedicular Dynamic Stabilization versus Total Disc Replacement in the Treatment of Lumbar Painful Degenerative Disc Disease: A Comparison of Clinical Results

Study Design. Prospective clinical study. Objective. This study compares the clinical results of anterior lumbar total disc replacement and posterior transpedicular dynamic stabilization in the treatment of degenerative disc disease. Summary and Background Data. Over the last two decades, both techniques have emerged as alternative treatment options to fusion surgery. Methods. This study was conducted between 2004 and 2010 with a total of 50 patients (25 in each group). The mean age of the patients in total disc prosthesis group was 37,32 years. The mean age of the patients in posterior dynamic transpedicular stabilization was 43,08. Clinical (VAS and Oswestry) and radiological evaluations (lumbar lordosis and segmental lordosis angles) of the patients were carried out prior to the operation and 3, 12, and 24 months after the operation. We compared the average duration of surgery, blood loss during the surgery and the length of hospital stay of both groups. Results. Both techniques offered significant improvements in clinical parameters. There was no significant change in radiologic evaluations after the surgery for both techniques. Conclusion. Both dynamic systems provided spine stability. However, the posterior dynamic system had a slight advantage over anterior disc prosthesis because of its convenient application and fewer possible complications.

Associação entre tropismo facetário e doença degenerativa de disco lombar

OBJETIVO: Documentar a presença de degeneração de disco e tropismo facetário em pacientes portadores de dor lombar crônica e sua distribuição por sexo e faixa etária. Avaliar também a associação de tropismo facetário e degeneração discal lombar além de avaliar a orientação das facetas de acordo com sexo e faixa etária. MÉTODOS: Estudo retrospectivo de imagens de ressonância magnética obtidas em 288 pacientes (N = 288; 118 homens e 170 mulheres) com média de idade de 53,33 anos, portadores de dor lombar crônica. As imagens foram avaliadas por dois médicos assistentes especialistas em cirurgia da coluna para avaliar e quantificar a orientação das facetas, o tropismo facetário e o grau de degeneração discal dos níveis L3-L4, L4-L5 e L5-S1. Foi analisada a associação entre tropismo facetário e doença degenerativa discal, além de associação com sexo e idade. RESULTADOS: Observa-se que 85,8% dos discos apresentam classificação de Pfirrmann superior ou igual ao Tipo III. Com relação ao grau de degeneração discal, não houve diferença entre os sexos e aumentou com o aumento da faixa etária. Com relação ao grau de tropismo, não difere entre os níveis avaliados e o sexo, aumenta de acordo com a elevação da faixa etária. Houve aumento do grau do degeneração discal com o aumento do grau de tropismo facetário. CONCLUSÃO: A maioria dos discos intervertebrais analisados de pacientes com dor lombar crônica encontram-se degenerados e grau de degeneração aumenta com a idade. O grau de tropismo facetário aumenta com a idade e se relaciona com o grau de degeneração discal.

Development and kinematic verification of a finite element model for the lumbar spine: application to disc degeneration

The knowledge of the lumbar spine biomechanics is essential for clinical applications. Due to the difficulties to experiment on living people and the irregular results published, simulation based on finite elements (FE) has been developed, making it possible to adequately reproduce the biomechanics of the lumbar spine. A 3D FE model of the complete lumbar spine (vertebrae, discs, and ligaments) has been developed. To verify the model, radiological images (X-rays) were taken over a group of 25 healthy, male individuals with average age of 27.4 and average weight of 78.6 kg with the corresponding informed consent. A maximum angle of 34.40° is achieved in flexion and of 35.58° in extension with a flexion-extension angle of 69.98°. The radiological measurements were 33.94 ± 4.91°, 38.73 ± 4.29°, and 72.67°, respectively. In lateral bending, the maximum angles were 19.33° and 23.40 ± 2.39, respectively. In rotation a maximum angle of 9.96° was obtained. The model incorporates a precise geometrical characterization of several elements (vertebrae, discs, and ligaments), respecting anatomical features and being capable of reproducing a wide range of physiological movements. Application to disc degeneration (L5-S1) allows predicting the affection in the mobility of the different lumbar segments, by means of parametric studies for different ranges of degeneration.

Spondylosis deformans and diffuse idiopathic skeletal hyperostosis (dish) resulting in adjacent segment disease

Spondylosis deformans and diffuse idiopathic skeletal hyperostosis (DISH) are usually incidental findings and in most dogs are either asymptomatic or associated with mild clinical signs. Severe spondylosis deformans and DISH can result in complete bony fusion of consecutive vertebral segments. One of the recognised complications following vertebral fusion in human patients is the development of adjacent segment disease, which is defined as degenerative changes, most commonly degenerative intervertebral disc disease, in the mobile vertebral segment neighboring a region of complete vertebral fusion. A similar syndrome following cervical fusion in dogs has been termed the domino effect. The purpose of this retrospective study was to investigate the hypothesis that vertebral fusion occurring secondary to spondylosis deformans or DISH in dogs would protect fused intervertebral disc spaces from undergoing degeneration, but result in adjacent segment disease at neighbouring unfused intervertebral disc spaces. Eight dogs with clinical signs of thoracolumbar myelopathy, magnetic resonance imaging of the thoracolumbar vertebral column, and spondylosis deformans or DISH producing fusion of > or = 2 consecutive intervertebral disc spaces were evaluated. Vertebral fusion of > or = 2 consecutive intervertebral disc spaces was correlated (P = 0.0017) with adjacent segment disease at the neighbouring unfused intervertebral disc space. Vertebral fusion appeared to protect fused intervertebral disc spaces from undergoing degeneration (P < 0.0001). Adjacent segment disease should be considered in dogs with severe spondylosis deformans or DISH occurring in conjunction with a thoracolumbar myelopathy.

Lumbar spine radiographic features and demographic, clinical, and radiographic knee, hip, and hand osteoarthritis

OBJECTIVE

To determine the prevalence of lumbar spine individual radiographic features (IRFs) of disc space narrowing (DSN), osteophytes (OST), and facet joint osteoarthritis (FOA); to describe the frequencies of demographic, clinical, and radiographic knee, hip, and hand osteoarthritis (OA) across lumbar spine IRFs; and to determine factors associated with lumbar spine IRFs.

METHODS

We conducted a cross-sectional study of 840 participants enrolled in the Johnston County Osteoarthritis Project (2003-2004). Sample-based prevalence estimates were generated for each lumbar spine IRF. The associations between lumbar spine IRFs and demographic, clinical, and peripheral joint OA were determined with logistic regression models.

RESULTS

Sample-based prevalence estimates were similar for DSN (57.6%) and FOA (57.9%) but higher for OST (88.1%), with significant differences across race and sex. Hand and knee OA frequencies increased across IRFs, whereas the effect was absent for hip OA. African Americans had lower odds of FOA (adjusted odds ratio [OR(adj) ] 0.45 [95% confidence interval (95% CI) 0.32-0.62]), while there was no racial association with DSN and OST. Low back symptoms were associated with DSN (OR(adj) 1.37 [95% CI 1.04-1.80]) but not OST or FOA. Knee OA was associated with OST (OR(adj) 1.62 [95% CI 1.16-2.27]) and FOA (OR(adj) 1.69 [95% CI 1.15-2.49]) but not DSN. Hand OA was associated with FOA (OR(adj) 1.67 [95% CI 1.20-2.28]) but not with DSN or OST. No associations were found with hip OA.

CONCLUSION

These findings underscore the importance of analyzing lumbar spine IRFs separately as the associations with demographic, clinical, and radiographic knee, hip, and hand OA differ widely.

Osthole, a herbal compound, alleviates nucleus pulposus-evoked nociceptive responses through the suppression of overexpression of acid-sensing ion channel 3 (ASIC3) in rat dorsal root ganglion

BACKGROUND

Osthole (Ost), a natural coumarin derivative, has been shown to inhibit many pro-inflammatory mediators and block voltage-gated Na+ channels. During inflammation, acidosis is an important pain inducer which activates nociceptors by gating depolarizing cationic channels, such as acid-sensing ion channel 3 (ASIC3). The aim of this study was to examine the effects of Ost on nucleus pulposus-evoked nociceptive responses and ASIC3 over-expression in the rat dorsal root ganglion, and to investigate the possible mechanism.

MATERIAL/METHODS

Radicular pain was generated with application of nucleus pulposus (NP) to nerve root. Mechanical allodynia was evaluated using von Frey filaments with logarithmically incremental rigidity to calculate the 50% probability thresholds for mechanical paw withdrawal. ASIC3 protein expression in dorsal root ganglions (DRGs) was assessed with Western blot and immunohistochemistry. Membrane potential (MP) shift of DRG neurons induced by ASIC3-sensitive acid (pH6.5) was determined by DiBAC(4) (3) fluorescence intensity (F.I.).

RESULTS

The NP-evoked mechanical hyperalgesia model showed allodynia for 3 weeks, and ASIC3 expression was up-regulated in DRG neurons, reaching peak on Day 7. Epidural administration of Ost induced a remarkable and prolonged antinociceptive effect, accompanied by an inhibition of over-expressed ASIC3 protein and of abnormal shift of MP. Amiloride (Ami), an antagonist of ASIC3, strengthened the antinociceptive effect of Ost.

CONCLUSIONS

Up-regulation of ASIC3 expression may be associated with NP-evoked mechanical hyperalgesia. A single epidural injection of Ost decreased ASIC3 expression in DGR neurons and the pain in the NP-evoked mechanical hyperalgesia model. Osthole may be of great benefit for preventing chronic pain status often seen in lumbar disc herniation (LDH).

Histomorphometric analysis of experimental disc degeneration

Symptomatic disc degeneration is a complex pathological condition that involves a cascade of events and is not totally understood. In this context, animal models gain an important role, allowing for better understanding of the degenerative process and therapeutic interventions. There are several models with different methods of evaluation of experimental disc degeneration (EDD), including imaging, biochemical, genetics, and histological approaches, but no real gold standard has been set. The authors aim to evaluate EDD by means of automated morphometric analysis and to determine values for differentiating normal and degenerated discs by this method. The criteria mean and total cellular area, mean and total cytoplasm area, and total nuclear area of cells in the nucleus pulposus were able to differentiate the condition of degeneration (p < 0.05). In conclusion, by applying the histomorphometric analysis of EDD, the authors could present an objective measure of EDD changes within the nucleus pulposus, reducing the evaluator bias in future studies and presenting highly sensitive and specific criteria for EDD.

Influence of lumbar intervertebral disc degeneration on the outcome of total lumbar disc replacement: a prospective clinical, histological, X-ray and MRI investigation

INTRODUCTION

The role of fusion of lumbar motion segments for the treatment of axial low back pain (LBP) from lumbar degenerative disc disease (DDD) without any true deformities or instabilities remains controversially debated. In an attempt to avoid previously published and fusion-related negative side effects, motion preserving technologies such as total lumbar disc replacement (TDR) have been introduced. The adequate extent of preoperative DDD for TDR remains unknown, the number of previously published studies is scarce and the limited data available reveal contradictory results. The goal of this current analysis was to perform a prospective histological, X-ray and MRI investigation of the index-segment's degree of DDD and to correlate these data with each patient's pre- and postoperative clinical outcome parameters from an ongoing prospective clinical trial with ProDisc II (Synthes, Paoli, U.S.A.).

MATERIALS AND METHODS

Nucleus pulposus (NP) and annulus fibrosus (AF) changes were evaluated according to a previously validated quantitative histological degeneration score (HDS). X-ray evaluation included assessment of the mean, anterior and posterior disc space height (DSH). MRI investigation of DDD was performed on a 5-scale grading system. The prospective clinical outcome assessment included visual analogue scale (VAS), Oswestry Disability Index (ODI) scores as well as the patient's subjective satisfaction rates.

RESULTS

Data from 51 patients with an average follow-up of 50.5 months (range 6.1-91.9 months) were included in the study. Postoperative VAS and ODI scores improved significantly in comparison to preoperative levels (p < 0.002). A significant correlation and interdependence was established between various parameters of DDD preoperatively (p < 0.05). Degenerative changes of NP tissue samples were significantly more pronounced in comparison to those of AF material (p < 0.001) with no significant correlation between each other (p > 0.05). Preoperatively, the extent of DDD was not significantly correlated with the patient's symptomatology (p > 0.05). No negative influence was associated with increasing stages of DDD on the postoperative clinical outcome parameters following TDR (p > 0.05). Increasing stages of DDD in terms of lower DSH scores were not associated with inferior clinical results as outlined by postoperative VAS or ODI scores or the patient's subjective outcome evaluation at the last FU examination (p > 0.05). Conversely, some potential positive effects on the postoperative outcome were observed in patients with advanced stages of preoperative DDD. Patients with more severe preoperative HDS scores of NP samples demonstrated significantly lower VAS scores during the early postoperative course (p = 0.02).

CONCLUSION

Increasing stages of DDD did not negatively impact on the outcome following TDR in a highly selected patient population. In particular, no preoperative DDD threshold value was identified from which an inferior postoperative outcome could have been deduced. Conversely, some positive effects on the postoperative outcome were detected in patients with advanced stages of DDD. Combined advantageous effects of progressive morphological structural rigidity of the index segment and restabilizing effects from larger distraction in degenerated segments may compensate for increasing axial rotational instability, one of TDR's perceived disadvantages. Our data reveal a "therapeutic window" for TDR in a cohort of patients with various stages of DDD as long as preoperative facet joint complaints or degenerative facet arthropathies can be excluded and stringent preoperative decision making criteria are adhered to. Previously published absolute DSH values as contraindication against TDR should be reconsidered.

The role of lumbar disc replacement in the surgical management of low back pain

Spinal fusion has long been the standard surgical treatment for degenerative disorders of the spine, but clinical outcomes are often unpredictable. Lumbar disc replacement allows removal of the pain source while preserving motion. This article explores the role of lumbar disc replacement in the surgical management of low back pain.

Association between single nucleotide polymorphism in collagen IX and intervertebral disc disease in the Indian population

BACKGROUND

Symptomatic intervertebral disc degeneration is being recently reported in younger population, questions the basis of its degenerative etiology. Latest evidences show that genetics play a significant role. Collagen IX, an important constituent of disc, is found to be altered in genetically predisposed individuals. Mutations have been reported in COL9A2 and COL9A3 genes, which encode Collagen IX, in Finnish and various other populations. The purpose of the present study is to test the significance of these genes in the Indian population.

MATERIALS AND METHODS

One hundred proven cases of intervertebral disc disease (IDD) of various regions of spine were selected for the study, along with matched controls. They were tested for the above mentioned alleles by allelic discrimination method with real-time polymerase chain reaction (PCR) study after isolation of DNA from blood sample. Each blood sample was classified into one of the three types - homozygous, heterozygous, and wild (normal) type allele - separately for COL9A2 and COL9A3 genes.

RESULTS

Homozygosity for COL9A2 allelic variation was associated with 100% occurrence of the disease. Heterozygous allele of COL9A2 was significantly higher in the study group (42%) as compared to the control group (17%). In contrast, allelic variation in COL9A3 gene was found to have no significant correlation with disc disease. There was no single patient with homozygous allelic variation for COL9A3, suggesting predominance of COL9A2 variation in the Indian population.

CONCLUSION

This candidate gene strategy approach adds considerably to our knowledge of genetic makeup of Indian populations in relation with disc disease. This study highlights importance of COL9A2 gene variation especially of homozygous variety in contrast to COL9A3 variation in causing disc disease in Indian population.

Molecular basis of intervertebral disc degeneration

Intervertebral disc (IVD) degeneration is a disease of the discs connecting adjoining vertebrae in which structural damage leads to degeneration of the disc and surrounding area. Degeneration of the disc is considered to be a normal process of aging, but can accelerate faster than expected or be precipitated by other factors. The scientific community has come a long way in understanding the biological basis and interpreting the lifestyle implications of IVD degeneration. Of all the diseases of the intervertebral disc, degeneration is the most common and has earned much attention due to its diversity in presentation and potential multiorgan involvement. We will provide a brief overview of the anatomic, cellular, and molecular structure of the IVD, and delve into the cellular and molecular pathophysiology surrounding IVD degeneration. We will then highlight some of the newest developments in stem cell, protein, and genetic therapy for IVD degeneration.

Kinematic Evaluation of Association between Disc Bulge Migration, Lumbar Segmental Mobility, and Disc Degeneration in the Lumbar Spine Using Positional Magnetic Resonance Imaging

Degenerative disc disease and disc bulge in the lumbar spine are common sources of lower back pain. Little is known regarding disc bulge migration and lumbar segmental mobility as the lumbar spine moves from flexion to extension. In this study, 329 symptomatic (low back pain with or without neurological symptoms) patients with an average age of 43.5 years with varying degrees of disc degeneration were examined to characterize the kinematics of the lumbar intervertebral discs through flexion, neutral, and extension weight-bearing positions. In this population, disc bulge migration associated with dynamic motion of the lumbar spine significantly increased with increased grade of disk degeneration. Although no obvious trends relating the migration of disc bulge and angular segmental mobility were seen, translational segmental mobility tended to increase with disc bulge migration in all of the degenerative disc states. It appears that many factors, both static (intervertebral disc degeneration or disc height) and dynamic (lumbar segmental mobility), affect the mechanisms of lumbar disc bulge migration.

Mid-term evaluation of the effects of dynamic neutralization system on lumbar intervertebral discs using quantitative molecular MR imaging

PURPOSE

To evaluate the mid-term effects of implant of dynamic neutralization system (Dynesys) on disc tissue in patients with lumbar discopathy, through the quantification of glycosaminoglycans (GAG) concentration, both in treated and adjacent levels, by analysis of delayed gadolinium-enhanced MRI contrast (dGEMRIC) images.

MATERIALS AND METHODS

Ten patients with low back pain underwent the dGEMRIC diagnostic protocol before, 6-months and after 2 years from surgery. Each patient was also evaluated with visual analog (VAS), Oswestry, and Prolo scales both at presurgery and during follow-up. From dGEMRIC images, a ΔT1 parametric map was obtained for each disc, as quantitative indicator of its GAG concentration, and divided in 13 sectors, which were classified at presurgery as normal or abnormal, based on a 70-ms threshold. Evolution of ΔT1 was studied during the follow-up.

RESULTS

Nine of ten patients completed the follow-up. VAS, Oswestry, and Prolo grades showed an improvement. This was accompanied by a reduction of ΔT1 in abnormal segments while normal segments showed a pattern of initial worsening at 6 months, followed by an improvement after 2 years.

CONCLUSION

Our study confirmed the improvement in clinical evaluation, and for the first time related this to the changes in discs GAG concentration.

Histological analysis of surgical lumbar intervertebral disc tissue provides evidence for an association between disc degeneration and increased body mass index

Background

Although histopathological grading systems for disc degeneration are frequently used in research, they are not yet integrated into daily care routine pathology of surgical samples. Therefore, data on histopathological changes in surgically excised disc material and their correlation to clinical parameters such as age, gender or body mass index (BMI) is limited to date. The current study was designed to correlate major physico-clinical parameters from a population of orthopaedic spine center patients (gender, age and BMI) with a quantitative histologic degeneration score (HDS).

Methods

Excised lumbar disc material from 854 patients (529 men/325 women/mean age 56 (15-96) yrs.) was graded based on a previously validated histologic degeneration score (HDS) in a cohort of surgical disc samples that had been obtained for the treatment of either disc herniation or discogenic back pain. Cases with obvious inflammation, tumor formation or congenital disc pathology were excluded. The degree of histological changes was correlated with sex, age and BMI.

Results

The HDS (0-15 points) showed significantly higher values in the nucleus pulposus (NP) than in the annulus fibrosus (AF) (Mean: NP 11.45/AF 7.87), with a significantly higher frequency of histomorphological alterations in men in comparison to women. Furthermore, the HDS revealed a positive significant correlation between the BMI and the extent of histological changes. No statistical age relation of the degenerative lesions was seen.

Conclusions

This study demonstrated that histological disc alterations in surgical specimens can be graded in a reliable manner based on a quantitative histologic degeneration score (HDS). Increased BMI was identified as a positive risk factor for the development of symptomatic, clinically significant disc degeneration.

Is greater lumbar vertebral BMD associated with more disk degeneration? A study using µCT and discography

It is well documented that osteoarthritis is associated with greater BMD in peripheral extremities. Yet the relationship between vertebral BMD and disk degeneration (DD) remains controversial in the lumbar spine, which may be due largely to the inadequacies of BMD and DD measures. Aiming to clarify the association between vertebral BMD and adjacent DD, we studied 137 cadaveric lumbar vertebrae and 209 corresponding intervertebral disks from the spines of 48 white men aged 21 to 64 years. DD was evaluated using discography. The vertebrae were scanned using a micro-computed tomography (µCT) system to obtain volumetric BMD for the whole vertebra, the vertebral body, the vertebral body excluding osteophytes, and the vertebral body excluding osteophytes and endplates. A random effects model was used to examine the association between the different definitions of vertebral BMD and adjacent DD. No significant association was found between the BMD of the whole vertebra and adjacent DD. However, when the posterior elements were excluded, there was a significant association between greater vertebral body BMD and more severe degeneration in the disk cranial to the vertebra. This association remained after further excluding osteophytes and endplates from the vertebral body BMD measurements. Also, a trend of greater BMD of the vertebral body associated with more adjacent DD was evident. These results clarify the association between vertebral BMD and DD and specifically indicate that it is higher BMD of the vertebral body, not the entire vertebra, that is associated with more severe adjacent DD. This association may be obscured by the posterior elements and is not confounded by osteophytes and endplate sclerosis.

Structure and biology of the intervertebral disk in health and disease

The intervertebral disks along the spine provide motion and protection against mechanical loading. The 3 structural components, nucleus pulposus, annulus fibrosus, and cartilage endplate, function as a synergistic unit, though each has its own role. The cells within each of these components have distinct origins in development and morphology, producing specific extracellular matrix proteins that are organized into unique architectures fit for intervertebral disk function. This article focuses on various aspects of intervertebral disk biology and disruptions that could lead to diseases such as intervertebral disk degeneration.