Mechanism of intervertebral disc degeneration caused by nicotine in rabbits to explicate intervertebral disc disorders caused by smoking

Progress in the study of molecular mechanisms of intervertebral disc degeneration

Degenerative intervertebral disc disease (IVDD) is one of the main spinal surgery, conditions, which markedly increases the incidence of low back pain and deteriorates the patient's quality of life, and it imposes significant social and economic burdens. The molecular pathology of IVDD is highly complex and multilateral however still not ompletely understood. New findings indicate that IVDD is closely associated with inflammation, oxidative stress, cell injury and extracellular matrix metabolismdysregulation. Symptomatic management is the main therapeutic approach adopted for IVDD, but it fails to address the basic pathological changes and the causes of the disease. However, research is still focusing on molecular aspects in terms of gene expression, growth factors and cell signaling pathways in an attempt to identify specific molecular targets for IVDD treatment. The paper summarizes the most recent achievements in molecularunderstanding of the pathogenesis of IVDD and gives evidence-based recommendations for clinical practice.

Understanding the etiopathogenesis of lumbar intervertebral disc herniation: From clinical evidence to basic scientific research

Lumbar intervertebral disc herniation, as a leading cause of low back pain, productivity loss, and disability, is a common musculoskeletal disorder that results in significant socioeconomic burdens. Despite extensive clinical and basic scientific research efforts, herniation etiopathogenesis, particularly its initiation and progression, is not well understood. Understanding herniation etiopathogenesis is essential for developing effective preventive measures and therapeutic interventions. Thus, this review seeks to provide a thorough overview of the advances in herniation-oriented research, with a discussion on ongoing challenges and potential future directions for clinical, translational, and basic scientific investigations to facilitate innovative interdisciplinary research aimed at understanding herniation etiopathogenesis. Specifically, risk factors for herniation are identified and summarized, including familial predisposition, obesity, diabetes mellitus, smoking tobacco, selected cardiovascular diseases, disc degeneration, and occupational risks. Basic scientific experimental and computational research that aims to understand the link between excessive mechanical load, catabolic tissue remodeling due to inflammation or insufficient nutrient supply, and herniation, are also reviewed. Potential future directions to address the current challenges in herniation-oriented research are explored by combining known progressive development in existing research techniques with ongoing technological advances. More research on the relationship between occupational risk factors and herniation, as well as the relationship between degeneration and herniation, is needed to develop preventive measures for working-age individuals. Notably, researchers should explore using or modifying existing degeneration animal models to study herniation etiopathogenesis, as such models may allow for a better understanding of how to prevent mild-to-moderately degenerated discs from herniating.

The Effects of Nicotine- and Cigarette-Related Products on Osteogenesis, Bone Formation, and Bone Mineralization: A Systematic Review

BACKGROUND

Many clinicians associate nicotine as the causative agent in the negative and deleterious effects of smoking on bone growth and spine fusion. Although nicotine is the primary driver of physiological addiction in smoking, isolated and controlled use of nicotine is one of the most effective adjuncts to quitting smoking.

OBJECTIVE

To explore the relationship between nicotine and noncombustion cigarette products on bone growth.

METHODS

One thousand five studies were identified, of which 501 studies were excluded, leaving 504 studies available for review. Of note, 52 studies were deemed to be irrelevant. Four hundred fifty-two studies remained for eligibility assessment. Of the remaining 452, 218 failed to assess study outcomes, 169 failed to assess bone biology, 13 assessed 5 patients or fewer, and 12 were deemed to be ineligible of the study criteria. Forty studies remained for inclusion within this systematic review.

RESULTS

Of the 40 studies identified for inclusion within the study, 30 studies were classified as "Animal Basic Science," whereas the remaining 10 were categorized as "Human Basic Science." Of the 40 studies, 11 noted decreased cell proliferation and boney growth, whereas 8 showed an increase. Four studies noted an increase in gene expression products, whereas 11 noted a significant decrease.

CONCLUSION

The results of this study demonstrate that nicotine has a variety of complex interactions on osteoblast and osteoclastic activities. Nicotine demonstrates dose-dependent effects on osteoblast proliferation, boney growth, and gene expression. Further study is warranted to extrapolate the effects of solitary nicotine on clinical outcomes.

Smoking, alcohol and coffee consumption and risk of low back pain: a Mendelian randomization study

PURPOSE

Low back pain (LBP) is a common health problem in the global population. This study aims to assess whether smoking initiation, alcohol consumption, and coffee consumption are causally with an increased risk of LBP.

METHODS

A two-sample Mendelian Randomization (MR) study was designed, based on summary-level data from the largest published genome-wide association studies. Single nucleotide polymorphisms with genome-wide significance level (P < 5.0 × 10-8) were selected as instrumental variables for each exposure. Standard inverse-variance weighted (IVW) method was used as the primary statistical method. The weighted median, MR-Egger regression, and MR-PRESSO methods, which relax some IV assumptions, were used for sensitivity analysis.

RESULTS

Genetically predicted smoking initiation was causally associated with higher odds of LBP. The pooled OR of LBP using IVW method was 1.36 (95%CI 1.22 1.52; P = 6.0 × 10-8) for one SD increase in the prevalence of smoking initiation, which was supported by the weighted median method (OR: 1.41, 95%CI 1.22, 1.64; P = 5.7 × 10-6). Sensitivity analysis confirmed the robustness of pooled OR of LBP. There was no evidence to suggest a causal effect of alcohol and coffee consumption on LBP. The pooled ORs of LBP were 1.36 (95%CI 0.94, 1.97; P = 0.10) for alcohol consumption and 1.00 (95%CI 0.99, 1.00; P = 0.17) for coffee consumption, respectively.

CONCLUSION

Smoking is casually associated with an increased risk of LBP. Smoking control should be recommended in LBP patients to avoid worsening the disease. The safety of LBP with moderate alcohol and coffee consumption merits more study.

Biomechanical Effect of Disc Height on the Components of the Lumbar Column at the Same Axial Load: A Finite-Element Study

Intervertebral discs are fibrocartilage structures, which play a role in buffering the compression applied to the vertebral bodies evenly while permitting limited movements. According to several previous studies, degenerative changes in the intervertebral disc could be accelerated by factors, such as aging, the female sex, obesity, and smoking. As degenerative change progresses, the disc height could be reduced due to the dehydration of the nucleus pulposus. This study aimed to quantitatively analyze the pressure that each structure of the spine receives according to the change in the disc height and predict the physiological effect of disc height on the spine. We analyzed the biomechanical effect on spinal structures when the disc height was decreased using a finite-element method investigation of the lumbar spine. Using a 3D FE model, the degree and distribution of von-Mises stress according to the disc height change were measured by applying the load of four different motions to the lumbar spine. The height was changed by dividing the anterior and posterior parts of the disc, and analysis was performed in the following four motions: flexion, extension, lateral bending, and axial rotation. Except for a few circumstances, the stress applied to the structure generally increased as the disc height decreased. Such a phenomenon was more pronounced when the direction in which the force was concentrated coincided with the portion where the disc height decreased. This study demonstrated that the degree of stress applied to the spinal structure generally increases as the disc height decreases. The increase in stress was more prominent when the part where the disc height was decreased and the part where the moment was additionally applied coincided. Disc height reduction could accelerate degenerative changes in the spine. Therefore, eliminating the controllable risk factors that cause disc height reduction may be beneficial for spinal health.

Relationship between lumbar disc degeneration on MRI and low back pain: A cross-sectional community study

Purpose:

Although an association has been suggested between disc degeneration (DD) and low back pain (LBP), some DD is thought to be an age-related change unrelated to symptoms. Age-inappropriate DD, however, may be associated with LBP. The purpose of this study was to investigate whether there is a difference in LBP and LBP-related quality of life between age-appropriate and age-inappropriate DD, as assessed by magnetic resonance imaging (MRI).

Participants and methods:

In this cross-sectional study, degenerative change in the lumbar intervertebral discs of 382 subjects (age range, 27-82 years) was evaluated by MRI. Degenerative Disc Disease (DDD) scores were assigned using the Schneiderman classification, as the sum of grades for all intervertebral levels (0-15). We classified subjects into three groups according to age and DDD score: Low DD (mild DD relative to age), Appropriate (age-appropriate DD), and High DD (severe DD relative to age). We compared the three groups in terms of LBP prevalence, LBP intensity, LBP-specific quality of life (QOL) according to the Roland-Morris Disability Questionnaire (RDQ), and the Short Form-36 Item Health Survey (SF-36).

Results:

Of 382 subjects, there were 35% in the Low DD group, 54% in the Appropriate group, and 11% in the High DD group. There were no significant differences among the groups in terms of prevalence of LBP, LBP intensity, RDQ score, or SF-36 score.

Conclusion:

No association was found between age-inappropriate DD (Low or High DD group) and age-appropriate DD (Appropriate group) in terms of prevalence of LBP, LBP intensity, RDQ, or SF-36.

Development, Pathogenesis, and Regeneration of the Intervertebral Disc: Current and Future Insights Spanning Traditional to Omics Methods

The intervertebral disc (IVD) is the fibrocartilaginous joint located between each vertebral body that confers flexibility and weight bearing capabilities to the spine. The IVD plays an important role in absorbing shock and stress applied to the spine, which helps to protect not only the vertebral bones, but also the brain and the rest of the central nervous system. Degeneration of the IVD is correlated with back pain, which can be debilitating and severely affects quality of life. Indeed, back pain results in substantial socioeconomic losses and healthcare costs globally each year, with about 85% of the world population experiencing back pain at some point in their lifetimes. Currently, therapeutic strategies for treating IVD degeneration are limited, and as such, there is great interest in advancing treatments for back pain. Ideally, treatments for back pain would restore native structure and thereby function to the degenerated IVD. However, the complex developmental origin and tissue composition of the IVD along with the avascular nature of the mature disc makes regeneration of the IVD a uniquely challenging task. Investigators across the field of IVD research have been working to elucidate the mechanisms behind the formation of this multifaceted structure, which may identify new therapeutic targets and inform development of novel regenerative strategies. This review summarizes current knowledge base on IVD development, degeneration, and regenerative strategies taken from traditional genetic approaches and omics studies and discusses the future landscape of investigations in IVD research and advancement of clinical therapies.

Overweight and smoking promote recurrent lumbar disk herniation after discectomy

PURPOSE

Recurrent lumbar disk herniation (rLDH) following lumbar microdiscectomy is common. While several risk factors for primary LDH have been described, risk factors for rLDH have only sparsely been investigated. We evaluate the effect of Body mass index (BMI) and smoking on the incidence and timing of rLDH.

METHODS

From a prospective registry, we identified all patients undergoing primary tubular microdiscectomy (tMD), with complete BMI and smoking data, and a minimum 12-month follow-up. We defined rLDH as reherniation at the same level and side requiring surgery. Overweight was defined as BMI > 25, and obesity as BMI > 30. Intergroup comparisons and age- and gender-adjusted multivariable regression were carried out. We conducted a survival analysis to assess the influence of BMI and smoking on time to reoperation.

RESULTS

Of 3012 patients, 166 (5.5%) underwent re-microdiscectomy for rLDH. Smokers were reoperated more frequently (6.4% vs. 4.0%, p = 0.007). Similarly, rLDH was more frequent in obese (7.5%) and overweight (5.9%) than in normal-weight patients (3.3%, p = 0.017). Overweight smokers had the highest rLDH rate (7.6%). This effect of smoking (Odds ratio: 1.63, 96% CI: 1.12-2.36, p = 0.010) and BMI (Odds ratio: 1.09, 95% CI: 1.02-1.17, p = 0.010) persisted after controlling for age and gender. Survival analysis demonstrated that rLDH did not occur earlier in overweight patients and/or smokers.

CONCLUSIONS

BMI and smoking may directly contribute to a higher risk of rLDH, but do not accelerate rLDH development. Smoking cessation and weight loss in overweight or obese patients ought to be recommended with discectomy to reduce the risk for rLDH.

Abcc6 Null Mice—a Model for Mineralization Disorder PXE Shows Vertebral Osteopenia Without Enhanced Intervertebral Disc Calcification With Aging

Chronic low back pain is a highly prevalent health condition intricately linked to intervertebral disc degeneration. One of the prominent features of disc degeneration that is commonly observed with aging is dystrophic calcification. ATP-binding cassette sub-family C member 6 (ABCC6), a presumed ATP efflux transporter, is a key regulator of systemic levels of the mineralization inhibitor pyrophosphate (PPi). Mutations in ABCC6 result in pseudoxanthoma elasticum (PXE), a progressive human metabolic disorder characterized by mineralization of the skin and elastic tissues. The implications of ABCC6 loss-of-function on pathological mineralization of structures in the spine, however, are unknown. Using the Abcc6^−/− mouse model of PXE, we investigated age-dependent changes in the vertebral bone and intervertebral disc. Abcc6^−/− mice exhibited diminished trabecular bone quality parameters at 7 months, which remained significantly lower than the wild-type mice at 18 months of age. Abcc6^−/− vertebrae showed increased TRAP staining along with decreased TNAP staining, suggesting an enhanced bone resorption as well as decreased bone formation. Surprisingly, however, loss of ABCC6 resulted only in a mild, aging disc phenotype without evidence of dystrophic mineralization. Finally, we tested the utility of oral K3Citrate to treat the vertebral phenotype since it is shown to regulate hydroxyapatite mechanical behavior. The treatment resulted in inhibition of the osteoclastic response and an early improvement in mechanical properties of the bone underscoring the promise of potassium citrate as a therapeutic agent. Our data suggest that although ectopic mineralization is tightly regulated in the disc, loss of ABCC6 compromises vertebral bone quality and dysregulates osteoblast-osteoclast coupling.

The prevalence and risk factors of chronic low back pain among adults in KwaZulu-Natal, South Africa: an observational cross-sectional hospital-based study

Background

Globally, chronic low back pain (CLBP) is the leading cause of disability associated with economic costs. However, it has received little attention in low-and-middle-income countries. This study estimated the prevalence and risk factors of CLBP among adults presenting at selected hospitals in KwaZulu-Natal.

Methodology

This cross-sectional study was conducted among adults aged ≥18 years who attended the selected hospitals in KwaZulu-Natal during the study period. A self-administered questionnaire was used to collect data on socio-demographic, work-related factors, and information about CLBP. The SPSS version 24.0 (IBM SPSS Inc) was used for data analysis. Descriptive statistics were used for demographic characteristics of participants. CLBP risk factors were assessed using multivariate logistic regression analysis. A p-value of ≤0.05 was deemed statistically significant.

Results

A total of 678 adults participated in this study. The overall prevalence of CLBP was 18.1% (95% CI: 15.3 – 21.3) with females having a higher prevalence than males, 19.8% (95% CI: 16.0 – 24.1) and 15.85% (95% CI: 11.8 – 20.6), respectively. Using multivariate regression analysis, the following risk factors were identified: overweight (aOR: 3.7, 95% CI: 1.1 – 12.3, p = 0.032), no formal education (aOR: 6.1, 95% CI: 2.1 – 18.1, p = 0.001), lack of regular physical exercises (aOR: 2.2, 95% CI: 1.0 – 4.8, p = 0.044), smoking 1 to 10 (aOR: 4.5, 95% CI: 2.0 – 10.2, p < 0.001) and more than 11 cigarettes per day (aOR: 25.3, 95% CI: 10.4 – 61.2, p < 0.001), occasional and frequent consumption of alcohol, aOR: 2.5, 95% CI: 1.1 – 5.9, p < 0.001 and aOR: 11.3, 95% CI: 4.9 – 25.8, p < 0.001, respectively, a sedentary lifestyle (aOR: 31.8, 95% CI: 11.2 – 90.2, p < 0.001), manual work (aOR: 26.2, 95% CI: 10.1 – 68.4, p < 0.001) and a stooped sitting posture (aOR: 6.0, 95% CI: 2.0 – 17.6, p = 0.001).

Conclusion

This study concluded that the prevalence of CLBP in KwaZulu-Natal is higher than in other regions, and that it is predicted by a lack of formal education, overweight, lack of regular physical exercises, smoking, alcohol consumption, sedentary lifestyle, manual work, and a stooped posture.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04790-9.

Platelet-Derived Biomaterials Inhibit Nicotine-Induced Intervertebral Disc Degeneration Through Regulating IGF-1/AKT/IRS-1 Signaling Axis

Apart from aging process, adult intervertebral disc (IVD) undergoes various degenerative processes. However, the nicotine has not been well identified as a contributing etiology. According to a few studies, nicotine ingestion through smoking, air or clothing may significantly accumulate in active as well as passive smokers. Since nicotine has been demonstrated to adversely impact various physiological processes, such as sympathetic nervous system, leading to impaired vasculature and cellular apoptosis, we aimed to investigate whether nicotine could induce IVD degeneration. In particular, we evaluated dose-dependent impact of nicotine in vitro to simulate its chronic accumulation, which was later treated by platelet-derived biomaterials (PDB). Further, during in vivo studies, mice were subcutaneously administered with nicotine to examine IVD-associated pathologic changes. The results revealed that nicotine could significantly reduce chondrocytes and chondrogenic indicators (Sox, Col II and aggrecan). Mice with nicotine treatment also exhibited malformed IVD structure with decreased Col II as well as proteoglycans, which was significantly increased after PDB administration for 4 weeks. Mechanistically, PDB significantly restored the levels of IGF-1 signaling proteins, particularly pIGF-1 R, pAKT, and IRS-1, modulating ECM synthesis by chondrocytes. Conclusively, the PDB impart reparative and tissue regenerative processes by inhibiting nicotine-initiated IVD degeneration, through regulating IGF-1/AKT/IRS-1 signaling axis.

Impact of Tobacco Smoking on Outcomes After Posterior Decompression Surgery in Patients With Cervical Spondylotic Myelopathy: A Retrospective Multicenter Study

STUDY DESIGN

This was a case-control study.

OBJECTIVE

The objective of this study was to clarify the surgical outcomes after cervical posterior decompression in patients who smoked.

SUMMARY OF BACKGROUND DATA

Smoking is associated with poor outcomes in the field of spinal surgery. However, the impact of tobacco smoking on the outcomes after posterior decompression surgery has not been fully evaluated in patients with cervical spondylotic myelopathy.

MATERIALS AND METHODS

In this retrospective multicenter study, 587 patients with cervical spondylotic myelopathy were enrolled at 17 institutions in Japan. Patients underwent cervical laminoplasty or laminectomy and were followed up for at least 1 year after surgery. Outcome measures were: preoperative smoking status, perioperative complications, the Japanese Orthopedic Association scale, and the Visual Analog Scale for neck pain. After adjusting for age and sex by exact matching, smoking and nonsmoking groups were compared using an unpaired t test for continuous variables or a χ test for categorical variables.

RESULTS

There were 182 (31%) current smokers and 405 (69%) nonsmokers including previous smokers. After matching, 158 patients were extracted from each group. Demographic data and surgical information were almost the same between the groups. Regarding postoperative complications, there was no significant difference in the rate of surgical site infection, cerebrospinal fluid leakage, hematoma, segmental motor paralysis, or neurological deficit. However, smokers showed a significantly higher risk for delirium (3.8% vs. 0.0%, P=0.039). Smokers and nonsmokers showed comparable changes in functional recovery according to Japanese Orthopedic Association scores (3.2±2.1 vs. 3.0±2.1, P=0.425) and in neck pain reduction using the Visual Analog Scale (-1.7±3.1 vs. -1.4±2.8, P=0.417) at the final follow-up.

CONCLUSIONS

Smokers exhibited functional restoration and neck pain reduction after cervical posterior decompression. Attention is required, however, for the postoperative complication of delirium, which could be caused by the acute cessation of tobacco smoking after admission.

LEVEL OF EVIDENCE

Level III.

Canine models of spine disorders

Neck and low back pain are common among the adult human population and impose large social and economic burdens on health care and quality of life. Spine-related disorders are also significant health concerns for canine companions with etiopathogeneses, clinical presentations, and diagnostic and therapeutic options that are very similar to their human counterparts. Historically, induced and spontaneous pathology in laboratory rodents, dogs, sheep, goats, pigs, and nonhuman primates have been used for study of human spine disorders. While each of these can serve as useful preclinical models, they all have inherent limitations. Spontaneously occurring spine disorders in dogs provide highly translatable data that overcome many of the limitations of other models and have the added benefit of contributing to veterinary healthcare as well. For this scoping review, peer-reviewed manuscripts were selected from PubMed and Google Scholar searches using keywords: "intervertebral disc," "intervertebral disc degeneration," "biomarkers," "histopathology," "canine," and "mechanism." Additional keywords such as "injury," "induced model," and "nucleus degeneration" were used to further narrow inclusion. The objectives of this review were to (a) outline similarities in key features of spine disorders between dogs and humans; (b) describe relevant canine models; and (c) highlight the applicability of these models for advancing translational research and clinical application for mechanisms of disease, diagnosis, prognosis, prevention, and treatment, with a focus on intervertebral disc degeneration. Best current evidence suggests that dogs share important anatomical, physiological, histological, and molecular components of spinal disorders in humans, such that induced and spontaneous canine models can be very effective for translational research. Taken together, the peer-reviewed literature supports numerous advantages for use of canine models for study of disorders of the spine when the potential limitations and challenges are addressed.

Prediction of outcome following laminoplasty of cervical spondylotic myelopathy: Focus on the minimum clinically important difference

The minimum clinically important difference (MCID) of the Japanese Orthopaedic Association (JOA) score has been reported to be around 2.5 points in cervical myelopathy. This study sought to define significant predictive factors on achieving the MCID following laminoplasty in a large series of patients with cervical spondylotic myelopathy (CSM). A total of 485 consecutive patients with CSM (295 males and 190 females; mean age: 67.0 years; age range: 42-91 years) who underwent laminoplasty were prospectively enrolled. The average postoperative follow-up period was 26.6 months (range: 12-66 months). We calculated the achieved JOA score. The relationships between outcomes and various clinical and imaging predictors including comorbidity and quantitative performance tests were examined. Logistic regression analysis was conducted to identify the predictors correlated with a JOA score of 2.5 points or more. Clinically meaningful gains were exhibited in 299 patients (61.6%) with a JOA score of ≥2.5 points, whereas 186 patients (38.4%) achieved a JOA score of <2.5 points. Univariate logistic regression analysis showed the predictive factors with a shorter duration of CSM symptoms, lower preoperative JOA scores, absence of hypertension, no use of anticoagulant/antiplatelet agents, and nonsmoking status. Multivariate logistic regression analysis determined that the duration of CSM symptoms (odds ratio: 0.771, 95% confidence interval: 0.705-0.844; p < 0.01) was the only significant predictive factor for achieving JOA scores of ≥2.5 points. An important predictor of MCID achievement following laminoplasty was shorter duration of CSM symptoms.

Transcriptomics Study to Determine the Molecular Mechanism by which sIL-13Rα2-Fc Inhibits Caudal Intervertebral Disc Degeneration in Rats

Background

Intervertebral disc degeneration is related to tissue fibrosis. ADAMTS can degrade the important components of the ECM during the process of intervertebral disc degeneration, ultimately resulting in the loss of intervertebral disc function. sIL-13Rα2-Fc can inhibit fibrosis and slow down the degeneration process, but the mechanism involved remains unclear.

Objective

To determine the mechanism by which sIL-13Rα2-Fc inhibits ECM degradation and reduces intervertebral disc tissue fibrosis using a transcriptomics analysis.

Methods

A rat model of caudal intervertebral disc degeneration was established, and Sirius red staining was used to observe the pathological changes in the caudal intervertebral disc. Transcriptome sequencing was employed to assess the gene expression profiles of the intervertebral disc tissues in the model group and the sIL-13Rα2-Fc-treated group. Differentially expressed genes were identified and analyzed using GO annotation and KEGG pathway analyses. Real-time fluorescence quantitative PCR was used to verify the expression levels of candidate genes. The levels of GAG and HA were quantitatively assessed by ELISA, and the levels of collagen I and collagen II were analyzed by western blotting.

Results

Sirius red staining showed that in the model group, the annulus fibrosus was disordered, the number of breaks increased, and the type I collagen protein levels increased, whereas in the sIL-13Rα2-Fc group, the annulus fibrosus was ordered, the number of breaks decreased, and the type II collagen protein levels increased. In comparison with the model group, we identified 58 differentially expressed genes in the sIL-13Rα2-Fc group, and these were involved in 35 signaling pathways. Compared with those in the model group, the mRNA expression levels of Rnux1, Sod2, and Tnfaip6 in the IL-13Rα2-Fc group were upregulated, and the mRNA expression levels of Aldh3a1, Galnt3, Fgf1, Celsr1, and Adamts8 were downregulated; these results were verified by real-time fluorescence quantitative PCR. TIMP-1 (an ADAMTS inhibitor) and TIMP-1 combined with the sIL-13Rα2-Fc intervention increased the levels of GAG and HA, inhibited the expression of type I collagen, and promoted the expression of type II collagen.

Conclusion

Adamts8 may participate in the degradation of ECM components such as GAG and HA and lead to an imbalance in the ECM of the intervertebral disc, resulting in intervertebral disc degeneration. sIL-13Rα2-Fc promoted anabolism of the ECM and increased the levels of ECM components by inhibiting the expression of Adamts8, thus maintaining the dynamic equilibrium of the ECM and ultimately delaying intervertebral disc degeneration.

The Impact of "Vaping" Electronic Cigarettes on Spine Health

“Vaping” or the use of electronic cigarettes (e-cigarettes) has greatly increased within the past decade, with growing popularity among adolescents. E-cigarettes have many harmful effects on multiple organ systems, but more research is needed to fully understand the extent of possible risks. Our narrative literature review aims to provide comprehensive insight into the impact of e-cigarette use on spinal health with a specific focus on intervertebral disc (IVD) health, bone health, and spinal fusion. There are many metallic compounds and chemical flavoring additives within e-cigarette liquids that are associated with human toxicity. These chemical toxins have been linked to increased oxidative stress leading to systemic inflammation. E-cigarette carcinogens have shown to have a toxic effect on osteoblast cells, and long-term use may decrease bone mineral density and increase the future risk for osteoporosis. Additionally, nicotine in e-liquids negatively impacts IVD health by creating hypoxic environments that degenerate the IVD vasculature and cellular matrix. While studies have demonstrated the inhibitory effects of nicotine use on spinal fusions in animal models, the impact of e-cigarette use on spinal fusion operations in human patients is currently lacking. Future research should focus on the influence of e-cigarette use on spinal health, particularly in adolescents with long-term follow-up, as childhood is a critical time for bone growth and development. Additionally, studies exploring the effects of e-cigarettes on spinal surgery outcomes, such as spinal fusions, are sparse in the literature. Further prospective research studies with a focus on the variety of e-cigarette chemical toxins and flavoring agents is needed to assess the impact on spinal health.

Detection of apoptosis and matrical degeneration within the intervertebral discs of rats due to passive cigarette smoking

Although low-back pain is considered to be associated with cigarette smoking, the influence of cigarette smoking on the intervertebral discs (IVD) has not been confirmed. We established a rat model of passive cigarette smoking-induced IVD degeneration, and investigated the cytohistological changes in the IVD and the accompanying changes in gene expression. IVD from rats exposed to 8 weeks of passive cigarette smoking were stained with Elastica van Gieson, and exhibited marked destruction of the supportive structure of the reticular matrix in the nucleus pulposus (NP). Positive signals on safranin O, alcian blue, type II collagen and aggrecan staining were decreased in the destroyed structure. Safranin O and type II collagen signals were also decreased in the cartilage end-plate (CEP) after 4- and 8-weeks of cigarette smoking. In the CEP, the potential for apoptosis was increased significantly, as demonstrated by staining for single-strand DNA. However, there were no signs of apoptosis in the NP or annulus fibrosus cells. Based on these findings, we hypothesized that passive cigarette smoking-induced stress stimuli first affect the CEP through blood flow due to the histological proximity, thereby stimulating chondrocyte apoptosis and reduction of the extracellular matrix (ECM). This leads to reduction of the ECM in the NP, destroying the NP matrix, which can then progress to IVD degeneration.

LINC00641 regulates autophagy and intervertebral disc degeneration by acting as a competitive endogenous RNA of miR-153-3p under nutrition deprivation stress

Emerging evidence supports the involvement of autophagy in the pathogenesis of intervertebral disc degeneration (IDD). MicroRNAs (miRNAs) and long noncoding RNAs (lncRNAs) play fundamental roles in various cellular processes, including autophagy. However, it remains largely unknown as to how autophagy is regulated by miRNAs and lncRNAs in IDD. Biological functions of miR-153-3p and long intergenic nonprotein coding RNA 641 (LINC00641) were investigated. Luciferase reporter assays was done to validate miR-153-3p targets. To induce nutritional stress, nucleus pulposus (NP) cells were cultured in the normal nutritional condition and the low nutritional condition. Quantitative reverse-transcription polymerase chain reaction (RT-qPCR) was used to analyze miR-153-3p and LINC00641 in response to nutrient deprivation. Autophagic activity was assessed by transmission electron microscopy, western blot analysis and green fluorescent protein-light chain 3 puncta. Pull-down assay and RNA fluorescent in situ hybridization were performed to validate LINC00641 target and the location. MiR-153-3p is downregulated in NP tissues from IDD patients. Further, LINC00641 can affect collagen II and matrix metalloproteinase-3 expressions. Upregulation of LINC00641 and downregulation of miR-153-3p are detected in NP cells under nutritional stress. LINC00641 can regulate autophagic cell death by targeting miR-153-3p and autophagy-related gene 5 (ATG5). MiR-153-3p inhibits autophagy and IDD by targeting ATG5. More important, LINC00641 targets miR-153-3p, and thus affects ATG5 expression, autophagic cell death and IDD. These findings uncover a novel regulatory pathway that is composed of LINC00641, miR-153-3p, and ATG5 in IDD. This mechanism may stimulate to a more understanding of IDD pathogenesis and provide new sights for the treatment of this disorder.

A retrospective study: Does cigarette smoking induce cervical disc degeneration?

OBJECTIVE

To investigate cigarette smoking's relevance with cervical disc degeneration.

METHODS

We randomly selected 320 patients who came to our spine disease department outpatient clinic with chief complaint of neck-shoulder pain during June 2014-June 2016. According to the detailed smoking history, these patients were divided into 3 different groups, which were active smoker group (AS), passive smoking group (PS) and never-smoker group (NS). Each patient's Miyazaki's magnetic resonance imaging (MRI) classification of cervical disc degeneration was analyzed based on their cervical MRI films. In addition, VAS scores were applied to evaluate the degree of patients' neck-shoulder pain. With the help of statistical techniques, relevance between cigarette smoking, cervical disc degeneration and neck-shoulder pain were analyzed.

RESULTS

In the NS group, the overall Miyazaki score, especially for C2/3, C3/4, C5,6 segments, are superior to those in the PS group, in addition, the Miyazaki scores for C1/2 - C6/7 segments in NS group beat the same segments in AS group with statistical significance (P < 0.05). In the AS and PS group, discs from C4/5 to C5/6 segments which score IV and V on Miyazaki classification account for a larger proportion than those discs from C1/2 to C3/4 segments with statistical significance (P < 0.05). In the AS group, male cases have larger proportion of Miyazaki level IV and V discs than female with statistical significance (P < 0.05). While in the AS and PS group, Miyazaki scores of patients whose smoking history ranges from 5 to 10 years are superior to those with smoking history longer than 10 years, with statistical significance (P < 0.05). In addition, VAS scores also vary among the three groups, in which, VAS scores in AS group are higher than those in the NS group.

CONCLUSION

Smoking could accelerate the process of cervical disc degeneration, presenting with more severe neck-shoulder pain on the patients. In addition, the impact of smoking on the lower cervical discs is greater than the upper cervical discs.

Behavior-Related Factors Associated With Low Back Pain in the US Adult Population

STUDY DESIGN

This study is based on data from the 2009-2012 National Health Interview Survey (NHIS) of the civilian population of the United States. The NHIS focuses on a number of health conditions, including low back pain.

OBJECTIVE

The objective of this study is to explore behavior-related factors associated with low back pain in the US adult population, including leisure-time physical activity, alcohol use, tobacco use, sleep duration, and obesity.

SUMMARY OF BACKGROUND DATA

Low back pain is a prevalent musculoskeletal health disorder with profound impact on individuals, business, and society. Addressing behavior-related factors holds the potential to reduce the burden of low back pain on a societal basis.

METHODS

To account for the complex sampling design of the NHIS, the Taylor linearized variance estimation methods were used to conduct weighted descriptive statistics and multivariate logistic regression analyses in exploring the relationships between low back pain and a set of behavior-related risk factors.

RESULTS

This study shows associations between self-reported lower back pain and reported leisure-time physical inactivity, current or former smoking, current or former alcohol drinking, short sleep duration, and obesity.

CONCLUSION

This study identified a number of behavior-related factors that appear to have a significant relationship with low back pain. Public health policy makers and clinicians should consider these factors to reduce the burden of low back pain. This study supports the need for longitudinal study design in future research.

LEVEL OF EVIDENCE

2.

Prevalence of Chronic Nonspecific Low Back Pain and Its Associated Factors among Middle-Aged and Elderly People: An Analysis Based on Data from a Musculoskeletal Examination in Japan

Study Design

A cross-sectional study.

Purpose

To clarify the prevalence of chronic nonspecific low back pain (CNSLBP) and its associated factors among middle-aged and elderly Japanese individuals using data from a musculoskeletal examination conducted in general Japanese populations.

Overview of Literature

Most studies evaluating low back pain-associated factors have been conducted in Western countries, but they have not always evaluated CNSLBP.

Methods

We obtained data on 213 subjects aged >50 years who responded to a survey regarding age, gender, body mass index, lifestyle-related diseases (diabetes mellitus, hypertension, and hyperlipidemia), glucocorticoid use, smoking and alcohol-drinking habits, labor intensity, and chronic low back pain (CLBP) and underwent screening for lumbar spinal stenosis, evaluation for quality of life (QOL), and evaluation for specific spinal pathology via thoracolumbar spine X-rays. We investigated the prevalence of CNSLBP and association between CNSLBP and measured variables.

Results

The prevalence of CNSLBP and chronic specific low back pain (CSLBP) was 15.4% and 9.3%, respectively. Among the subjects with CLBP, 62.2% had CNSLBP. In age-adjusted logistic models, smoking habits (p=0.049, odds ratio [OR]=2.594), low back pain (p<0.001, OR=0.974), lumbar function (p=0.001, OR=0.967), and social function (p=0.023, OR=0.976) in the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) were significantly associated with CNSLBP, whereas EQ-5D utility score (p=0.024, OR=0.068), low back pain (p=0.007, OR=0.981), lumbar function (p=0.001, OR=0.963), walking ability (p=0.001, OR=0.968), and social function (p=0.002, OR=0.966) in JOABPEQ were significantly associated with CSLBP.

Conclusions

CNSLBP among middle-aged and elderly individuals was associated with smoking habits and decreased QOL; however, CSLBP was considered to be more multilaterally associated decreased QOL.

The Effect of Smoking on Spinal Fusion

BACKGROUND

Spinal fusion surgery is performed about half a million times per year in the United States and millions more worldwide. It is an effective method for reducing pain, increasing stability, and correcting deformity in patients with various spinal conditions. In addition to being a well-established risk factor for a variety of medical conditions, smoking has deleterious effects on the bone healing of spinal fusions. This review aims to specifically analyze the ways in which smoking affects the outcomes of spinal fusion and to explore ways in which these negative consequences can be avoided.

PURPOSE

This article provides a complete understanding of the ways smoking affects spinal fusion from a biochemical and clinical perspective. Recommendations are also provided for ways in which surgeons can limit patient exposure to the most serious negative outcomes associated with cigarette smoking.

STUDY DESIGN/SETTING

This study was a retrospective literature review done using the NCBI database. The research was compiled at NYU Hospital for Joint Diseases and the NYU Center for Musculoskeletal Care.

METHODS

A comprehensive literature review was done spanning research on a variety of subjects related to smoking and spinal fusion surgery. The biochemistry of smoking and fusion healing were examined in great detail. In addition, both in vivo animal studies and human clinical studies were evaluated to explore fusion success related to the effects of smoking and its biochemical factors on spinal fusion surgery.

RESULTS

Smoking significantly increases the risk of pseudoarthrosis for patients undergoing both lumbar and cervical fusions. In addition to nonunion, smoking also increases the risk of other perioperative complications such as infection, adjacent-segment pathology, and dysphagia. Treatment options are available that can be explored to reduce the risk of smoking-related morbidity, such as nicotine replacement therapy and use of bone morphogenetic proteins (BMPs).

CONCLUSIONS

It has been clearly demonstrated from both a biochemical and clinical perspective that smoking increases the rate of perioperative complications for patients undergoing spinal fusion surgery, particularly pseudoarthosis. It has also been shown that there are certain approaches that can reduce the risk of morbidity. The most important recommendation is smoking cessation for four weeks after surgery. In addition, patients may be treated with certain surgical techniques, including the use of BMPs, to reduce the risk of pseudoarthrosis. Lastly, nicotine replacement therapy is an area of continued interest in relation to spinal fusion outcomes and more research needs to be done to determine its efficacy moving forward.

Treatment for Recurrent Lumbar Disc Herniation

PURPOSE OF REVIEW

Recurrent lumbar disc herniation (RLDH) is the most common indication for reoperation after a lumbar discectomy. The purpose of this manuscript is to review the incidence, risk factors, and treatment for RLDH.

RECENT FINDINGS

Patients who require revision surgery for RLDH improved significantly compared to baseline; however, the magnitude of improvement is less than in primary discectomy patients. Treatment with either repeat discectomy or instrumented fusion has comparable clinical outcomes. Repeat discectomy patients, however, have shorter operative times and length of stay. Hospital charges are dramatically lower for repeat discectomy compared to instrumented fusion. The incidence of RLDH is somewhere between 5 and 18%. Risk factors include younger age, lack of a sensory or motor deficit, and a higher baseline Oswestry Disability Index (ODI) score. Available evidence suggests that some patients may respond to nonoperative interventions and avoid the need for reoperation. For those that fail a trial of conservative management or present with neurologic deficit, both repeat lumbar discectomy and instrumented fusion appear to effectively treat patients with similar complication rates and clinical outcomes.

The Clinical Correlations between Diabetes, Cigarette Smoking and Obesity on Intervertebral Degenerative Disc Disease of the Lumbar Spine

Study Design

Retrospective analysis of a nationwide private insurance database. Chi-square analysis and linear regression models were utilized for outcome measures.

Purpose

The purpose of this study was to investigate any relationship between lumbar degenerative disc disease, diabetes, obesity and smoking tobacco.

Overview of Literature

Diabetes, obesity, and smoking tobacco are comorbid conditions known to individually have effect on degenerative disc disease. Most studies have only been on a small populous scale. No study has yet to investigate the combination of these conditions within a large patient cohort nor have they reviewed the combination of these conditions on degenerative disc disease.

Methods

A retrospective analysis of insurance billing codes within the nationwide Humana insurance database was performed, using PearlDiver software (PearlDiver, Inc., Fort Wayne, IN, USA), to identify trends among patients diagnosed with lumbar disc degenerative disease with and without the associated comorbidities of obesity, diabetes, and/or smoking tobacco. Patients billed for a comorbidity diagnosis on the same patient record as the lumbar disc degenerative disease diagnosis were compared over time to patients billed for lumbar disc degenerative disease without a comorbidity. There were no sources of funding for this manuscript and no conflicts of interest.

Results

The total number and prevalence of patients (per 10,000) within the database diagnosed with lumbar disc degenerative disease increased by 241.4% and 130.3%, respectively. The subsets of patients within this population who were concurrently diagnosed with either obesity, diabetes, tobacco use, or a combination thereof, was significantly higher than patients diagnosed with lumbar disc degenerative disease alone (p <0.05 for all). The number of patients diagnosed with lumbar disc degenerative disease and smoking rose significantly more than patients diagnosed with lumbar disc degenerative disease and either diabetes or obesity (p <0.05). The number of patients diagnosed with lumbar disc degenerative disease, smoking and obesity rose significantly more than the number of patients diagnosed with lumbar disc degenerative disease and any other comorbidity alone or combination of comorbidities (p <0.05).

Conclusions

Diabetes, obesity and cigarette smoking each are significantly associated with an increased diagnosis of lumbar degenerative disc disease. The combination of smoking and obesity had a synergistic effect on increased rates of lumbar degenerative disc disease. Patient education and preventative care is a vital goal in prevention of degenerative disc disease within the general population.

Trends analysis of surgical procedures for cervical degenerative disc disease and myelopathy in patients with tobacco use disorder

PURPOSE

This study defined the incidence and trends of surgeries performed for patients with cervical disc degeneration with and without tobacco use disorder (TUD).

METHODS

This study utilized the Humana Inc. database between 2007 and 2013 to identify patients with cervical disc degeneration with or without myelopathy. International Classification of Diseases, ninth revision (ICD-9) and Current Procedural Terminology (CPT) codes determined the initial diagnosis of disc degeneration, myelopathy status and TUD, whether patients received surgery, and TUD status at surgery.

RESULTS

The prevalence of disc degeneration with myelopathy increased by 32.8% between 2007 and 2013, while disc disease with myelopathy and TUD increased by 91.6%. For patients without myelopathy, the prevalence of disc degeneration alone increased by 65.4%, and disc degeneration with myelopathy increased by 148.7%. Of myelopathy patients, 1717 (6.4%) had TUD and 1024 (59.6%) received surgery, compared to 6508 patients without TUD (26.1%). For patients without myelopathy, 11,337 (3.5%) had TUD and 787 (6.9%) underwent surgery, compared to 9716 patients (3%) without TUD. Of surgical patients, 781 (76.3%) with myelopathy and TUD still had a TUD diagnosis at surgery, and 542 (68.9%) of patients without myelopathy still had a TUD diagnosis at surgery.

CONCLUSIONS

The prevalence of degenerative disc disease and TUD has increased more than disc disease alone. Patients with TUD were more likely to get surgery, and to have surgeries earlier than patients without TUD. Patients with TUD at the time of the diagnosis of their disc degeneration likely still had a TUD diagnosis at the time of surgery.

Acidification changes affect the inflammasome in human nucleus pulposus cells

BACKGROUND

Interleukin (IL)-1β is involved in the pathology of intervertebral disc degeneration. Under normal conditions, IL-1β is present in cells in an inactive form (pro-IL-1β). However, under pathological conditions, pro-IL-1β is turned into its active form (IL-1β) by the inflammasome, a multi-protein complex of the innate immune response that activates caspase-1. Under conditions of degeneration, the disc experiences an environment of increased acidification. However, the implications of acidification on the innate immune response remain poorly explored.

METHODS

Here we have studied how pH changes in human nucleus pulposus cells affect inflammasome activation by immunoblot analysis of protein lysates obtained from nucleus pulposus cells that were exposed to different pH levels in culture.

RESULTS

In this study, we have found that in nucleus pulposus cells, with increased acidification, there was a decrease in inflammasome activation consistent with lower levels of active IL-1β. However, this effect at a pH of 6.5, the lowest pH level tested, was abrogated when cells were treated with IL-1β.

CONCLUSIONS

Taken together, these findings suggest that the inflammatory response through IL-1β experienced by the human disc is not initiated in nucleus pulposus cells when the stimulus is acidification.

Predicting the minimum clinically important difference in patients undergoing surgery for the treatment of degenerative cervical myelopathy

OBJECTIVE

The minimum clinically important difference (MCID) is defined as the minimum change in a measurement that a patient would identify as beneficial. Before undergoing surgery, patients are likely to inquire about the ultimate goals of the operation and of their chances of experiencing meaningful improvements. The objective of this study was to define significant predictors of achieving an MCID on the modified Japanese Orthopaedic Association (mJOA) scale at 2 years following surgery for the treatment of degenerative cervical myelopathy (DCM).

METHODS

Seven hundred fifty-seven patients were prospectively enrolled in either the AOSpine North America or International study at 26 global sites. Fourteen patients had a perfect preoperative mJOA score of 18 and were excluded from this analysis (n = 743). Data were collected for each participating subject, including demographic information, symptomatology, medical history, causative pathology, and functional impairment. Univariate log-binominal regression analyses were conducted to evaluate the association between preoperative clinical factors and achieving an MCID on the mJOA scale. Modified Poisson regression using robust error variances was used to create the final multivariate model and compute the relative risk for each predictor.

RESULTS

The sample consisted of 463 men (62.31%) and 280 women (37.69%), with an average age of 56.48 ± 11.85 years. At 2 years following surgery, patients exhibited a mean change in functional status of 2.71 ± 2.89 points on the mJOA scale. Of the 687 patients with available follow-up data, 481 (70.01%) exhibited meaningful gains on the mJOA scale, whereas 206 (29.98%) failed to achieve an MCID. Based on univariate analysis, significant predictors of achieving the MCID on the mJOA scale were younger age; female sex; shorter duration of symptoms; nonsmoking status; a lower comorbidity score and absence of cardiovascular disease; and absence of upgoing plantar responses, lower-limb spasticity, and broad-based unstable gait. The final model included age (relative risk [RR] 0.924, p < 0.0001), smoking status (RR 0.837, p = 0.0043), broad-based unstable gait (RR 0.869, p = 0.0036), and duration of symptoms (RR 0.943, p = 0.0003).

CONCLUSIONS

In this large multinational prospective cohort, 70% of patients treated surgically for DCM exhibited a meaningful functional gain on the mJOA scale. The key predictors of achieving an MCID on the mJOA scale were younger age, shorter duration of symptoms, nonsmoking status, and lack of significant gait impairment.

The Effect of Smoking on Spinal Cord Healing Following Surgical Treatment of Cervical Myelopathy

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

The purpose of this study was to compare outcomes of surgical treatment of cervical myelopathy between smokers and nonsmokers as assessed by the Nurick score.

SUMMARY OF BACKGROUND DATA

The harmful effects of smoking on healing have been well established. However, the effect of smoking on postoperative outcomes for cervical myelopathy has not been specifically evaluated.

METHODS

The medical records of 212 patients who underwent surgery for cervical spondylotic myelopathy were reviewed. Inclusion criteria were the diagnosis of cervical spondylotic myelopathy with a Nurick score, surgical intervention, and at least 2 years of follow-up. The patients were categorized into 2 groups according to smoking status and stratified according to pack years and packs per day. Age at presentation, sex, preoperative and postoperative Nurick score, duration of symptoms preoperatively, duration of follow-up, procedure performed, surgical approach, number of levels fused, diabetes status, cocaine use, ethanol use, preoperative magnetic resonance imaging signal change, and whether the patient belonged to the Veterans Administration (VA) were recorded. Analysis was done using simple linear regression and multiple regression.

RESULTS

Univariate analysis demonstrated a postoperative improvement in nonsmokers of 1.53 points on the Nurick scale compared with 0.6 points in smokers (P < 0.001). There is a progressive decrease in improvement as the number of pack years and packs per day increase (P < 0.001). There is a greater improvement in Nurick score with greater (worse) preoperative score but only in patients with fewer than 25 pack years. Smoking status is not associated with preoperative Nurick score.

CONCLUSION

Smoking status is associated with poor improvement in Nurick score after surgical treatment of cervical myelopathy. Smoking may have a directly toxic effect on the intrinsic healing capability of the spinal cord, particularly beyond 25 pack years.

LEVEL OF EVIDENCE

3.

Effects of Tobacco Smoking on the Degeneration of the Intervertebral Disc: A Finite Element Study

Tobacco smoking is associated with numerous pathological conditions. Compelling experimental evidence associates smoking to the degeneration of the intervertebral disc (IVD). In particular, it has been shown that nicotine down-regulates both the proliferation rate and glycosaminoglycan (GAG) biosynthesis of disc cells. Moreover, tobacco smoking causes the constriction of the vascular network surrounding the IVD, thus reducing the exchange of nutrients and anabolic agents from the blood vessels to the disc. It has been hypothesized that both nicotine presence in the IVD and the reduced solute exchange are responsible for the degeneration of the disc due to tobacco smoking, but their effects on tissue homeostasis have never been quantified. In this study, a previously presented computational model describing the homeostasis of the IVD was deployed to investigate the effects of impaired solute supply and nicotine-mediated down-regulation of cell proliferation and biosynthetic activity on the health of the disc. We found that the nicotine-mediated down-regulation of cell anabolism mostly affected the GAG concentration at the cartilage endplate, reducing it up to 65% of the value attained in normal physiological conditions. In contrast, the reduction of solutes exchange between blood vessels and disc tissue mostly affected the nucleus pulposus, whose cell density and GAG levels were reduced up to 50% of their normal physiological levels. The effectiveness of quitting smoking on the regeneration of a degenerated IVD was also investigated, and showed to have limited benefit on the health of the disc. A cell-based therapy in conjunction with smoke cessation provided significant improvements in disc health, suggesting that, besides quitting smoking, additional treatments should be implemented in the attempt to recover the health of an IVD degenerated by tobacco smoking.

Establishment of intervertebral disc degeneration model induced by ischemic sub-endplate in rat tail

BACKGROUND CONTEXT

Microcirculatory dysfunction of the sub-endplate is considered to reduce nutrient supply to the intervertebral disc (IVD); however, direct interruption or destruction of blood vessels in the bone marrow of the vertebrae body adjacent to the endplate has not yet been described, especially with regard to the calcification and ossification of the cartilaginous endplate occurring during IVD degeneration.

PURPOSE

The purpose of the study was to evaluate the causal relationship between IVD degeneration and blocking of the main blood supply gateway through the endplate.

STUDY DESIGN/SETTING

The study describes a new IVD degeneration model induced by ischemic sub-endplate.

PATIENT SAMPLE

A total of 40 Sprague-Dawley rats were included in the study group.

OUTCOME MEASURES

To assess disc height, a radiograph was taken each month for 4 months. Changes in endplate, nucleus pulposus (NP), and annulus fibrosus (AF) were evaluated by histochemical and immunohistochemical staining to detect IVD degeneration.

METHODS

Injection of 30 μL absolute ethanol into the IVD of rat tail at Co7/Co8 was used to induce injury. Controls were injected with 30 μL of phosphate-buffered saline into the IVD at Co8/Co9.

RESULTS

In the ethanol-injected group, disc height gradually decreased and bone sclerosis developed in the endplate. In the NP, cell transformation occurred, changing from predominantly vacuolar cells to chondrogenic cells and eventually fibrocartilaginous cells, along with fibrosis of the NP. As degeneration progressed, the AF developed disordered morphology and rough lamellae, and eventually ruptures and fibrosis. The extent of degeneration increased gradually over time, while the wavy tidemark of the growth plate regressed, and eventually disappeared. Initially positive collagen type II staining gradually decreased on the ischemic side of the sub-endplate. Except at the 3-month time point, expression of collagen type II, aggrecan, and Sox-9 in NP decreased gradually as degeneration progressed, compared with the control group.

CONCLUSIONS

This model successfully reproduced IVD degeneration, which could be used for etiological studies on IVD degeneration and investigation of nutrient supply disturbance, and may provide a theoretical foundation for clinical intervention and therapy for IVD degeneration in the future.

Relationship between cigarette smoking and radiographic knee osteoarthritis in Chinese population: a cross-sectional study

The purpose of this paper was to estimate the cross-sectional association between cigarette smoking and radiographic knee Osteoarthritis (OA) in Chinese population. A total of 3,789 subjects (1,796 females and 1,993 males) participated in this study. A subject was diagnosed with radiographic knee OA if Kellgren-Lawrence (K-L) grade ≥2 in at least one leg. The smoking status was classified into four levels based on the daily smoking habit: (1) 0/day; (2) 1-10/day; (3) 11-20/day; and (4) >20/day. Linear trend and multivariable logistic regression were conducted for statistical analysis. The prevalence of radiographic knee OA was 28.4 % among the subjects of this study. An inverse association was observed between cigarette smoking and radiographic knee OA in the linear trend test. Such association remained valid after adjusting the factors of age, gender, body mass index, betel quilt chewing status, physical activity, alcohol drinking status, mean total energy intake and educational level in the multivariable logistic regression. This study suggested a negative association between cigarette smoking and radiographic knee OA in the Chinese population. The findings of this study need to be confirmed by further prospective research.

Drug-induced changes to the vertebral endplate vasculature affect transport into the intervertebral disc in vivo

Intervertebral disc health is mediated in part by nutrient diffusion from the microvasculature in the adjacent subchondral bone. Evidence suggests that a reduction in nutrient diffusion contributes to disc degeneration, but the role of the microvasculature is unclear. The purpose of this study was to induce changes in the endplate microvasculature in vivo via pharmaceutical intervention and then correlate microvasculature characteristics to diffusion and disc health. New Zealand white rabbits were administered either nimodipine (to enhance microvessel density) or nicotine (to diminish microvessel density) daily for 8 weeks compared to controls. Trans-endplate diffusion and disc health were quantified using post-contrast enhanced magnetic resonance imaging (MRI). Histology was utilized to assess changes to the subchondral vasculature. Results indicate that nimodipine increased vessel area and vessel-endplate contact length, causing a significant increase in disc diffusion. Surprisingly, nicotine caused increases in vessel number and area but did not alter diffusion into the disc. The drug treatments did affect the microvasculature and diffusion, but the relationship between the two is complex and dependent on multiple factors which include vessel-endplate distance, and vessel-endplate contact length in addition to vessel density. Our data suggest that drugs can modulate these factors to augment or diminish small molecule transport.

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.

Bacteriology of degenerated lumbar intervertebral disks

STUDY DESIGN

A prospective microbiological analysis of intervertebral disk material in surgically treated patients presenting lumbar disk degeneration.

OBJECTIVE

To determine the prevalence and species of bacteria in degenerated lumbar disks, their eventual role in the pathophysiology, and the possible influence of risk factors.

SUMMARY OF BACKGROUND DATA

Intervertebral disk degeneration results from biochemical, mechanical, genetic, and toxic factors. The hypothesis of low-grade infection has been raised but not elucidated to date.

METHODS

Eighty-three patients (34 males, 49 females, 41 y) were treated by lumbar disk replacement at L3-L4, L4-L5, or L5-S1. An intraoperative biopsy and microbiological culture were performed for each disk to determine if intradiskal bacteria were present. Magnetic resonance stages were Pfirrmann IV or V, with Modic I in 32, and Modic II in 25 cases. A preoperative discography was performed in 49 patients, 24 had previous nucleotomy.

RESULTS

Bacteria were found in 40 disks, 43 cultures were sterile. The following bacteria were evidenced: Propionibacterium acnes 18, coagulase-negative staphylococci 16, gram-negative bacilli 3, Micrococcus 3, Corynebacterium 3, others 5. Ten biopsies presented 2 different species. Multinucleated cells were evidenced histologically in 33% of positive biopsies. Bacteria were predominantly found in males (P=0.012). The mostly positive level was L4-L5 (P=0.075). There was no significant relationship between bacterial evidence and Modic sign. A preoperative discography or previous nucleotomy did not represent significant contamination sources. None of the patients presented infectious symptoms.

CONCLUSIONS

Although the hypothesis of biopsy contamination cannot be excluded, intradiskal bacteria might play a role in the pathophysiology of disk degeneration. However, the histologic presence of multinucleated cells may indicate an inflammatory process that could sustain the hypothesis of low-grade spondylodiscitis at 1 stage of the cascade of lumbar disk degeneration. These microbiological and histologic findings would need to be compared with nondegenerated disks.

LEVEL OF EVIDENCE

: Diagnostic level III.

Osteoporosis delays intervertebral disc degeneration by increasing intradiscal diffusive transport of nutrients through both mechanical and vascular pathophysiological pathways

Several studies have demonstrated an inverse correlation between osteoporosis and degenerative disc disease, so that patients with lower bone mass index, despite presenting greater risks of vertebral fractures, would paradoxically present delayed intervertebral disc degeneration. However the exact pathophysiological mechanisms underlying such phenomenon are not yet completely elucidated. In this article the author provides a general scheme to explain the causal relation between osteoporosis and delayed intervertebral disc degeneration by two main pathophysiological pathways: a vascular and a mechanical one. According to such model, osteoporosis positively affects disc nutrient diffusion through several mechanisms such as: increased endplate vascularization, decreased endplate resistance and decreased intradiscal strain. In the sequence a comprehensive review of the current literature on the issue is performed in order to provide a general overview about the current degree of evidence about the role of each factor postulated to be involved in such pathophysiological scheme. Finally the author provides overall directions for future research on the issue with special attention to the causal links which are supported by weak scientific evidence or by evidence from single studies.

Smoking Cessation Related to Improved Patient-Reported Pain Scores Following Spinal Care

BACKGROUND

Smoking is associated with low back pain, intervertebral disc disease, inferior patient outcomes following surgical interventions, and increased rates of postoperative complications. The purpose of the present study was to examine the effect of smoking and smoking cessation on pain and disability in patients with painful spinal disorders.

METHODS

We examined a prospectively maintained database of records for 5333 patients with axial or radicular pain from a spinal disorder with regard to smoking history and the patient assessment of pain on four visual analog scales during the course of care. Confounding factors, including secondary gain, sex, age, and body mass index, were also examined. The mean duration of follow-up was eight months. Multivariate statistical analysis was performed with variables including smoking status, secondary gain status, sex, depression, and age as predictors of pain and disability.

RESULTS

Compared with patients who had never smoked, patients who were current smokers reported significantly greater pain in all visual analog scale pain ratings (p < 0.001). The mean improvement in reported pain over the course of care was significantly different between nonsmokers and current smokers (p <0.001). Compared with patients who had continued to smoke, those who had quit smoking during the course of care reported significantly greater improvement in pain in visual analog scale pain ratings for worst (p = 0.013), current (p < 0.05), and average weekly pain (p = 0.024). The mean improvement in the visual analog scale pain ratings was clinically important in patients in all three groups of nonsmokers. As a group, those who had continued smoking during treatment had no clinically important improvement in reported pain.

CONCLUSIONS

Given a strong association between improved patient-reported pain and smoking cessation, this study supports the need for smoking cessation programs for patients with a painful spinal disorder.

Lumbar degenerative disc disease: current and future concepts of diagnosis and management

Low back pain as a result of degenerative disc disease imparts a large socioeconomic impact on the health care system. Traditional concepts for treatment of lumbar disc degeneration have aimed at symptomatic relief by limiting motion in the lumbar spine, but novel treatment strategies involving stem cells, growth factors, and gene therapy have the theoretical potential to prevent, slow, or even reverse disc degeneration. Understanding the pathophysiological basis of disc degeneration is essential for the development of treatment strategies that target the underlying mechanisms of disc degeneration rather than the downstream symptom of pain. Such strategies ideally aim to induce disc regeneration or to replace the degenerated disc. However, at present, treatment options for degenerative disc disease remain suboptimal, and development and outcomes of novel treatment options currently have to be considered unpredictable.

Pain, nicotine, and smoking: research findings and mechanistic considerations

Tobacco addiction and chronic pain represent 2 highly prevalent and comorbid conditions that engender substantial burdens upon individuals and systems. Interrelations between pain and smoking have been of clinical and empirical interest for decades, and research in this area has increased dramatically over the past 5 years. We conceptualize the interaction of pain and smoking as a prototypical example of the biopsychosocial model. Accordingly, we extrapolated from behavioral, cognitive, affective, biomedical, and social perspectives to propose causal mechanisms that may contribute to the observed comorbidity between these 2 conditions. The extant literature was 1st dichotomized into investigations of either effects of smoking on pain or effects of pain on smoking. We then integrated these findings to present a reciprocal model of pain and smoking that is hypothesized to interact in the manner of a positive feedback loop, resulting in greater pain and increased smoking. Finally, we proposed directions for future research and discussed clinical implications for smokers with comorbid pain disorders. We observed modest evidence that smoking may be a risk factor in the multifactorial etiology of some chronically painful conditions and that pain may come to serve as a potent motivator of smoking. We also found that whereas animal studies yielded consistent support for direct pain-inhibitory effects of nicotine and tobacco, results from human studies were much less consistent. Future research in the emerging area of pain and smoking has the potential to inform theoretical and clinical applications with respect to tobacco smoking, chronic pain, and their comorbid presentation. (PsycINFO Database Record (c) 2011 APA, all rights reserved).

Intervertebral disk nutrition: a review of factors influencing concentrations of nutrients and metabolites

The biomechanical behavior of the intervertebral disk ultimately depends on the viability and activity of a small population of resident cells that make and maintain the disk's extracellular matrix. Nutrients that support these cells are supplied by the blood vessels at the disks' margins and diffuse through the matrix of the avascular disk to the cells. This article reviews pathways of nutrient supply to these cells; examines factors that may interrupt these pathways, and discusses consequences for disk cell survival, disk degeneration, and disk repair.

Risk factors for illness absence due to musculoskeletal disorders in a 4-year prospective study of a petroleum-manufacturing population

OBJECTIVES

To quantify risk factors for nonoccupational absence from musculoskeletal disorders (MSD) among petroleum-manufacturing employees.

METHODS

We conducted a 4-year follow-up study including 860 employees with an MSD illness absence of 4 days or longer and 5691 employees with no MSD absence. Odds ratios were calculated using logistic regression.

RESULTS

Risk of MSD absence from low back and non-low back disorders was significantly associated with physically demanding job, overweight/obesity, prior absence from MSD, and absence from cardiovascular, respiratory, or mental illness, or accidents during the study period. Smoking also increased risk of low back disorders.

CONCLUSIONS

Results suggest it is possible to reduce the impact of MSD through integrated safety prevention and health promotion programs including traditional elements of job factor evaluation, training, and ergonomics, but also health counseling and support for weight reduction, smoking cessation, and personal fitness programs.