The pathophysiology of disc degeneration: a critical review

Growth factors and platelet-rich plasma: promising biological strategies for early intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a complex process with the mechanism not fully elucidated. The current clinical treatments for IDD are mainly focused on providing symptomatic relief without addressing the underlying cause of the IDD. Biological therapeutic strategies to repair and regenerate the degenerated discs are drawing more attention. Growth factor therapy is one of the biological strategies and holds promising prospects. As a promising bioactive substance, platelet-rich plasma (PRP) is considered to be an ideal growth factor "cocktail" for intervertebral disc (IVD) restoration. Results from many in vitro and in vivo studies have confirmed the efficacy of growth factors and PRP in IVD repair and regeneration. It is essential to advance the research on growth factor therapy and associated mechanism for IDD. This article reviews the background of IDD, current concepts in growth factor and PRP-related therapy for IDD. Future research perspectives and clinical directions are also discussed.

The correlation between ossification of the nuchal ligament and pathological changes of the cervical spine in patients with cervical spondylosis

STUDY DESIGN

A retrospective clinical data analysis.

OBJECTIVE

This study was conducted to investigate the correlation between ossification of the nuchal ligament (ONL) and pathological changes of the cervical spine in patients with cervical spondylosis.

SUMMARY OF BACKGROUND DATA

ONL can usually be found in cervical spondylosis. Thus, it is important to find the correlation between ONL and pathological changes of the cervical spine in patients with cervical spondylosis.

METHODS

The medical records of 100 patients with cervical spondylosis with the local type of ONL (ONL group) and 50 patients with cervical spondylosis only (control group) were reviewed. Data analysis included patients' sex, age, location of ONL, maximum cord compression level, osteophyte height ratio, and grade of cervical intervertebral disc degeneration. Radiological features were evaluated by lateral plain radiography and magnetic resonance imaging.

RESULTS

In total, 69.0% of subjects in the ONL group had ONL located at the maximum cord compression level; there was no difference based on sex (P = 0.248). The value of the osteophyte height ratio was higher at the ONL level than at its superior and inferior adjacent segments (P < 0.001). The osteophyte height ratio was also significantly different at the C4-C5 (P < 0.001) and C5-C6 (P = 0.008) levels between the ONL group and the control group. There was a significant difference in distribution of intervertebral disc degeneration grading between the ONL level and superior adjacent segments (P = 0.028), as well as inferior adjacent segments (P = 0.049). The distribution of intervertebral disc degeneration grading at the C5-C6 level between patients whose location of ONL and maximum cord compression level were both at C5-C6 and patients whose maximum cord compression level was at C5-C6 in the control group was also significantly different (P = 0.035).

CONCLUSION

The location of ONL commonly corresponds to the most stenotic level of the spinal canal. The location of ONL also correlates with the level of osteophyte formation and intervertebral disc degeneration, indicating that ONL has correspondence to instability-related cervical pathological changes in cervical spondylosis.

Gene expression profile analysis of human mesenchymal stem cells from herniated and degenerated intervertebral discs reveals different expression of osteopontin

Gene expression analysis provides an effective methodology to identify clinically relevant genes implicated in intervertebral disc (IVD) pathology. The analysis of gene profile in mesenchymal stem cells (MSCs) from human herniated IVD (H-IVD) and degenerated IVD (D-IVD) has not yet been investigated. We present in this study a characterization of MSCs isolated from clinically categorized H-IVD and D-IVD disc samples. H-IVD-MSCs and D-IVD-MSCs showed multipotent mesenchymal differentiation ability, expressing positivity for adipogenic, osteogenic, and chondrogenic markers with an immunophenotypical profile representative of MSCs. FACS analyses revealed a higher expression of CD44 in D-IVD-MSCs compared to H-IVD-MSCs. Gene expression profile revealed that most genes under investigation displayed large variations and were not significantly different in the two types of analyzed IVD-MSCs. Conversely, the gene expression of osteopontin (OPN), a protein involved in bone matrix mineralization and extracellular matrix destruction, was found markedly increased (more than 400-fold) in D-IVD-MSCs compared to H-IVD-MSCs. Moreover, the OPN protein expression was detectable only in D-IVD-MSCs, and its levels were directly related with D-IVD severity. These findings suggest that an abnormal expression of OPN in D-IVD-MSCs occurs and plays a pivotal role in the pathophysiological process of human disc degeneration. We speculate that the regulation of the OPN pathway might be a therapeutic target to counteract disc degeneration.

Cell and molecular biology of intervertebral disc degeneration: current understanding and implications for potential therapeutic strategies

Intervertebral disc degeneration (IDD) is a chronic, complex process associated with low back pain; mechanisms of its occurrence have not yet been fully elucidated. Its process is not only accompanied by morphological changes, but also by systematic changes in its histological and biochemical properties. Many cellular and molecular mechanisms have been reported to be related with IDD and to reverse degenerative trends, abnormal conditions of the living cells and altered cell phenotypes would need to be restored. Promising biological therapeutic strategies still rely on injection of active substances, gene therapy and cell transplantation. With advanced study of tissue engineering protocols based on cell therapy, combined use of seeding cells, bio-active substances and bio-compatible materials, are promising for IDD regeneration. Recently reported progenitor cells within discs themselves also hold prospects for future IDD studies. This article describes the background of IDD, current understanding and implications of potential therapeutic strategies.

Biologic treatment of mild and moderate intervertebral disc degeneration

Disc degeneration is the most common cause of back pain in adults and has enormous socioeconomic implications. Conservative management is ineffective in most cases, and results of surgical treatment have not yet reached desirable standards. Biologic treatment options are an alternative to the above conventional management and have become very attractive in recent years. The present review highlights the currently available biologic treatment options in mild and moderate disc degeneration, where a potential for regeneration still exists. Biologic treatment options include protein-based and cell-based therapies. Protein-based therapies involve administration of biologic factors into the intervertebral disc to enhance matrix synthesis, delay degeneration or impede inflammation. These factors can be delivered by an intradiscal injection, alone or in combination with cells or tissue scaffolds and by gene therapy. Cell-based therapies comprise treatment strategies that aim to either replace necrotic or apoptotic cells, or minimize cell death. Cell-based therapies are more appropriate in moderate stages of degenerated disc disease, when cell population is diminished; therefore, the effect of administration of growth factors would be insufficient. Although clinical application of biologic treatments is far from being an everyday practice, the existing studies demonstrate promising results that will allow the future design of more sophisticated methods of biologic intervention to treat intervertebral disc degeneration.

Modulating notochordal differentiation of human induced pluripotent stem cells using natural nucleus pulposus tissue matrix

Human induced pluripotent stem cells (hiPSCs) can differentiate into notochordal cell (NC)-like cells when cultured in the presence of natural porcine nucleus pulposus (NP) tissue matrix. The method promises massive production of high-quality, functional cells to treat degenerative intervertebral discs (IVDs). Based on our previous work, we further examined the effect of cell-NP matrix contact and culture medium on the differentiation, and further assessed the functional differentiation ability of the generated NC-like. The study showed that direct contact between hiPSCs and NP matrix can promote the differentiation yield, whilst both the contact and non-contact cultures can generate functional NC-like cells. The generated NC-like cells are highly homogenous regarding the expression of notochordal marker genes. A culture medium containing a cocktail of growth factors (FGF, EGF, VEGF and IGF-1) also supported the notochordal differentiation in the presence of NP matrix. The NC-like cells showed excellent functional differentiation ability to generate NP-like tissue which was rich in aggrecan and collagen type II; and particularly, the proteoglycan to collagen content ratio was as high as 12.5–17.5 which represents a phenotype close to NP rather than hyaline cartilage. Collectively, the present study confirmed the effectiveness and flexibility of using natural NP tissue matrix to direct notochordal differentiation of hiPSCs, and the potential of using the generated NC-like cells for treating IVD degeneration.

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.

Disc degeneration reduces the delamination strength of the annulus fibrosus in the rabbit annular disc puncture model

BACKGROUND CONTEXT

Degenerative disc disease is a common pathologic disorder accompanied by both structural and biochemical changes. Changes in stress distribution across the disc can lead to annulus fibrosus (AF) damage that can affect the strength and integrity of the disc. Given that some present degeneration therapies incorporate biological regrowth of the nucleus pulposus (NP), it is crucial that the AF remains capable of containing this newly grown material.

PURPOSE

To examine the resistance of AF to delamination using an adhesive peel test in experimentally degenerated rabbit discs.

STUDY DESIGN

Experimentally induced disc degeneration; excised AF tissue study.

METHODS

Disc degeneration was induced in eight New Zealand white rabbits by annular puncture; four additional rabbits served as controls. In experimental rabbits, an 18-gauge needle was inserted into the anterolateral AF region of levels L2-L3 and L4-L5, and disc height was monitored by X-ray. Animals were sacrificed at 4 and 12 weeks postsurgery and magnetic resonance images and X-rays were taken. Four discs were excised from the experimental animals; two punctured (L2-L3 and L4-L5) and two controls (L3-L4 and L6-L7). The same four discs were also excised from the age-matched control animals and served as nonpunctured control discs. To determine resistance to delamination, AF samples were dissected from each disc and subjected to a mechanical peel test at 0.5 mm/s.

RESULTS

Magnetic resonance imaging and X-ray images confirmed dehydration of the NP and reduced disc height, similar to that found in clinical degeneration. Resistance to delamination was significantly lower in punctured/degenerated discs compared with both the nonpunctured discs from the same animal (27% lower) and the nonpunctured control discs (30% lower) (p=.024).

CONCLUSIONS

The findings of this study suggest that degeneration increases the potential for delamination between AF layers. Given this substantial change to the integrity of the AF after degeneration, clinical treatments should not only target rehydration or regrowth of the NP, but should also target repair and strengthening of the AF to confine the NP.

Native nucleus pulposus tissue matrix promotes notochordal differentiation of human induced pluripotent stem cells with potential for treating intervertebral disc degeneration

Native porcine nucleus pulposus (NP) tissue harbors a number of notochordal cells (NCs). Whether the native NP matrix supports the homeostasis of notochordal cells is poorly understood. We hypothesized the NP matrix alone may contain sufficient regulatory factors and can serve as stimuli to generate notochordal cells (NCs) from human pluripotent stem cells. NCs are a promising cell sources for cell-based therapy to treat some types of intervertebral disc (IVD) degeneration. One major limitation of this emerging technique is the lack of available NCs as a potential therapeutic cell source. Human pluripotent stem cells derived from reprogramming or somatic cell nuclear transfer technique may yield stable and unlimited source for therapeutic use. We devised a new method to use porcine NP matrix to direct notochordal differentiation of human induced pluripotent stem cells (hiPSCs). The results showed that hiPSCs successfully differentiated into NC-like cells under the influence of devitalized porcine NP matrix. The NC-like cells expressed typical notochordal marker genes including brachyury (T), cytokeratin-8 (CK-8) and cytokeratin-18 (CK-18), and they displayed the ability to generate NP-like tissue in vitro, which was rich in aggrecan and collagen type II. These findings demonstrated the proof of concept for using native NP matrix to direct notochordal differentiation of hiPSCs. It provides a foundation for further understanding the biology of NCs, and eventually towards regenerative therapies for disc degeneration.

Matrix metalloproteinase-3, vitamin D receptor gene polymorphisms, and occupational risk factors in lumbar disc degeneration

BACKGROUND

Lumbar disc degeneration (LDD) is a process that begins early in life, contributing to the development of low back pain. LDD is a consequence of a variety of factors, and its etiology remains poorly understood. Objectives to investigate occupational and genetic risk factors inducing lumbar disc degeneration, and to evaluate the possible association of genetic polymorphisms of matrix metalloproteinase 3 (MMP-3) and vitamin D receptor (VDR) with the severity of LDD in an Egyptian population.

SUBJECTS AND METHODS

A case control study involving 84 LDD and 60 controls was carried out. Five types of work related factors were investigated by questionnaire, complete neurological examination for all subjects and MRI for the cases. Polymerase chain reaction and restriction fragment length polymorphism methods were applied to detect polymorphisms in MMP-3 Promoter (-1,171 6A/5A) (rs 731236) and VDR-Apa (rs 35068180).

RESULTS

We found that family history, back injury, smoking, high level of sitting, bending/twisting, physical workload, lifting, whole body vibration, mutant allele 5A of MMP-3 and mutant allele T of VDR were significantly associated with LDD (OR = 2.9, 3.1, 2.1, 11.1, 15.9, 11.7, 8.2, 12.6, 2.5 and 3.1 respectively, p < 0.05). Cases that carry allele 5A and/or allele T were associated with LDD severity.

CONCLUSION

LDD is closely associated in occurrence and severity with occupational, environmental risk factors and susceptibility genes namely MMP-3, and VDR (ApaI). This study throws light on the importance of screening for early detection of susceptible individuals and disease prevention.

Annulus fibrosus cell characteristics are a potential source of intervertebral disc pathogenesis

In the end stage of intervertebral disc degeneration, cartilage, bone, endothelial cells, and neurons appear in association with the worsening condition. The origin of the abnormal cells is not clear. This study investigated the properties of progenitor cells in the annulus fibrosus (AF) using one in vitro and two in vivo models. Cultivation of rabbit AF cells with chondrogenic media significantly increased expressions of collagen and aggrecan. Upon exposure to osteogenic conditions, the cultures showed increased mineralization and expression of osteopontin, runx2, and bmp2 genes. Two models were used in the in vivo subcutaneous implantation experiments: 1) rabbit AF tissue in a demineralized bone matrix (DBM) cylinder (DBM/AF), and, 2) rat intact and needle punctured lumbar discs. Bone formation in the AF tissue was detected and hypertrophic chondrocytes and osteoblasts were present 1 month after implantation of the DBM/AF to nude mice. In addition to collagen I and II, immunostaining shows collagen X and osteocalcin expression in DBM/AF specimens 4 months after implantation. Similar changes were detected in the injured discs. Almost the entire needle punctured disc had ossified at 6 months. The results suggest that AF cells have characteristics of progenitor cells and, under appropriate stimuli, are capable of differentiating into chondrocytes and osteoblasts in vitro as well as in vivo. Importantly, these cells may be a target for biological treatment of disc degeneration.

Tissue-engineered intervertebral discs: MRI results and histology in the rodent spine

Object

Tissue-engineered intervertebral discs (TE-IVDs) represent a new experimental approach for the treatment of degenerative disc disease. Compared with mechanical implants, TE-IVDs may better mimic the properties of native discs. The authors conducted a study to evaluate the outcome of TE-IVDs implanted into the rat-tail spine using radiological parameters and histology.

Methods

Tissue-engineered intervertebral discs consist of a distinct nucleus pulposus (NP) and anulus fibrosus (AF) that are engineered in vitro from sheep IVD chondrocytes. In 10 athymic rats a discectomy in the caudal spine was performed. The discs were replaced with TE-IVDs. Animals were kept alive for 8 months and were killed for histological evaluation. At 1, 5, and 8 months, MR images were obtained; T1-weighted sequences were used for disc height measurements, and T2-weighted sequences were used for morphological analysis. Quantitative T2 relaxation time analysis was used to assess the water content and T1ρ-relaxation time to assess the proteoglycan content of TE-IVDs.

Results

Disc height of the transplanted segments remained constant between 68% and 74% of healthy discs. Examination of TE-IVDs on MR images revealed morphology similar to that of native discs. T2-relaxation time did not differ between implanted and healthy discs, indicating similar water content of the NP tissue. The size of the NP decreased in TE-IVDs. Proteoglycan content in the NP was lower than it was in control discs. Ossification of the implanted segment was not observed. Histological examination revealed an AF consisting of an organized parallel-aligned fiber structure. The NP matrix appeared amorphous and contained cells that resembled chondrocytes.

Conclusions

The TE-IVDs remained viable over 8 months in vivo and maintained a structure similar to that of native discs. Tissue-engineered intervertebral discs should be explored further as an option for the potential treatment of degenerative disc disease.

A review of the value of MRI signs in low back pain

Low back pain is a common symptom that can lead to disability and major socio-professional repercussions. Despite advances in imaging, the etiology of the pain often remains unknown. Morphological changes related to normal ageing of the disc appear on MR imaging without any symptoms. The potential impact of changes seen on imaging, especially MRI, also warrants discussion. The purpose of this work is to review the state-of-the-art of this subject, underlining relevant key features for routine radiological practice. We will first discuss anterior and posterior segments of the spine with a focus on anatomical, physiopathological and semiological findings. Secondly we will discuss the diagnostic value of each sign.

Pelvic incidence-lumbar lordosis mismatch results in increased segmental joint loads in the unfused and fused lumbar spine

PURPOSE

Symptomatic adjacent segment disease (ASD) has been reported to occur in up to 27 % of lumbar fusion patients. A previous study identified patients at risk according to the difference of pelvic incidence and lordosis. Patients with a difference between pelvic incidence and lumbar lordosis >15° have been found to have a 20 times higher risk for ASD. Therefore, it was the aim of the present study to investigate forces acting on the adjacent segment in relation to pelvic incidence-lumbar lordosis (PILL) mismatch as a measure of spino-pelvic alignment using rigid body modeling to decipher the underlying forces as potential contributors to degeneration of the adjacent segment.

METHODS

Sagittal configurations of 81 subjects were reconstructed in a musculoskeletal simulation environment. Lumbar spine height was normalized, and body and segmental mass properties were kept constant throughout the population to isolate the effect of sagittal alignment. A uniform forward/backward flexion movement (0°-30°-0°) was simulated for all subjects. Intervertebral joint loads at lumbar level L3-L4 and L4-L5 were determined before and after simulated fusion.

RESULTS

In the unfused state, an approximately linear relationship between sagittal alignment and intervertebral loads could be established (shear: 0° flexion r = 0.36, p < 0.001, 30° flexion r = 0.48, p < 0.001; compression: 0° flexion r = 0.29, p < 0.01, 30° flexion r = 0.40, p < 0.001). Additionally, shear changes during the transition from upright to 30° flexed posture were on average 32 % higher at level L3-L4 and 14 % higher at level L4-L5 in alignments that were clinically observed to be prone to ASD. Simulated fusion affected shear forces at the level L3-L4 by 15 % (L4-L5 fusion) and 23 % (L4-S1 fusion) more for alignments at risk for ASD.

CONCLUSION

Higher adjacent segment shear forces in alignments at risk for ASD already prior to fusion provide a mechanistic explanation for the clinically observed correlation between PILL mismatch and rate of adjacent segment degeneration.

Assessment of intervertebral disc degeneration based on quantitative magnetic resonance imaging analysis: an in vivo study

STUDY DESIGN

Animal experimental study.

OBJECTIVE

To evaluate a novel quantitative imaging technique for assessing disc degeneration.

SUMMARY OF BACKGROUND DATA

T2-relaxation time (T2-RT) measurements have been used to assess disc degeneration quanti-tatively. T2 values correlate with the water content of intervertebral disc tissue and thereby allow for the indirect measurement of nucleus pulposus (NP) hydration.

METHODS

We developed an algorithm to subtract out magnetic resonance imaging (MRI) voxels not representing NP tissue on the basis of T2-RT values. Filtered NP voxels were used to measure nuclear size by their amount and nuclear hydration by their mean T2-RT. This technique was applied to 24 rat-tail intervertebral discs (IVDs), which had been punctured with an 18-gauge needle according to different techniques to induce varying degrees of degeneration. NP voxel count and average T2-RT were used as parameters to assess the degeneration process at 1 and 3 months postpuncture. NP voxel counts were evaluated against radiograph disc height measurements and qualitative MRI studies on the basis of the Pfirrmann grading system. Tails were collected for histology to correlate NP voxel counts to histological disc degeneration grades and to NP cross-sectional area measurements.

RESULTS

NP voxel count measurements showed strong correlations to qualitative MRI analyses (R = 0.79, P < 0.0001), histological degeneration grades (R = 0.902, P < 0.0001), and histological NP cross-sectional area measurements (R = 0.887, P < 0.0001).In contrast to NP voxel counts, the mean T2-RT for each punctured group remained constant between months 1 and 3. The mean T2-RTs for the punctured groups did not show a statistically significant difference from those of healthy IVDs (63.55 ms ± 5.88 ms mo 1 and 62.61 ms ± 5.02 ms) at either time point.

CONCLUSION

The NP voxel count proved to be a valid parameter to assess disc degeneration quantitatively in a needle puncture model. The mean NP T2-RT does not change significantly in needle-puncture-induced degenerated IVDs. IVDs can be segmented into different tissue components according to their innate T2-RT.

Interaction of micron and nano-sized particles with cells of the dura mater

Intervertebral total disc replacements (TDR) are used in the treatment of degenerative spinal disc disease. There are, however, concerns that they may be subject to long-term failure due to wear. The adverse effects of TDR wear have the potential to manifest in the dura mater and surrounding tissues. The aim of this study was to investigate the physiological structure of the dura mater, isolate the resident dural epithelial and stromal cells and analyse the capacity of these cells to internalise model polymer particles. The porcine dura mater was a collagen-rich structure encompassing regularly arranged fibroblastic cells within an outermost epithelial cell layer. The isolated dural epithelial cells had endothelial cell characteristics (positive for von Willebrand factor, CD31, E-cadherin and desmoplakin) and barrier functionality whereas the fibroblastic cells were positive for collagen I and III, tenascin and actin. The capacity of the dural cells to take up model particles was dependent on particle size. Nanometer sized particles readily penetrated both types of cells. However, dural fibroblasts engulfed micron-sized particles at a much higher rate than dural epithelial cells. The study suggested that dural epithelial cells may offer some barrier to the penetration of micron-sized particles but not nanometer sized particles.

Three-dimensional motion analysis of the cervical spine for comparison of anterior cervical decompression and fusion versus artificial disc replacement in 17 patients

Object

Cervical arthroplasty with an artificial disc (AD) has emerged as an alternative to anterior cervical discectomy and fusion (ACDF) for the management of cervical spondylosis. This study aims to provide 3D motion analysis data comparing patients after ACDF and AD replacement.

Methods

Ten patients who underwent C5–6 ACDF and 7 who underwent C5–6 AD replacement were enrolled. Using biplanar fluoroscopy and a model-based track technique (accurate up to 0.6 mm and 0.6°), motion analysis of axial rotation and flexion-extension of the neck was performed. Three nonoperative segments (C3–4, C4–5, and C6–7) were assessed for both intervertebral rotation (coronal, sagittal, and axial planes) and facet shear (anteroposterior and mediolateral).

Results

There was no difference in total neck motion comparing ACDF and AD replacement for neck extension (43.3° ± 10.2° vs 44.3° ± 12.6°, p = 0.866) and rotation (36.0° ± 6.5° vs 38.2° ± 9.3°, p = 0.576). For extension, when measured as a percentage of total neck motion, there was a greater amount of rotation at the nonoperated segments in the ACDF group than in the AD group (p = 0.003). When comparing specific motion segments, greater normalized rotation was seen in the ACDF group at C3–4 (33.2% ± 4.9% vs 26.8% ± 6.6%, p = 0.036) and C6–7 (28.5% ± 6.7% vs 20.5% ± 5.5%, p = 0.009) but not at C4–5 (33.5% ± 6.4% vs 31.8% ± 4.0%, p = 0.562). For neck rotation, greater rotation was observed at the nonoperative segments in the ACDF group than in the AD group (p = 0.024), but the differences between individual segments did not reach significance (p ≥ 0.146). Increased mediolateral facet shear was seen on neck extension with ACDF versus AD replacement (p = 0.008). Comparing each segment, C3–4 (0.9 ± 0.5 mm vs 0.4 ± 0.1 mm, p = 0.039) and C4–5 (1.0 ± 0.4 mm vs 0.5 ± 0.2 mm, p = 0.022) showed increased shear while C6–7 (1.0 ± 0.4 mm vs 1.0 ± 0.5 mm, p = 0.767) did not.

Conclusions

This study illustrates increased motion at nonoperative segments in patients who have undergone ACDF compared with those who have undergone AD replacement. Further studies will be required to examine whether these changes contribute to adjacent-segment disease.

Energy metabolism of intervertebral disc under mechanical loading

Intervertebral disc (IVD) degeneration is closely associated with low back pain (LBP), which is a major health concern in the U.S. Cellular biosynthesis of extracellular matrix (ECM), which is important for maintaining tissue integrity and preventing tissue degeneration, is an energy demanding process. Due to impaired nutrient support in avascular IVD, adenosine triphosphate (ATP) supply could be a limiting factor for maintaining normal ECM synthesis. Therefore, the objective of this study was to investigate the energy metabolism in the annulus fibrosus (AF) and nucleus pulposus (NP) of porcine IVD under static and dynamic compressions. Under compression, pH decreased and the contents of lactate and ATP increased significantly in both AF and NP regions, suggesting that compression can promote ATP production via glycolysis and reduce pH by increasing lactate accumulation. A high level of extracellular ATP content was detected in the NP region and regulated by compressive loading. Since ATP can serve not only as an intra-cellular energy currency, but also as a regulator of a variety of cellular activities extracellularly through the purinergic signaling pathway, our findings suggest that compression-mediated ATP metabolism could be a novel mechanobiological pathway for regulating IVD metabolism.

Characterization of microRNA expression profiles in patients with intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is associated with lower back pain and is a global burden with severe healthcare and socioeconomic consequences. However, the underlying mechanisms of IDD remain largely unelucidated. Accumulating evidence has indicasted that newly defined gene regulators, microRNAs (miRNAs), play a vital role in neurodegenerative, pathophysiological and certain reproductive disorders. To characterize the differential miRNA expression profiles between IDD and spinal cord injury, specimens from 3 patients with IDD and 3 with spinal cord injury were selected for microarray analysis. Total RNA from these 6 specimens was extracted and subjected to global miRNA expression analysis using the Exiqon miRCURY™ LNA Array (v.16.0). The microarray data were then validated by quantitative reverse transcription polymerase chain reaction (qRT-PCR). In addition, bioinformatics analysis was performed to investigate the dysregulated miRNA target genes and signaling pathways involved. Among the miRNAs analyzed, 25 miRNAs were found to be upregulated and 26 were found to be downregulated in the IDD group compared with the spinal cord injury group. The qRT-PCR results validated the microarray data. Bioinformatics analysis indicated that the signaling pathways most likely to be controlled by these miRNAs were the phosphoinositide 3-kinase (PI3K)-Akt, mitogen-activated protein kinase (MAPK), epidermal growth factor receptor (EGFR; ErbB) and Wnt pathways. Our results demonstrated that the miRNA expression in patients with IDD differed significantly from that in patients who sustained injury to the intervertebral disc. Our data indicate that the dysregulated miRNAs control the signaling pathways important for the maintenance of IDD. Further studies on miRNA target gene identification and biological functions may address the specific regulatory mechanisms of miRNAs in IDD, and may provide valuable insight into the diagnosis and treatment of IDD.

Continuous cyclic mechanical tension increases ank expression in endplate chondrocytes through the TGF-β1 and p38 pathway

The normal ANK protein has a strong influence on anti-calcification. It is known that TGF-β1 is also able to induce extracellular inorganic pyrophosphate (ePPi) elaboration via the TGF-β1-induced ank gene expression and the mitogen-activated protein kinase (MAPK) signaling acts as a downstream effector of TGF-β1. We hypothesized that the expression of the ank gene is regulated by mechanics through TGF-β1-p38 pathway. In this study, we investigated the mechanism of short-time mechanical tension-induced ank gene expression. We found that the continuous cyclic mechanical tension (CCMT) increased the ank gene expression in the endplate chondrocytes, and there was an increase in the TGF-β1 expression after CCMT stimulation. The ank gene expression significantly increased when treated by TGF-β1 in a dose-dependent manner and decreased when treated by SB431542 (ALK inhibitor) in a dose-dependent manner. Our study results indicate that CCMT-induced ank gene expressions may be regulated by TGF-β1 and p38 MAPK pathway.

Genes associated with disc degeneration identified using microarray gene expression profiling and bioinformatics analysis

Disc degeneration is strongly associated with back or neck pain, sciatica, and disc herniation or prolapse. It places an enormous economic burden on society and can greatly affect quality of life. Alternative treatment approaches, such as genetic therapies, are urgently needed to slow or reverse the disc degeneration process. We downloaded gene expression data from Gene Expression Omnibus during various stages of disc degeneration and identified differentially expressed genes (DEGs) as well as dysfunctional pathways through comparisons with controls. We identified 2 significant DEGs between grade II and III discs and 8 significant DEGs between grade II and IV discs. By constructing an interactive network of the DEGs, we found that mitogen-activated protein family genes and Ras homologous (Rho) family genes - in particular, MAP2K6 and RHOBTB2 - may play important roles in the progression of degeneration of grade III and IV discs, respectively. MAP2K6 and RHOBTB2 may be specific therapeutic molecular targets in the treatment of disc degeneration. However, further experiments are needed to confirm this result.

Pathophysiology, diagnosis, and treatment of discogenic low back pain

Discogenic low back pain is a serious medical and social problem, and accounts for 26%-42% of the patients with chronic low back pain. Recent studies found that the pathologic features of discs obtained from the patients with discogenic low back pain were the formation of the zones of vascularized granulation tissue, with extensive innervation in fissures extending from the outer part of the annulus into the nucleus pulposus. Studies suggested that the degeneration of the painful disc might originate from the injury and subsequent repair of annulus fibrosus. Growth factors such as basic fibroblast growth factor, transforming growth factor β1, and connective tissue growth factor, macrophages and mast cells might play a key role in the repair of the injured annulus fibrosus and subsequent disc degeneration. Although there exist controversies about the role of discography as a diagnostic test, provocation discography still is the only available means by which to identify a painful disc. A recent study has classified discogenic low back pain into two types that were annular disruption-induced low back pain and internal endplate disruption-induced low back pain, which have been fully supported by clinical and theoretical bases. Current treatment options for discogenic back pain range from medicinal anti-inflammation strategy to invasive procedures including spine fusion and recently spinal arthroplasty. However, these treatments are limited to relieving symptoms, with no attempt to restore the disc's structure. Recently, there has been a growing interest in developing strategies that aim to repair or regenerate the degenerated disc biologically.

Characterization of miRNA expression in human degenerative lumbar disks

BACKGROUND DATA

microRNAs (miRNAs) are short ∼22 nucleotide RNA sequences that regulate messengerRNA translation. miRNAs have shown to play a role in synthesis of inflammatory mediators. Since inflammation play a role in intervertebral disk (IVD) degeneration, the objective was to isolate miRNA from human lumbar intervertebral disks and subsequently characterize the difference in miRNA expression between the annulus fibrosus (AF) and nucleus pulposus (NP).

METHODS

Fourteen patients undergoing anterior interbody fusion for degenerative disk disease of the lumbar spine were included. During surgery biopsies from the intervertebral disks were obtained and immediately placed in RNAlater. The RNAlater was decanted and the samples frozen at -80˚C until RNA extraction. This was performed using the Trizol method. Global miRNA expression analysis was performed using the Affymetrix GeneChip® miRNA array.

RESULTS

We developed a method allowing the extraction of miRNA from human intervertebral disks usually yielding 1-4 µg of total RNA pr. 100 mg of disk. Twenty-seven miRNAs had a higher expression in the AF and 10 had the highest expression in the NP. Among the top 15 signaling pathways most likely to be controlled by these miRNAs were the transforming growth factor β (TGFβ), platelet-derived growth factor (PDGF), insulin-like growth factor (IGF) epidermal growth factor (EGF), and actin cytoskeletal pathway.

CONCLUSION

We have demonstrated the presence of miRNA in the human IVD. The miRNA expression differs from muscle tissue and there are differences between the miRNA expressed in the NP and AF. The miRNAs identified control signaling pathways important for maintenance of the IVD. Future studies may determine the importance of miRNA in the development of IVD disease.

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.

Does a fibronectin and aggrecan complex play a role in painful vertebral disks?

OBJECTIVE

To determine the presence of a fibronectin-aggrecan complex (FAC) in the disk space of persons with chronic low back pain as relates to provocative diskography.

DESIGN

A single-center prospective consecutive case series.

SETTING

A single private practice setting.

PATIENTS

Thirty-seven patients with symptomatic degenerative disk disease of the cervical, thoracic, or lumbar spine undergoing provocative diskography to identify a source of pain.

METHODS

Diskographic lavage for analysis was simultaneously performed at each disk level injected during diskography.

MAIN OUTCOME MEASURES

Visual analog scale (VAS) pain scores, Pfirrmann magnetic resonance imaging grade, and biochemical analysis of disk material were statistically analyzed.

RESULTS

A total of 105 levels in 37 patients had a complete set of data (mean age 43.2 ± 11.9 years; 15 male/22 female). The FAC was present in 43 of 108 levels and in at least one level in 25 of 37 patients. The Pfirrmann magnetic resonance imaging grade did not differ between complex-positive and negative levels (P = .125), nor did the intraoperative VAS (IO-VAS) score for pain by level (P = .206). A significant but loose correlation was found between Pfirrmann grade and IO-VAS (R(2) = 0.4, P < .001), but no significant correlation was found between VAS or IO-VAS and complex concentration (R(2) = 0.08, P = .11 and R(2) = 0.003, P = .5).

CONCLUSIONS

The FAC was identified in some painful disks by diskography. There was no significant correlation between the Pfirrmann grade or pre/intraoperative pain scores during diskography and complex concentrations within the disk measured by disk lavage.

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.

Histomorphometric and radiographical changes after lumbar implantation of the PEEK nonfusion interspinous device in the BB.4S rat model

STUDY DESIGN

An experimental animal study.

OBJECTIVE

To investigate histomorphometric and radiographical changes in the BB.4S rat model after PEEK (polyetheretherketone) nonfusion interspinous device implantation.

SUMMARY OF BACKGROUND DATA

Clinical effectiveness of the PEEK nonfusion spine implant Wallis (Abbott, Bordeaux, France; now Zimmer, Warsaw, IN) is well documented. However, there is a lack of evidence on the long-term effects of this implant on bone, in particular its influence on structural changes of bone elements of the lumbar spine.

METHODS

Twenty-four male BB.4S rats aged 11 weeks underwent surgery for implantation of a PEEK nonfusion interspinous device or for a sham procedure in 3 groups of 8 animals each: (1) implantation at level L4-L5; (2) implantation at level L5-L6; and (3) sham surgery. Eleven weeks postoperatively osteolyses at the implant-bone interface were measured via radiograph, bone mineral density of vertebral bodies was analyzed using osteodensitometry, and bone mineral content as well as resorption of the spinous processes were examined by histomorphometry. RESULTS.: Resorption of the spinous processes at the site of the interspinous implant was found in all treated segments. There was no significant difference in either bone density of vertebral bodies or histomorphometric structure of the spinous processes between adjacent vertebral bodies, between treated and untreated segments and between groups.

CONCLUSION

These findings indicate that resorption of spinous processes because of a result of implant loosening, inhibit the targeted load redistribution through the PEEK nonfusion interspinous device in the lumbar spinal segment of the rat. This leads to reduced long-term stability of the implant in the animal model. These results suggest that PEEK nonfusion interspinous devices like the Wallis implants may have time-limited effects and should only be used for specified indications.

In situ forming hydrogels composed of oxidized high molecular weight hyaluronic acid and gelatin for nucleus pulposus regeneration

Encapsulation of nucleus pulposus (NP) cells within in situ forming hydrogels is a novel biological treatment for early stage intervertebral disc degeneration. The procedure aims to prolong the life of the degenerating discs and to regenerate damaged tissue. In this study we developed an injectable oxidized hyaluronic acid-gelatin-adipic acid dihydrazide (oxi-HAG-ADH) hydrogel. High molecular weight (1900 kDa) hyaluronic acid was crosslinked with various concentrations of gelatin to synthesize the hydrogels and their viscoelastic properties were analyzed. Interactions between the hydrogels, NP cells, and the extracellular matrix (ECM) were also evaluated, as were the effects of the hydrogels on NP cell gene expression. The hydrogels possess several clinical advantages, including sterilizability, low viscosity for injection, and ease of use. The viscoelastic properties of the hydrogels were similar to native tissue, as reflected in the complex shear modulus (∼11-14 kPa for hydrogels, 11.3 kPa for native NP). Cultured NP cells not only attached to the hydrogels but also survived, proliferated, and maintained their round morphology. Importantly, we found that hydrogels increased NP cell expression of several crucial ECM-related genes, such as COL2A1, AGN, SOX-9, and HIF-1A.

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.

Cells from degenerative intervertebral discs demonstrate unfavorable responses to mechanical and inflammatory stimuli: a pilot study

OBJECTIVE

Mechanical forces and inflammatory signaling influence intervertebral disc matrix homeostasis. We hypothesized that annulus fibrosus cells from degenerative discs would have altered responses to mechanical and inflammatory stimuli compared with cells isolated from normal discs.

DESIGN

Annulus fibrosus cells were isolated from New Zealand White rabbits with normal and magnetic resonance imaging-confirmed degenerative discs created by annular stab. Cells were cultured with and without inflammatory and mechanical stimuli (tensile strain). After 4 or 24 hrs, the mRNA expression of inflammatory, catabolic, and anabolic genes was measured by reverse transcription polymerase chain reaction.

RESULTS

Baseline gene expression differences were noted between cells from normal and degenerative discs. Degenerative cells demonstrated a more proinflammatory response profile to inflammatory and mechanical stimuli and loss of the beneficial effects of mechanical signaling. Decreased expression of catabolic and anabolic genes was observed in degenerative cells under conditions of inflammatory and mechanical stimuli.

CONCLUSIONS

These data demonstrate that degenerative cells have a decreased capacity to respond positively to beneficial levels of mechanical strain and demonstrate an exaggerated response to an inflammatory stimulus. This may, in part, help to explain differential responses to motion-based therapies in patients with intervertebral disc degeneration.

Effectiveness of preventive back educational interventions for low back pain: a critical review of randomized controlled clinical trials

PURPOSE

A systematic search was conducted to study the efficiency of preventive educational interventions mainly focused on a biomechanical/biomedical model.

METHODS

The PubMed electronic database and the Cochrane Library were searched based on a combination of keywords related to low back pain (LBP) and posture education. Only randomized controlled trial (RCT) studying the efficiency on outcomes directly related to LBP of a preventive intervention programme mainly based on education of proper care of the back for subjects not seeking treatment were included. References of the articles meeting these inclusion criteria were also checked to identify other potential citations. Besides, a methodological study assessment of the included RCTs was performed.

RESULTS

Nine studies, all conducted at the workplace were included in this review. Their mean quality level was low (5.1/12) and among the four studies with a huge sample size (n > 400 subjects), only one had an acceptable methodological quality score (6/12). The education interventions differed widely from one study to another. No significant differences between the control and education groups were found at the follow-up in eight out of the nine studies on the incidence of back pain, disability and sick leave.

CONCLUSIONS

The results of the RCTs included in this review suggest that educational interventions mainly focused on a biomechanical/biomedical model are not effective in preventing LBP. However, taking into account the methodological quality level of the RCTs as well as the very short and heterogeneous interventions often proposed, additional high-quality studies with a longer education period are needed to conclude that such interventions are inefficient.

Thermosensitive hydrogel made of ferulic acid-gelatin and chitosan glycerophosphate

Reactive oxygen species-induced oxidative stress is involved in apoptosis of nucleus pulposus (NP) cells that can alter cellular phenotype and accelerate disc degeneration. Ferulic acid (FA) possesses an excellent antioxidant and anti-inflammatory properties. In the study, we developed the thermosensitive FA-gelatin/chitosan/glycerol phosphate (FA-G/C/GP) hydrogel which was applied as a sustained release system of FA to treat NP cells from the damage caused by oxidative stress. The gelation temperature of the FA-G/C/GP hydrogel was 32.17 °C. NP cells submitted to oxidative stress promoted by H(2)O(2), and post-treated with FA-G/C/GP exhibited down-regulation of MMP-3 and up-regulation aggrecan and type II collagen in mRNA level. The sulfated-glycosaminoglycan production was increased and the apoptosis was inhibited in the post-treatment group. The results suggest that the thermosensitive FA-G/C/GP hydrogel can treat NP cells from the damage caused by oxidative stress and may apply in minimally invasive surgery for NP regeneration.

Fluoroscopic lumbar interlaminar epidural injections in managing chronic lumbar axial or discogenic pain

Among the multiple causes of chronic low back pain, axial and discogenic pain are common. Various modalities of treatments are utilized in managing discogenic and axial low back pain including epidural injections. However, there is a paucity of evidence regarding the effectiveness, indications, and medical necessity of any treatment modality utilized for managing axial or discogenic pain, including epidural injections. In an interventional pain management practice in the US, a randomized, double-blind, active control trial was conducted. The objective was to assess the effectiveness of lumbar interlaminar epidural injections of local anesthetic with or without steroids for managing chronic low back pain of discogenic origin. However, disc herniation, radiculitis, facet joint pain, or sacroiliac joint pain were excluded. Two groups of patients were studied, with 60 patients in each group receiving either local anesthetic only or local anesthetic mixed with non-particulate betamethasone. Primary outcome measures included the pain relief-assessed by numeric rating scale of pain and functional status assessed by the, Oswestry Disability Index, Secondary outcome measurements included employment status, and opioid intake. Significant improvement or success was defined as at least a 50% decrease in pain and disability. Significant improvement was seen in 77% of the patients in Group I and 67% of the patients in Group II. In the successful groups (those with at least 3 weeks of relief with the first two procedures), the improvement was 84% in Group I and 71% in Group II. For those with chronic function-limiting low back pain refractory to conservative management, it is concluded that lumbar interlaminar epidural injections of local anesthetic with or without steroids may be an effective modality for managing chronic axial or discogenic pain. This treatment appears to be effective for those who have had facet joints as well as sacroiliac joints eliminated as the pain source.

Degenerative joint disease of the spine

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

Does back and neck pain become more common as you get older? A systematic literature review

BACKGROUND

It is generally believed that the prevalence of back pain increases with age and as the proportion of elderly will keep rising we may be facing serious public health concerns in the future.

AIM

The aim of this systematic literature review is to establish whether back pain (i.e. neck, mid-back and/or low back pain) becomes increasingly common in the older population, specifically to study 1) whether there is a significant increase in the prevalence of back pain after middle age, and 2) whether there is a significant gradually increasing prevalence of back pain with continued old age.

METHODS

A systematic literature search was conducted in Pubmed on articles in English, published between January 2000 and July 2011. Non-clinical studies from the developed countries with prevalence estimates on elderly people (60+) on any type of self-reported back pain and on different age groups with adequate sample sizes were included in the review. The included articles were extracted for information by two independent reviewers.

RESULTS

A total of 12 articles were included covering the entire spine. Neck pain was studied nine times, low back pain eight times, back pain three times, upper back two times and neck/shoulders once. All studies showed no significant increase of back pain with age, neither when passing from middle age (i.e. 45+ years of age) into the sixties, nor later in life. In contrast, most studies reported a decline for the oldest group.

CONCLUSIONS

Back pain is no more common in the elderly population (>60 years) when compared to the middle age population. Back pain does not increase with increasing age, but seems to decline in the oldest people.

Nucleus pulposus replacement and regeneration/repair technologies: present status and future prospects

Degenerative disc disease is implicated in the pathogenesis of many painful conditions of the back, chief among which is low back pain. Acute and/or chronic low back pain (A/CLBP) afflicts a large number of people, thus making it a major healthcare issue with concomitant cost ramifications. When conservative treatments for A/CLBP, such as bed rest, anti-inflammatory medications, and physical therapy, prove to be ineffectual, surgical options are recommended. The most popular of these is discectomy followed by fusion. Although there are many reports of good to excellent outcomes with this method, there are concerns, such as long-term adverse biomechanical consequences to adjacent functional spinal unit(s). A surgical option that has been attracting much attention recently is replacement or regeneration/repair of the nucleus pulposus, an approach that holds the prospect of not compromising either mobility or function and causing no adjacent-level injury. There is a sizeable body of literature highlighting this option, comprising in vitro biomechanical studies, finite element analyses, animal-model studies, and limited clinical evaluations. This work is a review of this body of literature and is organized into four parts, with the focus being on replacement technologies, regeneration/repair technologies, and detailed expositions on 14 areas for future study. This review ends with a summary of the salient points made.

Disc disease and back pain in young adults

Questions from patients about pain conditions and analgesic pharmacotherapy and responses from authors are presented to help educate patients and make them more effective self-advocates. This article contains a brief description of disc disease in young adults resulting in chronic low back pain. Topics including causes of early degeneration of disc, therapies, and suggestions for strengthening the discs are discussed.

Quantitative assessment of abdominal aortic calcification and associations with lumbar intervertebral disc height loss: the Framingham Study

BACKGROUND CONTEXT

Vascular disease has been proposed as a risk factor for disc height loss (DHL).

PURPOSE

To examine the relationship between quantitative measures of abdominal aortic calcifications (AACs) as a marker of vascular disease, and DHL, on computed tomography (CT).

STUDY DESIGN

Cross-sectional study in a community-based population.

PATIENT SAMPLE

Four hundred thirty-five participants from the Framingham Heart Study.

OUTCOME MEASURES

Quantitative AAC scores assessed by CT were grouped as tertiles of "no" (reference), "low," and "high" calcification. Disc height loss was evaluated on CT reformations using a four-grade scale. For analytic purposes, DHL was dichotomized as moderate DHL of at least one level at L2-S1 versus less than moderate or no DHL.

METHODS

We examined the association of AAC and DHL using logistic regression before and after adjusting for cardiovascular risk factors and before and after adjusting for age, sex, and body mass index (BMI).

RESULTS

In crude analyses, low AAC (odds ratio [OR], 2.05 [1.27-3.30]; p=.003) and high AAC (OR, 2.24 [1.38-3.62]; p=.001) were strongly associated with DHL, when compared with the reference group of no AAC. Diabetes, hypercholesterolemia, hypertension, and smoking were not associated with DHL and did not attenuate the observed relationship between AAC and DHL. Adjustment for age, sex, and BMI markedly attenuated the associations between DHL and low AAC (OR, 1.20 [0.69-2.09]; p=.51) and high AAC (OR, 0.74 [0.36-1.53]; p=.42).

CONCLUSIONS

Abdominal aortic calcification was associated with DHL in this community-based population. This relationship was independent of cardiovascular risk factors. However, the association of AAC with DHL was explained by the effects of age, sex, and BMI.

Ex vivo observation of human intervertebral disc tissue and cells isolated from degenerated intervertebral discs

PURPOSE

Disc degeneration, and associated low back pain, are a primary cause of disability. Disc degeneration is characterized by dysfunctional cells and loss of proteoglycans: since intervertebral tissue has a limited capacity to regenerate, this process is at present considered irreversible. Recently, cell therapy has been suggested to provide more successful treatment of IVD degeneration. To understand the potential of cells to restore IVD structure/function, tissue samples from degenerated IVD versus healthy discs have been compared.

METHODS

Discal tissue from 27 patients (40.17 ± 11 years) undergoing surgery for degenerative disc disease (DDD), DDD + herniation and congenital scoliosis, as controls, was investigated. Cells and matrix in the nucleus pulposus (NP) and annulus fibrosus (AF) were characterized by histology. AF- and NP-derived cells were isolated, expanded and characterized for senescence and gene expression. Three-dimensional NP pellets were cultured and stained for glycosaminoglycan formation.

RESULTS

Phenotypical markers of degeneration, such as cell clusters, chondrons, and collagen disorganization were seen in the degenerate samples. In severe degeneration, granulation tissue and peripheral vascularization were observed. No correlation was found between the Pfirrmann clinical score and the extent of degeneration.

CONCLUSION

The tissue disorganization in degenerate discs and the paucity of cells out of cluster/chondron association, make the IVD-derived cells an unreliable option for disc regeneration.

Magnetic resonance findings of acute severe lower back pain

Objective

To determine abnormal MRI findings in adults hospitalized with acute severe axial LBP.

Method

Sixty patients with back pain were divided into 3 groups consisting of 1) 23 adults with acute axial severe LBP who could not sit up or stand up for several days, but had not experienced previous back-related diseases or trauma (group A), 2) 19 adults who had been involved in a minor traffic accident, and had mild symptoms but not limited mobility (group B), and 3) 18 adults with LBP with radicular pain (group C)., Various MRI findings were assessed among the above 3 groups and compared as follows: disc herniation (protrusion, extrusion), lumbar disc degeneration (LDD), annular tear, high intensity zone (HIZ), and endplate changes.

Results

The MRI findings of A group were as follows: disc herniation (87%), LDD (100%), annular tear (100%), HIZ (61%), and end plate changes (4.4%). The findings of disc herniation, annular tear, HIZ, and LDD were more prevalent in A group than in B group (p<0.01). HIZ findings were more prevalent in A group than in group B or group C (p<0.05).

Conclusion

Patients with acute severe axial LBP were more likely to have disc herniation, LDD, annular tear, HIZ. Among LBP groups, there was a significant association of HIZ on MRI with acute severe axial LBP.

Biomechanics of intervertebral disk degeneration

Degenerative changes in the material properties of nucleus pulposus and anulus fibrosus promote changes in viscoelastic properties of the whole disc. Volume, pressure and hydration loss in the nucleus pulposus, disk height decreases and fissures in the anulus fibrosus, are some of the signs of the degenerative cascade that advances with age and affect, among others, spinal function and its stability. Much remains to be learned about how these changes affect the function of the motion segment and relate to symptoms such as low back pain and altered spinal biomechanics.

Does daily exposure to whole-body vibration and mechanical shock relate to the prevalence of low back and neck pain in a rural workforce?

OBJECTIVES

To determine whether whole-body vibration (WBV) and mechanical shock exposure from quad bike use are associated with the prevalence of neck and low back pain (LBP) in New Zealand farmers and rural workers.

METHODS

Full-day WBV and mechanical shock exposures were gathered from 130 farmers and rural workers. Participants were surveyed for a history of neck or LBP in the past 7 days and in the past 12 months. Anthropometric, personal, and workplace data were also gathered.

RESULTS

Physical exposures (mechanical shocks), employee status, and low levels of workplace satisfaction are all significantly associated with the 12-month prevalence of LBP in this rural workforce that regularly use quad bikes. Both vibration and mechanical shock exposure were strongly associated with 12-month prevalence of neck pain. The 7-day prevalence of neck pain showed a non-significant association with mechanical shock and vibration.

CONCLUSIONS

Knowledge of these findings will be valuable information for those who teach and advise on safe driving techniques for such vehicles in the rural workplace where reduction of physical exposures and injury rates is of high importance.

Herpes virus infection can cause intervertebral disc degeneration

It has been proposed that intervertebral disc degeneration might be caused by low-grade infection. The purpose of the present study was to assess the incidence of herpes viruses in intervertebral disc specimens from patients with lumbar disc herniation. A polymerase chain reaction based assay was applied to screen for the DNA of eight different herpes viruses in 16 patients and two controls. DNA of at least one herpes virus was detected in 13 specimens (81.25%). Herpes Simplex Virus type-1 (HSV-1) was the most frequently detected virus (56.25%), followed by Cytomegalovirus (CMV) (37.5%). In two patients, co-infection by both HSV-1 and CMV was detected. All samples, including the control specimens, were negative for Herpes Simplex Virus type-2, Varicella Zoster Virus, Epstein Barr Virus, Human Herpes Viruses 6, 7 and 8. The absence of an acute infection was confirmed both at the serological and mRNA level.

To our knowledge this is the first unequivocal evidence of the presence of herpes virus DNA in intervertebral disc specimens of patients with lumbar disc herniation suggesting the potential role of herpes viruses as a contributing factor to the pathogenesis of degenerative disc disease.

Constitutive expression of cathepsin K in the human intervertebral disc: new insight into disc extracellular matrix remodeling via cathepsin K and receptor activator of nuclear factor-κB ligand

Introduction

Cathepsin K is a recently discovered cysteine protease which cleaves the triple helical domains of type I to II collagen. It has been shown to be up-regulated in synovial tissue from osteoarthritic and rheumatoid patients, and is a component in normal and nonarthritic cartilage, where it increases with aging. Studies on heart valve development have recently shown that receptor activator of nuclear factor-κB ligand (RANKL) acts during valve remodeling to promote cathepsin K expression. Since extracellular matrix remodeling is a critical component of disc structure and biomechanical function, we hypothesized that cathepsin K and RANKL may be present in the human intervertebral disc.

Methods

Studies were performed following approval of the authors' Human Subjects Institutional Review Board. Six annulus specimens from healthier Thompson grade I to II discs, and 12 specimens from more degenerate grade III to IV discs were utilized in microarray analysis of RANKL and cathepsin K gene expression. Immunohistochemistry was also performed on 15 additional disc specimens to assess the presence of RANKL and cathepsin K.

Results

Cathepsin K gene expression was significantly greater in more degenerated grade III to IV discs compared to healthier grade I to II discs (P = 0.001). RANKL was also identified with immunohistochemistry and molecular analyses. RANKL gene expression was also significantly greater in more degenerated discs compared to healthier ones (P = 0.0001). A significant linear positive correlation was identified between expression of cathepsin K and RANKL (r² = 92.2; P < 0.0001).

Conclusions

Extracellular matrix remodeling is a key element of disc biology. Our use of an appropriate antibody and gene expression studies showed that cathepsin K is indeed present in the human intervertebral disc. Immunolocalization and molecular analyses also confirmed that RANKL is present in the human disc. Expression of RANKL was found to be significantly greater in more degenerated compared to healthier discs (P = 0.0001). Cathepsin K gene expression levels showed a positive, significant correlation with RANKL expression. Based on these data, we propose that cathepsin K plays a significant role in disc matrix remodeling and in matrix degradation in the proinflammatory cytokine-rich microenvironment of the degenerating disc.

Outcome of lumbar epidural steroid injection is predicted by assay of a complex of fibronectin and aggrecan from epidural lavage

STUDY DESIGN

A single-center, prospective, consecutive case series of patients undergoing epidural lavage before the treatment of radiculopathy due to lumbar disc herniation.

OBJECTIVE

To determine whether a novel complex of fibronectin and aggrecan predicts clinical response to epidural steroid injection (ESI) for the indication of radiculopathy from lumbar herniated nucleus pulposus (HNP).

SUMMARY OF BACKGROUND DATA

ESI for lumbar radiculopathy due to HNP is widely used despite variable effectiveness for this indication. With increased attention aimed at cost containment, it would be beneficial to identify those in whom ESI may be helpful. There are currently no accurate diagnostic tests to predict response to ESI in back pain and sciatica syndromes. We have previously investigated biomarkers of disc degeneration associated with radiculopathy.

METHODS

We embarked to determine whether a molecular complex of fibronectin and aggrecan predicts clinical response to ESI for the indication of radiculopathy from HNP. This prospective study was conducted at a single center and included 26 patients with radiculopathic pain and magnetic resonance imaging positive for HNP, who elected ESI. Epidural lavage with physiologic saline was performed immediately before ESI. The lavage fluid was assayed for the fibronectin-aggrecan complex (FAC) by using a heterogeneous sandwich enzyme-linked immunosorbent assay. The results were compared with the interval improvement in the physical component summary (PCS) score of the Medical Outcomes Study Short Form-36 instrument (SF-36) after injection compared with baseline.

RESULTS

The mean improvement from baseline PCS in patients with the FAC was 22.9 (SD, 12.4) and without the complex was 0.64 (SD, 3.97; P < 0.001). Differences in total SF-36 improvement were also highly significant (P < 0.001). The presence of the FAC predicts a clinically significant increase in PCS after lumbar ESI by receiver-operating-characteristic analysis (area under the curve = 0.97; P < 0.001). There was no significant difference in age (P = 0.25), sex (P = 0.84), laterality (P = 0.06), lumbar spinal level (P = 0.75), or payer type (worker's compensation vs. private insurance; P = 0.90) between groups with and without the marker.

CONCLUSION

A molecular complex of fibronectin and aggrecan predicts response to lumbar ESI for radiculopathy with HNP. The biomarker is accurate, objective, and not affected by demographic or psychosocial variables in this series.