bluuebunny/crossref_metadata_2025 huggingface dataset:
Operative Management of Lumbar Disc Herniation with End Plate Modic Changes Necessitates More Definite Procedures
Authors: Cao P.
Published: May 2014

Introduction

Nucleotomy through interlaminar fenestration has been the standard operation for lumbar disc herniation, but it does not always work well in clinical practice. End plate Modic changes are strongly linked with lower back pain, and Modic changes in the end plates of the herniation level may be one reason for the unpredictable result of nucleotomy alone. Studies on more definite surgical procedures for lumbar disc herniation with end plate Modic changes are still rare. To compare the clinical outcomes between two surgical options, nucleotomy alone and nucleotomy with additional posterolateral lumbar interbody fusion (PLIF), for lumbar disc herniation patients with end plate Modic changes, and to testify the hypothesis that end plate Modic change is an indication of interbody fusion for operative management of lumbar disc herniation.

Materials and Methods

A total of 91 patients who complained about both lower extremity radicular pain and lower back pain (lower back pain more severe than leg pain) were included, and all of them were of single segment disc herniation with Modic changes in the corresponding lumbar degenerative end plates. Of the 91 patients, 47 were treated with nucleotomy alone and 44 were treated with posterolateral lumbar interbody fusion (PLIF) in addition to nucleotomy. They were followed up for at least 2 years. Clinical outcomes were evaluated according to the Japanese Orthopaedic Association (JOA) score and visual analogue scale (VAS) for lower back pain and VAS for lower extremity radicular pain before operation and at each follow-up, and the results before surgery and at 18 months after operation were statistically compared.

Results

In both the groups, the JOA scores, as well as VAS, for lower back pain significantly improved 18 months after surgery. The improvement rate of JOA score and power of improvement of VAS for lower back pain also showed significant difference between the two groups, being better in nucleotomy with PLIF procedure than in nucleotomy alone procedure. On the contrary, the mean VAS of lower extremity radicular pain showed a significant reduction in both groups at the follow-up of 18 months after operation. However, a significant difference of the power of this improvement between both the groups was not found.

Conclusion

Operative management of lumbar disc herniation with end plate Modic changes necessitates more definite procedures in addition to nucleotomy. PLIF is a good and reliable option. Disclosure of Interest None declared
Spontaneous Regression of Extruded Cervical Disc Herniation in a 26-Year-Old Woman: A Case Report and Review of the Literature
Authors: Dechun D. , Chunlin T.
Published: May 2014

Introduction

The spontaneous regression of lumbar disc herniation was increasingly documented in the literatures. However, radiographically demonstrated regression of a cervical disc herniation with myelopathic symptoms was relatively rare, because most cases received early surgical intervention as soon as radiological presentation of serious extrusion in cervical vertebrae.

Materials and Methods

In this article, one case of spontaneous regression of extruded cervical herniated discs was presented. No history of trauma was reported in a 26-year-old woman, with 1-month history of gradual-onset neck pain and upper back pain, and left arm numbness. Magnetic resonance imaging (MRI) of the cervical spine revealed spine seriously compressed at the cervical C5-C6 levels. The patient denied operation and received conservative rehabilitation treatment.

Results

The disc regressions were correlated with clinical improvement and documented with follow-up MRI studies 6 months later. Nonsurgical conservative observation may be considered an option for treatment of some extruded cervical disc herniations that are likely to regress for very specific and predictable reasons based on thorough understanding of patient's case history and positive signs. It was necessary to take frequent follow-ups and excluded gradual spine lesion.

Conclusion

Nonsurgical conservative observation may be considered an option for treatment of some extruded cervical disc herniations that are likely to regress for very specific and predictable reasons based on thorough understanding of patient's case history and positive signs. It was necessary to take frequent follow-ups and excluded gradual spine lesion. Disclosure of Interest None declared References Ito T, Yamada M, Ikuta F, et al. Histologic evidence of absorption of sequestration-type herniated disc. Spine 1996;21(2):230–234 Slavin KV, Raja A, Thornton J, Wagner FC Jr. Spontaneous regression of a large lumbar disc herniation: report of an illustrative case. Surg Neurol 2001;56(5):333-336, discussion 337 Mochida K, Komori H, Okawa A, Muneta T, Haro H, Shinomiya K. Regression of cervical disc herniation observed on magnetic resonance images. Spine 1998;23(9):990-995, discussion 996–997 Saal JS, Saal JA, Yurth EF. Nonoperative management of herniated cervical intervertebral disc with radiculopathy. Spine 1996;21(16):1877–1883
Comparison of the Safety Outcomes between Anterior Lumbar Interbody Fusion and Extreme Lateral Interbody Fusion
Authors: Hartl R. , Christensen F. , Korge A. , Lam K. , Vialle E. , Zigler J. , McGuire R.
Published: May 2014

Introduction

This review compares the safety of the interbody fusion procedures anterior lumbar interbody fusion (ALIF) and extreme lateral transpsoas interbody fusion (ELIF) in the treatment of degenerative spinal disorders. ALIF is well established whereas ELIF is a novel procedure.

Materials and Methods

We performed a systematic literature search in the databases Cochrane (CENTRAL), MEDLINE, EMBASE, and the FDA register. Information was collected on study design, sample size, population, procedure, indication incl. number, and location of levels involved, follow-up (FU) time and adverse events. Moreover, information on conflict of interest and source of funding was captured.

Results

Of 32 eligible publications, 22 dealt with ELIF, 9 with ALIF, and 1 compared ELIF with ALIF. All of the ELIF studies were case series. The number of patients was 2,165 and 1,379, with a FU time from 45 days to 24 months and 24 months to 5 years for ELIF and ALIF, respectively. The risk to experience certain types of adverse events (e.g., reoperations, hardware failures, DVT, and cardiac) appeared significantly lower for patients undergoing ELIF. Pseudarthrosis was seen in 0.14 and 1.02% of ELIF and ALIF cases, respectively. Neurological complications occurred in 7.62% of ELIF and 9.43% of ALIF cases. [Table: see text]

Conclusion

ELIF procedures demonstrated a favorable safety outcome compared with ALIF, nonetheless the lack of comparative studies, length of follow-up, and low level of evidence is a limitation of this review. Disclosure of Interest R. Hartl: Conflict with DePuy Synthes, Spine Wave, Brainlab, Lanx F. Christensen: None declared A. Korge: None declared K. Lam: None declared E. Vialle: None declared J. Zigler: None declared R. McGuire: None declared
Elevated VEGF in Degenerative Intervertebral Discs in Rats with Injured Intervertebral Discs of the Caudal Vertebrae
Authors: Sato J. , Sakuma Y. , Yamauchi K. , Orita S. , Kubota G. , Oikawa Y. , Inage K. , Sainoh T. , Fujimoto K. , Takahashi K. , Ohtori S. , Miyagi M.
Published: May 2014

Introduction

Recently, inflammatory cytokines, which are elevated in degenerative intervertebral discs, have been recognized as targets of drug therapy for discogenic back pain. Some reports have shown that the level of vascular endothelial growth factor (VEGF), a protein involved in angiogenesis, is elevated at inflamed sites, and we believed that VEGF could be a target for the treatment of discogenic back pain. Thus, we investigated the presence of VEGF in degenerative intervertebral discs in rats with injured intervertebral discs of the caudal vertebrae.

Materials and Methods

Forty male rats (age, 8 weeks) were divided into two groups: injured group (intervertebral discs between the fifth and sixth, and sixth and seventh caudal vertebrae were punctured 10 times using a 26G needle) and noninjured group (intact discs). The intervertebral discs were collected at 1, 4, 7, and 14 days after the procedure ( n = 5 from each group at each time point), and quantitative evaluation of VEGF was performed using ELISA.

Results

The VEGF level was maximum 1 day after the procedure, and then the level gradually decreased. In addition, the VEGF levels during the entire study period were significantly higher in the injured group compared with those in the noninjured group ( p < 0.05).

Conclusion

In this study, injury to the intervertebral discs resulted in elevated VEGF levels. This finding confirms the increased production of inflammatory cytokines in injured intervertebral discs and indicates that VEGF might be involved in discogenic back pain. Moreover, the presence of elevated VEGF levels during the study period shows that VEGF might be responsible for lingering pain. Anti-VEGF antibodies are already in use in the ophthalmic field. On the basis of the findings in this study, a clinical trial involving the administration of anti-VEGF antibodies into the intervertebral discs for the treatment of low back pain in humans was approved by the review committee in September 2013 and will be performed in the near future. Disclosure of Interest None declared
Effects of Pedicle Screw and Spinous Process Distraction on Adjacent Foramina
Authors: Amor N. , Karas C.
Published: May 2014

Introduction

Surgical advances attempt to alleviate lumbar spinal stenosis, which burdens many people in our aging population. One goal of pedicle screw and spinous process distraction is to decompress the neural foramina of the affected segment. The objective of this study is to evaluate the change in the foraminal size adjacent to the distracted level.

Materials and Methods

The lumbar spine of a prone cadaveric specimen was exposed. Titanium pedicle screws were placed from L1-L5. A titanium rod spanning only two levels on either side of the spine was fastened down at the caudal end and secured at the cephalad end. The screws were distracted until maximal resistance on the left side was reached and then the cephalad set screw was secured. The same amount of distraction was applied to the right side and secured in the same fashion. A second prone cadaveric specimen was exposed. Titanium screws were instead inserted into the spinous processes at levels L1-L4. The distraction technique described above was used with two predetermined distances (3 mm and 6 mm). A CT scan was obtained before and after distraction at each level. Foraminal openings at the level of distraction as well as the adjacent above and below foramina were measured and analyzed.

Results

In the pedicle-distraction specimen, there was an overall positive percent change at the level of distraction and an overall negative percent change in the levels above and below. The level of L3-L4 on the right revealed the largest percent change (11.09%) in foramen distraction. The foramen superior to the L2-L3 distraction demonstrated the least amount of change (−9.71%). The spinous process-distraction specimen demonstrated an overall positive percent change at the level of the distraction but not an overall negative change at the adjacent levels. The L1-L2 superior adjacent foramina had negative percent changes at the 3 mm and 6 mm of −2.80% R, −12.52% L and −4.20% R,−15.46% L, respectively. Only the right, 3 mm distraction of the inferior adjacent of L1-L2 showed a negative percent change, the rest were positive changes. The L3-L4 distractions including above and below foramina were positive percent changes. The greatest percent change at L3-L4 for the 6 mm distraction was 43.1% at the level of distraction and 6.35% at the above adjacent level.

Conclusion

Distraction of the lumbar spine at any level does increase foramen size at that level, but adjacent levels are affected differently depending on the type of distraction. Distraction at the spinous process may be more beneficial particularly in the lower lumbar area. Further studies are necessary to reproduce these results to provide a basis for determining an optimal method for foraminal distraction which minimizes adjacent level stenosis. Disclosure of Interest None declared
Development New Pain Targets in the Genomic Era
Authors: Diatchenko Luda , Fillingim Roger B. , Smith Shad B. , Maixner William
Published: May 2014

Musculoskeletal pain conditions, such low back pain, are characterized by a report of pain greater than expected based on the results of a standard physical evaluation. The pathophysiology of these conditions is largely unknown, we lack biological markers for accurate diagnosis, and conventional therapeutics have limited effectiveness. Growing evidence suggests that chronic pain conditions are associated with both physical and psychological triggers, which initiate pain amplification and psychological distress; thus, susceptibility is dictated by complex interactions between genetic and environmental factors. Herein, we will review phenotypic and genetic markers of common musculoskeletal pain conditions, selected based on their association with musculoskeletal pain in previous research. The phenotypic markers of greatest interest include measures of pain amplification and “psychological” measures (such as emotional distress, somatic awareness, psychosocial stress, and catastrophizing). Genetic polymorphisms reproducibly linked with musculoskeletal pain are found in genes contributing to serotonergic and adrenergic pathways. Elucidation of the biological mechanisms by which these markers contribute to the perception of pain in these patients will enable the development of novel effective drugs and methodologies that permit better diagnoses and approaches to personalized medicine.

Acknowledgments for Grant Support

• 1K12DSE022793/PHS HHS/United States

• AG033906/AG/NIA NIH HHS/United States

• P01 NS045685/NS/NINDS NIH HHS/United States

• R01-DE16558/DE/NIDCR NIH HHS/United States

• U01-DE017018/DE/NIDCR NIH HHS/United States

Disclosure of Interest Substantial shareholders: Attagene, Inc., Algynomics, Inc.; Consultant: Clontech, Inc., Algynomics, Inc.; Officer position: Algynomics, Inc.
Is Low Back Pain a Genetic Problem?
Authors: Karppinen Jaro
Published: May 2014

Twin studies indicate that the (1) heritability of low back pain (LBP) is considerable varying between 30 and 46% depending on the setting, and (2) disc degeneration (DD) has a strong mediating effect in LBP with 11 to 13% of shared genetic effects. Until now, genetic research in LBP has focused on candidate genes; disease-related single-nucleotide polymorphisms have been found in structural, immune system, and nociception-related proteins. So far, no genome-wide association studies (GWAS) have been published in LBP. GWAS data will undoubtedly increase our knowledge on genetics of LBP. However, GWAS is able to detect only common variants (> 5% MAF) and it is reasonable to expect that rare variants, obtained by whole-genome sequencing, have a role in LBP as well as in other complex disorders.

Environmental factors have a significant role in LBP. Epigenetics describes heritable information not encoded in DNA. Different epigenetic mechanisms include such as methylation of cytosines in DNA, posttranslational modifications (mainly acetylation) of histones and microRNAs. Epigenetic regulation has an important role in complex disorders and preliminary evidence indicates that epigenetic mechanisms are important in DD as well.

The future of LBP genetics requires first an unambiguous phenotype (mere subjective experience of pain is not enough). Discovery of objective endophenotypes of LBP may clarify the phenotype issue. Second, we need to establish large consortiums with genetic and epigenetic sample collection and systematic assessment of environmental (includes also psychological factors) determinants. Methodologically, bioinformatics will be most likely the rate-limiting step—at least in the beginning. Genetic analyses will most likely shift from common-to-rare variants—covering more extensively also the nonprotein coding area. However, in time, genetic research in LBP will evolve and become more commonplace.

Disclosure of Interest

None declared

References

Battié MC, Videman T, Levalahti E, Gill K, Kaprio J. Heritability of low back pain and the role of disc degeneration. Pain 2007;131(3):272–280

Denk F, McMahon SB, Tracey I. Pain vulnerability: a neurobiological perspective. Nat Neurosci 2014;17(2):192–200

Diatchenko L, Fillingim RB, Smith SB, Maixner W. The phenotypic and genetic signatures of common musculoskeletal pain conditions. Nat Rev Rheumatol 2013;9(6):340–350

J Eskola P, Männikkö M, Samartzis D, Karppinen J. Genome-wide association studies of lumbar disc degeneration-are we there yet? Spine J 2014;14(3):479–482

Foulkes T, Wood JN. Pain genes. PLoS Genet 2008;4(7):e1IN1.02086

Livshits G, Popham M, Malkin I, et al. Lumbar disc degeneration and genetic factors are the main risk factors for low back pain in women: the UK Twin Spine Study. Ann Rheum Dis 2011;70(10):1740–1745

Mogil JS. Pain genetics: past, present and future. Trends Genet 2012;28(6):258–266

Näkki A, Battié MC, Kaprio J. Genetics of disc-related disorders: current findings and lessons from other complex diseases. Eur Spine J 2013; July 10 (Epub ahead of print)
Role of Cytokines and Proteases in the Pathogenesis of Intervertebral Disc Degeneration
Authors: Le Maitre Christine L.
Published: May 2014

The intact intervertebral disc (IVD) is considered an immune-privileged site with no inflammatory cells. Despite the lack of inflammatory cells, the IVD has been shown to be a source of a plethora of cytokines and chemokines, normally associated with inflammation.

These cytokines are produced by the nucleus pulpous (NP) and annulus fibrous (AF) of the disc and their expression is increased during disc degeneration together with expression of their receptors. Whereas a plethora of cytokines have been identified during disc degeneration, the main research focus has been toward interleukin 1 (IL-1) and tumor necrosis factor α (TNFα) initially driven by their known roles in osteoarthritis. These cytokines have been shown to regulate several characteristic features of disc degeneration, including increased expression of matrix degrading enzymes: MMPs and ADAMTS, the main proteases produced within the degenerate disc.

IL-1 and TNF have also been implicated in the down regulation of normal matrix synthesis, induction of factors which could lead to the ingrowth of blood vessels and nerves, and induction of cellular senescence and apoptosis. However, of these two cytokines, IL-1 appears to be the main regulator of the pathogenic events within the degenerate disc.

IL-1 stimulation induces the expression of a plethora of cytokines and chemokines by NP cells and inhibition of IL-1 by the natural inhibitor of IL-1: IL-1Ra in ex vivo tissue explants obliterates all matrix degrading enzyme activity. Recent studies have shown that in a mouse model where the natural inhibitor of IL-1: IL-1Ra is knocked out the mice demonstrated spontaneous degeneration, associated with increased expression of matrix degrading enzymes, thus implicating IL-1 as a causative agent in disc degeneration. This is further supported by the numerous studies which link polymorphisms in the IL-1 gene family to increased risk of IVD degeneration and herniation in humans.

This presentation will focus on the current understanding of the role of cytokines and chemokine's in the pathogenesis of disc degeneration and herniation, particularly on their role in regulating protease expression and other characteristic features of degeneration. Furthermore, the involvement of inflammation following herniation will be discussed, providing the distinction between true “inflammation” and “inflammatory cytokine” roles in the pathogenesis of disc degeneration and herniation, and how these can be targeted in therapeutic approaches.

Disclosure of Interest

None declared
CCN2 Functions as Anti-Inflammatory Molecule in the Intervertebral Disc
Authors: Risbud Makarand V.
Published: May 2014

The aim of the study was to delineate regulation of CTGF/CCN2 expression by cytokines, IL-1β and TNF-α. In addition, we addressed if CCN2 modulates cytokine action on NP cells. Our studies showed that cytokines suppress CCN2 expression and that this effect was mediated in an NF-κB dependent but MAPK independent fashion. Site-directed mutagenesis and genomic chromatin immunoprecipitation (ChIP) analyses showed that the conserved κB sites located at −93/−86 and −546/−537 bp in the CCN2 promoter interacted with p65/RelA and mediated this suppressive effect of cytokines on CCN2 expression. Concerning role of CCN2 under inflammatory state, it was seen that the treatment of NP cells with IL-1β along with CCN2 blocked the stimulatory effect of IL-1β on MMP-3, ADAMTS5, prolyl hydroxylase 3 and syndecan 4 expression. Furthermore, silencing of CCN2 in human NP cells resulted in increased expression of catabolic genes and inflammatory cytokines such as IL-6, IL-4, and IL-12 as measured by gene expression analysis and cytokine protein array, respectively, under basal state. However, reporter analysis clearly showed that the inhibitory effect of CCN2 on IL-1β was independent of regulation of NF-κB signaling pathway. Using echistatin and VLO4, peptide inhibitors to αvβ3 and α5β1 integrins, we also showed that CCN2 interaction with these integrins was necessary for the inhibition of IL-1β-induced catabolic gene expression. Finally, analysis of human tissues showed a trend of altered expression of these integrins during degeneration. Collective, our results suggest that CCN2 and cytokines may form a functional negative feedback loop in NP cells important in the pathogenesis of disc degeneration.

Disclosure of Interest

None declared
Schmorl Nodes, Disc Degeneration, and Pain
Authors: Cheung Kenneth M , Samartzis Dino , Mok Florence P. S. , Karppinen Jaro , Luk Keith D. K. , Fong Daniel Y. T.
Published: May 2014

Schmorl nodes (SNs) of the lumbar spine are an ill-defined entity sometimes referred to as intravertebral disc herniation and by others as end plate irregularities. They are often considered a radiographic curiosity with no clinical consequences. As part of a large-scale population-based study of the Hong Kong Degenerative Disc Disease cohort, sagittal T2-weighted magnetic resonance images of the lumbar spine were analyzed in 2,499 volunteers. SNs were found in 16.4% of the study population, being most common at L1/2 and L2/3 (54.1%). Multivariate logistic regression revealed that males, taller and heavier individuals had an increased likelihood of SN ( p < 0.005), suggesting mechanical factors may play a role in their pathogenesis. On the contrary, SNs were independent of age. Overall presence of SN was associated with disc degeneration ( p < 0.001), and linearly correlated ( R2 = 0.97) with increase in severity of degeneration. SN were particularly associated with severe disc degeneration at L1/2 and L2/3 with 22- to 15-fold increased odds, respectively ( p < 0.0001), but less than 5-fold increased odds ( p < 0.001) were noted in the lower lumbar spine.

This presentation will discuss the various radiologic appearances of end plate irregularities that may be considered as SNs and propose a new classification based on morphology. In addition, morphological patterns tend to cluster in a particular manner to suggest different etiological factors may be associated with different subtypes of SNs. The relevance of end plate changes in the etiology of lumbar disc degeneration will also be discussed.

Disclosure of Interest

None declared
Antibiotic Treatment in Patients with Chronic Low Back Pain and Vertebral Bone Edema, a Double-Blind RCT of Efficacy
Authors: Albert Hanne B. , Sorensen Joan Solgaard
Published: May 2014

Background

Modic type 1 changes (bone edema) in the vertebrae are present in 6% of the general population and in 35 to 40% of the low back pain population. It is strongly associated with low back pain (LBP). The aim was to test the efficacy of antibiotic treatment in patients with chronic LBP (> 6 months) and Modic type 1 changes (bone edema).

Methods

The study was a double-blind RCT with 162 patients whose only known illness was chronic LBP of greater than 6 months duration occurring after a previous disc herniation and who also had bone edema demonstrated as Modic type 1 changes in the vertebrae adjacent to the previous herniation. Patients were randomized to either 100 days of antibiotic treatment or placebo and were blindly evaluated at baseline; end of treatment and at 1-year follow-up. As primary outcome measures were disease-specific disability and lumbar pain. Secondary outcome leg pain, number of hours with pain last 4 weeks, global perceived health, EQ-5D thermometer, days with sick leave, bothersomeness, and constant pain.

Results

Of the 162 original patients, 144 were evaluated at 1-year follow-up. The two groups were similar at baseline. The antibiotic group improved highly statistically significant on all outcome measures and improvement progressed from 100 days follow-up until 1-year follow-up. At baseline, 100 days follow-up, and 1-year follow-up the disease-specific disability RMDQ changed; antibiotic 15, 11, 5.7, placebo 15, 14, 14. Leg pain; antibiotics 5.3, 3.0, 1.4, placebo 4.0, 4.3, 4.3. Lumbar pain; antibiotics 6.7, 5.0, 3.7, placebo 6.3, 6.3, 6.3 For the outcome measures, where a clinically important effect size was defined, improvements exceeded the thresholds, and a trend toward a dose-response relationship with double dose antibiotics being more efficacious.

Conclusions

The antibiotic protocol in this study was significantly more effective for this group of patients, (CLBP associated with Modic type I), than placebo in all the primary and secondary outcomes. Disclosure of Interest None declared
Cervical Disc Arthroplasty and Adjacent Segment Pathology
Authors: Riew K. Daniel
Published: May 2014

The advantages of arthroplasty include maintenance of motion, avoiding nonunions, and avoiding plate and screw complications such as backout, esophageal erosion, and periplate ossification. Thus far, the purported long-term benefit of reducing the incidence of adjacent segment pathology has not been born out in FDA-IDE trials reporting on up to 5-year results. Only one disc showed a difference. There is, however, some unpublished data that suggests that at > 5 years, another arthroplasty has benefits over ACDF. In this study, I will review the available data.

Disclosure of Interest

None declared
Principles and Mechanical Requirements of Nucleus Implants
Authors: Wilke Hans-Joachim
Published: May 2014

Nonfusion technologies in spinal surgery are continuously gaining popularity. New ideas are constantly being developed and turned into new products. Each idea has its own philosophy with the principle goal to maintain the motion in the treated segment. In contrast to total disc implants, nucleus implants are designed to preserve as many existing anatomical structures as possible, which include the annulus, the end plates of the vertebral bodies, and the ligaments. In theory, an optimum nucleus replacement should restore the mobility and reestablish the intact disc height, thereby restoring the nominal stresses and strains of the collagen fibers in the annulus. This seems to be a superior situation when compared with a disc left without augmentation following a discectomy.

The origin of the idea to replace the nucleus goes back to the 1950s. The first idea was to fill the nuclear cavity with polymethyl methacrylate or silicon. The first mechanical nucleus implant was suggested in 1966 by Fernstrom, who implanted a stainless steel ball as a spacer into the disc. Since that time, a variety of solutions to replace the nucleus have been developed. These different ideas can be classified into three categories mechanical nucleus devices, polymer implants, and tissue-engineered nucleus implants.

Like other implants, nucleus implants have to fulfill many mechanical and biomechanical requirements. Therefore, before being put into clinical practice, nucleus implants should be tested mechanically in static and dynamic tests. Aside from the mechanical challenges presented to the implant, the implant must reestablish the physiological biomechanics of a spinal segment. Therefore, biomechanical tests with the devices implanted into cadaveric specimens with respect to the surgical approaches for implantation should also be investigated in functional in vitro flexibility tests.

Despite the evaluation and subsequent use of several of these implants in patients, some of them have not performed successfully enough to survive on the market. Depending on the type of device, expulsion or subsidence of the implant has been identified as a problem.

Therefore, it became clear that aggressive testing is warranted. During in vitro testing, they can be subjected to complex cyclic loading with up to 100,000 load cycles. Some of the identified problems can be provoked with such in vitro tests and strategies developed to address the aforementioned issues. However, the ultimate arbiter of the implant's utility is not the biomechanical data, but rather it is still the clinical outcome.

Disclosure of Interest

None declared
Chinese Massage and acupuncture for Lumbar Disc Herniation: A Randomized Controlled Trial
Authors: Li Xiaoqun , Yang Feng , Zan Qiang , Xiaolingwang  , Wang Lei , Zhu Fengfeng
Published: May 2014

Lumbar disc herniation (LDH) is an increasing health problem. The object of the randomized controlled trial was designed to investigate the effects of Chinese massage and acupuncture for LDH. A total of 110 patients with LDH were randomly assigned to experimental group with Chinese massage and acupuncture or control group with intermediate frequency electric pulse therapy. The primary outcome was pain by the visual analog scale of pain (VASP). The secondary outcome was LDH severity by Japanese Orthopaedic Association (JOA) Score and the quality of life (QL) evaluated by the SF-36 Questionnaire. The outcomes have been assessed at baseline, 3 weeks and 3 months. The results indicated that the experimental group experienced significant reduction in VASP compared with control group ( p < 0.001). The reduction in pain was significantly greater; as for the JOA Score and QL, the experimental group was effective after the interventions and in the follow-up assessment ( p < 0.001). These findings suggest that Chinese massage and acupuncture may be a beneficial complementary and alternative therapy for LDH.

Disclosure of Interest

None declared
Using multiscale preconditioning to accelerate the convergence of iterative molecular calculations
Authors: Tempkin Jeremy O. B. , Qi Bo , Saunders Marissa G. , Roux Benoit , Dinner Aaron R. , Weare Jonathan
Published: May 2014

Iterative procedures for optimizing properties of molecular models often converge slowly owing to the computational cost of accurately representing features of interest. Here, we introduce a preconditioning scheme that allows one to use a less expensive model to guide exploration of the energy landscape of a more expensive model and thus speed the discovery of locally stable states of the latter. We illustrate our approach in the contexts of energy minimization and the string method for finding transition pathways. The relation of the method to other multilevel simulation techniques and possible extensions are discussed.
Multianalyte biosensor based on pH-sensitive ZnO electrolyte–insulator–semiconductor structures
Authors: Haur Kao Chyuan , Chen Hsiang , Ling Lee Ming , Chun Liu Che , Ueng Herng-Yih , Cheng Chu Yu , Jie Chen Yu , Ming Chang Kow
Published: May 2014

Multianalyte electrolyte–insulator–semiconductor (EIS) sensors with a ZnO sensing membrane annealed on silicon substrate for use in pH sensing were fabricated. Material analyses were conducted using X-ray diffraction and atomic force microscopy to identify optimal treatment conditions. Sensing performance for various ions of Na+, K+, urea, and glucose was also tested. Results indicate that an EIS sensor with a ZnO membrane annealed at 600 °C exhibited good performance with high sensitivity and a low drift rate compared with all other reported ZnO-based pH sensors. Furthermore, based on well-established pH sensing properties, pH-ion-sensitive field-effect transistor sensors have also been developed for use in detecting urea and glucose ions. ZnO-based EIS sensors show promise for future industrial biosensing applications.
Perturbative description of the fermionic projector: Normalization, causality, and Furry's theorem
Authors: Finster Felix , Tolksdorf Jürgen
Published: May 2014

The causal perturbation expansion of the fermionic projector is performed with a contour integral method. Different normalization conditions are analyzed. It is shown that the corresponding light-cone expansions are causal in the sense that they only involve bounded line integrals. For the resulting loop diagrams we prove a generalized Furry theorem.
Statistics of reversible transitions in two-state trajectories in force-ramp spectroscopy
Authors: Diezemann Gregor
Published: May 2014

A possible way to extract information about the reversible dissociation of a molecular adhesion bond from force fluctuations observed in force ramp experiments is discussed. For small loading rates the system undergoes a limited number of unbinding and rebinding transitions observable in the so-called force versus extension (FE) curves. The statistics of these transient fluctuations can be utilized to estimate the parameters for the rebinding rate. This is relevant in the experimentally important situation where the direct observation of the reversed FE-curves is hampered, e.g., due to the presence of soft linkers. I generalize the stochastic theory of the kinetics in two-state models to the case of time-dependent kinetic rates and compute the relevant distributions of characteristic forces. While for irreversible systems there is an intrinsic relation between the rupture force distribution and the population of the free-energy well of the bound state, the situation is slightly more complex if reversible systems are considered. For a two-state model, a “stationary” rupture force distribution that is proportional to the population can be defined and allows to consistently discuss quantities averaged over the transient fluctuations. While irreversible systems are best analyzed in the soft spring limit of small pulling device stiffness and large loading rates, here I argue to use the stiffness of the pulling device as a control parameter in addition to the loading rate.
On the influence of internal density variations on the linear stability characteristics of planar shear layers
Authors: Hajesfandiari A. , Forliti D. J.
Published: May 2014

Planar shear layers are known to be sensitive to density variation within the vorticity region. The current study will expand on the available literature on the stability characteristics of shear layers with density variation through consideration of new regimes in terms of the velocity and density profiles. Both spatial and spatio-temporal linear analyses were considered. In addition to the maximum density change within the shear layer, the effect of density to vorticity thickness ratio, and transverse shifting of the density profile relative to the velocity profile were considered. For a shear layer experiencing combustion, these effects relate to the relative position and thickness of the flame in the shear layer. Thick density profiles have a stabilizing affect that imposes essentially a low-pass attenuator modulation on the spatial stability. The shear layer is destabilized through the presence of an intense yet thin density reduction that overlaps with the peak vorticity profile, a condition that may be present near the shear layer origination point. The velocity ratio at which the flow transitions between absolute and convective instability is dependent on the magnitude of the density reduction in the shear layer as well as the relative density profile thickness and transverse location. The results generally indicate that the instability of the planar shear layer is strongly influenced by the characteristics of the density-weighted vorticity distribution within the shear layer.
Semi-analytical modeling of a partially wetted resonant mass sensor operated in a low-loss localized eigenmode
Authors: Peiker P. , Oesterschulze E.
Published: May 2014

We present a semi-analytical model, describing the mechanical behavior of a partially wetted low-loss microresonator, designed for mass sensing applications in both gaseous and liquid environment. In the course of this detailed modeling, realistic boundary conditions have been implemented, and the impact of the support structure on the spectral behavior of the resonator has been investigated. We proof the existence of localized eigenmodes, in spite of the diminishing clamping of the resonator, considering higher modes of the resonator/support system. The quality factor of the partially wetted resonator was evaluated including various types of damping mechanisms. The quantification of the detection limit is the key to optimize the geometry of this sensor type.
Three dimensional magnetohydrodynamic simulation of linearly polarised Alfven wave dynamics in Arnold-Beltrami-Childress magnetic field
Authors: Tsiklauri D.
Published: May 2014

Previous studies (e.g., Malara et al., Astrophys. J. 533, 523 (2000)) considered small-amplitude Alfven wave (AW) packets in Arnold-Beltrami-Childress (ABC) magnetic field using WKB approximation. They draw a distinction between 2D AW dissipation via phase mixing and 3D AW dissipation via exponentially divergent magnetic field lines. In the former case, AW dissipation time scales as S1∕3 and in the latter as log(S), where S is the Lundquist number. In this work, linearly polarised Alfven wave dynamics in ABC magnetic field via direct 3D magnetohydrodynamic (MHD) numerical simulation is studied for the first time. A Gaussian AW pulse with length-scale much shorter than ABC domain length and a harmonic AW with wavelength equal to ABC domain length are studied for four different resistivities. While it is found that AWs dissipate quickly in the ABC field, contrary to an expectation, it is found the AW perturbation energy increases in time. In the case of the harmonic AW, the perturbation energy growth is transient in time, attaining peaks in both velocity and magnetic perturbation energies within timescales much smaller than the resistive time. In the case of the Gaussian AW pulse, the velocity perturbation energy growth is still transient in time, attaining a peak within few resistive times, while magnetic perturbation energy continues to grow. It is also shown that the total magnetic energy decreases in time and this is governed by the resistive evolution of the background ABC magnetic field rather than AW damping. On contrary, when the background magnetic field is uniform, the total magnetic energy decrease is prescribed by AW damping, because there is no resistive evolution of the background. By considering runs with different amplitudes and by analysing the perturbation spectra, possible dynamo action by AW perturbation-induced peristaltic flow and inverse cascade of magnetic energy have been excluded. Therefore, the perturbation energy growth is attributed to a new instability. The growth rate appears to be dependent on the value of the resistivity and the spatial scale of the AW disturbance. Thus, when going beyond WKB approximation, AW damping, described by full MHD equations, does not guarantee decrease of perturbation energy. This has implications for the MHD wave plasma heating in exponentially divergent magnetic fields.
Molybdenum as a contact material in zinc tin oxide thin film transistors
Authors: Hu W. , Peterson R. L.
Published: May 2014

Amorphous oxide semiconductors are of increasing interest for a variety of thin film electronics applications. Here, the contact properties of different source/drain electrode materials to solution-processed amorphous zinc tin oxide (ZTO) thin-film transistors are studied using the transmission line method. The width-normalized contact resistance between ZTO and sputtered molybdenum is measured to be 8.7 Ω-cm, which is 10, 20, and 600 times smaller than that of gold/titanium, indium tin oxide, and evaporated molybdenum electrodes, respectively. The superior contact formed using sputtered molybdenum is due to a favorable work function lineup, an insulator-free interface, bombardment of ZTO during molybdenum sputtering, and trap-assisted tunneling. The transfer length of the sputtered molybdenum/ZTO contact is 0.34 μm, opening the door to future radio-frequency sub-micron molybdenum/ZTO thin film transistors.
Spin transport and precession in graphene measured by nonlocal and three-terminal methods
Authors: Dankert André , Kamalakar Mutta Venkata , Bergsten Johan , Dash Saroj P.
Published: May 2014

We investigate the spin transport and precession in graphene by using the Hanle effect in nonlocal and three-terminal measurement geometries. Identical spin lifetimes, spin diffusion lengths, and spin polarizations are observed in graphene devices for both techniques over a wide range of temperatures. The magnitude of the spin signals is well explained by spin transport models. These observations rules out any signal enhancements or additional scattering mechanisms at the interfaces for both geometries. This validates the applicability of both the measurement methods for graphene based spintronics devices and their reliable extractions of spin parameters.
On the limits of uniaxial magnetic anisotropy tuning by a ripple surface pattern
Authors: Arranz Miguel A. , Colino Jose M. , Palomares Francisco J.
Published: May 2014

Ion beam patterning of a nanoscale ripple surface has emerged as a versatile method of imprinting uniaxial magnetic anisotropy (UMA) on a desired in-plane direction in magnetic films. In the case of ripple patterned thick films, dipolar interactions around the top and/or bottom interfaces are generally assumed to drive this effect following Schlömann's calculations for demagnetizing fields of an ideally sinusoidal surface [E. Schlömann, J. Appl. Phys. 41, 1617 (1970)]. We have explored the validity of his predictions and the limits of ion beam sputtering to induce UMA in a ferromagnetic system where other relevant sources of magnetic anisotropy are neglected: ripple films not displaying any evidence of volume uniaxial anisotropy and where magnetocrystalline contributions average out in a fine grain polycrystal structure. To this purpose, the surface of 100 nm cobalt films grown on flat substrates has been irradiated at fixed ion energy, fixed ion fluency but different ion densities to make the ripple pattern at the top surface with wavelength Λ and selected, large amplitudes (ω) up to 20 nm so that stray dipolar fields are enhanced, while the residual film thickness t = 35–50 nm is sufficiently large to preserve the continuous morphology in most cases. The film-substrate interface has been studied with X-ray photoemission spectroscopy depth profiles and is found that there is a graded silicon-rich cobalt silicide, presumably formed during the film growth. This graded interface is of uncertain small thickness but the range of compositions clearly makes it a magnetically dead layer. On the other hand, the ripple surface rules both the magnetic coercivity and the uniaxial anisotropy as these are found to correlate with the pattern dimensions. Remarkably, the saturation fields in the hard axis of uniaxial continuous films are measured up to values as high as 0.80 kG and obey a linear dependence on the parameter ω2/Λ/t in quantitative agreement with Schlömann's prediction for a surface anisotropy entirely ruled by dipolar interaction. The limits of UMA tuning by a ripple pattern are discussed in terms of the surface local angle with respect to the mean surface and of the onset of ripple detachment.
Grid-connected photovoltaic converters: Topology and grid interconnection
Authors: Ngo Tuan , Santoso Surya
Published: May 2014

With the advances in high power converter technologies, photovoltaic (PV) power has been integrated into the utility system in greater pace in recent years. This paper aims to provide a broad overview of the various grid-connected PV system configurations and their power converter technologies for applications in single- and three-phase utility power systems. Grid-connected PV systems presented include module-integrated, string, and centralized configurations. Single- and three-phase power converters discussed include full-bridge (with an additional switch in the DC link and back-to-back IGBT on the AC terminals), and neutral point clamped converters. The synchronization techniques for grid-connected PV applications are discussed in this paper. An improved method to detect the grid frequency and voltage magnitude for single-phase system is introduced. More importantly, harmonic distortions resulting from the operation of grid-connected photovoltaic systems are addressed and analyzed. Methods for reducing harmonic currents using three types of passive filters, L, LC, and LCL, are presented. The LCL-filter design guidelines for a specific PV system are presented in detail. The effectiveness of these filters is demonstrated on 3 kW and 50 kW photovoltaic systems.
Determining the elastic properties of aptamer-ricin single molecule multiple pathway interactions
Authors: Wang Bin , Park Bosoon , Kwon Yongkuk , Xu Bingqian
Published: May 2014

We report on the elastic properties of ricin and anti-ricin aptamer interactions, which showed three stable binding conformations, each of which has its special elastic properties. These different unbinding pathways were investigated by the dynamic force spectroscopy. A series-spring model combining the worm-like-chain model and Hook's law was used to estimate the apparent spring constants of the aptamer and linker molecule polyethylene glycol. The aptamer in its three different unbinding pathways showed different apparent spring constants. The two reaction barriers in the unbinding pathways also influence the apparent spring constant of the aptamer. This special elastic behavior of aptamer was used to distinguish its three unbinding pathways under different loading rates. This method also offered a way to distinguish and discard the non-specific interactions in single molecule experiments.