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BACKGROUND: The static sitting position contributes to increased pressure on the lumbar intervertebral disc, which can lead to dehydration and decreased disc height. OBJECTIVE: To systematically investigate the of sitting posture on degeneration of the lumbar intervertebral disc. MATERIALS AND METHODS: One researcher carried out a systematic literature search of articles with no language or time limits. Studies from 2006 to 2018 were found. The searches in all databases were carried out on January 28, 2022, using the following databases: Pubmed, Scopus, Embase, Cochrane, and Physiotherapy Evidence Database (PEDro) databases, and for the grey literature: Google scholar, CAPES Thesis and Dissertation Bank, and Open Grey. The acronym PECOS was used to formulate the question focus of this study: P (population) - male and female subjects; E (exposure) - sitting posture; C (comparison) - other posture or sitting posture in different periods; O (outcomes) - height and degeneration of the lumbar intervertebral disc(s), imaging exam; and S (study) - cross-sectional and case control. RESULTS: The risk of bias was in its moderate totality in its outcome: height and degeneration of the lumbar intervertebral disc(s) - imaging. Of the four selected studies, three found a decrease in the height of the disc(s) in sitting posture. CONCLUSION: The individual data from the manuscripts suggest that the sitting posture causes a reduction in the height of the lumbar intervertebral disc. It was also concluded that there is a need for new primary studies with a more in-depth design and sample size.

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Background: Clinical in-stent restenosis (CISR) is the main limitation of coronary angioplasty with stent implantation. Objective: Describe the clinical and angiographic characteristics of CISR and the outcomes over a minimum follow-up of 12 months after its diagnosis and treatment. Methods: We analyzed in 110 consecutive patients with CISR the clinical presentation, angiographic characteristics, treatment and combined primary outcomes (cardiovascular death, nonfatal acute myocardial infarction [AMI]) and combined secondary (unstable angina with hospitalization, target vessel revascularization and target lesion revascularization) during a minimal follow-up of one year. Results: Mean age was 61 ± 11 years (68.2% males). Clinical presentations included acute coronary syndrome (ACS) in 62.7% and proliferative ISR in 34.5%. CISR was treated with implantation of drug-eluting stents (DES) in 36.4%, Bare Metal Stent (BMS) in 23.6%, myocardial revascularization surgery in 18.2%, balloon angioplasty in 15.5% and clinical treatment in 6.4%. During a median follow-up of 19.7 months, the primary outcome occurred in 18 patients, including 6 (5.5%) deaths and 13 (11.8%) AMI events. Twenty-four patients presented a secondary outcome. Predictors of the primary outcome were CISR with DES (HR = 4.36 [1.44–12.85]; p = 0.009) and clinical treatment for CISR (HR = 10.66 [2.53–44.87]; p = 0.001). Treatment of CISR with BMS (HR = 4.08 [1.75–9.48]; p = 0.001) and clinical therapy (HR = 6.29 [1.35–29.38]; p = 0.019) emerged as predictors of a secondary outcome. Conclusion: Patients with CISR present in most cases with ACS and with a high frequency of adverse events during a medium-term follow-up. .

Fundamento: A Reestenose Intrastent Clínica (RISC) é a principal limitação da angioplastia coronariana com implante de stent. Objetivo: Descrever as características clínicas e angiográficas da RISC e os desfechos em seguimento de pelo menos doze meses após seu diagnóstico e tratamento. Métodos: Em 110 pacientes consecutivos com RISC, analisaram-se a apresentação clínica, as características angiográficas, o tratamento e os desfechos primário combinado (morte cardiovascular, Infarto Agudo Miocárdio não fatal [IAM]) e secundário combinado (angina instável com internação, revascularização de vaso alvo e lesão alvo) em seguimento mínimo de um ano. Resultados: A média de idade da amostra foi de 61 ± 11 anos (68,2% do sexo masculino). A apresentação clínica foi como Síndrome Coronariana Aguda (SCA) em 62,7%, com RIS proliferativa em 34,5% dos casos. O tratamento realizado foi o implante de Stent Farmacológico (SF) em 36,4%; de Stent Não Farmacológico (SNF) em 23,6%; cirurgia de revascularização em 18,2%; angioplastia por balão em 15,5%; e tratamento clínico em 6,4%. Com seguimento mediano de 19,7 meses, o desfecho primário ocorreu em 18 pacientes, com seis (5,5%) óbitos e 13 (11,8%) IAM, e o secundário em 24 pacientes. Foram preditores de desfecho primário a RISC em SF (HR = 4,36; [1,44 - 12,85], p = 0,009) e o tratamento clínico da RISC (HR = 10,66, [2,53 - 44,87], p = 0,001). O tratamento da RISC com SNF (HR = 4,08 [1,75 - 9,48], p = 0,001) e tratamento clínico (HR = 6,29 [1,35 - 29,38], p = 0,019) foram preditores do desfecho secundário. Conclusão: A RISC se apresenta como SCA na maioria dos casos e os pacientes apresentam elevada frequência de eventos adversos durante o seguimento de médio prazo. .

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Low back pain is a major physical and socioeconomic problem. Degeneration of the intervertebral disc and especially that of nucleus pulposus (NP) has been linked to low back pain. In spite of much research focusing on the NP, consensus among the research community is lacking in defining the NP cell phenotype. A consensus agreement will allow easier distinguishing of NP cells from annulus fibrosus (AF) cells and endplate chondrocytes, a better gauge of therapeutic success, and a better guidance of tissue-engineering-based regenerative strategies that attempt to replace lost NP tissue. Most importantly, a clear definition will further the understanding of physiology and function of NP cells, ultimately driving development of novel cell-based therapeutic modalities. The Spine Research Interest Group at the 2014 Annual ORS Meeting in New Orleans convened with the task of compiling a working definition of the NP cell phenotype with hope that a consensus statement will propel disc research forward into the future. Based on evaluation of recent studies describing characteristic NP markers and their physiologic relevance, we make the recommendation of the following healthy NP phenotypic markers: stabilized expression of HIF-1α, GLUT-1, aggrecan/collagen II ratio >20, Shh, Brachyury, KRT18/19, CA12, and CD24.

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OBJECTIVE: Anterior-approach total disk replacement (TDR) devices are thought to retain close to so-called normal range of motion (ROM); however, they are also inherently unstable due to resection of the anterior longitudinal ligament and annulus. This instability/laxity is manifested as increased neutral zone (NZ) motion. The XL-TDR device (NuVasive, Inc., San Diego, California, United States) is implanted through a lateral approach that preserves the anterior ligamentous and annular structures. This potentially makes the XL-TDR device more stable than those delivered anteriorly. This study investigates XL-TDR biomechanical features in a cadaveric model. METHODS: Biomechanical evaluation consisting of nondestructive multidirectional testing was performed with the hybrid protocol on six fresh-frozen cadaveric specimens (L2-S1). Motion segment kinematics were obtained using an optoelectronic system. Test conditions were (1) intact spine, (2) XL-TDR at L4-L5, and (3) XL-TDR at L4-L5 with anterior annulus/ligament resected. ROM and NZ were calculated for each condition in each loading direction (flexion-extension total, flexion alone, extension alone, lateral bending, and axial rotation). RESULTS: Insertion of the XL-TDR device decreased ROM with respect to intact in all directions. NZ in all directions was not statistically different from intact (p < 0.05), although there was a trend toward decreased NZ in flexion (p = 0.078). Removing the anterior ligament/annulus increased ROM significantly with respect to the XL-TDR condition in all directions (p < 0.003). NZ also increased, with the most significant changes in extension, lateral bending, and axial rotation (p < 0.002). CONCLUSIONS: The kinematics of XL-TDR have demonstrated that the retention of the anterior ligament/annulus has a significant stabilizing effect, diminishing ROM to less than intact, with a more controlled motion (more natural NZ). Removing the anterior ligament/annulus illustrated its stabilizing role, with ROM and NZ increasing significantly. Future studies will investigate the potential benefit of controlled XL-TDR motion on facet kinematics that may have clinical implications related to limiting facet degeneration.

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STUDY DESIGN: In vitro biomechanical study. OBJECTIVE: To test the hypotheses: (1) an anchored spacer device would decrease motion similarly to a plate-spacer construct, and (2) the anchored spacer would achieve a similar reduction in motion when placed adjacent to a previously fused segment. SUMMARY OF BACKGROUND DATA: An anchored spacer device has been shown to perform similar to the plate-spacer construct in previous biomechanical evaluation. The prevalence of adjacent segment disease after fusion is well established in the literature.There is currently no evidence supporting the use of an anchored interbody spacer device adjacent to a previous fusion. METHODS: Eight human cervical spines (age: 45.1 ± 13.1 yr) were tested in moment control (±1.5 Nm) in flexion-extension, lateral bending, and axial rotation without preload. Flexion-extension was then retested under 150-N preload. Spines were tested intact and after anterior cervical discectomy and fusion (ACDF) at C4-C5 and C6-C7 with either a plate-spacer or anchored spacer construct (randomized). The specimens were tested finally with an ACDF at the floating C5-C6 segment using the anchored spacer device adjacent to the previous fusions. RESULTS: Both the plate-spacer and anchored spacer significantly reduced motion from the intact spine in flexion-extension, lateral bending, and axial rotation (P < 0.005). There was no statistically significant difference between the 2 fusion constructs in their abilities to reduce motions (P = 1.0). ACDF using the anchored spacer at the floating C5-C6 level (in between the plate-spacer and anchored spacer constructs) resulted in significant motion reductions in all modes of testing (P < 0.05). These motion reductions did not significantly differ from those of a single-level anchored-spacer construct or a single-level plated ACDF. CONCLUSION: The anchored spacer provided significant motion reductions, similar to a plated ACDF, when used as a single-level fusion construct or placed adjacent to a previously plated segment. LEVEL OF EVIDENCE: N/A.

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It is a well-known fact that computational biomechanics and mechanobiology have deserved great attention by the numerical-methods community. Many efforts and works can be found in technical literature. This work deals with the modeling of nutrients and their effects on the behavior of intervertebral discs. The numerical modeling was carried out using the Boundary ELement Method (BEM) and an axisymmetric model of the disc. Concentration and production of lactate and oxygen are modeled with the BEM. Results agree well enough with those obtained using finite elements. The numerical efforts in the domain and boundary discretizations are minimized using the BEM. Also, the effect of the calcification of the disc that causes the vascularization loss has been studied. The glucose, oxygen and lactate components behavior has been analyzed applying a mixed loading-unloading process, then allowing the study of the disc-height variations due to the degradation of the disc.

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The intervertebral disc (IVD) is a heterogeneous structure that contributes to load support and flexibility in the spine. IVD cells experience a broad range of physical stimuli under physiological conditions, including alterations in their osmotic environment. To date, the molecular mechanisms regulating the response of IVD to osmotic pressure are still not well understood. We obtained the gene expression profile of human IVD cells from NCBI and looked for potential therapeutic drug candidates. Based on microarray data, we concluded that RAP2A and GNA13 appear to have a role in response to osmotic stimuli in intervertebral discs. Using a computational bioinformatics method, we determined that thioridazine has potential as a therapeutic drug candidate for regulating osmotic pressure changes in IVD cells. We anticipate that our results will be used to generate hypotheses for laboratory, patient, and population-based studies.

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The in vivo mechanics of the annulus fibrosus of the intervertebral disc is one of biaxial rather than uniaxial loading. The material properties of the annulus are intimately linked to the osmolarity in the tissue. This paper presents biaxial relaxation experiments of canine annulus fibrosus tissue under stepwise changes of external salt concentration. The force tracings show that stresses are strongly dependent on time, salt concentration and orientation. The force tracing signature of a response to a change in strain, is one of a jump in stress that relaxes partly as the new strain is maintained. The force tracing signature of a stepwise change in salt concentration is a progressive monotonous change in stress towards a new equilibrium value. Although the number of samples does not allow any definitive quantitative conclusions, the trends may shed light on the complex interaction among the directionality of forces, strains and fiber orientation on one hand, and on the other hand, the osmolarity of the tissue. The dual response to a change in strain is understood as an immediate response before fluid flows in or out of the tissue, followed by a progressive readjustment of the fluid content in time because of the gradient in fluid chemical potential between the tissue and the surrounding solution.

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The in vivo mechanics of the annulus fibrosus of the intervertebral disc is one of biaxial rather than uniaxial loading. The material properties of the annulus are intimately linked to the osmolarity in the tissue. This paper presents biaxial relaxation experiments of canine annulus fibrosus tissue under stepwise changes of external salt concentration. The force tracings show that stresses are strongly dependent on time, salt concentration and orientation. The force tracing signature of are sponse to a change instrain, is one of a jumpin stress that relaxes partly as the new strain is maintained. The force tracing signature of a stepwise change in salt concentration is a progressive monotonous change in stress towards a new equilibrium value. Although the number of samples does not allow any definitive quantitative conclusions, the trends may shed light on the complex interaction among the directionality of forces, strains and fiber orientation on one hand, and on the other hand, the osmolarity of the tissue. The dual response to a change in strain is understood as an immediate response before fluid flows in or out of the tissue, followed by a progressive readjustment of the fluid content in time because of the gradient in fluid chemical potential between the tissue and the surrounding solution.

A mecânica in vivo do anel fibroso do disco intervertebral é baseada em carregamento biaxial ao invés de uniaxial. As propriedades materiais do anel estão intimamente ligadas à osmolaridade no tecido. O artigo apresenta experimentos de relaxação biaxiais do anel fibroso de um tecido canino sob mudanças abruptas na concentração externa de sal. A assinatura da força devido à mudança brusca de salinidade resulta em uma progressiva e monótona mudança na tensão em direção a um novo valor de equilíbrio. Embora o número de amostras não permita nenhuma conclusão quantitativa, as tendências podem abrir uma luz no entendimento das interações complexas na direção das forças, deformações e orientação das fibras por um lado e a osmolaridade do tecido por outro lado. A resposta dual devido à uma mudança na deformação é compreendida como uma resposta imediata antes do fluido escoar para dentro ou para fora do tecido, seguido de uma progressiva readaptação da quantidade de fluido notempo devido ao gradiente do potencial químico entre o tecido e a solução externa.

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A mensuracao da compressao do disco invertebral e uma das tecnicas aplicadas na analise da sobrecarga na coluna lombra.O objetivo deste trabalho foi estimar a compressao intradiscal(CI)em L5?S1 no momento final do exercicio de agachamento(AG)com peso.A amostra foi composta de 25 individuos com idade 25,8 +ou-5,3anos,estatura media 171,3+ ou- 9,9cm e peso medio 69,5+ou-13,9Kg fotografados com sobrecarga:de pe,AG com flexao minima e AG com flexao de tronco.As cargas utilizadas representaram um percentual medio do peso corporal de 25,0+ ou-7,7 por cento.Foram medidos,nas fotos,os angulos de flexao de tronco,joelho e tornozelo,utilizados como dados no aplicativo 2D STATIC STRENGTH PREDICTION PROGRAMVersion 4.2(Michigam University USA),alem de outras medidas antropometricas para estimativa da CI.Os valores estimados de CI foram comparados atravez do teste estatico Wilcoxon,o os resultados considerados significativos com p menor 5.Os resultados medios de CI na posicao em pe foi de 124,6 + ou-39,8lbs.A CI no exercicio com minima flexao de tronco foi 508,1 + ou-127,0lbs,significativamente menor que a no exercicio com flexao livre de tronco que foi de 670,3 + ou -128,7lbs.Os resultados masculinos apresentam valores medios maiores que os femininos.Mesmo exercutado corretamente, o AG aumenta significativamnete a CI,sendo fundamental a orientacao profissional na realizacao e indicacao do exercicio de AG

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