Prevalence of Low Back Pain in Computer Users of Lahore, Pakistan

Low back pain is the most occurring body disorder and most important reasons of disability in the advanced states. Numerous structures in the backbone may cause low back pain which includes ligaments that join vertebral column, outer bers of the annulus fibrosis, facet joints, vertebral periosteum, paravertebral muscu-lature and fascia.

BONE MORPHOGENETIC PROTEIN-2 INFLUENCE ON METABOLIC ACTIVITY AND PROTEOGLYCAN SYNTHESIS BY INTERVERTEBRAL DISC CELLS

Modern therapeutic strategies for intervertebral disc repair mainly focus on targeting molecular pathways of extracel-lular matrix degeneration. Anabolic strategies for regeneration are aimed to increase production of major extracellular molecules. Members of TGF-b superfamily proteins, particularly the bone morphogenetic proteins (BMP) have a high regenerative potential regarding the mesenchymal cells. The goal of this study is to study production of proteoglycans by the intervertebral disc cells under the influence of bone morphogenetic protein 2.Material and methods. The experiment was carried out on the cell cultures derived from the annulus fibrosis cells and nucleus pulposus cells of the human intervertebral disc. We studied cell livability, metabolic activity and proteoglycan expression. Cell livability was assessed using the trypan blue staining. Alamar blue test was used for the estimation of metabolic activity. Amount of sulfated glycosaminoglycans was assessed using the assay based on the reaction with 1,9-Dimethylmethylene Blue.Results. Cultivation with bone morphogenetic protein 2 in different concentrations did not decrease livability of the cells. Study cell cultures with application of bone morphogenetic protein 2 in different concentrations showed significant increase in metabolic activity and proteoglycan synthesis by the annulus fibrosis cells. Despite the relative increase in the number of the nucleus pulposus cells treated with the bone morphogenetic protein 2, the differences in metabolic and synthetic activity compared with control group was not significant. Conclusion. The bone morphogenetic protein 2 has an anabolic effect towards the intervertebral disc cells, particularly in the production of proteoglycans by the annulus fibrosis cells.

Quantifying Variability in Lumbar L4-L5 Soft Tissue Properties for Use in Finite-Element Analysis

Soft tissue structures of the L4-L5 level of the human lumbar spine are represented in finite-element (FE) models, which are used to evaluate spine biomechanics and implant performance. These models typically use average properties; however, experimental testing reports variation up to 40% in ligament stiffness and even greater variability for annulus fibrosis (AF) properties. Probabilistic approaches enable consideration of the impact of intersubject variability on model outputs. However, there are challenges in directly applying the variability in measured load–displacement response of structures to a finite-element model. Accordingly, the objectives of this study were to perform a comprehensive review of the properties of the L4-L5 structures and to develop a probabilistic representation to characterize variability in the stiffness of spinal ligaments and parameters of a Holzapfel–Gasser–Ogden constitutive material model of the disk. The probabilistic representation was determined based on direct mechanical test data as found in the literature. Monte Carlo simulations were used to determine the uncertainty of the Holzapfel–Gasser–Ogden constitutive model. A single stiffness parameter was defined to characterize each ligament, with the anterior longitudinal ligament (ALL) being the stiffest, while the posterior longitudinal ligament and interspinous ligament (ISL) had the greatest variation. The posterior portion of the annulus fibrosis had the greatest stiffness and greatest variation up to 300% in circumferential loading. The resulting probabilistic representation can be utilized to include intersubject variability in biomechanics evaluations.

Stress - Strain Response of the Human Spine Intervertebral Disc As an Anisotropic Body. Mathematical Modeling and Computation

The paper deals with the biomechanical investigation on the human lumbar intervertebral disc under the static load. The disc is regarded as a two - phased ambient consisting of a fibrous outer part called annulus fibrosis and a liquid inner part nucleus pulposus. Due to the fibrous structure, the annulus fibrosis can be treated by using a special case of anisotropy - transversal isotropy.In the paper the corresponding tensor of material constants is derived. The tensor consequently incomes to the constitutive equations determining the stress - strain relation in the material. In order to study the mechanical behaviour the disc is observed within the motion segment, the basic unit for motion tracing. The motion segment involves two neighbouring vertebrae and the intervertebral disc between them that connect them both.When constitutive equations are accomplished, they can be incorporated in the finite element analysis. The illustrative example of the intervertebral disc L2/L3, the disc between the second and the third lumbar vertebrae the lumbar part of spine, with its computer implementation is performed. Finally the comparison of the results of using anisotropic and homogenized approach is provided. The comparison illustrates the eligibility of such a kind of approach.