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BACKGROUND:Creation of a precise finite element model is an important basis for the finite element mechanical analysis of the spine. The reports on the precise finite element model are less. OBJECTIVE:To create L 3-L 5 lumbar three-dimensional finite element model and validate this model with normal CT data. METHODS:A 39-year-old male healthy volunteer with the height of 175 cm and weighted 65 kg was selected, then the L 3-L 5 lumbar spines were scanned with 16 row spiral CT to obtain 101 CT images with the thickness of 1.25 mm. Solid geometric model was established with Geomagic9.0 software, then determined the unit type, divided the finite element mesh, and established the finite element model for loading and calculating. RESULTS AND CONCLUSION:A L 3-L 5 lumbar three-dimensional finite element model was established. It included 213 736 nodes and 799 779 elements. The ranges of motion of L 3-L 4 and L 4-L 5 segments of the model were consistent with cadaveric biomechanical testing results, verified the effectiveness of the model, so the model could be used for experimental research.
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BACKGROUND:MATLAB has capabilities of large numerical calculation, mathematical drawing and simple finite element analysis. It can establish models rapidly and can be able to identify the grayscale with BMP and JPG format, and it can directly transform the identified data into ANSYS finite element software-readable format, thus avoiding personal error produced by the repositioning and secondary treatment in the Autocad software. OBJECTIVE:To find a simple, convenient and accurate method to construct the model of lumber fusion and to analyze the biomechanics of lumbar motion segment after lumbar fusion. METHODS:Lamel ar CT and Matlab (Matrix Laboratory) scientific computing software combining Ansys finite element software was used to construct the models of lumber fusion. Then the models were loaded to analyze the biomechanical change of the fusion model. RESULTS AND CONCLUSION:The established models were loaded with axial, bending and stretching loads, and the biomechanical analysis showed that interbody fusion had the best stability among al the fusion models. Combined with joint fusion, the axial displacements of interbody, rear side and rear fusion models were decreased by 5%, 1%and 4%than that of simple interbody fusion, posterolateral fusion and posterior fusion models. Under the stretch-buckling load conditions, the rotation angles were reduced by 23%, 11%and 45%. Stress concentration to the fusion parts showed fusion block could increase the load displacement. The technology of lamel ar CT, Matlab software and Ansys finite element software can accelerate the construction of lumber fusion model and make the model more accurate. Facet joint fusion combined with interbody fusion, posterolateral fusion and posterior fusion can get better lumbar stability, and this increased stability is more significant in the rear fusion. Stress distribution of posterior fusion is more reasonable.
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BACKGROUND:The monocyte chemoattactant protein-1 gene polymorphism is associated with spinal tuberculosis susceptibility. OBJECTIVE:To investigate the association between serum monocyte chemoattactant protein-1 expression level and spinal tuberculosis susceptibility in Han population of Hunan province. METHODS:The patients with spinal tuberculosis and the healthy volunteers were recruited in Xiangya Hospital of Central South University from December 2004 to December 2010. The empty peripheral venous blood 2 mL were col ected from the subjects in early morning, then the monocyte chemoattactant protein-1-362 genotypes were detected by polymerase chain reaction and DNA sequencing technology. And the serum monocyte chemoattactant protein-1 level was detected by enzyme linked immunosorbent assay technology. The ROC curve was used for diagnostic tests to calculate diagnostic threshold value of serum monocyte chemoattactant protein-1 level to spinal tuberculosis susceptibility, and to analyze the diagnostic titer. RESULTS AND CONCLUSION:208 patients with spinal tuberculosis and 210 healthy volunteers were included. The serum monocyte chemoattactant protein-1 level of the spinal tuberculosis patients was significantly higher than that of the healthy volunteers [(134.58±51.63) ng/L vs. (39.18±17.45) ng/L, P<0.01]. The serum monocyte chemoattactant protein-1 level could not be affected by gender, but over-expressed in patients with monocyte chemoattactant protein-1-362-CC genotypes. The serum monocyte chemoattactant protein-1 level higher than 101.65 ng/L indicated that the patients might suffered from spinal tuberculosis (sensitivity:85.5%, specificity:94.3%, Youden index:0.799, area under curve of ROC:0.946, 95%confidence interval:0.916-0.975, P<0.01). The serum monocyte chemoattactant protein-1 level may be associated with spinal tuberculosis susceptibility in Han population of Hunan province, highly expressed serum monocyte chemoattactant protein-1 can be used as one of the indicators for the diagnosis of spinal tuberculosis.
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BACKGROUND:Cervical decompression and fusion internal fixation wil accelerate adjacent segment disc degeneration, and it is not clear whether single segment instaibility can increase the adjacent segment disc degeneration. OBJECTIVE:To study the changes of morphology, proteoglycan and col agen type Ⅱ in the adjacent intervertebral disc of the cervical instability models. METHODS:Sixteen New Zealand white rabbits were divided into two groups randomly, with eight rabbits in the control group and eight rabbits in the model group. The animal cervical instability models were made by destroyed partly annulus fibrosus and absorbed C 5/6 nucleus pulposus through anterior cervical puncture. After 12 weeks, the animal models were tested by X-ray film. Al rabbits were sacrificed and 10 mg nucleus pulposus of the intervertebral discs of C 4/5 cut from sagittal plane were harvested and stored under 0 ℃. The content of proteoglycan in nucleus pulposus was tested with phloroglucinol method. Then, the paraffin sections of intervertebral disc tissues were taken for hematoxylin-eosin staining and SABC immunohistochemical staining. RESULTS AND CONCLUSION:The notochord cells of C4/5 intervertebral discs in the experimental group was decreased, and being replaced by fibroblast-like cells. Round chondrocytes could be seen occasional y and intervertebral discs annulus fibrosus became rough and arranged disorderly, the hyaline degeneration and pigmentation were observed as wel as the fibrochondrocytes, and there was a gap between inner and outer annulus fibrosus. The content of proteoglycan was decreased in the nucleus pulposus, and there was significant difference between two groups. The col agen type Ⅱ in the degenerative disc nucleus pulposus and annulus fibrosus of the experimental group was lower than that of the control group. Cervical instability can lead to adjacent intervertebral disc degeneration with the morphological changes and decreased content of proteoglycan and col agen type Ⅱ.
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BACKGROUND:The incidence rate of cervical abnormalities of the patients with skeletal class Ⅱ and normal occlusion has been studied abroad, but the researches on the incidence of cervical abnormalities in different malocclusion patients is rare at home. OBJECTIVE:To observe the imaging of patients with cervical abnormalities and to statistics the incidence of cervical abnormalities in different malocclusion patients through analyzing the lateral cephalogram of different malocclusion patients. METHODS:Skeletal class Ⅱ group was consisted of 93 patients, 41 male (aged 18-40 years) and 52 female (aged 22-35 years), with the A point-nasion-B point angle>5°. Class Ⅰ group was consisted of 45 patients, 31 female (aged 20-36 years) and 14 male (aged 17-38 years), with the 1°
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10.3969/j.issn.2095-4344.2013.26.014