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BACKGROUND:Among the pathogenic factors of cervical spondylosis,herniation of the intervertebral disc,dislocation of the facet joint and the stenosis of the intervertebral foramen are important factors leading to symptoms in patients.Moreover,inappropriate manipulation may aggravate the possibility of cervical disc rupture,leading to exacerbation of symptoms in patients. OBJECTIVE:To compare the effect between sagittal cervical manipulation and traditional cervical rotation manipulation on the area of the intervertebral disc,facet joint and intervertebral foramen at the operative segment by the finite element analysis. METHODS:The neck CT data of a male volunteer with a normal neck were selected and imported into Mimics 17.0 three-dimensional reconstruction software.Geo-magic Studio 12.0,Solidworks 2017 and Ansys Workbench 17.0 software were used for the construction of the finite element model of cervical vertebrae(C3-6)including intervertebral disc and articular cartilage.The lower end plate of the C5 vertebral body was fixed.A uniformly distributed vertical downward 50 N load was applied on the upper surface of the upper vertebral body(C3).The stress,deformation and deformation direction of the C4-5 intervertebral disc,joint capsule stress,the displacement of facet joints and the area of bilateral intervertebral foramen were compared between sagittal cervical manipulation and traditional rotation reduction. RESULTS AND CONCLUSION:(1)When using the rotation technique,the maximum normal equivalent stress(von Mises stress)of the C4-5 disc was 8.06 MPa;the total deformation was 1.05 mm,and the fiber ring expanded to the left and outside.When using the sagittal tip lifting technique,the maximum normal equivalent stress(von Mises stress)of the C4-5 disc was 2.60 MPa;the total deformation was 0.90 mm,and the fiber ring expanded to the left and back.Compared with the rotation technique,the pressure of the cervical manipulation technique on the disc was less(about 32.3%of the rotation technique),and the deformation degree of the disc was also light(about 85.7%of the rotation technique).(2)When the rotation technique was used,the maximum stresses of the left and right articular capsule ligaments were 0.37 MPa and 1.69 MPa,respectively.The overall displacement of the facet joint was 2.21 mm.The area of the right intervertebral foramen decreased by about 3.8%and the area of the left intervertebral foramen increased by about 0.9%.When the sagittal end lifting manipulation was performed,the maximum stresses of the left and right articular capsule ligaments were 0.27 MPa and 1.70 MPa,respectively;the overall displacement of the facet joint was 1.63 mm;the area of the right intervertebral foramen increased by about 2.6%,and the area of the left intervertebral foramen decreased by about 0.9%.Compared with rotation manipulation,sagittal end lifting manipulation had fewer changes in the displacement of facet joint,joint capsule stress and intervertebral foramen area,so it was safer to operate.(3)In conclusion,compared with cervical rotation manipulation,sagittal end lifting manipulation has fewer changes in facet joint displacement,intervertebral disc stress/deformation degree,joint capsule stress,and foraminal area.In clinical practice,more appropriate manipulation should be selected based on biomechanical results after an accurate assessment of patients'conditions.
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Objective@#To describe the secular trend of BMI and its consistency with self-rated BMI status in Chinese children and adolescents, and to further investigate the related factors affecting self-rated BMI,so as to provide a scientific reference for interventional measures.@*Methods@#A total of 6 238 children and adolescents aged 6-18 years were selected according to date from Chinese Health and Nutrition Svrvey during 2000-2015 and the criteria from National Health Commission of China.The Lambda-Mu-Sigma method(LMS) and Kappa consistency test were, respectively, applied to describe the percentiles for BMI and its agreement with self-rated BMI status. Multinomial Logistic model was used to assess the related factors influencing self-rated BMI status.@*Results@#P50 and P85 percentiles showed an increasing trend, especially the increase of high percentile of BMI. Regardless of age and sex, the measured and self-rated BMI showed low agreement. More than 50% of over-weighted or underweighted children perceived themselves as normal-weight, and about 1/4 of normal weight students misclassified themselves as abnormal in weight. Urban boys were more likely to evaluate themselves as underweight [OR(95%CI) =1.43(1.18-1.73)]. Boys who favored popular showed[OR(95%CI)=1.80(1.23-2.55) and cartoon [OR (95%CI) =1.39(1.00-1.96)] were more likely to consider themselves as overweight. Girls in the older age group [OR (95%CI)=2.74(2.08-3.61)] and urban [1.53(1.21-1.94)] who favored popular programs [OR(95%CI) =1.74(1.27-2.38)] were more likely to perceived themselves as overweight. But girls who like anime/cartoons were more likely to think they were underweight [OR(95%CI)=1.78(1.33-2.40)].@*Conclusion@#The trend of BMI has shown an increasing trend in the past decade and it demonstrated a large bias with perceived BMI. Age, area and type of video were significant factors that influenced the self-rated BMI status.