| Varicosity is common vascular disease of lower limb.The pressure compression stockings on leg gradually diminishes by ankle up,which can promote blood of leg's veins to flow to heart,and prevent or alleviate varicosity and venous thrombosis.By simulating the process of wearing compression stockings and analyzing the mechanical interaction between stockings and the leg including the influence of compression stockings on the vessel,the function of hosiery can be better explored,which is helpful to further optimization of the design of medical compression stockings.In order to analyze the mechanical changes in the process of wearing hosiery,three-dimensions dynamic simulation was carried out about the process.First of all,a3 D finite element model of elastic leg was established through the CT scans of the subject's leg with using MIMICS system to restruct the 3D model of leg,and then the3 D finite element models of compression stockings were established according to the parameter of them.And then the dynamic process of the leg with compression stockings of different grade was simulated to analyze the mechanical functions between stockings and leg including stress and pressure on the leg caused by hosiery,deformation of leg and hosiery,and internal stress and the displacement of leg's each section.The comparison between the simulated contact pressure and the measured pressure shows that the model is effective in simulating the distribution of contact pressure.The compression of the leg by the hosiery results in the internal stress and displacement of the leg,and the closer the leg's part was to the bone,the greater the stress was,and the more soft tissue and the farther away from the bone structure,the easier the deformation of part was.For exploring the internal stress transfer mechanism of the leg and analyzing the deformation of layers of soft tissues and vessels in the leg under the compression of hosiery,the leg's sections under the action of stockings were simulated in two dimensions.The 2D finite element models of leg's sections were established according to the scanning results and the sectional anatomy of the leg with applying the measured actual pressure of the hosiery on the leg's sections as the load on the models' surface,and then analyze the distribution and transfer of internal stress in sections,and explore the influence of different pressure on layers of soft tissue and vessel.The displacement and the change of inner cavity of main arteries and veins are especially analyzed in depth.It was found that the stress around vessels is much larger than that surrounding muscle and adipose tissue by simulating the stress on the section of the leg,and the stress in fat layer will be reduced greatly when transfer to the muscle layer.Both arteries and veins tended to be flattened and the internal cavity becomes narrowed due to compression.And the impact of medical compression stockings on the deep veins and arteries is greater than that of the superficial veins.In addition,by observing the shape changes and displacement of the internal lumen of each vessel in the longitudinal direction of the leg,it was found that the degree of contraction of the internal lumen of the vessel at ankle was slightly greater than that at calf and greater than that at thigh.In aspect of displacement,the displacement of vessel at calf was slightly larger than that at ankle,and the displacement of superficial veins at thigh was larger,and the deep veins' displacement at thigh was smaller due to the position change.In this study,the mechanical interaction between the tissues of leg and the compression stockings was simulated from the perspectives of 3D and 2D with the finite element analysis method,and the effect of hosiery on arteries and veins was added particularly.The results obtained can provide a reference for the further exploration of the medical function of the hosiery,as well as a theoretical basis for it's further optimization. |
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