BACKGROUND:Numerical stimulation technology is a good method to analyze blood flow changes after intracranial aneurysm stenting that oftenresult in restenosis.
OBJECTIVE:To explore the hemodynamic effect of stent implantation on patient-specific intracranial aneurysm and the distribution of the wal shear stress on the stent surface.
METHODS:Brain CT data from a patient with intracranial aneurysm were extracted and optimized to establish a patient-specific intracranial aneurysm materialization model. Meanwhile, a three-dimensional model of rectangular section spiral stent was designed to develop an aneurysm model with the stent by the method of boolean operation. Then, the possibility of restenosis was analyzed based on the distribution of wal shear stress on the surface of stent model.
RESULTS AND CONCLUSION:The wal shear stress on the stent surface which was more than 40 Pa increasedalong with the increase of blood velocity and blood viscosity at the same moment. However, the wal shear stress on the stent surface which was less than 0.5 Pa decreased along with the increase of blood viscosity, and its distribution was the largest when the blood velocity was 0. This stent provides a new insight into the controling of the aneurysm growth and rupture, but the restenosis area is too large. In order to prevent restenosis, the stent need to be optimized or reselected to keep the desired shear stress values of 0.5 to 40 Pa, and meanwhile to minimize the pulsating change of wal shear stress during a cardiac cycle.

BACKGROUND:Cerebral aneurysm is a kind of mortal hemangioma, and its treatments such as endovascular embolization and clipping both cause high postoperative recurrence rate and mortality. So the stent implantation for cerebral aneurysm is coming into being. OBJECTTVE:To evaluate the hemodynamic parameters after stent implantation into cerebral aneurysm and to provide a novel feasible strategy for clinical treatment. METHODS:A retrospective analysis was preformed based on the CT image data of 11 patients with cerebral aneurysm from the Affiliated Hospital of Xinjiang Medical University. Firstly, the flexible and solid model of cerebral aneurysm was established by the MIMICS and reverse engineering. Secondly, the matching stent model was implanted into the cerebral aneurysm, and then the blood flow structure of cerebral aneurysm was analyzed by the fluid dynamics theory and the Fluent with the method of two-way flow solid coupling. Final y, comparative analysis of the kinetic parameters of cerebral aneurysm before and after implantation, including wal pressure, blood velocity, path line of the blood flow, wal shear stress, wal deformation was conducted, and blood flow characteristics after stent implantation were analyzed under different entrance velocity. RESULTS AND CONCLUSION:After implantation, the wal surface pressure was reduced about 61.1%;the blood flow velocity around the stent and the inside of the cerebral aneurysm was decelerated obviously;under setting 2 000 lines of blood flow, the number of path line of blood flow into the cerebral aneurysm reduced about 75.0%, the maximum wal shear stress decreased about 79.3%, and the maximum wal deformation reduced to a lower level. The entrance velocity was respectively v1=0.1 m/s, v2=0.2 m/s, v3=0.3 m/s and the wal pressure was in a gradient ascent;the wal shear stress increased with the velocity, meanwhile,τzou (left neck of aneurysm)<τzhong (aneurysm )<τyou (right neck of aneurysm). The path lines of blood flow mainly concentrated in the top of the aneurysm, and the blood velocity markedly affected the surface deformation. These results indicate that main hemodynamic parameters are obviously improved after stent implantation into cerebral aneurysm, and the blood velocity should never be neglectful in the treatment process.

BACKGROUND:On the basis of modern design method and numerical simulation, studies can explore the action mechanisms of sand therapy in Uyghur medicine.
OBJECTIVE:To explore a kind of non-homogeneous and isotropic biological bone finite element modeling method based on CT value, and to study the influence of sand therapy in Uyghur medicine on the mechanical properties of rabbits’ femur.
METHODS:Eight adult New Zealand white rabbits were used to establish osteoarthritis models of right posterior femur with papain. These rabbits were divided into sand therapy group and control group. In the sand therapy group, after treatment with sand therapy in Uyghur medicine, rabbit femoral models were scanned with CT. The fault image data were imported into MIMICS software. 3D model of femur was generated. The meshing was done. The material properties were given. Three-point bending in the Ansys was simulated and solved.Simultaneously, the isolated three point bending tests were performed in al rabbit models. The corresponding deflection and the maximum stress values were obtained. Finaly, the results obtained from the three-dimensional finite element modeling method were compared with the results obtained from the experiments.
RESULTS AND CONCLUSION:(1) The deflection and the maximum stress obtained by the three-point bending simulation analysis with the three-dimensional finite element model of the rabbits’ femur were wel correlated with the data obtained from the experiments. (2) These results indicate that the finite element modeling method is consistent with the structural and material properties of bone, which can be used to analyze the stress and deformation ofbones.

The present paper is aimed to study the effect of sand-therapy with Uyghur medicine on biomechanical properties and femoral bone volume of the femur of osteoarthritis (OA) rabbits at two different ages. In the experiments, we injected Papain through the joint space of right knees into the bodies of New Zealand rabbits (16 in the growing group, and 16 in the mature group), and established an OA model. The 16 rabbits in the mature group were divided randomly into 2 sub-groups: 8 in control group (no sand therapy), and 8 sand-therapy group. The 16 rabbits in the growing group were divided randomly into 2 groups as well: 8 in the control group (no sand therapy), and 8 in the sand-therapy group. We carried out CT scanning four times (1 day before, 13th, 27th and 41st days after the establishment of the model, respectively). After importing the CT data to MIMICS, the different volumes of each sclerotin were recorded and change of the percentage of each sclerotins in total femur bone volume were analyzed. Finally the rabbit femurs were given three-point bending test, the elastic load and the elastic deflection were obtained and the inertia of the section, the maximum bending stresses, the bending modulus of elasticity and the structural rigidity were calculated. The experimental results showed that (1) Compared with 1 day before and 13th day after establishment of model at maturity, the cancellous bone volume increased and cortical bone volume decreased (P < 0.05), but compared with those in the control group, the cancellous bone volume of femurs decrease and cortical bone volume increased under sand-therapy (P < 0.05). Compared with those in the control group, there were no significant changes in the deflection and cross-sectional moment of inertia in the sand-therapy group (P > 0.05), but the maximum bending normal stress, maximum load, elastic modulus, and structural stiffness (P < 0.05) in the sand therapy group were larger than those in the control group. The study showed that sand-therapy in Uyghur medicine has benign effect on bone volume of the OA rabbit femur in two ages and the mechanical properties of the OA rabbit femur at the two ages induced by sand-therapy in Uyghur medicine have been improved.
Animals ; Bone Density ; Disease Models, Animal ; Elastic Modulus ; Elasticity ; Femur ; pathology ; Hot Temperature ; Osteoarthritis, Knee ; pathology ; therapy ; Rabbits