Abstract:Objective To study the effect of fluid flow shear stress on seeded cells for bone tissue engineering. Methods In this study we established a flow chamber perfusion system. The mesenchymal stem cells(MSCs) were implanted into the acellular bone exteracellular matrix, then cultured in the perfusion system under 1.0dyn/cm2 flow shear stress for 7days. Results Alkaline phosphatase(ALP) activity and osteocalcin content, which were two crucial osteoblast genes marker were increased. Cell numbers had no different with the static group. Conclusion It demonstrated that this system is useful for osteoblastic differentiation of bone seeded cells, and this 3D cultured model utilizing fluid flow may be helpful in the culture process of engineering bone.

Abstract:Objective To present a hemodynamics model to explain the mechanism of Chinese Traditional Medical Massage (CTMM) Swing manipulation (Rolling manipulation and Vibrating manipulation). Methods Pulsatile blood flow through an artery with mild stenosis moving axially is studied for modeling Rolling manipulation. Blood flow is governed by Navier-Stokes equations. The effect of dynamical variation of tissue pressure on exchange between capillary and tissue is investigated for Vibrating manipulation. The governing equation of blood flow in capillary is Stocks equation with boundary condition of Starling law. The tissue hydraulic pressure changes with Vibrating manipulation. Results Blood velocities change and average flow rate through the artery increases for the rolling manipulation model ; and a reduction of blood apparent viscosity in capillary is showed for the Vibrating manipulation . Conclusion The results could be used to explain the hemodynamics principle of CTMM Swing manipulation : removing blood stasis and promoting blood circulation .

Abstract:Objective A newly developed carbonated hydroxyapatite cement (CHC) was used as bone graft biomaterial and implanted into the bone. The biomechanical properties and histological features between CHC and bone were examined at different time points after implantation. Methods Mature male mongrels dogs were used, with CHC implanted into the distal femur as Detaching models' experimental group, while implantation with polymethylmethacrylate (PMMA) as control group. The biomechanical and histological properties at bone-implant interface were evaluated at different time points. Results The maximal bonding strength between CHC and bone increased along with the experimental time, up to 281N at week 16 after implantation. However, the maximal bending strength of the control group showed reverse results. Histologically, the CHC degraded gradually and replaced by new bone tissue, while the control groups showed fibrous tissue between PMMA and bone. Conclusion The CHC had excellent biocompatibility, and was able to integrated with bone directly. The bonding strength between CHC and bone increased with time post implantation.

Abstract:Objective Employing a new coupling method of left ventricle-systemic circulation to test the hypothes the hypothesisi that times of the beginning (t1) and end (t2) of systole are not the parameters but the results of coupling through which pressure and flow in artery are affected. Methods Arterial properties are estimated with a nine elements windkessel model. Left ventricle is simulated by E(t) model. Then they are coupled under the t1,t2-included principle of least cardiac work. Results This new method shows some improvement to improvments to approach the experimental results of the blood pressure and flow. The t1,t2-included mechanism can well interpret the changes in pressure and flow corresponding to the changes of other parameters. Conclusion t1,t2 should be the results of coupling and they play important roles in coupling between heart and artery.

Abstract:Objective This paper furnishes a simulation tool for blood flow in the branch and network of blood vessel. It supplies references for fundamental research and clinic application. Methods Finite-element model and JAVA language are used to compile computer program of simulating blood flow in the branch and reticulated blood vessel. Results The program can construct vessel model, input blood vessel parameters and deal boundary condition. Computer data can be presented by output directly and figure display. The results are verified. Conclusion The method can conveniently build and modify model to simulate cardiovascular abnormalities, such as hypotension, hypertension, stenoses and haemorrhage.

Abstract:Objective This experimental study aimed to evaluate biomechanical properties of human cadeavaric anterior longitudinal ligament of cervical spine for potential clinical use. Methods Anterior longitudinal ligament of C1-C4?C4-T1 segments was obtained from 8 fresh Chinese cadavers to test their tensile strength using Shimadzu AUTOGRAPH electronic universal testing machine. Results Mechanical properties of anterior longitudinal ligament of C1-C4?C4-T1 segments were obtained, including maximal tensile load and strain , Lagrange tensile stress and strain, Euler stress and elastic modulus With the least square method the stress and strain of the anterior longitudinal ligament of C1-C4?C4-T1 segments were plotted by stress-strain curve. Conclusion The stress of the C1-C4 segment was greater than that of the C4-T1 segment. There were no significant difference found in strain of the anterior longitudinal ligament of different segments. The modulus of elastic of the C4-T1 segment was however greater than that of the C1-C4 segment.

Abstract:Objective To study the influence of the preload on the stability of anterior cruciate ligament reconstruction by hamstring tendon knot embedding method. Methods Eighteen fresh frozen porcine distal femurs were drilled to form bottleneck-like bone tunnels. A knot was tied in the middle part of the hamstring tendons, and the double-stranded tendons were inserted and embedded in the bone tunnel. The tendons were preloaded at 50N?100N and 200N three times respectively before test. Pull-out experiments were performed on bio-material test machine. Results In 50N preload group, the displacement of 400 Newton load was higher than the other two groups and the stiffness was lower than the other two. The maximum load was similar with the 100N group (P>0.05), but higher than 200N group (P<0.01). There was no statistically significant difference between the 100N preload group and 200N preload group with regard to 400N displacement and stiffness (P>0.05). Conclusions The preload has an impact upon peak load?displacement and stiffness in hamstring tendon knot embedding fixation. When the preload was applied between 100 Newton and 200 Newton, the stiffness increased significantly, whereas the maximum load decreased slightly.

Abstract:Objective To observe the dynamic changes of opening angle in zero-stress state and the relationship between tension stress (T) and extension ratio (λ) in longitudinal extension of the portal vein during the pathogenesis of intrahepatic portal hypertension, and investigate the role of biomechanical properties of the portal veins in the process of the portal hypertension. Methods The models of intrahepatic portal hypertension were established in SD rats by means of carbon tetrachloride (CCl4) injection. Opening angle, the relationship between T and λ in longitudinal extension of the portal vein were determined in 2, 4, 6, 8, 10 weeks after CCl4 injection. Meanwhile the changes of several hemodynamic indexes such as portal venous pressure (PVP), portal venous flow (PVF), mean arterial pressure (MAP), portal vascular resistance (PVR) and splanchnic vascular resistance (SVR) were detected. Results After CCl4 injection, hemodynamic indexes in the CCl4 rats had changed markedly. Accordingly,opening angles, Parameter b in longitudinal extension were increased. At the tenth week, they were much greater than those of corresponding controls (P<0.05). Conclusion The portal hypertensive rats were in hyperdynamic circulatory state (HCS). Changes of biomechanical properties of portal vein can be induced by HCS.

Abstract:Objective Analyzing program was designed to get some important parameters in Javelin throwing process. Methods The human body was simplified as a multi rigid body system composed of fifteen rigid bodies; the Javelin throwing process of the athlete was photographed by high-speed photography. Results A series of images in the final thrust phase were obtained, and stick figure of human body and the parameters of joints were given (including velocity, accelerator, and the position of center mass, etc.). Conclusions By this program, the prescribed purpose was realized, and the throwing parameters of Javelin thrower's joints were obtained through the analyzing.

Abstract:Objective To investigate injury mechanisms of human calcaneus under impact loading in order to provide scientific references to clinical serice including operation, fixation, and rehabilitation. Methods An experimental model of calcacalcaneal dynamics was established using twenty fresh human cadaveric calcaneus for impact loading test. Results Based on the impact experiment results, the dynamic response of the human calcaneus to the impact loading at high crash rate was analyzed, the characteristics of the human calcaneal impact dynamics were obtained, and a typical compressive strain was found to produce calcaneal crushing fracture. Coclusion The testing results suggested the importance to establish classifications of human calcaneal injuries, including the impact injury mechanisms,the quantification of biomechanical response to the impact loading, the viscoelastic properties of the bone, the determination of threshold for the maximal impact loading, and the measures for injury prevention.

Abstract:Objective The methods for designing and manufacturing custom hip stems based on standard X-ray films was researched. Methods developing the software that includes X-ray scanning, femoral canal obtaining, implant designing, fit evaluation, and drawing a 2-D map. CAM technique also was used to manufacture hip stems. Results The paper introduce a manufacturing method of processing a hip stem, on general machine tools as possible as it can. Clinical results reflected that hip implants matched the femoral cavities very well. Conclusions The clinical result and analyse indicates that the method of designing and manufacturing hip implants is practicable.

Abstract:Objective To reconstruct three-dimensional finite element method models (FEM), including FEM for lower dentition and bilateral condyles for analyzing the characteristics of temporomandibular joint (TMJ) stress distribution result from alteration of dental occlusion . Methods A human cadaveric skull was used for CT scan at the plane parallel to the Frankfort Horizontal plane. Geometrical information of mandibular CT images was extracted for preparation of being imported into software. Occlusion surface of its plaster casts was then scanned in a 3D fashion (accuracy:0.5mm). The related parameters of both cast and CT images were converted into a coordinate system. A simulated disc was added on each of the condyles. Constraints were applied to the upper surface of the disc and the mandibular angle. Results After meshing the FEM containing bilateral condyles?simulated discs, and lower dentition was established. Conclusion By using the methods developed for this study, the FEM was established to study the result of TMJ stress distribution and its alterations accompanied with changes in occlusion.

Abstract:生物学固定概念的普及以及微创手术推广的同时,材料的生物力学研究仍是不同固定系统临床应用的基础。作者就胫骨平台骨折常用的内外固定器械,如松质骨螺钉、皮质骨螺钉、抗旋转螺钉、外侧支持钢板、内外侧双钢板、外侧支持钢板结合内侧抗旋转钢板、外固定支架等对不同类型胫骨平台骨折的生物力学研究进展进行综述。