1998, 13(1):1-4. DOI: 10.3871/j.1004-7220.1998.1.4.
Abstract:To understand the blomechanical behavior of lumbar spine after removal of nucleus pulposus (NP)and resection of posterlor structure(PS) by means of measurement of stiffness in compression, shear and torsion, and torsion strength. Materials and Methodst twenty-four FSUs made from eight adult fresh cadaver spine (L1-S1) were divided into three groups randomly. Two groups were removed of NP and PS respectively, and one group was chosen as a control. Each specimen were loaded in compression and shearing, then rotated to rupture. The stiffness of compression, shear and torsion of lumbar FSU were decreased after removal of NP or PS, as well as the torsion strength. The stiffness of shear in left/right and torsion decreased significantly(p<0.05), and the torsion strength decreased sign1ficantly(p<0.01) following removal of NP. After resection of PS, the stiffness of shear in left/right and torsion reduced significantly(p<0.05), and the stiffness of compression and shear in anterioposterlor and torsion strength decreased very significant1y(p<0.01).
1998, 13(1):5-9. DOI: 10.3871/j.1004-7220.1998.01.9.
Abstract:This paper deals with the mechanical characteristics of stainless steel top joint of thighbone, such as strength, dynamical response and its compatibility with thighbone, by means of 3-D isotroplc-parameter finite element technique. It has been shown that the stainless steel top joint could be very compatib1e with thighbone well and had excellent mechanical characteristics for medical purposes.
1998, 13(1):10-16. DOI: 10.3871/j.1004-7220.1998.01.16.
Abstract:In this paper, a human knee joint anatomically-based mathematical model in the sagittal plane is established, and its biodynamic responses are investigated by introducing a alternative solution technique. The forces assoclated with the four main ligaments, as well as the bone-to-bone contact forces in the knee joint are numerically obtained. The contact point locations are also presented together with the augular motions of the lower limb segments.
1998, 13(1):17-20. DOI: 10.3871/j.1004-7220.1998.01.20.
Abstract:Objectivet To explore the changes of biomechanical properties of cancellous aIlograft and its relationship with different biomechanical environment. Methodf Cancellous allograft was transplanted to each side of the midshaft diaphyseal ulnar of 40 rabbits. The left transplanted allograft underwent normal physiological load, while the right underwent lower load. Animals were kiIled and specimens taken for examination of bone mineral density, three-point-bending test and mean trabecular thickness. Results: Bone mineral density, maximal bending moment and mean trabecular thickness of graft were found to have been increasing constantly. At the sixteen week after transplantation, the above data of normal loaded graft is better than that of lower loaded graft (P<0.01,0.05,0.05 respectively). Conclusionf Changes of biomechanical properties of cancellous allograft shows more apparent correlation with the magnitude of load to which the graft would be subject.
1998, 13(1):21-24. DOI: 10.3871/j.1004-7220.1998.1.24.
Abstract:Our study ststically analyzes the difference of effects of occlusal problems on TMJD. The conclussion as followsf the highness reduced of pathological occlusion is the most harmful among occlusal problems. During chewing, there are injuries to bilateral TMJ when highness of occlusion is reduced whether unilateral or bilateral.
1998, 13(1):25-29. DOI: 10.3871/j.1004-7220.1998.1.29.
Abstract:In this paper, we studledthe mechanical properties of canine pulmonary arterles under acute pulmonary hypertenslon. The condltion was induced by infusion of the thromboxane A2 analogue U46619 using right heart catheterization techniques. The theoretical study was based a Windkessel Model. The results demonstrated a mlnimal difference of cardiac output (CO) (1.85- 0.21 vs 1.21 - 0.25 lml, P0.05) before and after the induced condition of acute pulmonary hypertension.However the results showed a significantly!ffle in pulmonary vessel resistance (PVR) under the induced condition as compared with the normal situation (31.4- 9.4 vs 148.7 12.3kPa s/L,P<0.01). As of the pulmonary arterlal compliance, Cm decreased noticeably (12.43 - 2.62 vs 10.30 - 3.12ml/kPa, P<0.05), while Co had only negligible variation. These results suggested that the change of PVR caused by small pulmonary artery contraction was a main factor influencing the acute pulmonary hypertension, therefore, the vasodi1ator which dilate small arterles was the optimal cholce in treating acute pulmonary hypertension.
1998, 13(1):30-35. DOI: 10.3871/j.1004-7220.1998.1.35.
Abstract:White-light speckle method, together with stereo-photographic method, was used in this paper to measure the 3- D displacements of mark points on the surface of the human articular specimens during spacial movement. As the articulars undergo finite displacement and rotation, index of plane tilt and plane rotation were introduced to describe the general movement instead of the common rotations about the three orthogonal axes. Primary experiments had proved the viability of the presented method, which will be helpful in evaluating the medical operations.
1998, 13(1):36-39. DOI: 10.3871/j.1004-7220.1998.01.39.
Abstract:On the basis of the study of the corpse samples, taking advantage of the technique of CT and DIP in this paper, 50 young female bodys were made investigations going through the scanning, image analysis,examination,statistics, the establishing mathematic model of the human body. Thus, the accuracy and reliability of the inertial data of the Chinese female young bodys (for example, the average value of the mass distribution, the mass center and the move inertia, et al.) was obtained leadinglly in our country. The quadratic circular equation that calculated immediately the inertial parameters of segments of the Chinese female young bodys was set up. It supplied the basic data for the descussion about the motionology and impelusology of the Chinese human bodys primarily and also provided a powerful means for the motive image analysis and the select athletes.
1998, 13(1):40-44. DOI: 10.3871/j.1004-7220.1998.1.44.
Abstract:In order to investigate The influence of loading angles of screw dental implant on the stress distribution patterns at the bone interface around dentaI implants, authors analyzed loading angles of screw dental implant on the stress distribution patterns at the bone interface around dental implants in the same load using three-dimension finite element method. The results showedt Increasing the loading angle of screw dental implants mainly affected the stress magnitudes at the neck bone around the implants and the motions of displacements, the more load angles, the more stress magnitudes and motions of disp1acements. When the lateral loads the most danger was the horizontal loads.
1998, 13(1):53-56. DOI: 10.3871/j.1004-7220.1998.01.56.
Abstract:In terms of medicine- the inclined angle of femur- neck fracture section, the general description about the type of femur- neck fracture is given in this paper. For the case of three needle fixing methed, the functional relations of the deflection of the femur in the action of the vertical loads, the axial pressure and the shear with the inclined angle a are divided and the mono-tonicity of the functions are discussed. The inclined angle 2 is divided into three Limits(a<30°,30°70°)and each is discussed about the problem of the fracture fixing and beal. Finally, some measures are give for solving the fracture fixing unstable problem when a is larger. The above conclusions could be generalized to the cases of two needle fixing and four needle fixing.