• Volume 12,Issue 3,1997 Table of Contents
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    • SEVERAL TYPICAL BLOOD HYSTERESIS LOOPS OF CAR-DIO-CEREBROVASCULAR DISEASE AND THEIR MATHEMATICAL CHARACTERIZATION

      1997, 12(3):129-133. DOI: 10.3871/j.1004-7220.1997.3.133.

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      Abstract:In this paper, several typical blood hysteresis loops of Cardio-Cerebrovascular disease were compared with normal hysteresis loops. The novel 5-parameter time-dependent constitutive equation was applied to characterize these blood hysteresis loops precisely. The calculated results with model were in excellent agreement with the experimental data. The viscoelasticity and thixotropy shown in these hysteresis loops have been revealed quantitatively. The blood viscoelastic and thixotropic indices of Cardio-cere brovascular disease were obtained, As compared with normal person, the viscoelasticity of Cardio-Cere ebrovascular disease were greater and the thixotropy were worse. So, the results were considered and could serve for reasonable. It may providing a novel method if clinical assisstant diagnosis and prevention of Cardio-Cerebrovascular disease by using blood dynamic rheological properties.

    • A STUDY OF STRESS-STRAIN RELATION OF AUTOGENOUS VEIN GRAFT: CIRCUMFERENTIAL VERSUS LONGITUDINAL

      1997, 12(3):134-137. DOI: 10.3871/j.1004-7220.1997.3.137.

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      Abstract:The stress-strain relation of the autogenous vein grafts were investigated 24 weeks postsurgically. Canine femoral veins were excised, reversed, and grafted to femoral arteries in the end-to-end anastomosis fashion. The stress-strain relations were reduced from uniaxial tensile tests of the longitudinal and circumferential specimens of the vessels. Results show that the longitudinal stress-strain relations of vein graft (24 wks postsurgically) and the normal vein can be expressed in form of T=C1(e-1) for small stress (T<10kPa), or T=C2e-β for large stress (T≥10kPa); The circumferential stress strain relations can be expressed in form of T=C3(e-1.Both the longitudinal and the circumferential stress-strain relations of the vein graft is shifted left-ward. Both structural stiffness and material stiffness of the vein graft is larger than the normal vein. e.g. longitudinally, the values a2(mean±SD) are 34.06±7.30 and 19.21±2.35 for the vein graft and normal vein respectively, while circumferentially, the values of a3(mean±SD) are 55.76±20.16 and 27.56±2.82 for the vein graft and the normal vein respectively. In conclusion, the stiffness of the vein graft increases postsurgically, and the changes are mechanically anisotropic-differing in the longitudinal and circumferential directions.

    • TO OBTAIN FEMUR IONGITUDINAL SECTION OUTLINES FROM CROSS SECTION CT IMAGIS

      1997, 12(3):138-142. DOI: 10.3871/j.1004-7220.1997.3.142.

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      Abstract:In this paper a new method to develop femur longitudinal section outlines from cross section CT images is introduced. The femur longitudinal section outlines developped from cross section CT images and its corresponding calculation process differ from the femur Xray images chiefly in two advantageous aspects. First, in one view direction, many femur longitudinal section outlines at different depth can be achieved instead of only one outline obtained from X ray film. In addition, the femur longitudinal section outlines developped from crossaee whole femur. That is unable to sive a precise relationship among the different rectional outlines. The precise femur outline developped with this method can be used to ensure a more precise design of arificial hip joint.

    • THE MECHANICAL ANALYSIS OF CHOOSING THE DIAMETER OF AUTOGENOUS VEIN GRAFT

      1997, 12(3):143-148. DOI: 10.3871/j.1004-7220.1997.3.148.

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      Abstract:Choosing the diameter is one of the basic problems of autogenous vein graft. In order to achieve theobject that the inner diameter of autogenous vein graft is equal to that of artery under the arterial pressure, we analyze the method for choosing the diameter of autogenous vein graft, by considering the effects of the longitudinal stretch ration and blood pressure on the diameter, the wall thickness and the pressurediameter relationship. Using the data from the rabbit femoral arteries and veins, we can know that the longitudinal stretch ratio and the diameter of artery have some effects on choosing the diameter of autogenous vein graft.

    • EFFECT OF COMPRESSIVE INJURY ON THE STABILITY OF THORACOLUMBER SPINE

      1997, 12(3):149-151. DOI: 10.3871/j.1004-7220.1997.3.151.

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      Abstract:To investigate the effect of flex-compression on the stability of lumbar segment movement. Methods: Specimens of thoracolumbar segment (from T12 to L2) were obtained from 7 fresh adult male corpse. Three-dimensional (3D) movement were measured by a 3D spinal motion test machine and stereophotogrammentry before and after the specimens were compressed to failure with a flex-compression load. Results: The results showed that after failure the anterior height and posterior height of the vertebral body were decreasd, and three is a significant effect on the motion of T12-L1, L1-L2 segments in flexion, and L1-L2 segment in left rotation. It has almost no effect on the movement of lateral bending after failure. Conclusion: Lumbar spine lost part of its segmental stability after injury under flex-compression load.

    • A NEW TYPE STEM CUP FEMORAL HEAD PROSTHESIS AND IT'S BIOMECHANICAL EVALUATION

      1997, 12(3):152-155. DOI: 10.3871/j.1004-7220.1997.3.155.

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      Abstract:Surface replacement of the hip possesses some features namely, removing only the diseased surfaces of the joint while preserving the normal structure and biomechanical function of the hip. Preservation of the femoral neck and head is beneficial in that the hip could be fused and easeier for revision to a conventional total hip arthroplasty. But it has a higher rate of long-term failure than Charley total hip prostheses. To better distribution the stress under the femoral component the new head cup system TC (Triwing head cup BC) was desighed, and BC (Post belt head cup).they have center post with a higher biomechincal stabilit as compared with WC(Wanger cup), The results demonstrated that the strain values of the femoral neck osseous part that fixed in TC as the smallest and the maximum destroed torque values of the specimens fixed in TC were significantly the biggest among the three groups fixed in three kinds of cups. The higher long-term survival rate for TC could be expected, and this a more ideal femoral head cup prosthesis provided for clinical use id possible of nealigation.

    • THE EFFECT OF OVARIECTOMY ON MECHANICAL STRENGTH OF VERTEBRAE IN RATS

      1997, 12(3):156-160. DOI: 10.3871/j.1004-7220.1997.3.160.

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      Abstract:In order to study the effect of ovariectomy on mechanical strength of vertebrae, 64 3-month-old female SD rats, weighing 180200g were divided into two payes for performing ovariectomy (OVX) and sham-operated(Sham-O), respectivly. The rats were sacrificed at 1,3,5,7 months later. Andanother group of 48 3 -month bipedal rats also renderment OVX and Sham-0 'operation and sacrificed at 2,5,7th month later. All L2 vertebra were measured morphogeometrically and then vertical compression test was caried. The results showed: in OVX rats, the average height of vertebrag became shortened(P<0.05), and the upper sagittal diameter become bigger(P<0.05). In abnormal high mechanical stress OVX rats, the average height of vertebrae became shorte-n(P<0.05), and both the upper and lower arrow diameter became bigger(P<0.05). The mechanical strength declined from 1st month and continued to the lowest at 7th month. Also the mechanical strength showed decline change but less than normal OVX group. Such alterations in bipedal rats may be related to the high mechanical stress in vertebrae. The mechanical strength is so low that the fracture risk is higher even in case of a slight trauma.

    • RELATIONSHIP BETWEEN REFERENCE VALUE(WINTROBE) OF CHINESE HEALTHY PEOPLE TWO HEMORHEOLOGY AND ALTITUDE

      1997, 12(3):161-165. DOI: 10.3871/j.1004-7220.1997.3.165.

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      Abstract:In order to supply a basis for uniting the reference value (wintrobe) standard of Chinese healthymen ESR and Chinese elderly female hematocrit, a research is made between the reference value (wintrobe) of 22707 examples of Chinese men ESR and altitude in China's 226 areas,and also a research is made between the reference value (wintrobe) of 15608 examples of Chinese elderly female hematocrit and altitude in China's 312 areas,which are determined by the way of wintrobe lows.It is found as the altitude increase gradually, the reference value (wintrobe) of Chinese healthy men ESR decrease gradually.but the reference value (wintrobe) of Chinese healthy elderly female hematocrit increase gradually, the correlation is all quite obvious.Applying the method of mathematical regression analysis, two regression equations are given out. If altitude index values are obtained in some area.the reference value (wintrobe) of Chinese healthy men ESR and Chinese healthy elderly female hematocrit of this area can be reckoned using the regression equations.

    • A STUDY ON THE RADIAL DISTRIBUTION OF HAVERSIAN SYSTEM AND THE POROSITY OF THE CORTICAL BONE OF TIBIA

      1997, 12(3):165-169. DOI: 10.3871/j.1004-7220.1997.3.169.

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      Abstract:The microstructure of bone is closely correlated to its mechanical property. The present study was carried with cortical bone of bovine and human tibia diaphyses, The radial distribution regularity of Haversian system was obtained by observing the microstructure on sections of tibia with scanning electro-microseope. The value and the distribution regularity of the porosity on the sections were detected and calculated with image processing system, Basing on the results a preliminary analysis was made.

    • DYNAMIC FOOT-PRESSURE MEASUREMENTS AND ITS APPLICATION TO CLINICAL ORTHOPAEDICS

      1997, 12(3):170-174. DOI: 10.3871/j.1004-7220.1997.3.174.

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      Abstract:We developed an imaging apparatus for measurement of pressure under the foot by means of planter pressure direct imaging technique, and conducted experiments to determine the functional relationship between the images and plantar pressures. With use of a computer video-image processing system, we collected dynamic measurements and analyzed the distribution of pressures and its changes during the entire process of a gait cycle. We have used the system in assessment of function of the donor foot after 2nd toe-to-hand transfer and at long-term follow-up of early procedures achieving dynamic balance in congenital clubfoot, with the results providing a valuable guidance for formulating surgical strategy and treatment plan.

    • A BIOMECHANICAL STUDY AND FLINICAL APPLICATION OF COMPRESSION INTRAMEDULLARY LOCKING SCREW FOR TREATING FEMORAL FRACTURE

      1997, 12(3):184-189. DOI: 10.3871/j.1004-7220.1997.3.189.

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      Abstract:The author designed a newtype compression intramedullary locking screw with dynamic stability, which is extensively used in the hospital for femoral fracture. This locking screw was mostly satisfactory by biomechanics test compared with GK and cloverleaf type intramedullary nail, for its greater bearing capacity, stronger and harder than the later two(P<0.01). The clinical results were shown better in thirty cases and the application of it is noted for its safety .reliability and simplicity.

    • A BIOMECHANICAL EXPERIMENTAL STUDY OF SINGLD NAIL-GROOVE LIMB PLATE

      1997, 12(3):190-193. DOI: 10.3871/j.1004-7220.1997.3.193.

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      Abstract:Authors studied ana designed single nail-groove limb plate for reduction and fixation of lumbar spondyiohsthesis,First model of lumbar spondylolysis and spondylolisthesis was made in L3-S3 of six adult corpse. Ther reduction and fixation was Performed according to surgical technique of clinical I, on each plate there were six pieces of resistance straingage. Central and excentral load test as conducted, so as bend and torsion test. Lastly analysed of the data was carried with the help of computer type 586 and obtained linear equation and linear correlation coefficient. The plate was not loosened when central and excentral load amount to 900N, while bend and torsion reached 833N.cm and 666.4N.cm respectively stress of the stress point of plate increased linearly,which suggested that single nail-groove limb plate for reduction and fixation of lumbar spondylolisthesis had adequate biomechanical basis. Furthermore, the operation was simple, with adequate reduction and good stability.

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