• Volume 18,Issue 2,2003 Table of Contents
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    • BONE TO BONE REPAIR AND BONE TO TENDON HEALING IN PATELLA-PATELLAR TENDON COMPLEX——A COMPARATIVE STUDY IN RABBITS

      2003, 18(2):65-70. DOI: 10.3871/j.1004-7220.2003.2.70.

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      Abstract:Objective To compare the healing quality of bone to bone and bone to tendon repair in a patella-patellar tendon complex. Methods A standard transverse osteotomy was performed at the distal one-third of patella of one hindlimb of 60 mature female rabbits. Both patellar fragments were reattached for bone to bone group while the patellar tendon was reattached to the remaining patella after removing the distal one-third of patella for bone to tendon group. Patella-patellar tendon complex was harvested at 8, 12 and 24 weeks post-operatively for biomechanical and histological evaluations. Results No significant differences in the failure loads were found between two groups. However, greater ultimate stress was found in bone to bone group as compared with bone to tendon group at week 8 and 24 (both P<0.05). Histology revealed that the bone to bone healing was via endochondral ossification at the healing interface. In bone to tendon group, extensive scar tissue was formed to overbridge the healing interface and remodeled with healing over time. The structural integration at the tendon and bony healing interface was poor and no typical intermitted fibrocartilage zone as seen in normal bone to tendon junction was formed. Conclusion The findings of this study may suggest that the anatomical reconstruction of patella-patellar tendon complex injury may be the primary concern in decision making for selecting either bone to bone or bone to tendon repair. However whenever possible, to initial fracture (bone-to-bone) fixation for ensuring better and predictable repair at the healing interface.

    • BIOMECHANICAL STUDY OF INTERNAL FIXATION OF ABRUPTION OF LOWER TIBIOFIBULAR LIGAMENT UNION

      2003, 18(2):71-75. DOI: 10.3871/j.1004-7220.2003.2.75.

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      Abstract:Objective To evaluate the biomechanical characteristics of Hook-plate fixation (HPF) in abruption of lower tibiofibular ligament union,comparing with screw,plate,hook fixation. Methods 6 fresh specimen of adult foot were used. Biomechanical tests such as stress analysis and press sensitive film patch technique were performed to measure the change of intensity,strain,load area,contact pressure of lower tibiofibular,carrying capacity of digitoplantar and stability of ankle joint in each fixation. Results HPF was superior to the other three fixations. The difference was significant(P<0.01) Conclusion This study suggests that HPF was favorable to improve the biomechanical capability and stability of the ankle joint,save once operation and screw broken, improving carrying capacity of digitoplantar. It was one the best fixations of abruption of lower tibiofibular ligament union.

    • PRESSURE CALCULATION AND EXPERIMENT OF MEMORY-COMPRESSIVE-CONNECTOR APPLIED TO CATAGMATIC HUMERUS

      2003, 18(2):76-80. DOI: 10.3871/j.1004-7220.2003.2.80.

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      Abstract:Objective In this study the force were estimated through numerical calculation and experiment measurement while the connector was well fixed to the humerus. The results can be applied for the optimization of the memory-compressive-connector and the stress analysis. Methods The Mohr Theory was applied to calculate the pressure range between connectors and humerus. The selective prescale pressure sensitive film was then applied to measure the contact pressure in the experiment. Results The calculation showed that the force was 24N when the strain reached maximum. The maximum value was 22.68N in the experiment measurement. So the calculation result was close to the experimental value. Conclusion The prescale sensitive film is sensitive enough to measure the contact pressure. The loads can be confirmed according to the level of the colors. It is convenient for operations to apply the prescale sensitive film. The value through calculation is close to the experimental result. This demonstrated that the calculation and experiment procedures are applicable.

    • COMPARISON AND ANALYSIS BETWEEN TWO 3D GEOMETRY MODEL OF ACETABULAR BONE JOINT SURFACE

      2003, 18(2):81-84. DOI: 10.3871/j.1004-7220.2003.2.84.

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      Abstract:Objective To establish the 3D geometric model with a better fit for human acetabular joint surface. Methods Acetabulum 3D point data was acquired by the 3D laser surface scanner. Two kinds of parameterized 3D model, a spherical model and a rotating elliptical model, were built by means of a spherical surface and a rotating elliptical surface approaching to the acetabulum bone joint surface, respectively. The parameters of two models as well as fitting errors were statisticly analyzed. Results The fitting error of the rotating elliptical model was significantly less than that of the spherical model (P<0.001). The semi major and semi minor axis of ellipsoid model was positively correlated with the radius of sphere model. Conclusion The rotating elliptical model had a better fit for human acetabular bone joint surface than the spherical model.

    • A BOUNDARY TRACKING APPROACH FOR ACETABULUM CONTOUR DETECTION IN CT IMAGE

      2003, 18(2):85-86. DOI: 10.3871/j.1004-7220.2003.2.86.

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      Abstract:Objective In order to reconstruct and measure anatomic structure of acetabulum, a lot of information in the CT image were required to detect the aetabulum contour coordinate. Methods The algorithm of histogram-threshold segmenting and Kirsh boundary detection were employed for making a binary contour image. The coordinate of contour were detected by "maze" boundary tracking algorithm . Results This approach could process the information of image contour in the manner of large scale, rapid process and less error.

    • THE EFFECTS OF WOMERSLEY NUMBER AND REYNOLDS NUMBER ON THE UNSTEADY FLOW OF ABDOMINAL AORTIC ANEURYSM

      2003, 18(2):87-92. DOI: 10.3871/j.1004-7220.2003.2.92.

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      Abstract:Objective The effects of Womersley number and Reynolds on the wall shear stress and wall pressure are discussed. Then the effects of flow patterns on the endothelium and the elasticity of the vascular wall are analyzed. Methods Two-dimensional symmetrical models are used to simulate the unsteady flow in the AAA models. Results Mean Reynolds number and Womersley number that affect the flow pattern and wall shear stress and wall pressure in the aneurysm are dealt with. The mean Reynolds number and Womersley number increase the strength of the vortex in the AAA. Conclusion This rapid oscillating nature of the shear stresses and wall pressure over a long period of time may be directly correlated with endothelial biology and atherogenesis and could have some weakening effects on the strength of the artery wall. These should have facilitated the initiation, growth and rupture of the aneurysm to some extent.

    • THREE-DIMENSIONAL NUMERICAL SIMULATION OF STEADY FLOW IN ABDOMINAL AORTIC ANEURYSM MODELS

      2003, 18(2):93-96. DOI: 10.3871/j.1004-7220.2003.2.96.

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      Abstract:Objective This study reveals steady flow characteristics in rigid asymmetrical AAA models. Methods Three-dimensional symmetrical models are used to numerically simulate the steady flow in the AAA models. Results The results show that the main vortex are found in the x-z plane and two pairs of symmetrical vortices are found in the cross-section plane. Regions of high wall shear stress were observed at the distal end of the aneurysm and the wall shear stresses change dramatically at the same place, especially the z component.Conclusion The distal end of the aneurysm becomes thus the most vulnerable region in the rupture of the aneurysm.

    • ANALYSIS OF THREE-DIMENSIONAL FINITE ELEMENT FOR THE MANDIBULAR STRESS DISTRIBUTION

      2003, 18(2):97-101. DOI: 10.3871/j.1004-7220.2003.2.101.

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      Abstract:Objective To study the mandibular stress distribution and the displacement of the mandibular protraction and to expound the mechanisms of mandibular orthodontic therapy. Methods The model was constructed from class Ⅱ malocclusion in the period of puberty to adulthood. Transverse sections of mandibule were scanned by means of CT. The data was input in the computer. The protrutive relation was set to re established the articulation. The geometry model constructed in CAD software was put into MSC.PATRAN to set up the three dimensional finite element model. Results The results revealed that tensile stress distributed in the posterior edge of the condyle and the molar area and that compressive stress distributed in the inferior edge of the mandible and the gonion area. Conclusion The mandibular protraction could change the stress distribution and treat effectively the skeletal Class Ⅱ malocclusion.

    • MECHANICAL PROPERTIES OF THE DEGRADABLE CHAIN-EXPANDED PLA POLYMER

      2003, 18(2):102-106. DOI: 10.3871/j.1004-7220.2003.2.106.

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      Abstract:Objective To study the factors influencing the mechanical properties of the degradable chain expanded PLA polymer. Methods Using GB 9641 88 to make the chain expanded PLA polymer into dumbbell shaped samples , the tensile strength was tested at a speed of 5mm/min by a universal testing machine of high polymer under different conditions of temperature ,time, molecular weight of chain expanding agent , PLA and PCL.Results In the course of chain expanding reaction the mixing temperature , mixing period , curing temperature , curing period , the molecular weight of the chain expand agent , the cross linking agent and PLA each had an influence on the tensile strength of the chain expanding PLA polymer. Conclusion The maximum tensile strength was 24.47 MPa when the ratio of PLA to PCL period equaled to 1∶4 , mixing temperature was 100°C , mixing period was 4min , curing temperature was 130°C , curing period was 6h , the molecular weight of chain expanding agent A , cross-linking agent 1 and PLA.

    • THE BIOLOGICAL EFFECTS ON VASCULAR ENDOTHELIAL CELLS UNDER FLUID SHEAR STRESS

      2003, 18(2):107-113. DOI: 10.3871/j.1004-7220.2003.2.113.

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      Abstract:生物医学技术的不断发展 ,为心血管人工移植物 (如人工血管、人工瓣膜 )的临床应用提供了广阔的发展空间。内皮细胞与平滑肌细胞作为血管壁的主要组成细胞在人工血管的构建研究中占有重要地位。体外培养是研究内皮细胞与平滑肌细胞细胞形态和功能的重要手段。但静态条件下的内皮细胞与平滑肌细胞的联合培养缺少在体条件下的力学环境 ,因而近年来国内外开始将两种研究方法结合起来 ,研究在力学环境下内皮细胞与平滑肌细胞的相互作用 ,从而为人工血管移植物的研究提供理论基础

    • THE PROBLEMS ON THE DYNAMICS OF BLOOD FLOW FOR INTRAVASCULAR INTER VENTIONAL TREATMENT

      2003, 18(2):114-119. DOI: 10.3871/j.1004-7220.2003.2.119.

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      Abstract:本文结合作者等人的工作 ,从血流动力学的角度对血管内介入治疗进行了综述。论述了神经系统血管病介入治疗、动脉瘤介入治疗、肝癌介入治疗和肺癌介入治疗等临床上存在的急切需要解决的血流动力学问题。其中 ,还着重介绍了作者等人在肺癌介入治疗的血流动力学问题上的研究成果。这些研究成果为解决肺癌介入治疗临床上严重存在的“高位截瘫”并发症问题提供了一个有效的原理和方法

    • THE EFFECT OF DIFFERENT FACTOR ON VENOUS COMPLIANCE AND MEASUREMENT OFIT

      2003, 18(2):120-124. DOI: 10.3871/j.1004-7220.2003.2.124.

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      Abstract:静脉顺应性是反映静脉对内压力的应变性的重要指标 ,其测量方法分为在体与离体两类 ,前者又分无创性与有创性两种。被测对象的年龄、静脉的解剖结构、组织学状况、血管压力与轴向伸长率、重力环境等诸多因素均影响着静脉顺应性。作者就目前国内外有关静脉顺应性的影响因素和测量方法的研究进展作一简要的综述报道

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