• Volume 12,Issue 2,1997 Table of Contents
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    • THE DIFFERENT FIXATIONS FOR COMMINUTED PHALANGEAL FRACTURES——A BIOMECHANICAL STUDY

      1997, 12(2):65-72. DOI: 10.3871/j.1004-7220.1997.2.72.

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      Abstract:The rigidities of five fixation methods have been studied with the comminuted phalangeal fracture modle. Mechanical testing of compression,bending and torsion were performed for each fixation. Auseful reference on biomechanical properties of these five fixation methods have been provided.The lateral plating with six screws(LP6) seems to provide a more rigid fixation.If such lateral plating including the butterfly fragment is not practicable (e.g. in multi-fragmented fracture, which lacks adequate normal cortex for placement of screws) the 4K wire would be a satisfactory alternative .We hope that knowledge of rigidity of these fixation methods will have a positive influence on the surgeon's selection of fixation method.

    • THE ORETICAL AND EXPERIMENTAL STUDIES OF THE SOFT LAYER ARTIFICIAL HIP JOINTS

      1997, 12(2):73-81. DOI: 10.3871/j.1004-7220.1997.2.81.

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      Abstract:Aseptic loosening of the artificial hip joint occurs frequently and causes thigh pains. Consequently,revision surgery is needed to replace it with a new implant. One of the major causes of its aseptic loosening is osteolysis of the surrounding bone tissue adjacent to the articular surfaces of the prosthetic joint as a direct consequence of the bone reaction to the wear particles. The purpose of this paper, is to review theoretical and experimental studies of the soft layer artificial hip joints the present author has conducted extensively over the past few years. The major advantage of the soft layer artificial hip joint over its conventional counterparts is its superior frictional,lubrication and wear properties. This new technology largely overcomes the problem of the aseptic loosening due to the wear particles and.hence, should have important clinical implications.

    • APPLICATION OF A PARTICLE-IN-CELL METHOD TO SOLID MECHANICS

      1997, 12(2):82-94. DOI: 10.3871/j.1004-7220.1997.2.94.

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      Abstract:An extension to solid mechanics of the FLIP particle-in-cell method is presented. The particle-in-cell method uses two representations of the continuum,one based on a collection of material points and the other based on a computational grid. The material points are followed throughout the deformation of a solid and provide a Lagrangian description that is not subject to mesh tangling. This feature permits constitutive equations with history-dependent variables to be applied at these material points with no requirement for mapping the history parameters from one point to another. A grid, which can be held fixed or adapted as the need arises, is used to determine spatial gradients. Since the grid is used as an updated Lagrangian frame, the nonlinear convection term associated with Eulerian formulations does not appear. With the use of maps between material points and he grid, the advantages of both Eulerian and Lagrangian schemes are utilized. No-slip impact between bodies, inelastic, elastic, or rigid, is handled automatically by the method without resorting to a special contact algorithm.

    • A GEOMETRIC CURVE DESIGN OF THE UPPER PART OF FEMORAL STEM OF ARTIFICIAL HIP

      1997, 12(2):95-99. DOI: 10.3871/j.1004-7220.1997.2.99.

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      Abstract:Based on A-P view and lateral view of X-Ray Photograph, upper geometric curves quedullary canal are measured and drawn from each of 84 Chinese femur bone specimens. All curves are parameterized by least mean square method. A statistical analysis on parameterized data is made for finding out the growth law of femur in Chinese population. The shape of the femur is classified into 7 types. This result of the study is for the design of Chinese-Type artificial femur. that is in accord with the biomechanics characteristic.

    • STRESS AND VASCULAR REMODELING

      1997, 12(2):100-107. DOI: 10.3871/j.1004-7220.1997.2.107.

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      Abstract:Vascular remodeling is a common phenomenon existed in the process of the organism/s growth, development, decrepitude and cardiovascular disease. The relationship of arterial wall stress and vascular rem癲eling is reviewed in this paper. The vascular wall stress is of great importance in the vascular remodeling process induced either by the change of blood flow or by hypertension.

    • AN EXPERIMENTAL BIOMECHANIC STUDY OF MEDULLARY PIN INTERNAL FIXATION FOR FEMUR FRATURE

      1997, 12(2):108-111. DOI: 10.3871/j.1004-7220.1997.2.111.

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      Abstract:Fresh specimen of human femutn was measured with electrical technique to observeand analyze the stress - strain relationship under different loadings.In patients with transverse fracture of the femur treated with bone lengthening and internal fixation of medullary pins, the effects of loading compression and deformity endurance of the internal fixation were determined.It was found that when a loading of 980N was given, the compression of the medial side of the femoral shaft was- 8.04?106?1.96?106pa,higherthan posterior side.At the same time, the lateral side of the corresponding transverse section sustained-8.82?106?1.27?106pa,higher than ante-nolateral side.It was also shown that the stability of the fracture fragments is dependent upon a reliable internal fixation. When the closely contacted fractured ends were under loading, both bone and the medullary pins sustained the compression loading stress of which 62% was sustained by the medullary pins and 38% by the bone tissue.When the femur was lengthened,the filling of the defect in the compression stress area with a large Piece of bone tissue from the ileum could effectively increase the anti-bending loading and anri-compression strength o: the femur.Before the healing of fracture, the loading of the medullary Pm should not exceed 196N. Over loading is bound to result in the weakening and plastic deformty the pin metal,which is known as 'Baushinger effect'. Consequently, the medullary pin will be bonded and even broken to delay the healing of fracture. 原

    • CORRELATION BETWEEN EPIPHYSEAL DISRACTION AND BIOMECHANICAL PROPERTIES OF THE EPIPHYSEAL PLATE

      1997, 12(2):112-114. DOI: 10.3871/j.1004-7220.1997.2.114.

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      Abstract:The effectiveness of epiphyseal distraction was investigated in vivo and in vitro by forces applied to the distal femoral growth plates of New Zealand white immature rabbits. Distraction forces of 5N and 10N were applied every 3 days to the distal growth plate of the right femur in vivo, in 16 rabbits Four weeks later the length of all distracted femurs was significant longer than both the length of control side and the same one of group ON. Histological study showed hyperplasia of the growth plate, an increase in chondrocytes division rate, and no evidence of epiphyseolysis. The in vitro breaking forces of the growth plate were measured after in vivo distraction. The mean breaking force of the distracted side was not lower than mean values for the undistracted control side. Sixteen femora from 8 rabbits underwent epiphseal distraction in vitro, with 20N, 60N and 100N forces. the mean plastic deformation of the growth plate was great in connection with increasing traction. The subsequence breaking force of these growth plates was no influenced. The results obtained in this study indicated that limb lengthening might be achieved by chondrodiatasis with the proper distraction force and/or a slow distraction rate.

    • THE STRESS ANALYSIS OF THE ELLIPTICHOLE PERIPHERY IN THE NEW HOLE MODEL OF DECAYED TOOTH

      1997, 12(2):126-129. DOI: 10.3871/j.1004-7220.1997.2.129.

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      Abstract:The calculated results about the new hole-model of decayed tooth by the finite element method have been analysed in this paper, and, on the elliptic-hole Periphery, there are the varying patterns of the stress, the points of stress concentration and the stress values. These Provided the Scientific basis for the hole-mode analysis.

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