• Volume 14,Issue 1,1999 Table of Contents
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    • BIOMECHANICAL ANALYSIS OF SPINAL BURST FRACTURE EXPERIMENT

      1999, 14(1):1-6. DOI: 10.3871/j.1004-7220.1999.01.6.

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      Abstract:Since advent of three-column theory, brust fracture of the spinal column has long been recognized as the most common fracture of the thoracolumbar spine. Due to canal compromise by the retropulsed bony fragment, neuralgic defect was prevailed in this type of spinal injury. In the literature recently, new information being presented on the classification, concepts of stability and instability, need for surgery, and selection of the most appropriate surgical implant. Distraction force with kyphosis correction has been thought the most effective way in reducing the retropulsed fragment, either during the operation by variable implants or by traction device preoperatively, such as traction bow device. A number of biomechanical studies has been done on the isolated lumber spine under axial loads to determine the load distribution. Little study was performed on the whole spine under traction to determine the relative distribution of strain. The purpose of this study is to use the whole spine of goat under the axial load in INSTRON machine and Traction Bow to investigate the biomechanical properties such as train distribution, deformation of disc, and load- to-failure. Next, we try to reproduce a burst fracture model for further study in traction -reduction experiment. From the strain distribution diagram, the junction of thoracolumber spine bears the larger strain. The strain in the thoracic region is mediate, in contrast, the strain in lower lumbar is smaller in our experiment. The mean deformation of disc is 2.86mm, 5.09mm,6.45mm at the loading of 10kg, 20kg, 30kg reapective. The mean maximum loading of goat spine is 91.40kg in the load-to -failure test. In this study, strain distributions of spinal column observed by INSTRON machine and Traction bow are similar. However, the strain values from traction Bow is smaller. In conclusion, the junction of thoracolumbar spine is more effective in traction from its larger strain distribution. Hence, using the appropriate traction force in intact cervical vertebrae will have a better reduction effect to burst fracture of thoracolumbar vertebrae. The load -deformation disgram, total deformation, and maximum loading in this study will be helpful for related researches in the future.

    • IMPORTANCE OF MUSCLE SIMULATION FOR CADAVERIC STUDY OF LUMBER SPINE

      1999, 14(1):7-10. DOI: 10.3871/j.1004-7220.1999.01.10.

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      Abstract:Parasplnal muscle action was included in the simulation of flexlon and extension of the lumbar spine in an in-vitro biomechanical study. An axial preload was applied anteriorly to a lumbar spine specimen to simulate the body weight with balance being maintained by a pair of cables attached to the posterior of the specimen, simulating the action of the erector spinae muscle in vivo. In each simulated posture, the three-dimensional orientation of each vertebra and intradiscal pressures of intervertebral discs were determined and analyzed. Six human cadaveric specimens were tested. The results showed that the L4-5 segment was the principle contributor to flexion while in extension the L5-S1 level contributed most. The relative contribution of each segment to the total flexion and extension of the lumbar spine varied with level. These data suggested that inter-segmental mobility of each level in flexion and extension ranges should not be combined as a single quantity I)ut should be studied separately. This study also Indicates that muscle simulation is important for cadaveric study of the lumbar spine. The magnitudes of intradiscal pressures recorded in this study were found to be similar to that measured in vivo of normal lumbar discs. Although the authors recognize that the conditions simulated in this investigation are not truly physiological, they maintain that the spinal motions obtained in this study are closer to those occurring in vivo than would he the case if experiments were conducted without muscle simulation.

    • THE EFFECT OF CHANGES IN SPLENIC ARTERIAL FLOW AND VENOUS PRESSURE ON SPLENIC BLOOD AND RED CELL ACCUMULATION

      1999, 14(1):11-15. DOI: 10.3871/j.1004-7220.1999.1.15.

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      Abstract:A flow model for splenic circulation system was proposed, according to the knowledge of its circulatory characteristics. The effect of increments in splenic arterial flow(SAF) and splenic venous pressure(SVP) on splenic blood and red cell accumulation were analyzed by using the model. The results showed that an increase in SAF or SVP caused a rise in splenic size and hematocrit, concomitantly a greater accumulation of the splenic raf cell. These results were justified by the experimental study of dog spleen in vitro

    • A STUDY ON SUPRACONDYLAR PART OF HUMERUS WITH THE METHODS OF TWO DIMENSIONAL PHOTOELASTICITY AND THREE DIMENSIONAL FINITE ANALYSS

      1999, 14(1):16-19. DOI: 10.3871/j.1004-7220.1999.1.19.

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      Abstract:In this paper, the mechanical properties of supracondylar part of humerus were studied with the experimental methods of two dimensional photoelasticity and three dimensional finite element analyse. The results showed that' O In the supinator position,there was conpressive stress in the medial side, while there was tensile stress in the lateral side. In the pronator and neutral position, the result was contrary to it. @The shearing stress in supinator, pronator and neutral position didn' t change much. ③In the supinator position, there was medial displacement in the medial and lateral sides. In the prnator and neutral position, the result was contrary to it, but the displacement hadn' t significat difference in both sides. Integrating with Salterl's theory, the authors suggest the rational fixation methods for the fractures of supracondyle of humerus.

    • GUSFRIC ANTRUM MOTILITY IN FUNCTIONAL DYSPEPSIA EFFECTS OF MASSAGE THERAPY AND CISAPRIDE

      1999, 14(1):20-24. DOI: 10.3871/j.1004-7220.1999.01.24.

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      Abstract:Objective The aim of the study is to investigate the Gas-trio antrum motility in healthy subject (HS) and in patients with functional despepsia (FD) and the effect on the motility of massuge therapy and cisapride. Methods 30 HS and 90 FD were studied by detecting Gastric antrun motility. Results the number of MMC for fasting 3 hours is reducedsignificantly and the gastric antrum motility parameters are reduced in patients with FD for postprandial 2 hours as compared to that of controls (P<0.01, all) After treatment by massage and cisapride, the gastric antrummotility parameters are increased significantly in patients with FD as compared with that before theatment. No significant difference is observed between the above parameters in patients with FD after treatment and before treatment by placebo. Conclusion the massage and cisapride therapy can improve the gastric antrum motility partial patients with FD. these parameters can be put to objetive basis evaluated the effectiveness of the treatment.

    • A EXPERIMENTAL INVESTIGATION ON THE FAILURE PROPERTIES OF TENDON AND IT'S INSERTION

      1999, 14(1):32-36. DOI: 10.3871/j.1004-7220.1999.01.36.

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      Abstract:The purpose of this work is to investigate the mechanical properties of patellar tendon, Achilles tendon and it's insertions. In the experiment three types of insertion was found under microscopy. They are trochlea, pulling, and pulling--inflectlve insertion. The stress-strain coefficients had great difference between tendons and insertions. The mechanical strengths of tendons were more higher than the trochlea and pulling' inflective insertion. The difference of strengths between tendon and pulling insertion has not significant.

    • AN EXPERIMENTAL ANIMAL MODEL OF IMPACT ARTICULAR FRACTURE

      1999, 14(1):35-31. DOI: 10.3871/j.1004-7220.1999.01.31.

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      Abstract:Objective: To produce an experimental animal model of injured articular fracture. Methods: 11rabbits (22 legs) were used to produce the model. With the energy weight of an iron hammar falling down that, the wedge would split a femoral condyle, with the capsula articularis intact. A high speed camera was used to measure the time of the procedure. Another 21 rabbits were used to measure the destructive load, intensity, elastic modulus and other biological characters of femur. Results:18 of 22 legs(82%) were successful to produce the animal model of articular fracture. A comminuted fracture was found in 1 leg, whereas the line of fracture was oblique onto condylus lateralis in 3 legs. The time of the procedure was 8.5 milliseconds and the force was 303.64 Newton, which is more than the horizontal femoral destructive load(131.2Newton). Conclusion: In our procedure, breaking up femoral with popliteal incision will produce a rabbit model of articular fractur.

    • A STUDY ON INFLUENTIAL FACTORS IN THE BLOOD VISCOSITY TESTING BY CONE AND PLATE VISCOMETERS

      1999, 14(1):37-40. DOI: 10.3871/j.1004-7220.1999.01.40.

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      Abstract:Objective: To study the testing repeation and inf'luential factors in the blood viscosity testing with the cone and plate viscometers. Methods f Blood viscosities of SD rat and hamster were tested in different temperatures and shear rates. Results f When the shear rates were in 11.25~45s, the blood viscosities come down quickly with the increase of the shear rate, when the shear rates were higher then 150s , two of the testing values tended to be constant; When the temperatures were below 37℃, the blood viscosity of the hamster in high shear(225s ') and low shear (11.25s-1) went up with the temperatues fell, When the temperature were higher than 43oC two kinds of blood viscosity went up with the increase of temperature. When the temperatures were in 37-43℃, the changes of the blood viscosity with the temperatures were less, The changes of the plasma viscosity was negatively related to that of the temperatures (r=-0.96, p<0.01); Some other factors such as erythrocyte sedimentation in the testing couse were also affect testing values. Conclusion: The testing values teasted by the cone and plate viscometers were affected by manifold factors.

    • EXPERIMENTAL STUDY ON CHANGE OF THE BIOMECHANICAL PROPERTY IN PATELLOFEMORAL MALALIGNMENT

      1999, 14(1):41-45. DOI: 10.3871/j.1004-7220.1999.1.45.

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      Abstract:Objectived Using electric stress analysis and pressure measuring film techniques, to determine muscular stress changes, contact and pressure distribution over the patellofemoral joint. Materials and Methods f & human knee specimens with reserved capsule and quadriceps tendon. The pressure measuring films were put into the retropatellar space and the stress transducers were fixed on the tendons. Results f (1)the unbalanced quadriceps forces may influence the patellar stability, the normal contact and pressure distribution of the patellofemoral joint. (2)On the specimens of the experimentally produced malalignment, we found that the pressure in the lateral facet increased significantly and were limited in scope, resulting in a stress concentration.(3) After releasing of the lateral retinaculum the high contact pressure in the lateral facet decreased significantly, but the influence of quadriceps forces still remained. Conclusions attention should be paied to the rehabilitation of the quadriceps forces, especially vastus medialis.

    • AN EXPERIMENTAL STUDY OF INFLUENTIAL FACTORS ON MECHANICAL CHARACTOR OF HUMAN FEMUR

      1999, 14(1):46-49. DOI: 10.3871/j.1004-7220.1999.01.49.

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      Abstract:A technique for electrical test of strain was used to study the mechanical charactor of human femur under the load of torsion,and the influence of selected materials, geometric structure and apparent density of femur were also discussed. These data provide a theoretical basis for medical studies on fracture healing, joint replacement and so on.

    • A BIOMECHANICAL STUDY OF POSTERIOR CERVICAL LIGAMENTS AND CLINICAL IMPORTANCE

      1999, 14(1):50-53. DOI: 10.3871/j.1004-7220.1999.01.53.

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      Abstract:In order to r'eveal the effect of debriding posterior cervical ligaments on the mechanical stability of cervical spines, we performed this experiment in which four cervicalspines of fresh human cadervers were studied(C2-T1). By simulating the normal physical actions of human neck, such as flexion, extension.Sone mechanical were tested before and after removing the posterior cervical ligament elements(the supraspinous ligaments and the interspinous ligaments). The results showed that the compressive stiffness of cervical vertebrae decereased greatly after removing the posterior ligaments, while the strains of which increased abnormally. In contrast to intactstate there were significant difference(p<0.01). At the same time, the total displacements of cervical spines enlarged markedly while vertical compressive stiffness of cervical spines lessend, there were significant differences in comparison with intactspecimens(p<0.01). After incision of the ligaments the slantangle of cervical spines enhanced gradually, the increments were significant, especially. In the flexion state (p<0.01). Conclusion: The mechanical stability of cervical spine reduce after depriving of posterior cervical ligaments. If the figments were injuried, either acute or chronic instability would occur.

    • THE CONSTANT PRESSURE MICROMETER FOR MEASURING THE EFFECTS OF IMMOBILIZATION ON CROSS-SECTIONAL AREA OF PATELLAR TENDON

      1999, 14(1):54-57. DOI: 10.3871/j.1004-7220.1999.01.57.

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      Abstract:The purpose of this study is to introduce an area micrometerfor measuring the cross-sectional area of soft tissue. Havingmeasured the depth of PT of rabbit repeatedly, we found the coefficientof variation of this micrometer is less than 0.9%. Compared withnormal group, the cross-sectional area of PT in immobilized groupincreased significantly. This change may be relevant to the level ofcollagen metabolism of PT.

    • AN EXPERIMENTAL ANALYSIS OF THE FEMORAL NECK SUPPORTING NAIL

      1999, 14(1):58-61. DOI: 10.3871/j.1004-7220.1999.1.61.

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      Abstract:A supporting nail was designed according to the biomechanic principle and the feature of structure of bone trabecula of upper femur with an aid of guiel-pin, the upper and lower nail, passed through the compression group and tension group respectively and interlocked in the femoral head. The supihe triangular supporting frame was formed. The loading force line was re-established. Studies of experimental mechanics in vitro was performed on the cadava femur samples, which were divided randomly in 5 groups No changes of bone structure occured when the supporting nail was loaded over 2608 Newtons. The exprimental results shows the supporting nail has excellent stability of yarns or valgus motion and the axis of anti shearing dislocation.

    • MATHEMATICAL EXPRESSION ON THREE-DIMENSIONAL MOTION OF THE HUMAN SPINAL COLUMN

      1999, 14(1):62-64. DOI: 10.3871/j.1004-7220.1999.01.64.

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      Abstract:In this paper, three-dimensional motion of the human spinal column is mathematically expressed by a spatial curve, which is defined and passed through each vertebral centroid. In order to evaluate three-dimensional deformity of the spine column, three-dimensional Cobb angle is introduced and defined, which can be calculated by spatial curve of the spinal column.

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