Performance Test of Web Based 3D Medical Image System using Image Streaming Technique / 대한의료정보학회지

OBJECTIVE: It is still the important subject that 3D visualizing of medical images to help patient diagnose. There were many challenges for fast 3D visualization but it has some limitations that volume rendering without high price's hardware and software. Some techniques through the web were suggested to construct high quality's 3D visualization even though it was an only poor personal computer. This technique could share the volume rendering board and diagnose 3D images together. However there are some problems to construct web based 3D visualization. These are network delay, optimized visualization and security etc. The purpose of this paper was to visualize and control the 3D medical image having a high quality on the web. METHODS: To construct this system, we used mainly three tools which were VolumePro1000 board, WMV9(Windows Media Video 9 Codec) and socket functions based on TCP(Transmission Control Protocol). VolumePro1000 board could calculate quickly heavy matrixes of 3D images using phong's shading and shear-warp factorization. WMV9 was able to compress efficiently live images and to apply image streaming technique. Socket functions based on TCP transmitted messages to control the 3D images. RESULTS: We developed 3D visualization system and evaluated about image qualities and transmission conditions of different compression rates on unfixed network condition. CONCLUSION: It was big advantages that WMV9 encoder could decode automatically in many platforms(desk top, PDA, notebook, cellular phone, etc) without installing specific decoding programs if they only have Windows Media player. We expect 3D visualization system to be utilized various biomedical fields such as IIGS(Interactive Image Guided Surgery), CAD(Computer Aided Diagnosis) and Tele-medicine technologies.

Hypertrophy of the Patellar Tendon induced by Local Injection of TGF-beta1 in Mature Rats / 대한정형외과연구학회지

PURPOSE: The effects of local injection of TGF-beta1 on the normal patellar tendon and the characteristics of remaining tendon after the partial resection of hypertrophic one were investigated. MATERIALS AND METHODS: TGF-beta1 was injected into the right patellar tendon of mature rats weekly for 3 weeks. Histological study, biomechanical analysis and the transmission electron microscopic evaluation were done. Half of hypertrophic tendon was resected at 4 weeks after the last injection and the same analyses were RESULTS: TGF-beta1 treated tendon increased in cross sectional area but decreased significantly in maximum tensile stress. The hypertrophic tissue was mainly composed of small collagen fibrils. After the partial resection of hypertrophic tendon, there was no significant difference in maximum tensile stress between remaining and control tendons. There were relatively larger collagen fibrils in the remaining tendon tissue than in non-resected hypertrophic one. CONCLUSION: Local injection of TGF-beta1 induced the hypertrophy of normal tendon. After the partial resection of hypertrophic tendon, the remaining one showed the more similar biomechanical properties to normal one.

The Effect of the Cross-pins on the Fixation Stiffness using Finite Element Method in Fracture of Femoral Shaft / 대한정형외과연구학회지

PURPOSE: A compression plate fixation was generally used in the fracture of a femoral diaphysis but it produced the stress shielding problem which resulted in a decrease of bone mass and impaired mechanical properties. This study was designed to compare with the stiffnesses of three different internal fixation types ; fixation with only plate, with only cross-pins, and with both a plate and cross-pins. MATERIALS AND METHODS: To compare the stress distribution and stiffness of three types of fixation devices, the device-bone system are analyzed under axial compression(70Kg) and 3-point bending(500Nmm) in planes using the 2-D finite element method(ABAQUS 5.8). Also the stiffness of each device was evaluated at seven different time points during fracture healing by increasing Young's modulus of callus. RESULTS: The plate fixation model had the highest stress distribution and occurred the stress concentration in the cortex beneath the plate. During the healing of bone fracture, the fixation with cross-pins relatively had a higher compression and bending stiffness. The fixation with only cross-pins was as stiff as that with an only plate in bending but less stiff than in compression. CONCLUSION: The internal fixation added to cross-pins may decrease the stress shielding problems due to dispersing the stress concentration and also improve the stiffness of a device-bone system.

The Effect of Cyclic Compressive Strain on the Differentiation of Osteoblast-Like Cells (MC3T3-E1) in 3-D Scaffold / 대한정형외과연구학회지

We examined the effect of an applied cyclic compressive strain on the growth and differentiation of MC3T3-E1 cultured in a three-dimensional chitosan scaffold. The specially designed testing apparatus for mechanical stimulus was developed for uniaxial cyclic compressive strain. Cyclic compressive strain was applied over a period of 17 days with 150 cycles per day at a frequency of 0.5hz. Strain magnitude was 2.5% of the scaffold length. Control group and mechanically stimulated group were incubated and harvested at the indicated times. (day 3, 7, 10, 14, 17) The total amount of protein and alkaline phosphatase activity were examined. The total amount of protein of the control group was higher than that of the mechanically stimulated group. This was due to cell death for the nodule formation and calcium deposit of the mechanical stimuli group which resulted in cell differentiation. The alkaline phosphatase activity increased slightly in the control group. However, in the mechanical stimuli group, it increased significantly and reached its peak level on day 7 and subsequently its activity dropped to a level that was higher than the level at day 4(p < 0.05). Conclusively, it can be noted that the mechanical stimulus significantly accelerated the differentiation of MC3T3-E1 cells.

The Effect of a Chitosan Coating of Dental Implant on the shock Absorption under Impact Test

With the object of providing a temporary artificial periodonal ligament-like membrane around the dental implant, 10 Branemark type implants were coated with commercially available chitosan(Fluka Co., Buchs, Switzerland) which has a molecular weight of 70,000 and 80% deacetylation degree. Once this bioactive hydrophillic polymer(chitosan) contacts with blood or wound fluids, it becomes swollen and penetrates into the adjacent cancellous bone. Thus the interface between implant and surrounding bone is completely filled with chitosan. This tight junction in early healing phase enhances primary stability. The chitosan coated dental implants were implanted into the fresh patella bones from porcine knees, since the thickness of cortical bone is relatively even and their cancellous structure is homogenous. To test the shock absorbing effect, 1mm delta-rogette strain gage was installed behind the implant. The results showed 1. the principal strain peak value directed to the impact of coated implant was 0.064 0.018(p<0.05) and that of uncoated implant was 0.095(0.032 p<0.05). 2. the peak time delay of coated implant was 0.056sec(0.011 p<0.05) and that of uncoated implant was 0.024sec(0.009 p<0.05). It can be reasoned from this results that the chitosan coating has a shock absorbing effect comparable with a temporary artificial periodontal ligament.

A Study on the Optimal Culture Condition and Biomechanical Properties of In Vitro Tissue Engineered Cartilage Using a Fibrin Glue Scaffold

The purpose of this study was to examine the feasibility of using fibrin glue polymer designed to produce tissue-engineered cartilage by in vitro culture and to determine the optimal fibrinogen and chondrocyte concentrations required to generate cartilage and to evaluate the biomechanical properties of the generated cartilages. The most favorable fibrinogen and chondrocyte concentrations were determined by measuring the volume and weight gains, evaluating the histologic changes and measuring the biomechanical properties after construction of 12 different chondrocyte-fibrin glue constructs. The results are as follows. 1. The fibrin glues without chondrocytes degraded during 8 weeks of culture period. 2. The construct gains more weight in those with higher chondrocyte and fibrinogen concentration. 3. Histologic analysis of the generated cartilage showed nearly homogeneous cartilage when using 80 mg/cc fibrinogen and 4 x 10(7) chondrocyte/cc at 8 weeks in vitro culture. 4. The compressive modulus is higher in constructs with higher fibrinogen concentration and is 35.4 -36.8% of the normal joint cartilage. 5. The yield stress is higher in constructs with higher fibrinogen concentration and is 11% of the normal joint cartilage. This study demonstrates that fibrin glue is a suitable polymer for generation of cartilage by in vitro culture method. The construct with 80 mg/cc fibrinogen and 4 x 10(7) chondrocyte/cc yields the best quality of cartilage at 8 weeks when analyzed by weight and volume changes, histology and biomechanical properties. The compressive modulus and yield stress of the generated cartilage are lower than those of normal joint cartilage, and may still be adequate for the purpose of craniofacial reconstruction which seeks more pliant cartilage not requiring weight bearing strength.

New Chronic Osteomyelitis Model in White Rabbit: A Preliminary Report / 대한정형외과연구학회지

The purpose of this study was to develope a rabbit model for the chronic osteomyelitis, which is reproducible, controllable in quantity of bacteria and suitable for toxicologic research and therapeutic intervention studies. Osteomyelitis was induced in white rabbits by injecting varying numbers of S. aureus(ATCC 19636, 49230) and Alginate-CaCl2 into the proximal metaphysis of tibia. Three rabbits were used in each number of S. aureus respectively. The tibia were harvested at 8 weeks later and evaluation was done by clinical, radiological and histological findings. Clinical sings of infection consisted of soft tissue swelling and limping in rabbits, Radiologic findings were periosteal reaction, osteolysis, new bone formation in proximal tibias. Histology showed chronic active inflammation, debris of alginate, clusters of bacterial and granulation tissue. In ATCC 19636(more than 6X105) inoculated rabbits, osteomyelitis was established consistently in all three rabbits. Using Alginate-CaCl2 and ATCC 19636 Staphylococcus aureus, we made a new chronic osteomyelitis model, reproducible and controllable in quantity of bacteria.

Estimation of Young's Modulus and Apparent Density of Human Trabecular Bone by Spherical Indentatin Test and CT / 대한정형외과연구학회지

We intended to evaluate the Young's modulus of trabecular bone and apparent density from Computed Tomography(CT) and Spherical Indentation test and to quantify relation ship between them. The distal femurs(31 age, male, left and right) were prepared for exprimentatin and were embedded with repect to anatomical orientation. Then the specimens were scnned at 1 mm intervals on GE9800 CT scanner and the Hounsfield Units(HU, or CT number) were extracted from each CT image. After scanning, the bones were sectioned with diamond saw, producing 8 mm cubes of trabecular bone(72 eachs) from the metaphyseal region of both distal femur. The cubes were mechanically tested in inferior-superior(IS), anteriorposterior(AP), and medial-lateral(ML) direction with custom-made device, Spherical Indentatin Tester. After testing, the real apparent density of specimens were measured. The results of this study showed that the IS modulus was singificantly greater than both the AP and ML modulus and the AP modulus was also greater than ML modulus significantly(p<0.01). A linear relation ship between HU and real apparent density was found to be significant(R2=0.68) and significant power relationship between the apparent density and the tangent moduli(either by CT or physical measures) was also found.

Transplantation of Cultured Allogenic Chondrocyte-Collagen Gel Composite into the Articular Cartilage Defect of Rats / 대한정형외과연구학회지

As one of many cell-many cell-based cartilage repairing methods, transplantation of chondrocyte-embedded-collagen gels in cartilage defect was performed for more satisfactory regeneration of cartilage. The authors performed this study to investigate whether the TGF-beta1 treatment of chondrocytes can do some additional synergistic effect on the transplantation of chondrocyte-embedded-collagen gels for crtilage repair. Chondrocytes were isolated from the articular cartilage of newborn Sprague-Dawley rats. Chondrocytes cultured for 10 days in monolayer were embedded in the 0.45% type I collagen gel. Full-thickness cartilage defect was made in the patellar groove of adult Sprague-Dawley rats. Chondrocytes culdefect was made in the patellar groove of adult Sprague-Dawley rats. The cartilage defects were treated with the following methods in a total of 200 animals, which were assigned to 5 different groups of 40 rats. In the control group, the deffect was left without any treatment, in group I, the defect was filled with collagen gel only, in group II, with collagen gel coontaining 10 ng/ml concentration of TGF-beta1, in group III, with collagen gel containing chondrocytes, and in group IV, with collagen gel containing chondrocytes and TGF-beta1. At 1, 2, 4, 8, 12 weeks after the operation, eight rats of each group were sacrificed, and their distal femurs were harvested for the histologic and biomechanical tests. The section s were stained with hematoxilin and eosin. Alcian-blue, and Safranin-O. Regenerated cartilage was analyzed by the semiquantitative histological grading system. Point indentation test was performed as a biomechanical evaluation, and the stiffness was calculated. The results of the histological grading system revealed that the scores gradually increased with time in all groups, and the scores of group III and IV were higher than those of control, group I and II. The biomechanical study showed that the stiffness gradually increased to reach a plateau level in each group. In control, group I and II, the stiffness increased up to the eighth week and remained around the increased level at the twelfth week, and did not show any statistically significant difference between the groups. In group III and IV, the stiffness was higher than in control group, and increased markedly at the fourth week and the increased level was maintained onwards. The results of this study showed that the transplantation of chondrocyte-embedded-collagen gels enhanced the healing process, and the treatment of TGF-beta1 demonstrated at least partially significant improvement.

Biomechanical Analysis of Unilateral-Ring Hybrid External Fixation / 대한정형외과연구학회지

The mechanical stiffness of Unilateral-Ring Hybrid External Fixation(URHEF) was analyzed and compared with conventional Ilizarov circular external fixation system and unilateral fixation with DynaExtor(R). Our URHEF is basically a unilateral external fixation system which affords easier incorporation and removal of the Ilizarov rings(200mm in diameter) coupled with connecting clamps at anytime, if needed. It allows controlled axial micromotion in due time. For mechanical test, URHEF system was constructed using a DynaExtor(R) fixed with two or three half pins(6 mm in diameter) attached with two proximal and distal Ilizarov rings fixed with an olive pin and a half pin on each ring. Unilateral fixation system was constructed with a DynaExtor(R) fixed with 2 or 3 half pins. Ring fixation system was constructed with four Ilizarov rings(140mm in diameter). Ilizarov system were assembled into 90degrees-90degrees and 45degrees-13 5degrees configurations with 2 olive pins, respectively. The distance between the center of pylon and the pin-clamp interface was equalized, being 70mm, in all the systems. Stiffness in axial compression, anteroposterior and lateral bending was measured. On axial compression and lateral bending tests, URHEF was stiffer than DynaExtor(R) and Ilizarov systems. On anteroposterior bending test, URHEF was less stiff than 90degrees-50degrees configuration of the Ilizarov system but stiffer than 45degrees-135degrees configuration. Considering the fact that instead of 90degrees-90degrees transfixing pin fixatin system, 45degrees-135degrees configuration system is generally used in clinical practice, URHEF appears to be significantly stiffer than unilateral(DynaExtor(R)) and circular (Ilizarov)fixation systems. This mechanical study implicates that URHEF can be beneficially applied in the clinical use with assurance of mechanical stability.

Wear Properties of Surface Modified Ultra-high Molecular Weight Polyethylene / 대한정형외과연구학회지

The wear debris of ultra-high molecular weight polyethylene (UHMWPE) used as a bearing material in total joint arthroplasty evokes a serious adverse biological reaction (osteolysis). In this study, therefore, the wear resistance of UHMWPE is enhanced by attaching a hydrophilic graft on the UHMWPE surface and by improving surface hardness without deteriorating the mechanical properties, which may result in the formation of lubrication film and the increased resistance to penetration, scratching or deformation during articulation. This was done by ion-implantation technique. The results showed that the wettability and the surface hardness of the modified UHMWPE by the above treatments increased due to the increased cross-linking density and hydrophilic graft attachment on the surface. The wear test was performed by a wear testing machine of pin-on-disk type. The modified UHMWPE revealed about 30~50% less volumetric wear than the control specimen. It was also shown that the volumetric wear depended not only on the optimal treatment condition but on the applied load and the sliding speed.

Development of Spine Motion Analyzer and Comparison of Motion in Normal and Lumbar Fusion Cases / 대한정형외과학회잡지

Many kinds of lumbar diseases cause lumbar segmental instability and/or limitation of motion. But, there is no reliable method for measuring accurate trunk motion. In order to measure relative trunk motion respect to the pelvis in vitro, external linkage type of spine motion analyzer was developed. Special programs for calculation of the relative angular motion and graphical display were also developed. The developed device was tested to compare spine motion pattern between 15 normal volunteers and 18 lumbar fusion patients in flexion, extension, lateral bending and axial rotation. It was rather simple and reliable method for spine motion analysis. And it was possible to measure not only angular displacement but also angular velocity and angular acceleration. There were more coupling motions in lateral bending and axial rotation than in flexion and extension. Compared to the normal subjects, patients showed different angular motion, especially in the angular acceleration. Optimal trajectory of the trunk motion derived from mathematical model in flexion and extension matched well with measurement for normal subjects.

Improved stress analyses of dental systems implant by homogenization technique / 대한치주과학회지

Homogenization technique is employed to investigate the series of stress analyses of mandible for three different types of dental implants. This technique helps to make proper material model of bone and analyze such a non homogeneous structure at the level of individual microstructural unit. The stress analyses with homogenization technique show much higher stress level in the sponge bone, compared to those of conventional FEM. It also manifested that even a minor lateral force results in crucial stresses in the dental implant system and that the macroscale model should take the shape and size after real mandible to produce reasonable solution in the analyses of dental implant systems. The shapes of dental implants simulated in this study are rectangularcross-sectioned type, hemi-sphere rooted type, and wedge type implant. The stress states of mandible with hemisphere rooted type implant and wedge type implant show similar levels, while those with sectioned rectangular implant results in higher stresses. It is suggested that the distance between the implant tip and cortical bone be kept far enough to prevent stress concentrations in the mandible.