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( Kyoung Tak Kang ),( Joon Hee Park ),( Ho Joong Kim ),( Hwan Mo Lee ),( Kwang Il Lee ),( Ms ),( Hone Hee Jung ),( Hwa Yong Lee ),( Young Bock Shim ),( Ju Woong Jang ) 한국조직공학·재생의학회 2011 조직공학과 재생의학 Vol.8 No.4
Different from primitive tissue engineering, current tissue engineering and biomedical research focuses on tissue regeneration using stem cells. By autotransplantation, Adult stem cells can overcome problems that embry-onic stem cells have, such as immunologic disharmony, and formation of variant carcinomas, making adult stem cell research more prominent. In differentiation of adult stem cells, mechanical stimuli are one of the most important factors in that they enhance differentiation. In case of mesenchymal stem cells, it can be differentiated into fibro-blasts, chondrocytes, and osteoblasts by the magnitude of mechanical stimuli. Additionally, the magnitude and fre-quency of mechanical stimuli is a key factor to determining the proliferation rate of each tissue. Therefore, the purpose of this research is to study tissue differentiation by mechanical stimuli. Tissue differentiation algorithm by magnitude of mechanical stimuli was suggested, and tissue proliferation and apoptosis was modeled mathematically. The cell density of each phenotype was predicted using numerical models of tissue differentiation and proliferation. Cell experimental data were used to determine differentiation and proliferation patterns. A numerical model predict-ing tissue differentiation by the magnitude and frequency of mechanical stimuli was suggested, and bone fracture healing was simulated. The results from the numerical model analysis, using magnitude and frequency as cell pro-liferation controlling factor, showed better description about bone healing process. With simulation of bone healing process with two numerical models, the model with considering proliferation and apoptosis rate gives more accurateresult. Time for bone fracture healing was shorter in model with the proliferation and apoptosis rate, and more fit to validation data.
Kang, Kyoung-Tak,Kim, Ho-Joong,Son, Juhyun,Yeom, Jin S.,Chun, Heoung-Jae Korean Society for Precision Engineering 2015 International Journal of Precision Engineering and Vol.16 No.1
In this study finite element model of the human lumbar spinal segments (L2-L5) was developed to parametrically examine the stiffness of a dynamic stabilization device and its influence on the mobility of adjacent intervertebral segments. Five models were analyzed and compared: (1) a lumbar spine with intact discs, a reference; (2) a fused spine with a fixation device following interbody fusion and total laminectomy; (3) a spine stabilized with a dynamic stabilization device following total laminectomy; and (4) an additional vertically parallel paired dynamic posterior fixator and paired rigid fixator implemented at levels L3-L5. The disc pressure on the adjacent segments in the fused spine was greater than that of the intact spine, but the disc pressure of the dynamically stabilized spine was similar to that of the intact spine. The use of dynamic stabilization devices restored functionality more closely to that of the intact spine compared to the fused spine. The stiffness values utilized in the device were determined to be important design parameters for manufacturing dynamic stabilization devices.
Kyoung-Tak Kang(강경탁),Heoung-Jae Chun(전흥재),Ho-Joong Kim(김호중),이광일,장주웅,심영복 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
Facet joint orientation and facet tropism are presented as the potential anatomical predisposing factors for lumbar degenerative changes that may lead in turn to early degeneration and herniation of the corresponding disc or to degenerative spondylolisthesis. However, no biomechanical study of this concept has been reported. Three models, F50, F55, and F60 were simulated with different facet joint orientations (50°, 55°, and 60° relative to coronal plane) at both L2-3 facet joints. A facet tropism (FT) model was also simulated to represent a 50° facet joint angle at the right side and a 60° facet joint angle at the left side in the L2-3 segment. The F50, F55, and F60 models did not differ in the intradiscal pressures generated under four pure moments: but under anterior shear force, the F60 and FT models showed increases of intradiscal pressure. The F50 model under extension and the F60 model under torsion each generated an increase in facet contact force. In all conditions tested, the FT model yielded the greatest increase of intradiscal pressure and facet contact force of all the models.
척추 유합술 후, 인접 분절의 스트레스에 대한 척추경 나사못에 대한 영향
강경탁(Kyoung-Tak Kang),전흥재(Heoung-Jae Chun),손주현(Ju-Hyun Son),김호중(Ho-Joong Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
Since the advent of pedicle screw fixation system, posterior spinal fusion has markedly increased. This internal fixation system has been reported to enhance the fusion rates, thereby becoming very popular procedure in posterior spinal arthrodesis. Although some previous studies have shown the complications of spinal instruments removal, i.e. loss of correction and spinal collapse in scoliosis or long spine fusion patients, there has been no study describing the benefit or complications in lumbar spinal fusion surgery of one or two level. In order to clarify the effect of removal of instruments on mechanical motion profile, we simulated a finite element model of instrumented posterolateral fused lumbar spine model, and investigated the change of mechanical motion profiles after the removal of instrumentation.
성인 척추 측만증에서 황색인대와 신경근사이의 경계조건에 따른 Stress변화에 관한 연구
강경탁(Kyoung-Tak Kang),전흥재(Heoung-Jae Chun),김호중(Ho-Joong Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
The purpose of this study is to investigate the mechanism of nerve root impairment caused by the rotation and the lateral translation of scoliotic curve in degenerative lumbar scoliosis using finite element analysis. Few studies have shown the relationship between the curve pattern and nerve root symptoms in degenerative lumbar scoliosis (DLS), and the understanding of the mechanism about DLS also remains unclear. Here, the authors used a finite element model of DLS to investigate the mechanism of nerve root stretching, as caused by the rotation and the lateral translation or bending of the scoliotic curve in DLS. In order to investigate this issue, the finite element analysis model of degenerative lumbar scoliosis were considered in this study. In each simulation, the stress between nerve root and ligament flavum was calculated according to boundary condition in both sides of each vertebral segment.
강경탁(Kyoung-Tak Kang),전흥재(Heoung-Jae Chun),손주현(Ju-Hyun Son),김호중(Ho-Joong Kim),문성환(Seong-Hwan Moon),이환모(Hwan-Mo Lee),김가연(Ka-Yeon Kim) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.7
Previous studies have introduced the technique of spinous process osteotomy to decompress spinal stenosis, a procedure which aims to afford excellent visualization while minimizing destruction of tissues not directly involved in the pathologic process. However, biomechanically it has not been investigated whether the sacrifice of posterior spinous process might have potential risk of spinal instability or not, even though supra-spinous and inter-spinous ligaments are preserved. Therefore the aim of this study is to evaluate the biomechanical properties after spinous process osteotomy, using finite element analysis. The model of spinous process osteotomy exhibited no significant increase in disc stress or change in segmental range of motion. It is due to the fact that the instability of lumbar spine has been maintained by the two-types of ligaments compared with the prior surgical technique. Therefore, according to the finite element result on this study, this osotetomy was considered to be a clinically safe surgical procedure and could not cause the instability of the lumbar spine.
강경탁(Kyoung-Tak Kang),전흥재(Heoung-Jae Chun),손주현,김호중(Ho-Joong Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
The aim of this study is to evaluate the bio-mechanical properties after spinous process osteotomies, using finite element analysis. We developed a three-dimensional, non-linear finite element model of the lumbar spine that consisted of three lumbar vertebrae, intervertebral discs and associated spinal ligaments. The validation part included the loading model with 9 Nm of bending moment in various loading modes without any preload, for the intact model. For the physiologic load, the range of motion of the simulated intact model was within one standard deviation of previous cadaveric studies. In the model of spinous process osteotomy, the disc pressure and segmental range of motion was not changed significantly. Therefore, these procedures are considered as bio-mechanically safe procedure, and could not cause the instability