• 한국정밀공학회지
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• 제24권8호통권197호
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• pp.122-129
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• 2007

To evaluate the effect of artificial disc implantation and fusion on the biomechanics of adjacent motion segment, a nonlinear three-dimensional finite element model of whole lumbar spine (L1-S1) was developed. Biomechanical analysis was performed for two different types of artificial disc, ProDisc and SB $Charit{\acute{e}}$ III model, inserted at L4-L5 level and these results were also compared with fusion case. Angular motion of vertebral body, forces on the spinal ligaments and facet joint under sagittal plane loading with a compressive preload of 150 N at a nonlinear three-dimensional finite element model of Ll-S1 were compared. The implant did not significantly alter the kinematics of the motion segment adjacent to the instrumented level. However, $Charit{\acute{e}}$ III model tend to decrease its motion on the adjacent levels, especially in extension motion. Contrast to motion and ligament force changes, facet contact forces were increased in the adjacent levels as well as implanted level for constrained instantaneous center of rotation model, i.e. ProDisc model.

• 대한정형도수물리치료학회지
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• 제7권2호
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• pp.23-39
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• 2001

Dysfunction of the anterior and dorsal muscles of the trunk have been studied in relation to low back pain of many years. Many muscles of the trunk are capable of contributing to the stabilization and protection of the lumbar spine, recent evidence has suggested that transversus abdominis may be critically involved and has been the focus of rehabilitation. The delay in onset of contraction of trunk muscles associated with movement of the upper or lower limb in patients with low back pain indicates a significant deficit in the automatic motor command for control of disturbance to the spine. The function of transversus abdominis has been largely ignored in the evaluation of spinal stabilization and protection. The most essential stabilizing muscles for the lumbar column are the transversus abdominis and the multifidus. Sling exercise therapy(SET) concept consists of a system of diagnosis and treatment. The system of diagnosis involves testing the muscle's tolerance through progressive loading in open and close kinetic chains. The SET system contains elements such as relaxation, increasing the range of movement, traction, training the stabilizing musculature, sensorimotor exercises, training in open and close kinetic chains, dynamic training of the mobilizing musculature, cardiovasc+ular exercises, group exercise, personal exercise at home. Sensorimotor training is an essential element of the SET concept. The emphasis is on closed kinetic chain exercises on an unstable surface, thereby achieving optimum stimulation of the sensorimotor apparatus.

• 대한기계학회논문집A
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• 제33권7호
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• pp.637-644
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• 2009

We have analyzed the biomechanical characteristics of cervical spine after total disc replacement using finite element analysis. A finite element model of C2-C7 spinal motion segment was developed and validated by other experimental studies. Two types of artificial discs, semi-constraint and un-constraint, were inserted at C6-C7 segments. Inferior plane of C7 vertebra was fixed and 1Nm of moment were applied on superior plane of C2 vertebra with 50N of compressive load along follower load direction. Mobility of the cervical spine in which each artificial disc inserted was higher than that of intact one in all loading conditions. Also, high mobility at the surgical level after total disc replacement could lead higher facet joint force and ligaments axial stresses. The results of present study could be used to evaluate surgical option and validate the biomechanical characteristics of the implant in total disc replacement in cervical spine.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.248-251
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• 2005

To investigate the degeneration process in the intervertebral disc, a three dimensional (3D) poroelastic finite-element (FE) model was developed. Disc was modeled as two different regions, such as annulus modeled with fiber reinforced 20 node poroelastic ground matrix and nucleus having large porosity. Excess Von Mises stress in the disc element assumed to be a possible source of degeneration under compressive loading condition. Recursive calculation was continued until the desired convergence was attained by changing the permeability and porosity of those elements, which could be predicted from the previous iteration. The degenerated disc model showed that relatively small compressive stresses were generated in the nucleus elements compared to normal disc. Its distribution along the sagittal plane was matched well with a previously reported experimental result. Contrasts to this result, pore pressures in the nucleus were higher than those in the normal disc. Total stress indicated similar values for two different models. This new approach using poroelastic modeling could provide the explanation of the interaction between fluid and solid matrix in the disc during the degeneration process.

• 대한의용생체공학회:의공학회지
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• 제28권3호
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• pp.397-409
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• 2007

Owing to needs of biomechanical comprehension and analysis to obtain various medical treatment designs which are related with the spine in order to cure and diagnose LBP patients, the FE modeling and nonlinear analysis of lumbosacrum including a partial ilium and iliolumbar ligaments, were carried out. First, we investigated whether the geometrical configuration of vertebrae displayed by DICOM slice files is regular and normal condition. After constructing spinal vertebrae including a partial ilium, a sacrum and five lumbars (from L1 to L5)with anatomical shape reconstructed using softwares such as image modeler and CAD modeler, we added iliolumbar ligaments, lumbar ligaments, discs and facet joints, etc.. And also, we assigned material property and discretized the model using proper finite element types, thus it was completely modeled through the above procedure. For the verification of each segment, average sagittal ROM, average coronal ROM and average transversal ROM under various loading conditions(${\pm}10Nm$), average vertical displacement under compression(400N), ALL(Anterior Longitudinal Ligament) and PLL(Posterior Longitudinal Ligament) force at L12 level, strains of seven ligaments on sagittal plane at L45 level and maximal strain of disc fibers according to various loading conditions at L45 level, etc., they were compared with experimental results. For the verification of multilevel-lumbosacrum spine including partial ilium and iliolumbar ligaments, the cases with and without iliolumbar ligaments were compared with ROM of experiment. The results were obtained from analysis of the verified FE model as follows: I) Iliolumbar ligaments played a stabilizing role as mainly posterior iliolumbar ligaments under flexion and as both posterior and anterior iliolumbar ligaments of one side under lateral bending. 2) The iliolumbar ligaments decreased total ROM of 1-8% in total model according to various motion conditions, which changed facet contact forces of L5S level by approximately 0.8-1.4 times and disc forces of L5S level by approximately 0.8-1.5 times more than casewithout ilioligaments, under various loading conditions. 3) The force of lower discs such as L45 and L5S was bigger than upper discs under flexion, left and right bending and left and right twisting, except extension. 4) It was predicted that strains of posterior ligaments among iliolumbar ligaments would produce the maximum 16% under flexion and the maximum 10% under twisting. 5) It's expected that this present model applies to the development and design of artificial disc, since it was comparatively in agreement with the experimental datum.

• 대한의용생체공학회:의공학회지
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• 제36권6호
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• pp.276-282
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• 2015

Recently, during the multi-level fusion with pedicle screws, interspinous spacer are sometimes substituted for the most superior level of the fusion in an attempt to reduce the number of fusion level and likelihood of degeneration process at the adjacent level. In this study, a finite element (FE) study was performed to assess biomechanical efficacies of the interspinous spacer combined with posterior lumbar fusion with a previously-validated 3-dimensional FE model of the intact lumbar spine (L1-S1). The post-operative models were made by modifying the intact model to simulate the implantation of interspinous spacer and pedicle screws at the L3-4 and L4-5. Four different configurations of the post-op model were considered: (1) a normal spinal model; (2) Type 1, one-level fusion using posterior pedicle screws at the L4-5; (3) Type 2, two-level (L3-5) fusion; (4) Type 3, Type 1 plus Coflex$^{TM}$ at the L3-4. hybrid protocol (intact: 10 Nm) with a compressive follower load of 400N were used to flex, extend, axially rotate and laterally bend the FE model. As compared to the intact model, Type 2 showed the greatest increase in Range of motion (ROM) at the adjacent level (L2-3), followed Type 3, and Type 1 depending on the loading type. At L3-4, ROM of Type 2 was reduced by 34~56% regardless of loading mode, as compared to decrease of 55% in Type 3 only in extension. In case of normal bone strength model (Type 3_Normal), PVMS at the process and the pedicle remained less than 20% of their yield strengths regardless of loading, except in extension (about 35%). However, for the osteoporotic model (Type 3_Osteoporotic), it reached up to 56% in extension indicating increased susceptibility to fracture. This study suggested that substitution of the superior level fusion with the interspinous spacer in multi-level fusion may be able to offer similar biomechanical outcome and stability while reducing likelihood of adjacent level degeneration.

• 대한의용생체공학회:의공학회지
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• 제28권4호
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• pp.512-519
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• 2007

The purpose of this study is to investigate the potential of a novel tissue engineering approach to regenerate intervertebral disc. In this study, thermosensitive scaffold (chitosan-Pluronic hydrogel) and nanofiber were used to replace the nucleus pulposus (NP) and annulus fibrosus of a degenerated intervertebral disc, leading to an eventual regeneration of the disc using the minimally invasive surgical procedure and organ culture. In preliminary study, disc cells were seeded into the scaffolds and cellular responses were assessed by MTT assay and scanning electron microscopy (SEM). Based on these results, we could know that tissue engineered scaffolds might provide favorable environments for the regeneration of tissues. Organ culture was performed in fresh porcine spinal motion segments with endplates on both sides. These spinal motion segments were classified into three groups: control (Intact), injured NP (Defect), and inserting tissue engineered scaffolds (Insert). The specimens were cultivated for 7 days, subsequently structural stability, cell proliferation and morphological changes were evaluated by the relaxation time, quantity of DNA, GAG and histological examination. In these results, inserting group showed higher relaxation time, reduced decrement of DNA contents, and accumulated GAG amount. Consequently, the tissue engineered scaffolds used in this study seen to be a promising base scaffolds for regenerative intervertebral disc due to its capacity to absorb external dynamic loading and the possible ideal environment provided for disc cell growing.

• 한국콘텐츠학회논문지
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• 제11권5호
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• pp.224-232
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• 2011

본 연구는 허리통증 환자를 대상으로 한국판 일상동작 공포설문지에 대한 신뢰도와 타당도를 검증하기 위하여 실시하였다. 허리 통증이 있는 총 73명의 환자를 대상으로 하였고, 각 대상자는 10가지의 일상동작들에 대한 두려움 정도를 자기-기입식으로 설문지를 작성하였다. 평가-재평가에 신뢰도를 알아보기 위하여 급간내상관계수를 구하였고, 각 문항에 대한 내적일치도는 Cronbach's ${\alpha}$값을 이용하였다. 구성타당도를 알아보기 위하여 요인분석을 실시하였고, 시각 상사척도(VAS)와 Oswestry 장애지수(ODI)와의 피어슨 상관관계 계수를 구하여 공인타당도를 분석하였다. 한국판 일상동작 공포설문지의 평가-재평가간 급간내상관계수(ICC)는 0.96(95%CI 0.94~0.98)으로 높은 신뢰도를 보였고, Cronbach's ${\alpha}$값은 0.93으로 내적일치도가 높게 나타났다. 요인분석 결과 척추부하, 척추운동/자세유지로 총 2요인으로 분리되었고, 총 분산은 76.1%였다. 통증과 기능장애와 관련된 공인타당도는 양호한 양의 상관관계를 나타내었다. 따라서 한국판 일상동작 공포설문지는 허리통증 환자들의 일상동작 시 발생할 수 있는 두려움을 평가하는데 유용하게 쓰일 수 있을 것으로 본다.

• 한국전문물리치료학회지
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• 제6권2호
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• pp.56-66
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• 1999

The purpose of this study focused how to show physiological responses comparing exercise group and non exercise group for progressive maximal wheelchair ergometer exercise loading in complete paraplegia. It also examined the various factors which would be influenced physiological responses. Sixteen subjects have been investigated in this study, and the subjects are divided into two groups as follows: 1) exercise group (7 subjects) 2) non exercise group (9 subjects). Each test was terminated by physical exhaustion and/or an inability to maintain a flywheel velocity. The results were as follows: 1) No difference was noted in pulmonary function test between two groups. 2) $\dot{v}$ Emax value during maximal exercise was significantly different between the groups (p<0.05). The mean $\dot{v}$ Emax of exercise group was $69.67{\ell}/min$, non exercise group was $41.47{\ell}/min$. 3) $\dot{v}$ $O_2max$(${\ell}/min$) value during maximal exercise was significantly different between the groups (p<0.05). The mean $\dot{v}$ $O_2max$(${\ell}/min$) of exercise group was $1.72{\ell}/min$, non exercise group was $1.15{\ell}/min$. 4) $\dot{v}$ $O_2$ max(ml/kg/min) value during maximal exercise was significantly different between the groups (p<0.05). The mean $\dot{v}$ $O_2max$($ml/kg{\cdot}min$) of exercise group was $25.99ml/kg{\cdot}min$, non exercise group was $18.61{\ell}/min$. 5) Maximal heart rate(HRmax) value during maximal exercise was significantly different between the groups (p<0.05). The mean HRmax of exercise group was 180.43 beats/min, non exercise group was 175.00 beats/min. 6) $\dot{v}\;E/\dot{v}\;O_2$ value during maximal exercise was not significantly different between the groups (p>0.05). The mean $\dot{v}\;E/\dot{v}\;O_2$ of exercise group was $36.36{\ell}/{\ell}\;O_2$, non exercise group was $45.46{\ell}/{\ell}\;O_2$. Considering the results which explore the exercise group with paraplegia has shown the maximal aerobic power compared with non exercise group, regular and consistent physical training is highly assumed as a main factor to improve cardiopulmonary fitness.

• 한국산업보건학회지
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• 제18권3호
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• pp.239-247
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• 2008

Low back disorders (LBDs) have been the most common musculoskeletal problem in Korean workplaces. It affects many workers, and is associated with high costs to many companies as well as the individual, which can negatively influence even the quality of life of workers. The _evaluation of low back disorder risk associated with manual materials handling tasks can be performed using variety of ergonomic assessment tools such as National Institute for Occupational Safety and Health (NIOSH) Revised Lifting Equation (NLE), the Washington Administrative Code 296-62-0517 (WAC), the Snook Tables etc. But most of these tools provide limited information for choosing the most appropriate assessment method for a particular job and in finding out advantage and disadvantage of the methods, and few have been assessed for their predictive ability. The focus of this study was to _evaluate spinal loads in real time with lifting and pulling heavy cow leathers in variety of postures. Data for estimating mean trunk motions were collected as employees did their work at the job site, using the Lumbar Motion Monitor. Eight employees (2 males, 6 females) were selected in this study, in which the load weight and the vertical start and destination heights of the activity remained constant throughout the task. Variance components (three dimensional spaces) of mean trunk kinematic measures were estimated in a hierarchical design. They were used to compute velocity and acceleration of multiple employees performing the same task and to repetitive movements within a task. Therefore, a results of this study could be used as a quantitative, objective measure to design the workplace so that the risk of occupationally related low back disorder should be minimized.