• Journal of the Korean Society for Precision Engineering
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• v.25 no.1
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• pp.145-150
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• 2008

One of the unresolved questions in articular cartilage biomechanics is the magnitude of the dynamic modulus and tissue compressive strains under physiological loading conditions. The objective of this study was to characterize the dynamic modulus and compressive strain magnitudes of bovine articular cartilage at physiological compressive stress level and loading frequency. Four bovine calf shoulder joints (ages 2-4 months) were loaded in Instron testing system under load control, with a load amplitude up to 800 N and loading frequency of 1 Hz, resulting in peak engineering stress amplitude of ${\sim}5.8\;MPa$. The corresponding peak deformation of the articular layer reached ${\sim}27%$ of its thickness. The effective dynamic modulus determined from the slope of stress versus strain curve was ${\sim}23\;MPa$, and the phase angle difference between the applied stress and measured strain which is equivalent to the area of the hystresis loop in the stress-strain response was ${\sim}8.3^{\circ}$. These results are representative of the functional properties of articular cartilage in a physiological loading environment. This study provides novel experimental findings on the physiological strain magnitudes and dynamic modulus achieved in intact articular layers under cyclical loading conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.173-174
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• 2006

Understanding chondrocyte behavior inside complex, three-dimensional environments with controlled patterning of geometrical factors would provide significant insights into the basic biology of tissue regenerations. One of the fundamental limitations in studying such behavior has been the inability to fabricate controlled 3D structures. To overcome this problem, we have developed a three-dimensional microfabrication system. This system allows fabrication of predesigned internal architectures and pore size by stacking up the photopolymerized materials. Photopolymer SL5180 was used as the material for 3D scaffolds. The results demonstrate that controllable and reproducible inner-architecture can be fabricated. Chondrocytes harvested from human nasal septum were cultured in two kinds of 3D scaffolds to observe cell adhesion behavior. Such 3D scaffolds might provide effective key factors to study cell behavior in complex environments and could eventually lead to optimum design of scaffolds in various tissue regenerations such as cartilage, bone, etc. in a near future.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.335-339
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• 2003

The aim of this study is to optimize the monolayer cultivation of human articular chondrocytes in serum-free media. For this purpose, chondrocytes were isolated from human articular cartilage and monolayer cultures were performed in DMEM/F12 medium with 10% fetal bovine serum (FBS) or serum-free media (SFM) containing various supplements and epidermal growth factor (EGF). Western blotting analysis, RT-PCR, dimethylmethylene blue (DMB) assay were carried out to evaluate the synthesis of collagen type II (Col. II) and glycosaminoglycans (GAGs). We observed that SFM with EGF stimulated the cell growth while the amounts of synthesized GAGs and Col. II were decreased gradually. However, the Col. II mRNA level was increased when the SFM was replaced by media containing 10% FBS. This study suggests that it is possible to obtain large amount of human articular chondrocytes by short-term monolayer cultures in SFM.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1493-1494
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1425-1426
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• 2011

• Journal of the Korean Society for Precision Engineering
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• v.25 no.10
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• pp.137-143
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• 2008

The objective of this study was to characterize the role of synovial fluid and hyaluronan in the frictional response of bovine articular cartilage. Seven cylindrical cartilage specimens were harvested from three fresh bovine humoral heads (4-6 months old). Reciprocal sliding motion (1mm/s) was provided by a custom-made friction testing apparatus with a normal load of 22.3 N. From the measured time-dependent normal and frictional forces, the minimum and maximum frictional coefficients were calculated. Synovial fluid reduced the minimum frictional coefficient by ${\sim}75$ % and maximum frictional coefficient by ${\sim}11%$, while the reduction of the minimum and maximum frictional coefficients with hyaluronan was ${\sim}42%$ and ${\sim}24%$, respectively. To the best of our knowledge, this experimental study investigates the first such comparisons of frictional response of articular cartilage with and without synovial fluid and hyaluronan, and provides significant insights into their role in the articular cartilage friction and lubrication.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.11
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• pp.119-125
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• 2008

The objective of this study was to compare micro-scale friction coefficients with and without synovial fluid, and micro-scale measurements were performed using atomic force microscopy (AFM) with a $5{\mu}m$ spherical probe. Four cylindrical cartilage specimens were harvested from two fresh bovine humeral heads (4-6 months old). $Average{\pm}standard$ deviation values of the micro-scale AFM frictional coefficients calculated from the liner fit of friction versus normal force was $0.177{\pm}0.012$ and $0.130{\pm}0.010$ with and without synovial fluid coating on AFM probe respectively, showing its reduction by ${\sim}27%$ with synovial fluid. To the best of our knowledge, this experimental study investigates the first such comparisons of frictional response of articular cartilage with and without synovial fluid coating on AFM probe, and provides significant insights into the role of synovial fluid in the articular cartilage friction and lubrication independently of the confounding effect of fluid pressurization in the articular cartilage.

• The Journal of the Korean bone and joint tumor society
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• v.14 no.2
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• pp.79-85
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• 2008

Soft tissue tumor classifications should be an important part of radiology, oncology and, for orthopedic clinicians and pathologists, they provide diagnostic instruction and prognostic guidelines. In soft tissue tumor classification systems, the World Health Organization (WHO) classifications have become dominant, enabled by the timely publication of new blue books which included detailed text and numerous good illustrations. The new WHO classification of soft tissue tumors was introduced in 2002. Because the classification represents a broad consensus concept, it has gained widespread acceptance around the globe. This article reviews the changes which were introduced the vascular tumors, chondroid-osseous tumors and tumors of uncertain differentiation which have been first recognized or properly classified during the past decade.

• Proceedings of the KOR-BRONCHOESO Conference
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• 2003.09a
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• pp.110-110
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• 2003

후두기관외상은 두경부 부위의 다른 외상에 비해 흔하지 않은데, 이는 연골의 유연성과 후두의 가동성, 후두가 하악과 흉골사이에 위치하여 외상시 보호 받게 되는 해부학적 특성에 기인한다. 그러나, 후두는 호흡과 발성에 중요한 기관으로 조기 진단과 정확한 평가, 적절한 치료를 못할 경우 생명을 위협 할 수 있고 삶의 질에 지대한 영향을 줄 수 있다. 이에 저자들은 급성 후두기관손상으로 수술적 치료를 받은 환자를 대상으로 손상 기전 및 임상 양상, 손상부위, 손상 정도 치료 등을 알아보고 향후 치료에 도움을 얻고자 하였다. 1996년부터 2003년까지 급성 후두기관 손상으로 수술적 치료를 받은 10명을 대상으로 후향적으로 조사를 하였다. 손상정도는 Schaefer의 분류를 따랐으며 술후 결과는 발성과 기도유지로 평가하였다. 발성의 경우 수상전과 동일하거나 유사할 경우 성공(good)으로, 수상전과는 다르지만 기능을 하는 경우는 양호(fair)로, 거의 음성이 나지 않거나 알아들을 수 없는 경우 불량(poor)로 분류하였고, 기도유지는 수상전과 동일하거나 유사할 경우 성공(good)으로, 경한 흡인이나 운동 유발성 호흡곤란이 있는 경우(fair)로 발관이 되지 않는 경우를 불량(poor)으로 분류하였다. 남녀 성비는 8대 2였고 30～40대가 4명으로 가장 많았다. 손상의 원인은 둔상인 경우(4예) 교통사고가 2례, cloth line 손상 2례, 관통상(6례)는 모두 칼에 의한 좌상이었다 증상은 피하기종이 9례, 애성이 7례, 호흡 곤란이 6례로 많았으며 손상부위는 갑상연골 골절이 5례(50％), 기도손상과 갑상선 손상이 각각 4례에서 관찰되었다. 그 외에도 윤상 연골 골절과 윤상갑상막 손상 등이 관찰되었다. 또한 점막 손상이 7례에서 관찰되었다. 성대마비는 내원시 4례에서 관찰되었다 치료는 수상 후 조기수술을 시행하였고 수상 부위를 개방하여 손상된 연조직을 일차 봉합하거나, 골절을 정복 고정하였고 3례에서 스텐트를 삽입하였다. 술후 기도유지는 모두 성공적이었고 발성기능은 6례에서 성공(good)적이었고 4례에서 양호(fair)의 결과를 보였다. 양호의 결과를 보인 모든 예가 내원시 성대 움직임의 마비나 저하를 보인 예였다. 급성 후두기관손상환자에서 조기 진단과 적절한 수술적 치료는 환자의 생명을 유지시키고 술후 발성 지능의 보존에 양호한 결과를 보였다.

• Journal of Korean Orthopaedic Sports Medicine
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• v.8 no.1
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• pp.33-38
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• 2009

Purpose: We wanted to report the clinical characteristics and arthroscopic findings of radial tear in medial meniscus posterior horn insertion, commonly occurs in patient over middle age with documentary review. Materials and Methods: Retrograde study using hospital records was done to 40 cases in 40 patients who visited our hospital and had been performed knee arthroscopic surgery due to medial meniscus posterior horn insertion tear between January, 2005 to April, 2007. Seven cases were male and 33 cases were female with the mean age of 61 (range, 47-80). Trauma history, stage of arthritis, period between pain and operation, MRI findings, clinical symptoms and operation methods were evaluated. Results : Six cases had trauma history while 34 cases didn't. In simple x-ray, using Kellgren-Lawrence classification, 31 cases were between stage 0 and II while 9 cases were stage III. In arthroscopic exam, there were 17 cases of Outerbridge grade IV, 4 cases of grade III, 9 cases of grade II, 9 cases of grade I. The mean duration of pain was 5.3 months. In MRI, at least one finding of cleft in axial or coronal view or ghost sign in sagittal view was found in all cases. The shape of meniscus tears were blunt in 18 cases, transverse in 12 and degenerative tear in 10. Subtotal meniscectomy was performed in 16 cases, partial meniscectomy in 10 cases and meniscal repair in 14 cases. Conclusion : Medial meniscus posterior horn insertion tear occurs in patients over middle age is rarely related to trauma history but causes painful mechanical symptom and usually accompany arthritis. Meniscectomy can be done for the treatment but repair can be considered is some cases. Further study on the treatment result will be needed.