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한국성 농흉환자에서 강내 유로키나제의 단.장기 치료효과
정태곤 대한영상의학회 1995 대한영상의학회지 Vol.32 No.1
Purpose : The purpose of this study was to evaluate the short and long-term effectivensess of intracavitaryurokinase with percutaneous catheter drainage in loculated thoracic empyemas. Materials and Methods : 15 patientswere identified as second stage of loculated thoracic empyema by estimating nature of pleural fluid, chest PA, lateral decubitus view and CT scan. Under the guidance of fluoroscopy or ultrasound, catheter was insertedpercutaneously. Instillation of urolinase with 100ml of normal saline. Trial of urokinase was repeated untilcomplete drainage of empyema was demonstrated on plain chest film obtained after 48 hours. Results : Successfulcomplete drainage was achieved in 14 of 15 patients. Average dosage of used urokinase was 330, 000U and meanduration of catherter insertion was 35 days. Conclusion : Intracavitary urokinase with percutaneous catheterdrainage is a safe and effective method to facilitate drainage of loculated empyema and to prevent recurrence.
형상기억합금의 척추변형 교정용 강봉으로서의 생체역학적 평가
정태곤,김승수,권순영,김영곤,이성재,안세영,정의룡 한국생체재료학회 2005 생체재료학회지 Vol.9 No.2
This study was intended to systematically investigate biomechanical and clinical feasibilities of the pedicle screw system made of shape memory alloy (Nitinol) rod as a longitudinal member for the surgical management of the scoliosis. First, bending stiffness and elastic modulus of the nitinol rods of various diameters were assessed along with other commercially available rods of different metal alloys. Second, the correctional capacity with respect to various levels of spinal deformities was assessed by inducing phase transformation of the nitinol alloys. After assembling the rods with locking mechanism, the construct stiffness of the pedicle screw system as an assembled body was tested. Results showed that the larger the diameter of the rod, the greater the bending stiffness. Bending stiffness of the nitinol rod (=6 mm) after martensite temperature was 58.1±2.8 N/mm, lower than that of commercial rod of Ti-alloy (88.4 N/mm), and showed Young's modulus of elasticity of 68.0±2.1 GPa. But construct stiffness of the nitinol rod system with a new locking mechanism exhibited about 15.91±1.58 N/mm in flexion and 19.79±2.13 N/mm in extension, superior than the other commercially available Ti-alloy system. Its correctional forces ranged 720-2700 N depending on its rod diameter, well above the level that has been suggested in literature for correction of spinal deformities regardless of severity in deformity and diameter of rods. Particularly, the system with a 6-mm nitinol rod showed sufficient correctional forces regardless of severity in deformity, consistently below 1000N. This suggested biomechanical and clinical efficacies of the system with less likelihood of correctional damages including reduction of stress shielding to the anchoring host bone.
정태곤,이성재,우수헌,박광민,장종욱,한동욱 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.
Recently, many cervical total disc replacement (TDR) devices have been introduced in a variety of designs in an attempt to recreate motion behavior of the normal cervical spine thereby to limit the progression of adjacent degeneration. The purposes of this study were to evaluate and compare the range of motion (ROM) and location of instant center of rotation (COR), and load sharing characteristics of two major products with different design concepts in cervical TAR- Prodisc-C® and Prestige-LP®. A 3-D finite element (FE) model of intact cervical spine (C3-6) was made from CT scans of a normal person and validated. Based on this model,postoperative FE models simulating TDR implantation at the C4-5 disc space were made for Prodisc-C® (Synthes Spine, Paoli, PA)and Prestige-LP® (Medtronic Sofamor Danek, Memphis, TN), respectively. These two TDR devices feature different design concepts that affect kinematics: Rotations and some translations were allowed at the articulating surface of Prestige LP® as the ‘concave down’articulating surface is less constrained whereas only rotations were allowed with Prodisc-C® that features ball & socket articulating surface in ‘concave up’ orientation. Hybrid protocol (intact: 1Nm) with a compressive follower load of 73.6N were applied at the superior endplate of the C3 vertebral body. The inferior endplate of C6 vertebral body was constrained in all directions. At the index level, Prestige-LP® showed 15% less motion than Prodisc-C® in extension and about the same in flexion. Differences in ROM were negligible at the adjacent level. Here, the COR of Prestige-LP® was located more postero-inferiorly than that of Prodisc-C® by about 1-mm during extension at the index level. Facet load was less with Prestige-LP® by about 10% at the index level but 14% more at the adjacent level. The results of this study indicated that the biomechanical behavior of the postoperative cervical spine can be indeed influenced by the design features such as concavity orientation and extent of constraint of the articulating surfaces. Particularly, ROM and COR location as well as the facet loads at the index level and adjacent levels were more sensitive during extension. It would be interesting to note that resulting differences in facet load at the index and adjacent levels between the two designs will manifest to different clinical results in terms of postoperative facet degeneration.
Validation of the Finite Element Model of the Femur and a Novel Internal Distractible Plate System
정태곤,양재혁,한동욱,서승우,이성재 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.
For distraction osteogenesis, external fixators such as mono or circular type were used popularly. However, there are many reported complications such as infection of pin site, vascular and neurological injury and the discomfort during walking. The purpose of this study is to introduce a novel internal distractible plate system (IDPS) and to validate of the finite element model of the femur and IDPS before clinical application and finite element analysis with multiple biomechanical factors. After validating the finite element model of femur and femur with IDPS using the structural stiffness and strain of cadaveric femur during compression test,biomechanical stability of a novel IDPS was analyzed. Reconstructed finite element models showed similar result comparing with the values of cadaveric test in vitro. Through validation procedures using the finite element model of the intact femur and the 30mmdistracted femur with the IDPS, the material properties and the coefficient of friction of the finite element models for finite element analysis can be understood as reliable. Also, clinical stability of a novel IDPS was confirmed.
약물-용출 생분해성 고분자 스텐트를 위한 EGCG와 디자인 파라미터의 영향에 대한 연구
정태곤,이종호,이준재,현승휴,한동욱,Jung, T.G.,Lee, J.H.,Lee, J.J.,Hyon, S.H.,Han, D.W. 대한의용생체공학회 2013 의공학회지 Vol.34 No.3
Finite element analysis(FEA) has been extensively applied in the analyses of biomechanical properties of stents. Geometrically, a closed-cell stent is an assembly of a number of repeated unit cells and exhibits periodicity in both longitudinal and circumferential directions. This study concentrates on various parameters of the FEA models for the analysis of drug-eluting biodegradable polymeric stents for application to the treatment of coronary artery disease. In order to determine the mechanical characteristics of biodegradable polymeric stents, FEA was used to model two different types of stents: tubular stents(TS) and helicoidal stents(HS). For this modeling, epigallocatechin-3-O-gallate (EGCG)-eluting poly[(L-lactide-co-${\varepsilon}$-caprolactone), PLCL] (E-PLCL) was chosen as drug-eluting stent materials. E-PLCL was prepared by blending PLCL with 5% EGCG as previously described. In addition, the effects of EGCG blending on the mechanical properties of PLCL were investigated for both types of stent models. EGCG did not affect tensile strength at break, but significantly increased elastic modulus of PLCL. It is suggested that FEA is a cost-effective method to improve the design of drug-eluting biodegradable polymeric stents.
키높이 인솔두께에 따른 족부의 생체역학적 특성변화에 대한 연구
박태현,정태곤,한동욱,이성재,Park, T.H.,Jung, T.G.,Han, D.W.,Lee, Sung-Jae 대한의용생체공학회 2013 의공학회지 Vol.34 No.2
Recently, functional insoles of wedge-type it is for the young to raise their height inserted between insole and heel cause foot pain and disease. Additionally, these have a problem with stability and excessively load-bearing during gait like high-heel shoes. In this study, we compared the changes in biomechanical characteristics of foot with different insole thickness then we will utilize for the development of the insole with the purpose of relieving the pain and disease. Subjects(male, n = 6) measured COP(center of pressure) and PCP(peak contact pressure) on the treadmill(140cm/s) using F-scan system and different insole thickness(0~50 mm) between sole and plantar surface during gait. Also, we computed changes of stresses at the foot using finite element model with various insole thickness during toe-off phase. COP moved anterior and medial direction and, PCP was increased at medial forefoot surface, $1^{st}$ and $2^{nd}$ metatarsophalangeal, ($9%{\uparrow}$) with thicker insoles and it was show sensitive increment as the insole thickness was increased from 40 mm to 50 mm. Change of the stress at the soft-tissue of plantar surface, $1^{st}$ metatarsal head represents rapid growth($36%{\uparrow}$). Also, lateral moments were increased over the 100% near the $1^{st}$ metatarsal as the insole thickness was increased from 0 mm to 30 mm. And it is show sensitive increment as the insole thickness changed 10 mm to 20 mm. As a result, it was expected that use of excessively thick insoles might cause unwanted foot pain at the forefoot region. Therefore, insole thickness under 30 mm was selected.