• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.79-79
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• 2017

Metallic biomaterials have been mainly used for the fabrication of medical devices for the replacement of hard tissue such as artificial hip joints, bone plates, and dental implants. Because they are very reliable on the viewpoint of mechanical performance. This trend is expected to continue. Especially, Ti and Ti alloys are bioinert. So, they do not chemically bond to the bone, whereas they physically bond with bone tissue. For their poor surface biocompatibility, the surface of Ti alloys has to be modified to improve the surface osteoinductivity. Recently, ceramic-like coatings on titanium, produced by plasma electrolytic oxidation (PEO), have been developed with calciumand phosphorus-enriched surfaces. A lso included the influences of coatings, which can accelerate healing and cell integration, as well as improve tribological properties. However, the adhesions of these coatings to the Ti surface need to be improved for clinical use. Particularly Silicon (Si) has been found to be essential for normal bone, cartilage growth and development. This hydroxyapatite, modified with the inclusion of small concentrations of silicon has been demonstrating to improve the osteoblast proliferation and the bone extracellular matrix production. Strontium-containing hydroxyapatite (Sr-HA) was designed as a filling material to improve the biocompatibility of bone cement. In vitro, the presence of strontium in the coating enhances osteoblast activity and differentiation, whereas it inhibits osteoclast production and proliferation. The objective of this work was to study Morphology of bone-like apatite formation on Sr and Si-doped hydroxyapatite surface of Ti-6Al-4V alloy after plasma electrolytic oxidation. Anodized alloys was prepared at 270V~300V voltages with various concentrations of Si and Sr ions. Bone-like apatite formation was carried out in SBF solution. The morphology of PEO, phase and composition of oxide surface of Ti-6Al-4V alloys were examined by FE-SEM, EDS, and XRD.

• Journal of Korean Foot and Ankle Society
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• v.23 no.4
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• pp.183-188
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• 2019

Purpose: Bone contusion is usually treated with conservative therapy for 3 months. Bone contusion around knee and hip joints has been extensively reported on, but there are scant reports on this condition in foot and ankle joints. This study evaluated the nature, characteristics and location of bone contusion around foot and ankle joints to enlighten clinicians on how to better treat this disease entity. Materials and Methods: We classified bone contusion of the 76 patients into three types (102 sites; 47 ankle sprains, 18 traffic accidents, 11 falls) according to the Costa-Paz system with employing magnetic resonance imaging (MRI), and the study then analyzed the common sites and areas of occurrence according to the mechanism of injury and duration of pain after first conducting conservative therapy. Results: Of the 76 patients (102 sites) on the MRI, 43 case (42.2%) for talus, 19 cases for distal tibia, and 12 cases for calcaneus were involved. The classification, according to the Costa-Paz system, was Type I, 51 cases; Type II, 32 cases; and Type III, 19 cases. The duration of pain after conservative treatment was 12.15±2.17 weeks for Type I, 14.5±2.15 weeks for Type II, and 21.0±3.8 weeks for Type III. Conclusion: The most common location of post-traumatic bone contusion around both the foot and ankle is the talus, distal tibia, and calcaneus. The most common type of injury noted on MRI is a diffuse signal with change of the medullary component (Type I), In cases of bone contusion extending to a subjacent articular surface or disruption or depression of the normal contour of the cortical surface (Types II, III), the patients' pain appears to last longer. Thus, it is necessary to consider a longer period of conservative treatment in cases of Types II and III bone contusion because the patients' pain may last longer than 3 months.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.540-540
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• 2000

This paper explores design and control methods of a surgical robot for total hip replacement surgery which can be easily maneuvered by a surgeon Like an advanced surgical tool. The 3-DOF in-parallel surgical robot is fixed directly onto patient's femur by the bone clamp during surgery. With the master/slave combined surgical robot, the surgeon can directly control the motion of the surgical robot with surgeon's experience and judgment during operation. For the easiness of operation, the master/slave combined robot is controlled using admittance control paradigm. And for the precise operation, the robot motion is restricted at the surgical boundary using virtual hard wall display.

• Journal of muscle and joint health
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• v.8 no.2
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• pp.278-286
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• 2001

With the aging of society a great deal of interest is being placed on the value of longitudinal data in evaluating physiological losses. We present data on test-one/test-two reliability and reproducibility for measures of training, bone density from a longitudinal study of master athletes. Fifty-two males (mean age at test $1=58.2{\pm}9.8\;years$) and thirty-two females ($54.4{\pm}8.8\;years$) were selected from the study population. Bone mineral density was determined using DEXA (Hologic 1500). The characteristics of the subjects are presented below as $means\;{\pm}\;S.D$. The data was imported into the Statistical Package for the Social Science (SPSS 9.0, Chicago, IL). Paired t-tests were performed between visit 1 and visit 2 in subjects. Pearson correlations were performed. The results of this study indicate the measures of training history, body mass and bone density are reasonably stable and reproducible. We conclude that body composition and bone density parameters are stable and reproducible over time in active older subjects. Physiologic measures in master athletes are fairly stable, and reproducible over time Longitudinal studies investigating age-related changes in master athletes need to be conducted on a time schedule of greater than two years.

• Biomaterials and Biomechanics in Bioengineering
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• v.3 no.2
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• pp.85-104
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• 2016

Stability and loosening of implanted femoral stems in Total Hip Replacement have been well established as barriers to the primary concerns of osseointegration and long term implant survival. In-vitro experiments and finite element modeling have for years been used as a primary tool to assess the bone stem interface with variable methodologies leading to a wide range of micromotion, interference fit and stress shielding values in the literature. The current study aims to provide a comprehensive review of currently utilized methodologies for in-vitro mechanical testing as well as finite element modeling of both micromotion and interference of implanted femoral stems. A total of 12 studies detailed in 33 articles were selected for inclusion. Experimental values of micromotion ranged from 12 to $182{\mu}m$ while finite element analysis reported a wider range from 2.74 to $1,277{\mu}m$. Only two studies were found that modeled bone/implant contact with consideration for interference fit. In studies evaluating stem micromotion in THA, the reference surface at the bone/stem interface should be well defined. Additionally, the amount of penetration considered should be disclosed and associated with bone density and roughness.

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.335-344
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• 2012

Osteoporosis is increasing in Korea as it becomes an aging society with the rapid economic growth and the development of medical technology. Osteoporosis also develops due to chemo and radiation therapy of cancer which also increases owing to Westernized diet. Osteoporosis is caused by reduced bone density, has close relationship with the change of geometry of proximal femur, which is a factor of hip fracture risk. The purpose of this study was the analysis of the correlations of osteoporosis and the change of geometry of proximal femur, which was observed according to T-score variance. The 350 male and female patients are chosen from D hospital in Busan, who were classified by age, sex and T-score values (normal, osteopenia, and osteo porosis). The results show that the age and gender have significant difference in the incidence of osteoporosis; the disease classification according to T-score value has significant difference in the geometry of the proximal femur such as Cortical ratio calcar, Cortical ratio shaft, Hip/shaft Angle, Strength index, Section modulus, CSMI, and CSA, and is highly correlated with the incidence of osteoporosis. Therefore, the findings of this research is that the change of the geometry of the proximal femur could be used as an indicator in the diagnosis of osteoporosis, could enhance the accuracy of the diagnosis in the future, and could be used as a clinical predictive factors through the analysis of the correlations of T-score variance and the geometry changes of the proximal femur.

• Journal of the Korean Society of Radiology
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• v.83 no.6
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• pp.1286-1297
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• 2022

Purpose To assess the usefulness of various metal artifact reduction (MAR) methods in patients with hip prostheses. Materials and Methods This retrospective study included 47 consecutive patients who underwent hip arthroplasty and dual-energy CT. Conventional polyenergetic image (CI), orthopedic-MAR (OMAR), and virtual monoenergetic image (VMI, 50-200 keV) were tested for MAR. Quantitative analysis was performed in seven regions around the prostheses. Qualitative assessments included evaluation of the degree of artifacts and the presence of secondary artifacts. Results The lowest amount of image noise was observed in the O-MAR, followed by the VMI. O-MAR also showed the lowest artifact index, followed by high-keV VMI in the range of 120-200 keV (soft tissue) or 200 keV (bone). O-MAR had the highest contrast-to-noise ratio (CNR) in regions with severe hypodense artifacts, while VMI had the highest CNR in other regions, including the periprosthetic bone. On assessment of the CI of pelvic soft tissues, VMI showed a higher structural similarity than O-MAR. Upon qualitative analysis, metal artifacts were significantly reduced in O-MAR, followed by that in VMI, while secondary artifacts were the most frequently found in the O-MAR (p < 0.001). Conclusion O-MAR is the best technique for severe MAR, but it can generate secondary artifacts. VMI at high keV can be advantageous for evaluating periprosthetic bone.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.7
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• pp.703-708
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• 2013

Conventional total hip joint replacement(THR) surgery requires a long incision and long rehabilitation time. The stem used in THR is inserted into the cancellous bone of the femur where it plays the role of the artificial joint. Minimally invasive surgery(MIS) has been devised to reduce muscle damage to patients. In this study, a mechanical stem was developed on the basis of MISto reduce the incision length through the principle of the gear. The mechanical stem consists of six components. A prototypical model for a mechanical stem was fabricated using an acryl-based polymer, and its workability was confirmed. To actualize the mechanical stem, a three-dimensional Bio-CAD modeling technique was applied. The hip joint area based on computed tomography(CT) was reconstructed. The safety of the mechanical stem by applying more load than the weight of a man under virtual surgery environment conditions was confirmed by finite element analysis.

• Journal of Nutrition and Health
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• v.37 no.1
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• pp.52-60
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• 2004

This study was conducted to investigate the bone mineral density (BMD) and the anthropometric measurements, socioeconomic factors, family history of osteoporosis and other environmental factors affecting BMD in children. One hundred sixty children (80 males, 80 females) in second grade of elementary school in Seoul were recruited; the mean age was 7.7 $\pm$ 0.47 years. Bone mineral density was measured in the lumbar spine (LS), femoral neck (FN), femoral trochanter (FT), and Ward's triangle (WT) by Dual Energy X-ray Absorptiometry (DEXA). Socioeconomic factors, family history of osteoporosis, and other environmental factors were assessed by questionnaire. Bone mineral densities of LS, FN, FT, and WT were 0.677, 0.637, 0.618, and 0.658 g/$\textrm{cm}^2$. BMD of boys was higher than that of girls (LS: 0.685 vs. 0.669, FN: 0.660 vs. 0.614, FT: 0.632 vs. 0.604, WT: 0.678 vs. 0.639 g/$\textrm{cm}^2$). Anthrometric measurements (height, weight relative body weight, circumference of waist and hip) were positively correlated with BMD. With increasing family income, BMD of LS was significantly lowered, and negative correlation was observed between mother's age at birth of subject and the BMD of FN. And the BMD of children with a family history of osteoporosis was significantly lower. However BMDs were not different by educational level of parents, family pattern, delivery term, birth weight, and type of feeding. Further studies are needed to clarify the factors affecting BMD of children and earlier age, included infants and even prenatal life. If any association is revealed and persist until the attainment of peak bone mass, osteoporosis prevention programs are needed to be start very early in the life cycle.

• Clinical and Experimental Pediatrics
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• v.45 no.2
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• pp.256-260
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• 2002

Bone marrow necrosis is a rare complication of a variety of diseases affecting the marrow. The cause and incidence are unknown, and reports of treatment response are rare. We describe a case of relapsed acute mixed type leukemia with bone marrow necrosis. The patient was a 10 year old female diagnosed with acute mixed type leukemia four years ago. She had been on second remission state for 1 year, presented with severe back pain, tenderness in lower extremities, low-grade fever and general weakness. Her level of serum lactic dehydrogenase on admission was increased. Bone marrow aspiration from both posterior iliac crest showed marrow necrosis. Subsequent examination showed the same feature. Hip MRI showed heterogenous low signal intensity in both iliac bone on T-1 weighted image and heterogenous high signal intensity on T-2 wieghted image. Remission induction therapy was started but she expired on 59th hospital day due to the complication of sepsis.