• The Journal of the Korean bone and joint tumor society
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• v.20 no.1
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• pp.27-31
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• 2014

Osteochondromadevelop most commonly at distal femur, proximal humerus and proximal tibia, but the rib osteochondroma was reported less commonly. In this report, scapular snapping syndrome complicated by adventitious bursa and soft tissue pseudotumor surrounding the osteochondroma of the $6^{th}$ rib body was treated successfully by surgical excision of them. We report this rare case with reviewing the relevant literature.

• Journal of Korean Foot and Ankle Society
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• v.20 no.3
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• pp.140-144
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• 2016

Osteochondroma is one of the most common bone tumors. It can occur anywhere, although it is most frequent mainly around the metaphysis of long bones. Prediction sites are distal femur, proximal humerus, proximal tibia, and so on. However, osteochondroma in sesamoid is very rare. Herein, we report a case of a 56-year-old woman with symptomatic extra-articular osteochondroma in hallucal sesamoid with a brief literature review.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.263-266
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• 1997

Three dimensional numerical model based on the finite element method(FEM) were developed to predict the mechanical behavior of hip implants. The purpose of this study is to investigate the stress distribution of two types of cementless total hip replacement femoral component -a straight stem and a curved stem, and to compare their effect on the stress shielding between two types by three dimensional finite element method. The authors analyzed von Mises stress in the cortex & stem and compared the stress between the straight and the curved stem. In comparison of stresses between two different design of femoral stem, there was 25% more decrease of stress in straight stem than curved stem in the medial cortex at proximal region. The straight stem had consistently much lower stresses than the curved stem throughout the whole medial cortex with maximum 70% reduction of stress. However, there was little change in stress between nature and 2 implanted femur throughout the lateral cortex. Stress of femoral stem was much higher in the straight stem than the curved stem up to 60%. The straight stem had more chance of stress shielding and a risk of fatigue fracture of the stem compared with the curved stem in noncement hip arthroplasty. In design of femoral stem still we have to consider to develop design to distribute more even stress on the proximal medial cortex.

• Journal of radiological science and technology
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• v.43 no.3
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• pp.187-194
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• 2020

Bone mineral density is a examination to measure the amount of bone in patients with metabolic bone disease. It is a low dose, but may cause unnecessary exposure to the gonads and other organs located in the periphery when examining the lumbar and proximal femurs. Therefore, the purpose of this study was to evaluated the exposure dose for each organ exposed during the bone mineral density through simulation, and analyzed the applicability of the subject to radiation shielding devices using 3D printing materials. As a result, the highest dose was shown at 11.47 uSv in the breast during lumbar examination and 8.98 uSv in the testis during proximal femur examination. Also, the farther away from the examination site, the lower the effect of the scattering-ray. The shielding effect of using 3D printing shielding device showed high results in proportion to the effective atomic number and specific gravity of the printing material. Among the printing materials, ABS + W showed an effect of at least 78.72 to 96.3 9% compared to the existing lead material.

• Proceedings of the KOSOMBE Conference
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• v.1994 no.12
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• pp.71-74
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• 1994

In cementless total hip arthroplasty(THA), an initial stability of the femoral component is mandatory to achieve bony ingrowth and secondary long term fixation. Bone ingrowth depends strongly on relative micromotion and stress distributions at the interface. Primary stability of the femoral component can be obtained by minimizing the magnitude of relative micromotions at bone-prosthesis interface, Hence an accurate evaluation of interface behavior and stress/strain fields in the bone implant system may be relevant for better understanding of clinical situations and improving THA design. However, complete evaluation of load transfer in the bone remains difficult to assess experimentally, Hence, recently finite element method (FEM) was introduced in orthopaedic research field to fill the gap due to its unique capacity to evaluate stress in structure of complex shape, loading and material behavior. The authors developed the 3-dimensional numerical finite element model which is composed of totally 1179 elements off and 8 node blick. We also analyzed the micromotions at the bone-stem interface and mechanical behavior of existing bone prosthesis for a loading condition simulating the single leg stance. The result indicates that the values of relative motion for this well fit Multilock stem were $150{\mu}m$ in maximum, $82{\mu}m$ in minimum, and the largest relative motion developed in medial region of proximal femur with anterior-posterior direction. The proximal region of the bone was much larger in motion than the distal region and the stress pattern shows high stress concentration on the cortex near the tip of the stem. These findings indicates that the loading in the proximal femoral bone in the early postoperative situation can produce micromotions on the interface and clinically cementless TEA patient should not be allowed weight bearing strictly early in the postoperative period.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.6
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• pp.131-135
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• 2009

In this study, we performed the compressive strength test of trabecular bone in knee joint for measuring the elastic modulus and ultimate strength. The main knee joint is femorotibial articulation between the lateral and medial femorotibial condyle. In the case of osteoarthritis, some patients have only medial condylar osteoarthritis. We performed the mechanical test for comparison the difference of the each condylar strength. We used diamond core-drill and linear precision saw for making the specimens. Specimens were cored from both condyle in distal femur and proximal tibia in fresh cadaver (male 10, female 12), and tested by universal test machine with temperature control saline circulation system. Results of the test in distal femoral parts, averaged elastic modulus was $360.61{\pm}159.40MPa$ for male, $150.89{\pm}70.65MPa$ for female. Averaged ultimate strength was $6.79{\pm}2.91MPa$ for male, $2.89{\pm}1.31MPa$ for female. Male was 2.4 times stronger than female. In the proximal tibial parts, averaged elastic modulus was $108.80{\pm}52.88MPa$ for male, $73.45{\pm}55.06MPa$ for female. Averaged ultimate strength was $2.59{\pm}1.39MPa$ for male, $1.75{\pm}1.16MPa$ for female. Male was 1.5 times stronger than female. In the distal femoral condyle, medial condyle had more strength than lateral condyle at middle region. But lateral condyle had more strength than medial condyle at anterior & posterior regions (p<0.02). In the proximal tibial condyle, medial condyle had more strength than lateral condyle. (p<0.01).

• Journal of Veterinary Clinics
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• v.33 no.6
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• pp.340-345
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• 2016

The present study determined the normal reference ranges for the femoral and tibial joint orientation angles of small-breed dogs. For this purpose, 60 each of cadaveric canine femurs and tibias from normal small-breed dogs (Maltese, Poodle, Shih Tzu, Yorkshire Terrier) were examined with radiographs and photographs. Axial and frontal radiographs and photographs of each bone were obtained, from which anteversion and inclination angles, anatomic lateral proximal and distal femoral angles (aLPFA and aLDFA), mechanical lateral proximal and distal femoral angles (mLPFA and mLDFA), and mechanical medial proximal and distal tibial angles (mMPTA and mMDTA) were measured. The 95% CI for radiographic values of all femurs and tibiae were anteversion angle, $23.4-27.4^{\circ}$; inclination angle, $128.4-130.4^{\circ}$; aLPFA, $117.8-122.1^{\circ}$; aLDFA, $93.7-95.2^{\circ}$; mLPFA $113.8-117.3^{\circ}$; mLDFA $99.2-100.5^{\circ}$; mMPTA $96.8-98.5^{\circ}$; mMDTA $89.4-90.7^{\circ}$. The Maltese had a larger anteversion angle than the Poodle and the Yorkshire Terrier and a larger mLPFA than the Poodle. In the comparison between the radiographs and the photographs, significant differences were found in the anteversion angle, mLPFA, mMPTA, and mMDTA. The established normal reference values might be useful for determining whether a valgus or varus deformity of the femur or the tibia is present and if so, the degree of angular correction needed.

• Clinical and Experimental Pediatrics
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• v.62 no.2
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• pp.62-67
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• 2019

Purpose: We aimed to determine the prognostic significance of lymphocyte counts and the lymphocytemonocyte ratio (LMR) in pediatric patients with osteosarcoma. Methods: We retrospectively reviewed the medical records of 27 pediatric patients with localized extremity osteosarcoma, treated at the Korea Cancer Center Hospital between May 2002 and March 2016. Leukocyte counts and LMR before treatment and on day 14 (LMR14) of the first cisplatin-doxorubicin chemotherapy round were evaluated. Patients were dichotomized according to the median value of these parameters, and survival rates were compared. Results: The median age of the 27 patients was 9.9 years (range, 3.2-14.1 years) and tumor sites were: distal femur (n=14), proximal humerus (n=7), proximal tibia (n=2), proximal fibula (n=2), and elsewhere (n=2). Patients were followed up on for a median of 76.4 months (range, 4.5-174.7 months), and 5-year overall (OS) and event-free survival (EFS) rates were $66.0%{\pm}9.8%$ and $60.9%{\pm}9.7%$, respectively. Patients with a higher pretreatment lymphocyte count (${\geq}2,320/{\mu}L$) had better OS (90.9% vs. 46.2%, P=0.04) and EFS (83.9% vs. 38.5%, P=0.02). However, the day 14 lymphocyte count was not associated with survival. While no survival difference was observed between patients grouped according to pretreatment LMR (median value, 6.3), patients with a higher LMR14 (${\geq}5$) fared better than those with lower LMR14 (5-year OS: 83.3% vs. 46.3%, P=0.04). Conclusion: Pretreatment lymphocyte count and LMR during chemotherapy had prognostic significance in pediatric osteosarcoma patients. Further studies involving larger cohorts are necessary to validate our findings.

• Korean Journal of Applied Biomechanics
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• v.33 no.4
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• pp.164-174
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• 2023

Objective: The aim of this study was to quantitatively analyze the impact characteristics of the lower extremity on strike pattern during running. Method: 19 young subjects (age: 26.53 ± 5.24 yrs., height: 174.89 ± 4.75 cm, weight: 70.97 ± 5.97 kg) participated in this study. All subjects performed treadmill running with fore-foot strike (FFS), mid-foot strike (MFS), and rear-foot strike (RFS) to analyze the impact characteristics in the lower extremity. Impact variables were analyzed including vertical ground reaction force, lower extremity joint moments, impact acceleration, and impact shock. Accelerometers for measuring impact acceleration and impact shock were attached to the heel, distal tibia, proximal tibia, and 50% point of the femur. Results: The peak vertical force and loading rate in passive portion were significantly higher in MFS and FFS compared to FFS. The peak plantarflexion moment at the ankle joint was significantly higher in the FFS compared to the MFS and RFS, while the peak extension moment at the knee joint was significantly higher in the RFS compared to the MFS and FFS. The resultant impact acceleration was significantly higher in FFS and MFS than in RFS at the foot and distal tibia, and MFS was significantly higher than FFS at the proximal tibia. In impact shock, FFS and MFS were significantly higher than RFS at the foot, distal tibia, and proximal tibia. Conclusion: Running with 3 strike patterns (FFS, MFS, and RFS) show different impact characteristics which may lead to an increased risk of running-related injuries (RRI). However, through the results of this study, it is possible to understand the characteristics of impact on strike patterns, and to explore preventive measures for injuries. To reduce the incidence of RRI, it is crucial to first identify one's strike pattern and then seek appropriate alternatives (such as reducing impact force and strengthening relevant muscles) on that strike pattern.

• Journal of Mechanical Science and Technology
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• v.20 no.12
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• pp.2168-2177
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• 2006

The purpose of this investigation was to determine the specific fracture mechanics response of cracks that initiate at the stem-cement interface and propagate into the cement mantle. Two-dimensional finite element models of idealized stem-cement-bone cross-sections from the proximal femur were developed for this study. Two general stem types were considered; Rectangular shape and Charnley type stem designs. The FE results showed that the highest principal stress in the cement mantle for each case occurred in the upper left and lower right regions adjacent to the stem-cement interface. There was also a general decrease in maximum tensile stress with increasing cement mantle thickness for both Rectangular and Charnley-type stem designs. The cement thickness is found to be one of the important fatigue failure parameters which affect the longevity of cemented femoral components, in which the thinner cement was significantly associated with early mechanical failure for shot-time period.