• Journal of Korean Foot and Ankle Society
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• v.10 no.2
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• pp.133-139
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• 2006

Purpose: To evaluate the results of mosaicplasty and microfracture after surgical treatments for symptomatic osteochondral lesion of talus (OLT) by second-look arthroscopy. Materials and Methods: 7 cases of mosaicplasty and 7 cases of microfracture were reviewed who undertook second-look arthroscopy at 6 months or one year after undertaking mosaicplasty or microfracture for OLT between December 2004 and October 2005. The mean age at first operation was 43.6 years (Range, 20-59) (Mosaicplasty; 43.9 years, Microfracture; 43.4 years). The mean size of cartilage defect was $15.0{\times}7.7\;mm$ in mosaicplasty and $7.1{\times}6.6\;mm$ in microfracture. Clinical outcomes were evaluated by Freiburg ankle score. Cartilage healing state was evaluated by Insall's classification for chondromalasia during second-look arthroscopy. Results: By the Freiburg ankle score, 9 ankles (6 in mosaicplasty, 3 in microfracture) had excellent and 5 (1 in mosaicplasty, 4 in microfracture) had good results at the times of second-look arthroscopy. By Insall's classification, consistency of the osteochondral grafts and congruity between grafts and native cartilage (Grade I) were shown in 9 (6 ankles in mosaicplasty, 3 ankles in microfracture), a fissuring (Grade II) in one ankle of mosaicplasty, a fasciculation (Grade III) in one ankle of microfracture, and partial exposure of subchondral bone (Grade IV) in 3 ankles of microfractures. Conclusion: Mosaicplasty was more excellent in consistency and hardness of cartilage than microfracture. In some cases of microfracture, cartilage healing was incomplete at 6 months postoperatively, so second-look arthroscopy is necessary to identify. If incomplete cartilage healing was shown, additional procedure such as microfracture or mosaicplasty was needed.

• Journal of Korean Foot and Ankle Society
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• v.19 no.1
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• pp.7-10
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• 2015

Microfracture as a reparative strategy is the treatment of choice for an osteochondral lesion of talus. Although the results of microfracture are generally excellent, at least 30% of patients who received microfracture have acute or chronic ankle pain with several or unknown causes. The most important factor for unsatisfactory outcome after microfracture is the size of the lesion. For failed osteochondral lesion of talus, the second options are autologous osteochondral graft, autologous chondrocyte implantation, or re-microfracture. In this article, we present the autologous chondrocyte implantation as a second procedure for failed microfracture and compare its clinical outcome with other methods based on a literature review.

• Journal of Korean Foot and Ankle Society
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• v.19 no.2
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• pp.47-50
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• 2015

Microfracture procedure has been widely recognized as the primary surgical treatment for an osteochondral lesion of the talus. However, if symptoms persist after initial surgery, selection of a secondary procedure can be difficult. The author desciribes the advantage and value of autologous osteochondral transplantation as a secondary procedure after failed microfracture for osteochondral lesion with a review of sevral previous published articles.

• The Journal of Engineering Geology
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• v.24 no.2
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• pp.161-169
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• 2014

We present the results of an experimental physical weathering study that focuses on fresh and slightly weathered gneiss samples from the Wonju area of Korea. The study investigated changes in the physico-mechanical properties of these samples during accelerated laboratory-based weathering, including analyses of microfracture formation. The deteriorated samples used in the study were subjected to 100-150 freeze-thaw cycles, with index properties and microfracture geometries measured between each cycle. Each complete freeze-thaw cycle lasted 24 hours, and consisted of 2 hours of saturation in a vacuum chamber, 8 hours of freezing at $-21^{\circ}C{\pm}1^{\circ}C$, and 14 hours of thawing at room temperature. Specific gravity and seismic velocity values were negatively correlated with the number of freeze-thaw cycles, whereas absorption values tended to increase. The amount of deterioration of the rock samples was dependent on the degree of weathering of the rock prior to the start of the analysis. Absorption, specific gravity, and seismic velocity values can be used to infer the amount of physical weathering experienced by a gneiss in the study area. The sizes and density of microfracture in the rock specimens varied with the number of freeze-thaw cycles. We found that box fractal dimensions can be used to quantify the formation and propagation of microfracture in the samples. In addition, these box fractal dimensions can be used as a weathering index for the mid-and long-term prediction of rock weathering. The present results indicate that accelerated-weathering analysis can provide a detailed overview of the weathering characteristics of deteriorated rocks.

• Journal of the Korean Arthroscopy Society
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• v.15 no.2
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• pp.83-91
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• 2011

Purpose: Microfracture has been used as a first-line treatment to repair articular cartilage defects. In this study, a new technique using an extracelluar matrix biomembrane to cover the cartilage lesions after microfracture was evaluated in terms of cartilage repairability and clinical outcome compared with conventional microfracture technique in a prospective randomized trial. Materials and Methods: A total of 53 patients (59 cases) without osteoarthritis who had focal full thickness articular cartilage lesions were randomly assigned in two group. Seventeen patients (17 cases) underwent conventional microfracture procedure (control group) and thirty-six patients (42 cases) received microfracture and placing biomembrane cover (ArtiFilm$^{TM}$) concomitantly (experimental group). Clinical assessment was done through 6 months postoperatively using the subjective International Knee Documentation Committee IKDC questionnaire, and visual analog scale (VAS) for pain and satisfaction. Magnetic resonance imaging (MRI) was performed at 6 months after the operation in all patients. Results: In clinical outcomes, the significant difference was observed between both groups in IKDC, but not in VAS for pain and for satisfaction (final outcomes of IKDC, p=0.001; VAS for pain, p=0.074; VAS for satisfaction, p=0.194). The MRI showed good to complete defect fill (67 to 100%) in 33 patients (78.6%) of experimental group and 4 patients (23.5%) of control group, respectively. In control group, 9 of 17 patients (52.9%) showed poor defect fill (less than 33%), whereas 5 (11.9%) in experimental group (p=0.001). Assessment of peripheral integration revealed no gap formation in 35 patients (83.3%) in experimental group and 6 patients (35.3%) in control group (p=0.001). No serious complications or adverse effects related to the biomembrane were found. Conclusion: Good short-term follow-up clinical results were obtained in the group whose cartilage defects in the knee joint were covered with biomembrane after the microfracture, with the MRI findings confirming the excellent regeneration of the defective cartilage area. This suggests that the surgery to cover the defective area with biomembrane (ArtiFilm$^{TM}$) after the microfracture procedure is a safe, more effective treatment to induce cartilage regeneration.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.4
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• pp.40-45
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• 2003

In this paper, to choose the optimum CBN wheel for Internal Grinding at LM Guide, among 7 types of CBN-wheels, the 2 types of CBN-wheels, which were the macrofracture CBN wheel and the microfracture CBN wheel, have been used, and the SCM420H have been used as the workpiece. The working conditions in the grinding experiments were depth-of-cut, table speed, and spindle speed for 4 types of the CBN grinding wheels, 2 types of the lubrications. By the experiments, the loading effect of the microfracture types of the CBN-wheel needed a short dressing interval and resulted in grinding wheel wear and bad surface roughness. However, a macrofracture type of CBN-wheel with the concentration of 100, CB120Q100V showed the best surface roughness quality at a low table speed for internal grinding at LM-guide.

• Korean Journal of Metals and Materials
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• v.47 no.12
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• pp.797-810
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• 2009

A study was made of the effects of a Sn addition on the microstructure and microfracture mechanism of squeeze cast AZ51-xSn magnesium alloys. Microstructural observation, in situ fracture testing, and fractographic observations were conducted on these alloys to clarify the microfracture process. The microstructural analyses indicated that $Mg_2Sn$ particles as well as $Mg_{17}Al_{12}$ particles precipitated mainly along the solidification cell boundaries; the volume fraction of these hard particles increased as the amount of added Sn increased, with increased the strength. From in situ fracture observations of the AZ51-7Sn alloy, coarse precipitates located on the cell boundaries worked as easy crack propagation sites and caused abrupt intercellular fracturing. On the other hand, the overall fracture properties of the AZ51-3Sn alloy improved because crack propagation proceeded into the Mg matrix rather than into the cell boundaries as twins developed actively, as confirmed by an R-curve analysis. These findings suggest that the addition of 3~5 wt.% Sn is effective in improving both the tensile and fracture properties on the basis of well-developed twins, the blocking of crack propagation, and crack blunting.

• Journal of Korean Foot and Ankle Society
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• v.24 no.2
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• pp.48-54
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• 2020

Osteochondral lesion of the talus (OLT) is a broad term used to describe an injury or abnormality of the talar articular cartilage and adjacent bone. Various terms are used to describe this clinical entity, including osteochondritis dissecans, osteochondral fractures, and osteochondral defects. Several treatment options are available; the choice of treatment is based on the type and size of the defect and the treating clinician's preference. Arthroscopic microfracture (a bone marrow stimulation technique) is a common and effective surgical strategy in patients with small lesions or in those in whom non-operative treatment has failed. This study had the following aims: 1) to review the historical background, etiology, and classification systems of OLT; 2) to describe a systematic approach to arthroscopic bone marrow stimulation for OLT; and 3) to determine the characteristics that are useful for assessing osteochondral lesions, including age, size, type (chondral, subchondral, cystic), stability, displacement, location, and containment of the lesion.

• Korean Journal of Metals and Materials
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• v.47 no.12
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• pp.787-796
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• 2009

The fracture toughness improvement of Ni-Mn-Ga-Fe ferromagnetic shape memory alloys containing ductile particles was explained by direct observation of microfracture processes using an in situ loading stage installed inside a scanning electron microscope (SEM) chamber. The Ni-Mn-Ga-Fe alloys contained a considerable amount of ductile particles in the grains after the homogenization treatment at $800{\sim}1100^{\circ}C$. ${\gamma}$ particles were coarsened and distributed homogeneously along {$\beta}$ grain boundaries as well as inside {$\beta}$ grains as the homogenization temperature increased. The in situ microfracture observation results indicated that ${\gamma}$ particles effectively acted as blocking sites of crack propagation, and provided stable crack growth that could be confirmed by the R-curve analysis. This increase in fracture resistance with increasing crack length improved overall fracture properties of the alloys containing ${\gamma}$ particles.

• Journal of Korean Foot and Ankle Society
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• v.27 no.2
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• pp.71-74
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• 2023

A medial opening wedge supramalleolar osteotomy (SMO) introduced by Takakura et al. is a useful realignment procedure for patients with ankle joint arthritis and varus malalignment by shifting the weight-bearing axis laterally and redistributing the loads on the ankle joint. When pain persists after arthroscopic microfracture in patients with medial osteochondral lesion of the talus (OLT), redo arthroscopy, osteochondral autograft transplantation, autologous chondrocyte implantation, or matrix-induced chondrogenesis might be indicated. On the other hand, there is insufficient scientific evidence for realignment surgery through SMO, while the effect of realignment surgery has been studied consecutively for osteochondral lesions of the knee. Therefore, this paper reports a patient with medial OLT who underwent redo arthroscopy combined with SMO for persistent pain after primary arthroscopic microfracture.