• Journal of Biomedical Engineering Research
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• v.29 no.6
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• pp.451-456
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• 2008

Total knee arthroplasty(TKA) using computer-assisted navigation has been increased in order to improve the accuracy of femoral and tibial components implantation. Recently, a few clinical studies have reported on the femoral stress fracture after TKA using computer-assisted navigation. The purpose of this study is to investigate the stress concentration around the femoral pin-hole for different pin-hole diameter, the modes of pin penetration by finite element analysis to understand the effects of pin-hole parameters on femoral stress fracture risk. A three-dimensional finite element model of a male femur was reconstructed from 1 mm thick computed tomography(CT) images. The bone was rigidly fixed to a 25 mm above the distal end and 1500 N of axial compressive force and 12 Nm of axial torsion were applied at the femoral head. For all cases, transcortical pin penetration mode showed the highest stress fracture risk and unicortical pin penetration mode showed the lowest stress concentration. Pin-hole diameter increased the stress concentration, but pin number did not increase the stress dramatically. The results of this study provided a biomechanical guideline for pin-hole fracture risk of the computer navigated TKA.

• Journal of Korean Neurosurgical Society
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• v.48 no.1
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• pp.73-78
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• 2010

Objective : Streptococcus pyogenes is a beta-hemolytic bacterium that belongs to Lancefield serogroup A, also known as group A streptococci (GAS). There have been five reported case in terms of PubMed-based search but no reported case of brain abscess caused by Streptococcus pyogenes as a result of penetrating skull injury. We present a patient who suffered from penetrating skull injury that resulted in a brain abscess caused by Streptococcus pyogenes. Methods : The patient was a 12-year-old boy who fell down from his bicycle while cycling and ran into a tree. A wooden stick penetrated his skin below the right lower eyelid and advanced to the cranium. He lost consciousness on the fifth day of the incident and his body temperature was measured as $40^{\circ}C$. While being admitted to our hospital, a cranial computed tomography revealed a frontal cystic mass with a perilesional hypodense zone of edema. There was no capsule formation around the lesion after intravenous contrast injection. Paranasal CT showed a bone defect located between the ethmoidal sinus and lamina cribrosa. Results : Bifrontal craniotomy was performed. The abscess located at the left frontal lobe was drained and the bone defect was repaired. Conclusion : Any penetrating lesion showing a connection between the lamina cribrosa and ethmoidal sinus may result in brain abscess caused by Streptococcus pyogenes. These patients should be treated urgently to repair the defect and drain the abscess with appropriate antibiotic therapy started due to the fulminant course of the brain abscess caused by this microorganism.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.141-144
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• 1997

Femoral neck anteversion is the angle between the neck and the knee axis projected on a plane perpendicular to the longitudinal axis. Conventional methods that use cross-sectional Computed Tomography(CT) images to estimate femoral anteversion have several problems because of the complex 3D structure of the femur. These are the ambiguity of defining the longitudinal axis, the femoral neck axis and condylar line, and the dependence on patient positioning. Especially the femoral neck axis that is known as a major source of error is hard to determine from a single or multiple 2D transverse images. So we developed a new method for measuring femoral anteversion by 3D modeling method. In this method, femoral head is modeled as a sphere. The center of femoral neck is the mid-point of the 2D reconstructed oblique image in the femoral neck part. Then neck axis is a line connecting foregoing two centers. We model the longitude of femur as a cylinder, and the long axis is defined from the fitted cylinder. The knee axis which is tangent to the back of the femoral condyles is easily determined by table-top method. By the definition of femoral anteversion, the femoral anteversion is easily calculated from this model.

• Journal of Veterinary Clinics
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• v.26 no.1
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• pp.109-112
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• 2009

A three-week old female Chihuahua dog weighing 80 g was presented with the absence of skull palpation, suckling disability, and growth retardation. Physical examination revealed asymmetry of the lips slanting to the left side when feeding milk. Also there were head tilt to the left side and corneal ulcer of the left eye. The absence of the frontal and parietal bones were shown on radiographs. Lateral ventricular enlargement was identified on the ultrasonographic examination. On computed tomographs, frontal and parietal bone defect, ventricle enlargement, and intracranial arachnoid cyst were observed. The dog was dead after 1 day of presentation. The dog was diagnosed as the primary acalvaria by necropsy.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.4
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• pp.391-395
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• 2000

Malignant tumors of the maxilla represent about 3-4% of head and neck malignant neoplasm and the origins are maxillary gingiva, hard palate and maxillary sinus. We are to investigate clinical features and results according to various treatment modalities of maxillary malignant tumor to get information for better treatment results. Sixty patients with malignant maxillary tumors treated at Yonsei medical center from 1992 to 1997 were studied retrospectively. They are evaluated according to clinical signs & symptoms, stages at first diagnosis, primary site, histopathologic features, treatment method, recurrence and survival rate with clinical records, biopsy results and CT radiograph. The most common primary site was maxillary sinus and most common histopathology was squamous cell carcinoma. The local recurrence rate was 18% at 5 years, neck failure was 3% and distant metastasis was 18%. Overall survival rate was 78% at 2 years and 69% at 5 years. Failure at primary site is the main problem in the curative treatment. So, to improve survival in these patients efforts should be directed toward improvement of local control.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.3
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• pp.282-288
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• 2010

Surgery with the computer navigation system can make it possible to identify important anatomical structures which are difficult to be confirmed with the naked eye in the operation, and has extended their applications in various surgical fields. The head and neck surgery especially requires detailed anatomical knowledges and these knowledges have influences on postoperative functions and esthetics of a patient. In the orthognathic surgery, we should take osteotomies in the precise locations of the jawbones and move segments to the intended positions. There are so many important anatomical structures around the osteotomy-sites in the orthognathic surgery that the prevention of damage to these structures to obtain satisfactory results without any complication. There are vessels of the pterygoid plexus posterior to the pterygoid plate in the maxilla and the mandibular nerve enters the mandibluar foramen in the mandibular ramus. These locations should be confirmed perioperatively to avoid any injury to these structures. The navigation-assisted surgery may be helpful for this purpose. We performed navigational orthognathic surgeries with preoperative CT images and obtained satisfactory results. The osteotomy was performed in the proper location and damaging the surrounding important anatomical structures was avoided by keeping the saw away from them with the real-time navigation. It may be required to develop proper devices and protocols for the navigation-assisted orthognathic surgery.

• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.2
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• pp.113-118
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• 2002

Conventional radiograph, computed tomograph (CT), magnetic resonance image (MRI) are commonly used methods for diagnosis of oro-maxillofacial cancer. MRI is an effective tool to verify soft tissue lesion however, metal produces black artifacts in the image. Therefore, metal structure should be removed before taking MRI to diagnose head and neck cancer patients. A 52-year-old female patient with adenocarcinoma in the posterior right soft palate was referred to take a MRI before surgery. She has 7-unit porcelain fused to metal bridge in the maxilla. Eight-unit Tagis-Vectris fixed partial denture was fabricated to replace her existing PFM bridge to take a MRI without any artifact before and after surgery. The patient satisfied with her restorations in terms of esthetics, function after 11 months. Even though minor staining was detected, Tagis-Vectris restoration fixed partial denture was intact during observation period.

• Journal of Korean Medicine Rehabilitation
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• v.25 no.3
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• pp.119-125
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• 2015

A chronic subdural hematoma (CSDH) is an old collection of blood and blood breakdown products between the surface of the brain and its outermost covering. We present two cases with tibia fracture caused by traffic accident progressed to chronic subdural hematoma. A 72-year-old male patient had shown signs of headache, urinary incontinence and mental storm when he has been in the hospital after 3weeks without CSDH diagnosis. And a 78-year-old male patient with mild head injury suffered from right side headache after traffic accident. We took korean medical treatments associate with tibial fracture. And we knew subdural hematoma through Brain CT. It is good report which shows CSDH can can occur from traffic accident. It requires correct diagnosis and closed observation for traffic accident patients.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.3 no.2
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• pp.217-221
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• 2000

Solid and papillary epithelial neoplasm of the pancreas is an uncommon low-grade malignant tumor found predominantly in young females. It is rare in childhood. The origin of the tumor is probably from a multipotential stem cell of the pancreas. Neoplasm usually behave like a very low grade malignancy, so that complete removal is the treatment of choice for the tumor arising anywhere in the pancreas. We report a case of solid and papillary epithelial neoplasm of the pancreas in a 14 year -old girl who presented with intermittent abdominal pain and abdominal mass. CT scan shows a large, about $7{\times}6\;cm$ sized, well-marginated hypodense round mass in the head of the pancreas with some ill defined enhancing solid internal portion. She had taken complete excision of the pancereatic mass and Roux-en-Y pancreaticojejunostomy and histologically comfirmed solid and papillary epithelial neoplasm of the pancreas. A brief review of literature was made.

• Journal of International Society for Simulation Surgery
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• v.4 no.1
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• pp.9-12
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• 2017

Purpose Surgery for separating craniopagus twins involves many critical issues owing to complex anatomical features. We demonstrate a 3D printed model and virtual reality (VR) technologies that could provide valuable benefits for surgical planning and simulation, which would improve the visualization and perception during craniopagus surgery. Material & Methods We printed a 3D model extracted from CT images of craniopagus patients using segmentation software developed in-house. Then, we imported the 3D model to create the VR environment using 3D simulation software (Unity, Unity Technologies, CA). We utilized the HTC Vive (HTC & Valve Corp) head-mount-display for the VR simulation. Results We obtained the 3D printed model of craniopagus patients and imported the model to a VR environment. Manipulating the model in VR was possible, and the 3D model in the VR environment enhanced the application of user-friendly 3D modeling in surgery for craniopagus twins. Conclusion The use of the 3D printed model and VR has helped understand complicated anatomical structures of craniopagus patients and has made communicating with other medical surgeons in the field much easier. Further, interacting with the 3D model is possible in VR, which enhances the understanding of the craniopagus surgery as well as the success rate of separation surgery while providing useful information on diagnosing and surgery planning.