• Journal of the Korean Orthopaedic Association
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• v.56 no.2
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• pp.150-156
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• 2021

Purpose: To determine how the location, displacement, intra-articular involvement, comminution of a 5th metatarsal base fracture affect results of early weight-bearing treatment. Materials and Methods: From January 2013 to July 2017, 34 cases of 34 patients diagnosed with a fracture of the zone I and II 5th metatarsal base were enrolled. The mean follow-up period was 13 months (6-15 months). One patient was excluded as a refracture during the follow-up period, and 33 patients underwent conservative treatment. Anteroposterior, lateral, and simple oblique radiography and computed tomography of the foot were performed to evaluate the location and displacement of the fracture, the degree of joint involvement, and comminution. In all 33 patients, a short leg cast or boot brace was selected immediately after the injury, tolerable weight bearing was allowed. If the pain disappeared, full weight bearing was performed after wearing a plain shoe or postoperative shoe. As a clinical result, the American Orthopedic Foot and Ankle Society (AOFAS) score was evaluated at the final follow-up. During outpatient follow-up, a simple radiograph of the foot was taken to confirm the time of radiological bone union and return to work. Results: Nine males and 24 females, with an average age of 48.7 years, were enrolled in the study. Twenty-four patients had zone I fractures, and nine patients had zone II fractures. Twenty-two out of 33 patients had a fracture displacement of 2 mm or more. Nine and five patients had joint involvement and comminution, respectively. There was a statistically significant return to work from zone I to zone II. The AOFAS score was excellent at the final follow-up and there was no significant difference. When classifying and comparing the degree of fracture displacement, joint involvement, and comminution, there were no significant differences in the radiological union time and return to work. In all cases, satisfactory results were obtained at the final follow-up. Conclusion: Satisfactory clinical results can be obtained by allowing early weight-bearing regardless of the fracture location, displacement, joint involvement, or comminution in zone I and II 5th metatarsal base fractures.

• Journal of the Korean Society of Safety
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• v.33 no.2
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• pp.8-13
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• 2018

The light weight composite materials have been replacing in high performance structures. The object of this study is to examine the effects of the initial crack location about a delamination in a PVC foam cored sandwich composite that is used for the strength improvement of structures. The initial crack location and fiber laminates thickness were changed with several types. The MMB specimen was used for evaluating the fracture toughness and crack behaviors. The material used in the experiment is a commercial twill carbon prepreg in CFRP material and Airex in PVC foam core. Sandwich laminate composites are composed by PVC foam core layer between CFRP face sheets. The face sheets were fabricated as 2 types of 5 and 8 plies. The initial cracks were located in a PVC form core and the interface of upper CFRP sheet. From the results, the crack initiation was affected with the location of the initial crack inserted in the PVC foam core. Among them, the initial crack at 1/3 of the upper part of the PVC foam core was the most rapid progression. And the critical energy release rate was $0.40kJ/m^2$, which is the lowest value when the initial crack was inserted into the interface between a PVC foam core and CFRP laminated with 5 plies. Meanwhile, the highest value of $1.27kJ/m^2$ was obtained when the initial crack was located at the center line in case of the 8 plies.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.8
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• pp.780-788
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• 2009

AE technique was applied to the static structural test of the composite wing structure to evaluate the structural integrity and damage. During the test, strain and displacements measurement technique were used to figure out for static structural strength. AE parameter analysis and source location technique were used to evaluate the internal damage and find out damage source location. Design limit load test, the 1st and 2nd design ultimate load tests and fracture test were performed. Main AE source was detected by an sensor attached on skin near by front lug. Especially, at the 1st design ultimate test, strain and displacements results didn't show internal damage but AE signal presented a phenomenon that the internal damage was formed. At the fracture test, AE activities were very lively, and strain and displacements results showed a tendency that the load path was changed by severe damage. The internal damage initiation load and location were accurately evaluated during the static structural test using AE technique. It is certified from this paper that AE technique is useful technique for evaluation of internal damage at static structural strength test.

• Steel and Composite Structures
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• v.39 no.5
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• pp.543-564
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• 2021

In this study free vibration analysis of a cracked Goland composite wing is investigated. The wing is modelled as a cantilevered beam based on Euler- Bernoulli equations. Also, composite material is modelled based on lamina fiber-reinforced. Edge crack is modelled by additional boundary conditions and local flexibility matrix in crack location, Castigliano's theorem and energy release rate formulation. Governing differential equations are extracted by Hamilton's principle. Using the separation of variables method, general solution in the normalized form for bending and torsion deflection is achieved then expressions for the cross-sectional rotation, the bending moment, the shear force and the torsional moment for the cantilevered beam are obtained. The cracked beam is modelled by separation of beam into two interconnected intact beams. Free vibration analysis of the beam is performed by applying boundary conditions at the fixed end, the free end, continuity conditions in the crack location of the beam and dynamic stiffness matrix determinant. Also, the effects of various parameters such as length and location of crack and fiber angle on natural frequencies and mode shapes are studied. Modal analysis results illustrate that natural frequencies and mode shapes are affected by depth and location of edge crack and coupling parameter.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.3
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• pp.571-577
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• 2008

Root fracture of primary teeth is relatively uncommon because the more pliable alveolar bone allows displacement of the tooth. Root fracture of primary teeth is occupied $2{\sim}7%$ in trauma pattern of primary teeth. A horizontal root fracture is classified based on the location of the fracture in relation to the root tip : the apical third, middle third, or cervical third of the root. The prognosis worsens the further cervically the fracture has occurrer. Root fracture of primary teeth should be treated by splinting the incisor to the adjacent normal teeth with a resin-wire splint for $8{\sim}12$ weeks. However, if a portion of the root is abscessed or extremely mobile, it can be extracted, and the remaining root fragment will resorb normally. For coronal third fracture in primary teeth, the coronal third is extracted, leaving the apical portion of the root to resorb normally. These root fracture cases of primary teeth were treated by resin-wire splinting despite extremely mobile coronal fragment. Even though they seems like healing well, They need to be monitored regularly until their successors erupt.

• Journal of the Korean Orthopaedic Association
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• v.56 no.3
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• pp.215-223
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• 2021

Purpose: Distal radius fractures in youth are treated conservatively in most cases, but there are some cases of redisplacement in the follow-up period after cast immobilization, even after complete reduction. This study examined the risk factors of redisplacement in reduced unstable distal radius fractures. Materials and Methods: From February 2011 to June 2018, 44 unstable distal radius fractures were managed with a closed reduction and cast immobilization. The patients were aged between 6 and 14 years. The cases of redisplacement were analyzed with the fracture characteristics (fracture obliquity, fracture level ratio, ulnar fracture combined), cast qualities (gap index, cast index, 3 point index, and radius-2nd metacarpal angle) and host factors (age, sex). Results: The mean angulation in the union was 9.2° (0°-32.8°). In the categorical grouping 29 cases were within 10° angulation, and 15 cases were more than 10°. No significant differences in the factors of the cast indices or host factors were noted. The meaningful factor was the fracture level calculated by the relative width of the fracture site divided by the sum of width of diaphysis and epiphysis (p=0.001) and combined ulnar fracture (p=0.019). Conclusion: Unstable distal radius fractures should be treated with more stubborn guidelines lest the fracture loses its anatomical alignment. In particular, in patients with less remodeling power, operative treatment would secure a better result if the fracture occurs in a more proximal location.

• Journal of Veterinary Clinics
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• v.34 no.5
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• pp.396-399
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• 2017

This is a case report of a northern goshawk (Accipiter gentilis), admitted to the wildlife rescue center with right coracoid and scapular fracture which received conservative treatment and was soft-released successfully. At the admission, the goshawk had callus formed on the fractured bones, scars on eyebrows and severely damaged tail feathers with inability to fly. Cage rest was indicated to prevent further occurrence of fracture and to promote reunion of the fracture surface. The bird went through a rehabilitation process with appropriate physical training in flying cage to recover its fitness and flying ability. Complete molting of flight feathers with damaged rectrices was achieved during the rehabilitation period and its flight ability was recovered favorably. It was released into a proper habitat for northern goshawks, but the bird was found near the aviary where its last phase of rehabilitation was performed. A soft-release program was applied and finally the bird returned to near the first rescue location 235 km away from the release site.

• Archives of Craniofacial Surgery
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• v.21 no.5
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• pp.294-300
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• 2020

Background: Mandibular fractures are one of the most common types of facial fractures, the treatment of which can be delayed due to the severity of the trauma resulting in an increase of complications; thus, early evaluation of trauma severity at the time of visit is important. In South Korea, trauma patients are triaged and intensively treated in designated regional trauma centers. This study aimed to analyze the relationship between trauma severity and mandibular fracture patterns. Methods: A medical records review was performed on patients who visited the regional trauma center at our hospital for mandibular fracture between 2009 and 2018. Epidemiologic data and mandibular fracture patterns were analyzed and compared with the conventional facial injury severity scale (FISS). Results: Among 73 patients, 51 were classified as non-severe trauma patients and 22 as severe trauma patients. A higher trauma severity was associated with older age (odds ratio [OR], 1.164; 95% confidence interval [CI], 1.057-1.404) and lower risk was associated with fractures located in the angle (OR, 0.001; 95% CI, 0-0.022), condylar process (OR, 0.001; 95% CI, 0-0.28), and coronoid process (OR, 0.004; 95% CI, 0-0.985). The risk was lower when the injury mechanism was a pedestrian traffic accident (OR, 0.004; 95% CI, 0-0.417) or fall (OR, 0.004; 95% CI, 0-0.663) compared with an in-car traffic accident. Higher FISS (OR, 1.503; 95% CI, 1.155-2.049) was associated with a higher trauma severity. The proposed model was found to predict the trauma severity better than the model using FISS (p< 0.001). Conclusion: Age, location of mandibular fractures, and injury mechanism showed significant relationships with the trauma severity. Epidemiologic data and patterns of mandibular fractures could predict the trauma severity better than FISS.

• Journal of Korean Neurosurgical Society
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• v.52 no.6
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• pp.528-533
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• 2012

Objective : In the pediatric population the skull has not yet undergone ossification and it is assumed that the diagnostic rate of skull fractures by simple X-rays are lower than that of adults. It has been recently proposed that the diagnostic rates of skull fractures by 3-dimensional computer tomography (3D-CT) are higher than simple X-rays. The authors therefore attempted to compare the diagnostic rates of pediatric skull fractures by simple X-rays and 3D-CTs with respect to the type of fracture. Methods : One-hundred patients aged less than 12 years who visited the Emergency Center for cranial injury were subject to simple X-rays and 3D-CTs. The type and location of the fractures were compared and Kappa statistical analysis and the t-test were conducted. Results : Among the 100 pediatric patients, 65 were male and 35 were female. The mean age was $50{\pm}45$ months. 63 patients had simple skull fractures and 22 had complex fractures, and the types of fractures were linear fractures in 74, diastatic fractures 15, depressed fractures in 10, penetrating fracture in 1, and greenstick fractures in 3 patients. Statistical difference was observed for the predictive value of simple skull fractures' diagnostic rate depending on the method for diagnosis. A significant difference of the Kappa value was noted in the diagnosis of depressed skull fractures and diastatic skull fractures. Conclusion : In the majority of pediatric skull fractures, 3D-CT showed superior diagnosis rates compared to simple skull X-rays and therefore 3D-CT is recommended whenever skull fractures are suspected. This is especially true for depressed skull fractures and diastatic skull fractures.

• Journal of Korean Foot and Ankle Society
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• v.2 no.2
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• pp.57-63
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• 1998

Stress or march fractures among military personnel, especially recruits, has been appreciated for many years. According to the classical references, the second metatarsal was one of the first sites identified as a focus for march fractures and radiological evidence of fracture appeared as late as several weeks. The purpose of this study was to document the clinical feature of march fractures in Korean infantry soldiers. From 1997 to 1998, at one infantry medical company of OO infantry corps in Korea, 15 (19cases) patients with march fracture were detected among infantry soldiers. There were some different finding in the fracture site and its clinical features from the previous foreign reports. 1. There were pain and local swelling in all cases as clinical manifestation. By physical examination, direct point tenderness on the location of the fractured metatarsal shaft was characteristic. 2. On roentgenographic examination, cortical fissuring or break was seen one week after onset of symptoms and external callus was seen from two weeks or at the least four weeks. Oblique view was more useful than AP view in the diagnosis of march fractures. 3. The third metatarsal was the most frequently involved site(7 cases, 48%). and the second metatarsal was Jess frequent(3 cases, 20%). This difference of frequent site with previous reports might be attributed to the relatively long shaft of the third metatarsal, but should be analyzed in further study. 4. The incidence of the development of march fracture was 1 per 104 infantry soldiers.