• The korean journal of orthodontics
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• v.40 no.4
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• pp.250-259
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• 2010

Objective: Intraoral noncompliance upper molar distalization techniques have gained in popularity and have subsequently found to be successful in Class II correction. The aim of the present study was to introduce a screw supported intraoral distalization appliance and investigate its efficiency. Methods: Twenty-one subjects (11 females, 10 males; average age of 14.9 years) with Angle Class II malocclusion participated in this study. Two screws were inserted behind the incisive foramen and immediately loaded to distalize the upper first molars. An intraoral screw supported distalization appliance was used to distalize the upper molars in order to achieve a Class I molar relationship. Skeletal and dental changes were evaluated using cephalometric and three-dimensional (3D) model analysis. Results: Upper molars were distalized 3.95 mm on average and a Class I molar relationship was achieved without any anchorage loss. The upper molars were tipped only $1.49^{\circ}$ and the upper right and left molars were rotated only $0.54^{\circ}$ and $0.74^{\circ}$ respectively which were statistically non-significant (p > 0.05). Conclusions: The newly designed screw supported noncompliance distalization appliance was found to be an effective device for achieving bodily molar distalization without any anchorage loss.

• Journal of Korean Foot and Ankle Society
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• v.12 no.1
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• pp.26-30
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• 2008

Purpose: The authors evaluated the differences between K-wires and Bold screw for fixing the proximal metatarsal chevron osteotomy of moderate and severe hallux valgus. Materials and Methods: There were 59 patients (81 feet) who were moderate and severe degree hallux valgus according to the classification of Mann. They all got the proximal chevron osteotomy when correcting the deformity. All patients were followed up at least 6 months. We divided the patients into 2 groups, K-wires fixed group as A, Bold screw fixed group as B. Group A were 42 patients (63 feet) and Group B were 18 patients (19 feet). Among the Group B, 2 feet who were failed to fix the oetotomy site with Bold screw, were fixed with K-wires during operation. We measured the AOFAS score preoperatively, postoperatively and at final follow-up, VAS score at 2 weeks after the operation. Also preoperative, postoperative and follow-up hallux valgus angle (HVA) and intermetatarsal angle (IMA) were measured for each patients. Results: Mean follow up period was 1.34 year (range: 6 months-6.16 years). Mean VAS score of group A was $3.21{\pm}1.7$ and group B $1.76{\pm}1.0$. Preoperative mean AOFAS score of group A was $45.61{\pm}8.3$, group B $44.41{\pm}8.9$, the final mean score of group A was $88.87{\pm}8.3$ and group B $92.47{\pm}4.4$. Preoperative mean HVA was $30.82{\pm}6.6$ degrees in group A and $32.88{\pm}14.5$ degrees in group B, the final mean angle of group A was $14.89{\pm}8.3$ degrees and group B $17{\pm}4.4$ degrees. The preoperative mean IMA of group A was $13.69{\pm}3.6 $degrees and group B $12.35{\pm}5.2$, the final mean angle of group A was $9.26{\pm}3.6$ degrees and group B $12.35{\pm}5.8$ degrees. Conclusion: There were no statistical differences in radiologic and clinical results (p>0.05) but, group B exceeded group A in VAS score (p=0.0007) and had no statistical significance in terms of reduction angle loss (p=0.06). Early returning to normal life activity may be possible for patients using Bold screws.

• Journal of Korean Neurosurgical Society
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• v.58 no.1
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• pp.50-53
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• 2015

Objective : The purpose of this study was to evaluate radiographic/clinical outcomes of adolescent idiopathic scoliosis (AIS) patients treated by a Korean neurosurgeon. Methods : Ten AIS patients were treated by a single neurosurgeon between January 2011 and September 2013 utilizing segmental instrumentation with pedicle screws. Basic demographic information, curve pattern by Lenke classification, number of levels treated, amount of correction achieved, radiographic/clinical outcomes [by Scolisis Resarch Society (SRS-22r) questionnaire] and complications were evaluated to determine the surgical results. Pulmonary function test was utilized to assess forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) before and after surgery. Results : The average percentage of correction of the major structural curve was 73.6% (ranged from 64% to 81.5%). Preoperative and final postoperative absolute FVC averaged 3.03 L and 3.76 L (0.73 L increase, p=0.046), and absolute FEV1 averaged 2.63 L and 3.49 L (0.86 L increase, p=0.021). Preoperative and final postoperative average self-image and function scores of SRS-22r were, $2.6{\pm}0.5$, $3.3{\pm}0.1$, $4.0{\pm}0.5$, and $4.6{\pm}0.0$, respectively. There was a significant improvement of the self-image and function scores of SRS-22r questionnaires before and after surgery (p<0.05). There was no case of neurological deficit, infection and revision for screw malposition. One patient underwent a fusion extension surgery for shoulder asymmetry. Conclusion : Radiographic/clinical outcomes of AIS patients treated by a Korean neurosurgeon were acceptable. Fundamental understanding of pediatric spinal deformity is essential for the practice of AIS surgery.

• Journal of Korean Neurosurgical Society
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• v.61 no.4
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• pp.503-508
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• 2018

Objective : Anterior odontoid screw fixation is a safe and effective method for the treatment of odontoid fractures. The surgical technique is recommended for perforation of the apical cortex of the dens by the lag screw. However, overpenetration of the apical cortex may lead to potentially serious complications such as damages of adjacent vascular and neural structures. The purpose of this study was to assess the role of three-dimensional computed tomography (CT) scan to evaluate the safe margin beyond dens tip to ventral dura for anterior odontoid screw fixation. Methods : We retrospectively analyzed the three-dimensional CT scans of the cervical spines in 55 consecutive patients at our trauma center. The patients included 38 males and 17 females aged between 22 and 73 years (mean age${\pm}$standard deviation, $45.8{\pm}14.2years$). Using sagittal images of 3-dimensional CT scan, the safe margins beyond dens tip to ventral dura as well as the appropriate screw length were measured. Results : The mean width of the apical dens tip was $9.6{\pm}1.1mm$. The mean lengths from the screw entry point to the apical dens tip and posterior end of dens tip were $39.2{\pm}2.6mm$ and $36.6{\pm}2.4mm$. The safe margin beyond apical dens tip to ventral dura was $7.7{\pm}1.7mm$. However, the safe margin beyond the posterior end of dens tip to ventral dura was decreased to $2.1{\pm}3.2mm$, which was statistically significant (p<0.01). There were no significant differences of safe margins beyond dens tip to ventral dura with patient gender and age. Conclusion : Extension by several millimeters beyond the dens tip is safe, if the trajectory of anterior odontoid screw is targeted at the apical dens tip. However, if the trajectory of the screw is targeted to the posterior end of dens tip, extension beyond dens tip may lead to damage immediately adjacent to the vental dura mater.

• Journal of Biomedical Engineering Research
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• v.26 no.2
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• pp.123-127
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• 2005

Compression Hip Screw (CHS) is one of the most widely-used prostheses for the treatment of intertrochanteric fractures because of its strong fixation capability. Fractures at the neck and screw holes are frequently noted as some of its clinical drawbacks, which warrant more in-depth biomechanical analysis on its design variables. The purpose of this study was to evaluate changes in the strength with respect to the changes in design such as the plate thickness and the number of screw holes. Both mechanical test and FEM analysis were used to systematically investigate the sensitivities of the above-mentioned design variables. For the first part of the mechanical test, CHS (n=20) were tested until failure. The CHS specimens were classified into four groups: Group Ⅰ was the control group with the neck thickness of 6-㎜ and 5 screw holes on the side plate, Group Ⅱ 6-㎜ thick and 8 holes, Group Ⅲ 7.5-㎜ thick and 5 holes, and Group Ⅳ 7.5-㎜ thick and 8 holes. Then, the fatigue test was done for each group by imparting 50% and 75% of the failure loads for one million cycles. For the FEM analysis, FE models were made for each group. Appropriate loading and boundary conditions were applied based on the failure test results. Stresses were assessed. Mechanical test results indicated that the failure strength increased dramatically by 80% with thicker plate. However, the strength remained unchanged or decreased slightly despite the increase in number of holes. These results indicated the higher sensitivity of plate thickness to the implant strength. No fatigue failures were observed which suggested the implant could withstand at least one million cycles of fatigue load regardless of the design changes. Our FEM results also supported the above results by showing a similar trend in stress as those of mechanical test. In summary, our biomechanical results were able to show that plate thickness could be a more important variable in design for reinforcing the strength of CHS than the number of screw holes.

• Journal of Yeungnam Medical Science
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• v.3 no.1
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• pp.361-366
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• 1986

Fracture of the carpal scaphoid bone is the most common fracture of the carpus. Unfortunately. nonunion are common since the symptoms do not alert patients to seek early medical treatment and the diagnosis is easily missed. Fracture of the scaphoid is a common condition whose management remains controversial. The conservative treatment has many complications, these include inability to work while in plaster, stiffness of the wrist afterwards, muscle wasting, weakness and malunion. So various operative treatments of scaphoid fracture have been developed. Open reduction by use of screws suggested by Maclaughlin first in 1954. In 1984 a new and simple operative technique has been developed to provide rigid internal fixation for all types of fractures of the scaphoid by T.J. Herbert. This involves the use of a double-treaded bone screw which provides good fixation that, after operation, a plaster cast is rarely required and most patients are able to return to work within a few weeks. Authors have experienced 10 cases of scaphoid fracture and accomplished good result in all cases by internal fixation using Herbert screw. The results are as follows : Of these 10 fractures, 2 were fresh fractures and 8 were non unions of scaphoid fracture. In nonunion cases, the time interval between fracture and operation was from 5 months to 5 years. The postoperative immobilization period was average of 4 weeks. Short period of immobilization achieved early functional recovery of the wrist. The bony unions in roentgenogram were seen from 3 months to 9 months after operation. In 2 cases the fracture gap was seen after 9 months. But in these cases the symptoms such as pain and range of motion of wrist were improved.

• Journal of Yeungnam Medical Science
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• v.11 no.2
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• pp.284-292
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• 1994

In transtrochanteric rotational osteotomy to treat osteonecrosis of the femoral head, the necrotic superior anterior femoral head is rotated anteriorly around the longitudinal neck axis so that the weight bearing force is transferred to the intact posterior surface. The ratio of transposed intact articular surface of the femoral head to the weight-bearing surface of the acetabulum on postoperative anteroposterior view of the hip roentgenograph is the most important indicator of the prognosis. During the period from December 1992 to June 1994, we treated 31 hips in 28 patients who were indicated for the anterior rotational osteotomy among the patients of osteoncrosis of the femoral head. Among the patients, male were 27 and female was one. Age distribution was from 13 to 62 years old and mean age was 44.3. According to the Ficat and Arlet classification, II A was most in number as 16 II B was 7 and III was 8. As their etiolgic factors, alcohol was most in number as 18, steroid was 3, idiopathic was 5 and trauma was 2. The mean rate of the intact area of the posterior part of the femoral head to the total articular surface on the preoperative lateral view of the hip roentgenograph was 41.8%, The mean ratio of transposed intact articular surface of the femoral head to the weight bearing surface of the acetabulum was 53.8%, Fixation devices were screws or dynamic hip screw.

• Journal of Korean Neurosurgical Society
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• v.42 no.4
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• pp.311-316
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• 2007

Objective : The objective of this study is to investigate the safety, surgical efficacy, and advantages of a polyaxial screw-rod system for posterior occipitocervicothoracic arthrodesis. Methods : Charts and radiographs of 32 patients who underwent posterior cervical fixation between October 2004 and February 2006 were retrospectively reviewed. Posterior cervical polyaxial screw-rod fixation was applied on the cervical spine and/or upper thoracic spine. The surgical indication was fracture or dislocation in 18, C1-2 ligamentous injury with trauma in 5, atlantoaxial instability by rheumatoid arthritis (RA) or diffuse idiopathic skeletal hyperostosis (DISH) in 4, cervical spondylosis with myelopathy in 4, and spinal metastatic tumor in 1. The patients were followed up and evaluated based on their clinical status and radiographs at 1, 3, 6 months and 1 year after surgery. Results : A total of 189 screws were implanted in 32 patients. Fixation was carried out over an average of 3.3 spinal segment (range, 2 to 7). The mean follow-up interval was 20.2 months. This system allowed for screw placement in the occiput, C1 lateral mass, C2 pars, C3-7 lateral masses, as well as the lower cervical and upper thoracic pedicles. Satisfactory bony fusion and reduction were achieved and confirmed in postoperative flexion-extension lateral radiographs and computed tomography (CT) scans in all cases. Revision surgery was required in two cases due to deep wound infection. One case needed a skin graft due to necrotic change. There was one case of kyphotic change due to adjacent segmental degeneration. There were no other complications, such as cord or vertebral artery injury, cerebrospinal fluid leak, screw malposition or back-out, or implant failure, and there were no cases of postoperative radiculopathy due to foraminal stenosis. Conclusion : Posterior cervical stabilization with a polyaxial screw-rod system is a safe and reliable technique that appears to offer several advantages over existing methods. Further biomechanical testings and clinical experiences are needed in order to determine the true benefits of this procedure.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.5
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• pp.407-416
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• 2008

Purpose: The aim of the present study is to evaluate the effect of repetitive distraction and compression on new bone formation during distraction period. Materials and methods: Sixteen healthy rabbits, weighing about 2.5kg, were used in this experiment. A unilateral mandibular osteotomy was performed in the left mandible and the distractor(Track 1 $plus^{(R)}$, Gebruder Martin $GmbH^{(R)}$, Germany) was fixed with four screws (Cross driver screw $TI^{(R)}$, Gebruder Martin $GmbH^{(R)}$, Germany). After 4 days, the mandibles were distracted at a rate of 0.6mm/day for 10 days to obtain the amount of 6mm distraction in the control group(n=4). In the experimental group A(n=6), they were distracted at a rate of 1.2mm/day for 5 days and then compression of 0.6mm length and distraction of 0.6mm per 12 hours were carried out as counter direction for 5 days, relatively. In the experimental group B(n=6), distraction of 1.2mm length and compression of 0.6mm length per 12 hours were repeated for 10 days to obtain the amount of 6mm distraction finally. The experimental animals were sacrificed at 2 and 4 weeks after surgery and block specimens were obtained. With histologic and histomorphometric analysis, we observed the histologic changes of the cells and bone formation after H-E and Masson- Trichrome staining and then, measured Bone Deposition Rate with TOMORO $ScopeEye^{TM}$ ver. 3.5(Olympus, Japan), Results: Histologically, new bone formation was examined in all experimental groups and the control. But, the ability of bone formation of the experimental group A was somewhat better than any other groups. On the histomorphometric analysis, Bone Deposition Rate was higher in the experimental group A$(50.67{\pm}4.36%)$ than in the control group$(45.94{\pm}3.97%)$ and in the experimental group B$(42.68{\pm}5.70%)$. These data showed significant differences statistically(p<0.05). Conclusion: These results show that the distraction osteogenesis using repetitive compression and distraction force in the early consolidation period may be effective for new bone formation.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.4
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• pp.321-327
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• 2020

Purpose: The purpose of this study was to measure and compare the strain value exerted on the cervical area using different screw tightening protocols in implant-supported, screw-retained 3-unit prostheses. Materials and methods: Strain gauges were attached to four implants: two external and two internal. Thereafter, two study model were designed each type using acrylic resin. CAD-CAM was used to design hex and nonhex abutments for each group (EH, ENH, IH, and INH group) and Screw-cement-retained prostheses were also designed using a nonprecious base metal. Abutment was fixed with 10 Ncm torque, and the prosthesis was cemented. Screws were fixed with 30 Ncm torque using different three protocols. After 5 min, the strain gauge level was measured, and group analysis was performed (α=.05). Results: External group showed significantly lower strain values than internal group and the EH group showed significantly lower strain values than the ENH group (P<.05). There was no difference in strain value based on the types of screw tightening protocols in same group (P>.05). The IH group exhibited significantly higher strain values than the INH group and the IH group showed a significant difference in strain values based on the types of screw tightening protocols used (P<.05). Conclusion: There was no significant effect on the external type in the implant-supported, screw-retained prostheses. However, strain values were high in the internal type, and the types of screw tightening protocol significantly affected these implants.