• Journal of Korean Neurosurgical Society
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• 제60권5호
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• pp.498-503
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• 2017

Objective : The purpose of the present study was to compare inter-fragmentary compression pressures after fixation of a simulated type II odontoid fracture with the headless compression Herbert screw and a half threaded cannulated lag screw. Methods : We compared inter-fragmentary compression pressures between 40- and 45-mm long 4.5-mm Herbert screws (n=8 and n=9, respectively) and 40- and 45-mm long 4.0-mm cannulated lag screws (n=7 and n=10, respectively) after insertion into rigid polyurethane foam test blocks (Sawbones, Vashon, WA, USA). A washer load cell was placed between the two segments of test blocks to measure the compression force. Because the total length of each foam block was 42 mm, the 40-mm screws were embedded in the cancellous foam, while the 45-mm screws penetrated the denser cortical foam at the bottom. This enabled us to compare inter-fragmentary compression pressures as they are affected by the penetration of the apical dens tip by the screws. Results : The mean compression pressures of the 40- and 45-mm long cannulated lag screws were $50.48{\pm}1.20N$ and $53.88{\pm}1.02N$, respectively, which was not statistically significant (p=0.0551). The mean compression pressures of the 40-mm long Herbert screw was $52.82{\pm}2.17N$, and was not statistically significant compared with the 40-mm long cannulated lag screw (p=0.3679). However, 45-mm Herbert screw had significantly higher mean compression pressure ($60.68{\pm}2.03N$) than both the 45-mm cannulated lag screw and the 40-mm Herbert screw (p=0.0049 and p=0.0246, respectively). Conclusion : Our results showed that inter-fragmentary compression pressures of the Herbert screw were significantly increased when the screw tip penetrated the opposite dens cortical foam. This can support the generally recommended surgical technique that, in order to facilitate maximal reduction of the fracture gap using anterior odontoid screws, it is essential to penetrate the apical dens tip with the screw.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제28권3호
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• pp.196-204
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• 2002

For the study of its stability when the screw has been fixed after sagittal split ramus osteotomy(SSRO) of the mandible, the methods of screw arrangement are classified into two types, triangular and straight. The angles of screws to the bone surface are classified as perpendicular arrangements, the $60^{\circ}$ anterioinferior screw, known as triangular, and the most posterior screw, called straight arrangement, thus there are four types. The finite element method model has been made by using a three dimensional calculator and a supercomputer. The load directions are to the anterior teeth, premolar region, and molar region, and the bite force is 1 Kgf to each region. The distribution of stress, the von-Mises yield strength, and safety of margin refer to the total sum of transformed energy have been studied by comparison with each other. The following conclusion has been researched : 1. When shear stress is compared, in the triangular arrangement in the form of "ㄱ", the anterosuperior screw is seen at contributing to the support of the bone fragment. In the straight arrangement, substantial stress is seen to be concentrated on the most posterior angled screw. 2. When the von-Mises yield strength is compared, it seemed that the stress concentration on the angled anteroinferior screw is higher, it shows a higher possibility of fracture than any other screw. In the straight arrangement, stress appeared to be concentrated on the most posteriorly angled screw. 3. When the safety margins of the transfomed energy are compared, the energy conduction is much greater in the case of the angled screw than in the case of the perpendicular screw. The triangular arrangement in the form of "ㄱ" shows a superior clinical sign to that of the straight arrangement. Judging from the above results, when the screw fixation is made after SSRO in practical clinical cases, two screws should be inserted in the superior border of mandibular ramus and a third screw of mandibular inferior border should be inserted in the form of triangular. All screws on the bony surface should be placed perpendicularly-$90^{\circ}$ angles apparently best promote bony support and stability.

• The Journal of Advanced Prosthodontics
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• 제7권5호
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• pp.375-379
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• 2015

PURPOSE. The purpose of this study was to evaluate the influence of tightening technique and the screw coating on the loosening torque of screws used for Universal Abutment fixation after cyclic loading. MATERIALS AND METHODS. Forty implants (Titamax Ti Cortical, HE, Neodent) (n=10) were submerged in acrylic resin and four tightening techniques for Universal Abutment fixation were evaluated: A - torque with 32 Ncm (control); B - torque with 32 Ncm holding the torque meter for 20 seconds; C - torque with 32 Ncm and retorque after 10 minutes; D - torque (32 Ncm) holding the torque meter for 20 seconds and retorque after 10 minutes as initially. Samples were divided into subgroups according to the screw used: conventional titanium screw or diamond like carbon-coated (DLC) screw. Metallic crowns were fabricated for each abutment. Samples were submitted to cyclic loading at $10^6$ cycles and 130 N of force. Data were analyzed by two-way ANOVA and Tukey's test (5%). RESULTS. The tightening technique did not show significant influence on the loosening torque of screws (P=.509). Conventional titanium screws showed significant higher loosening torque values than DLC (P=.000). CONCLUSION. The use of conventional titanium screw is more important than the tightening techniques employed in this study to provide long-term stability to Universal Abutment screws.

• Journal of Korean Neurosurgical Society
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• 제46권4호
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• pp.317-321
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• 2009

Objective : In the thoracic spine, insertion of a pedicle screw is annoying due to small pedicle size and wide morphological variation between different levels of the spine and between individuals. The aim of our study was to analyze radiologic parameters of the pedicle morphometry from T1 to T8 using computed tomographic myelography (CTM) in Korean population. Methods : For evaluation of the thoracic pedicle morphometry, the authors prospectively analyzed a consecutive series of 26 patients with stable thoracic spines. With the consent of patients, thoracic CTM were performed, from T1 to T8. We calculated the transverse outer diameters and the transverse angles of the pedicle, distance from the cord to the inner cortical wall of the pedicle, and distance from the cord to the dura. Results : Transverse outer pedicle diameter was widest at T1 ($7.66{\pm}2.14\;mm$) and narrowest at T4 ($4.38{\pm}1.55\;mm$). Transverse pedicle angle was widest at T1 ($30.2{\pm}12.0^{\circ}$ and it became less than $9.0^{\circ}$ below T6 level. Theoretical safety zone of the medial perforation of the pedicle screw, namely, distance from the cord to inner cortical wall of the pedicle was more than 4.5 mm. Conclusion : Based on this study, we suggest that the current pedicle screw system is not always suitable for Korean patients. Computed tomography is required before performing a transpedicular screw fixation at the thoracic levels.

• Journal of Korean Neurosurgical Society
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• 제37권6호
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• pp.416-421
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• 2005

Objective: Despite general agreement on the goals of surgical treatment in thoracolumbar burst fractures, considerable controversy exists regarding the choice of operative techniques. This study is to evaluate the efficacy of short-segment fixation for thoracolumbar burst fractures after long-term follow-up and to analyze the causes of treatment failures. Methods: 48 out of 60 patients who underwent short-segment fixation for thoracolumbar burst fractures between January 1999 and October 2002 were enrolled in this study. Their neurological status, radiological images, and hospital records were retrospectively reviewed. Simple radiographs were evaluated to calculate kyphotic angles and percentages of anterior body compression (%ABC). Results: The average kyphotic angles were $20.0^{\circ}$ preoperatively, $9.6^{\circ}$ postoperatively, and $13.1^{\circ}$ at the latest follow-up. The average %ABC were 47.3% preoperatively, 31.2% postoperatively, and 33.3% at the latest follow-up. The treatment failure, defined as correction loss by $10^{\circ}$ or more or implant failure, was detected in 6 patients (12.5%). 5 out of 6 patients had implant failures. 2 out of 5 patients were related with osteoporosis, and the other 2 were related with poor compliance of spinal bracing. 3 patients with poor initial postoperative alignment had implant failure. 4 patients with screws only on the adjacent vertebrae and not on the injured vertebra itself showed poor initial and overall correction. Conclusion: With proper patient selection, adequate intraoperative reduction with screw fixation involving the injured vertebra, and strict postoperative spinal bracing, the short-segment fixation is an efficient and safe method in the treatment of thoracolumbar burst fracture.

• Archives of Plastic Surgery
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• 제35권2호
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• pp.181-186
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• 2008

Purpose: Until now, many kinds of treatment modalities for facial bone fractures have been proposed. Among them, the semi-rigid fixation using miniplates has become the most popular procedure due to its simplicity and good clinical results. However, achieving anatomic reduction of bone fragments with miniplates may be difficult because of inadequate instrumentation for fracture fragment stabilization. We examined the use of inter-maxillary fixation screws or titanium screws tied with stainless steel wire to assist in positioning of fractured segment. Methods: We used this method for reduction in 50 cases of facial bone fractures. Inter-maxillary fixation screws or titanium screws tied with stainless steel wire were used to assist in aligning bony segment. Postoperative radiologic and clinical follow-ups were performed.Results: Radiologic follow-up showed correct reduction and fixation in all cases. Nonnunion and malunion were not shown. Clinical follow-up showed an satisfactory results. Conclusion: By using Inter-maxillary fixation screws tied with stainless steel wire, it was shown that reducing the bony segment to their preinjury position is easy to perform and it enables us to make more accurate reduction, ensure wider visual field.

• Journal of Korean Neurosurgical Society
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• 제42권4호
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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.

• 대한족부족관절학회지
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• 제15권2호
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• pp.62-67
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• 2011

Purpose: The authors evaluated the differences between K-wires and Cannulated screw, plate for fixing the proximal metatarsal chevron osteotomy of moderate and severe hallux valgus. Materials and Methods: There were 62 patients (79 feetz) 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. We divided the patients into 4 groups, Two K-wire fixed group as A, one cannulated screw fixed group as B. Two cannulated screw fixed group as C, Plate fixed group as D, Group A were patients (26 feet) and Group B were patients z(9 feet), Group C were patients (31 feet) and Group D were patients (13 feet). Preoperative, postoperative and follow-up hallux valgus angle (HVA) and intermetatarsal angle (IMA) were measured for each patient. ANOVA test and Student t-test were done for statistical analysis. Results: Mean follow up period was 43.8 months (range: 12~82 months). Preoperative mean IMA was $16.4{\pm}3.5$, $17.7{\pm}11.3$, $17.3{\pm}5.9$ and $16.6{\pm}2.3$ degrees in respectively group A, B, C, D. Immediate postoperative mean IMA was $5.6{\pm}3.4$, $7.3{\pm}4.4$, $7.6{\pm}4.4$ and $6.7{\pm}2.8$ degrees in respectively group A, B, C, D. The final mean IMA was $8.9{\pm}4.5$, $15.2{\pm}7.5$, $10.3{\pm}4.4$ and D $7.7{\pm}3.5$ degrees in respectively group A, B, C, D. There were significant statistical increase in final mean IMA of group B and C (p<0.05). Conclusion: The IMA was significantly increased in the group which used one or two cannulated screw for fixation on follow up, therefore more caution should be needed when using one or two cannulated screw fixation technique after proximal chevron osteotomy.

• Clinics in Shoulder and Elbow
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• 제9권2호
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• pp.189-195
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• 2006

Purpose: To analyze the result of the accurate open reduction of acromioclavicular (AC) joint and pin fixation, coracoclavicular (CC) screw fixation without CC ligament repair for AC joint injuries. Materials and Methods: Between January 2000 and December 2003, seventeen cases with at least one year follow-up among twenty-one cases underwent operation for AC-CC ligament injuries. A transverse incision approximately 5 cm in length was made over the clavicle, and the AC joint was reduced accurately. Under the image intensifier, a cannulated screw and washer were inserted for the CC ligament. Two Steinman pins were inserted for the AC joint and the AC ligament was repaired with nonabsorbable suture. Gentle passive range of motion was begun postoperative 2 weeks. The pins were removed at $6{\sim}8$ weeks and the screw was removed at $10{\sim}12$ weeks. The results were evaluated by a distance between AC and CC joints on plain films and ASES score at last follow-up. Results: At the last follow-up, there was no limitation of motion and average ASES score was 96($86{\sim}100$ points). There was no failure showing over 5 mm difference of distance compared to opposite side on the plain films. Seven cases had the skin damages and local infection due to pin migration and three cases showed the loosening of CC screw. Conclusion: We could have satisfactory results by accurate reduction of AC joint and simple pins and screw fixation for AC-CC ligament injuries.

• 대한관절경학회지
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• 제6권1호
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• pp.25-30
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• 2002

목적 : 전위된 경골 과간 융기부 골절시 슬개골 하단을 통한 삽관 나사못 고정술의 효용성을 분석하고자 한다. 대상 및 방법 : 1998년 12월부터 2001년 5월까지 성인에서 전위된 경골 과간 융기부 골절을 관절경의 도움 하에 슬개골 하단을 통한 삽관 나사못 고정술을 시행하고 1년 이상 추시가 가능하였던 10예를 대상으로 임상적 및 방사선적 결과를 분석하였다. 결과 : 모든 예에서 골유합을 얻었으며 방사선적 골유합은 평균 9.2주였다 최종 추시시 전방 전위는 전방 stress 방사선상 평균 1.8 mm를 보였으며 KT-2000 arthrometer에서는 평균 1.1 mm였다. 신전 제한은 평균 4.1도를 보였다. 기능적 결과는 우수가 7예, 양호가 3예로 모두에서 만족할만한 결과를 보였다. 결론 : 성인에서 전위된 경골 과간 융기부 골절시 관절경적 수술 방법인 슬개골 하단을 통한 삽관 나사못 고정술은 슬개골 하단의 비관절면을 통하여 삽관 나사못을 고정함으로서 정확한 정복과 견고한 고정을 얻을 수 있었으며, 술 후 조기에 능동적 관절 운동을 허용할 수 있어 간편하면서도 유용한 수술방법이라 사료된다.