• The Journal of Advanced Prosthodontics
• /
• 제7권2호
• /
• pp.160-165
• /
• 2015

PURPOSE. In this study, a temporal abutment fixation screw, designed to fracture in a controlled way upon application of an occlusal force sufficient to produce critical micromotion was developed. The purpose of the screw was to protect the osseointegration of immediate loaded single implants. MATERIALS AND METHODS. Seven different screw prototypes were examined by fixing titanium abutments to 112 Mozo-Grau external hexagon implants (MG Osseous$^{(R)}$; Mozo-Grau, S.A., Valladolid, Spain). Fracture strength was tested at $30^{\circ}$ in two subgroups per screw: one under dynamic loading and the other without prior dynamic loading. Dynamic loading was performed in a single-axis chewing simulator using 150,000 load cycles at 50 N. After normal distribution of obtained data was verified by Kolmogorov-Smirnov test, fracture resistance between samples submitted and not submitted to dynamic loading was compared by the use of Student's t-test. Comparison of fracture resistance among different screw designs was performed by the use of one-way analysis of variance. Confidence interval was set at 95%. RESULTS. Fractures occurred in all screws, allowing easy retrieval. Screw Prototypes 2, 5 and 6 failed during dynamic loading and exhibited statistically significant differences from the other prototypes. CONCLUSION. Prototypes 2, 5 and 6 may offer a useful protective mechanism during occlusal overload in immediate loaded implants.

• 대한정형외과스포츠의학회지
• /
• 제10권2호
• /
• pp.109-112
• /
• 2011

전위성 슬개골 골절에 있어서 해부학적 정복 및 견고한 고정은 슬관절 기능과 강도, 그리고 조기 관절 운동 범위의 회복을 위해서 필요하다. 골절의 형태와 다양한 수술 기법에 따라서, 수술 후 많은 합병증들이 보고 되어져 왔다. 본 저자들은 운동 선수들에게서 발생한 종골절 1예와 이분성 슬개골의 골편 전위 골절 1예에서 유관 나사못 횡 고정술을 시행한 뒤 새로운 횡골절이 발생한 증례를 경험하여 보고하고자 한다.

• 대한치과의사협회지
• /
• 제53권5호
• /
• pp.307-317
• /
• 2015

Although the long-term success of osseointegrated endosseous implants for the support of fixed dental prostheses has been reported, the increasingly widespread use of implant-supported prostheses has led to problems associated with their structural integrity. The most common biomechanical complications observed in dental implant treatment are fracture and screw loosening. The nature of loosening or fracture of dental implant components is complex, since it involves fatigue, fitness, and varied chewing patterns and loads. To assess the service life of the components of the prosthetic system, a knowledge of the loads transmitted through the system is necessary. Design of the final restoration and occlusion in relation to the geometry of a prosthetic restoration has a great influence on the mechanical loading of the implant. It is proposed that control of force in oral cavity may play a larger role in failures than previously believed. Based on theoretic consideration and clinical experiences with dental implant, this article gives simple guidelines for controlling these loads.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2012년도 추계총회 및 학술대회 논문집
• /
• pp.115-116
• /
• 2012

In this study, fitness and fatigue test were performed to estimate the coating effects of abutment screw for implant system after fatigue test. The purpose of this study was to investigate fatigue fracture phenomena of dental implant fixture used titanium nitride coated abutment screw under cyclic load.

• 대한족부족관절학회지
• /
• 제19권4호
• /
• pp.181-187
• /
• 2015

Purpose: The purpose of this study is to retrospectively analyze the clinical results of screws and Kirschner wire (K-wire) fixation in patients with fracture dislocation of Lisfranc joint and the consequence of screw breakage. Materials and Methods: Sixty patients underwent Lisfranc joint open reduction and removal of internal fixators from January 2007 to December 2011. Forty-nine cases (81.7%) underwent operations with screw alone, and 11 cases (18.3%) underwent operations with both screws and K-wires. Type of internal fixators, duration of internal fixator removal, breakage of internal fixators and satisfaction with reduction were investigated. Additionally, American Orthopaedic Foot and Ankle Society (AOFAS) midfoot scales were analyzed. Results: The internal fixator was broken in 5 cases (8.3%). The average duration of instrument removal was 154 days in the non-broken screw group and 268.6 days in the broken screw group (p<0.05). The average AOFAS midfoot scale was 77.4 in the non-broken screw group and 74.2 in the broken screw group. The most commonly damaged portion was the first tarsometatarsal (Lisfranc) joint. Conclusion: Treatment with screws and K-wires was effective in patients with fracture dislocation of Lisfranc joint. The appropriate time for screw removal should be considered.

• 대한정형외과스포츠의학회지
• /
• 제11권1호
• /
• pp.62-65
• /
• 2012

소아 전방 십자인대 견열 골절은 비교적 드물게 발생하며, 주로 청소년기에 발생하고 경쟁 경기 중의 발생빈도가 증가하고 있다. 수술 후 합병증을 감소시키기 위해 최근에는 관절경적 수술방법이 많이 사용되고 있다. 나사못, K-강선, 봉합 나사못 등이 사용되고 있으며, 유관 나사못 고정술은 수술 술기가 가장 간단하나 단점으로 성장판 손상의 가능성이 있다. 저자들은 8세 여아의 전방 십자인대 견열 골절에서 관절경을 이용한 유관 나사못 고정술로 좋은 결과를 얻었기에 문헌 고찰과 함께 보고하는 바이다.

• 대한족부족관절학회지
• /
• 제12권2호
• /
• pp.168-173
• /
• 2008

Purpose: To evaluate the results of treatments by percutaneous Acutrak screw fixation for intra-articular joint depression type fracture of calcaneus. Materials and Methods: Thirteen cases with intra-articular joint depression type fracture of calcaneus, from September 2004 to March 2006, were reviewed. There were 9 males and 4 females with 52.5 years old mean age (range: $31{\sim}74$ years old). The average follow-up period was 18 months (range: $8{\sim}32$ months). Steinmann pins and Freers were used for closed reduction. After closed reduction, Acutrak screws and K-wires were inserted. The patients were evaluated with Creighton-Nebraska health foundation assessment sheet for calcaneal fracture, the extent of recovery of Bohler angle, fragment size, and state of subtalar joint. Results: Clinical results according to Creighton-Nebraska health foundation assessment sheet for calcaneal fracture were excellent in 6 cases (46%), good in 4 cases (30%), fair in 2 cases (15%), and poor in 1 case (7%). Average preoperative Bohler angle was $7.6^{\circ}$ (range: $2^{\circ}{\sim}13^{\circ}$). Average postoperative Bohler angle was $24.4^{\circ}$ (range: $4^{\circ}{\sim}33^{\circ}$). There were no soft tissue complications. There were one mild subtalar arthritis and one moderate subtalar arthritis. Conclusion: We think that closed reduction and percutaneous Acutrak screw fixation with or without K-wire is a good option for joint depression type fracture of calcaneus.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 추계학술대회
• /
• pp.1234-1239
• /
• 2003

A failure analysis of holddown spring screw was performed using fracture mechanics approach. The spring screw was designed such that it was capable of sustaining the loads imposed by the initial tensile preload and operational loads. In order to investigate the cause of failure, a stress analysis of the top nozzle spring assembly was done using finite element analysis and a life prediction of the screw was made using a fracture mechanics approach. The elastic-plastic finite element analysis showed that the local stresses at the critical regions of head-shank fillet and thread root significantly exceeded than the yield strength of the screw material, resulting in local plastic deformation. Primary water stress corrosion cracking life of the Inconel 600 screw was predicted by using integration of the Scott model and resulted in 1.42 years, which was fairly close to the actual service life of the holddown spring screw.

• Journal of Korean Neurosurgical Society
• /
• 제53권1호
• /
• pp.26-30
• /
• 2013

Objective : The purpose of this study was to compare the results of three types of short segment screw fixation for thoracolumbar burst fracture accompanying osteopenia. Methods : The records of 70 patients who underwent short segment screw fixation for a thoracolumbar burst fracture accompanying osteopenia (-2.5< mean T score by bone mineral densitometry <-1.0) from January 2005 to January 2008 were reviewed. Patients were divided into three groups based on whether or not bone fusion and bone cement augmentation procedure 1) Group I (n=26) : short segment fixation with posterolateral bone fusion; 2) Group II (n=23) : bone cement augmented short segment fixation with posterolateral bone fusion; 3) Group III (n=21) : bone cement augmented, short segment percutaneous screw fixation without bone fusion. Clinical outcomes were assessed using a visual analogue scale and modified MacNab's criteria. Radiological findings, including kyphotic angle and vertebral height, and procedure-related complications, such as screw loosening or pull-out, were analyzed. Results : No significant difference in radiographic or clinical outcomes was noted between patients managed using the three different techniques at last follow up. However, Group I showed more correction loss of kyphotic deformities and vertebral height loss at final follow-up, and Group I had higher screw loosening and implant failure rates than Group II or III. Conclusion : Bone cement augmented procedure can be an efficient and safe surgical techniques in terms of achieving better outcomes with minimal complications for thoracolumbar burst fracture accompanying osteopenia.

• 대한족부족관절학회지
• /
• 제14권1호
• /
• pp.79-83
• /
• 2010

Purpose: To compare the clinical and radiological results between the anterior and posterior screw fixation for the treatment of talar neck fracture. Materials and Methods: Among 30 patients who received surgical treatment for talar neck fracture from 2001 to 2008. Twenty-seven patients with a follow-up period of more than 1 year were divided into two groups. Twelve patients were treated with anterior screw fixation and 15 patients with posterior approaches. We analyzed preoperative, postoperative and follow-up radiographs. Clinical results were evaluated by Hawkins criteria. Results: The posteriorly inserted screws were placed across the more central portion of the talar neck and perpendicular to the plane of fracture (p<0.05). There were no difference in clinical results, the duration of union, and complications including avascular necrosis between two groups. However, 2 patients complained of pain around the talonavicular joint in the anterior insertion group. Conclusion: Although the clinical results were good irrespective of insertion methods, the posterior approach of screw fixation for talar neck fractures allows for a better mechanical advantage than anterioly placed screws. This may allow early motion with a reduced risk of failure of fixation or of displacement of the fracture.