INTRODUCTION: The fixation strength of transpedicular screw system in the vertebral hody relied on bone quality and anatomical characteristics of vertebral pedicle, designs of screw and types of connection(rod or plate) with screw. The purpose of this study is to verify the biomechanical nature of the transpedicular fixation in spine under various conditions with porcine vertebrae. MATERIAL AND METHOD: Fresh porcine vertebrae and the custom-made screws were used in this experiment. To reduce the errors caused by vertebral bodies of different size and quality, vertebral bodies having regular range of pedicular width(10.0 to 11.5mm) and hone density(more than 1.0 gm/cm2) were used. The pedicle screws were inserted in the same procedure and axial pull out test was performed with using the Material Testing System(lntron8511, Canton, USA). The experiments were performed in four types to assess the difference of strength accroding to designs of the screw hy using two group of screws. The first group of screw was designed according to the outer and inner diameter and the second group was designed according to the shape, pitch, and thread profile of screw. Experiment I was perfomed to evaluate the effect of screw diameters on the biomechanical pull-out strength hy using the first group of custom-made pedicle screw which fixed all other factors except the diameter of screw. Experiment I was to verify the effect of screw shape, experiment III to verify the effect of pitch and experiment IV to verify the effect of thread profile. RESULTS: The results of experiments were summarized as follows: Experiment I showed that the screw of larger outer diameter had greater holding strength. Experiment II showed that the holding strength of cylindrical shaped screw is superior to that of conical shaped screw. Experiment III showed that there is no statistical significance between different modes of pitch. Experiment IV showed that the holding strength of buttress shape of thread profile is superior to that of V-shape. CONCLUSION: It seemed that the fixation strength of the screw was more powerful with 1 mm increment of outer diameter in 4-7mm of outer diameter, 3mm of pitch and buttress shape of thread of the screw with the same operation technique.
Spine

This correction is being published to correct the errors of sentences and spelling in abstract.

OBJECTIVES: This study was performed to analyze the cumulative survival rate of Osstem implants (Osstem Implant Co., Ltd.) over a seven-year period. MATERIALS AND METHODS: A total of 105 patients who had 467 Osstem implants that were placed at the Section of Dentistry, Seoul National University Bundang Hospital (Seongnam, Korea) from June 2003 through December 2005 were analyzed. The life table method and a cross-tubulation analysis, log rank test were used to evaluate the survival curve and the influence that the prognostic factors. The prognostic factors, i.e., age and gender of patients, diameter and length, type of implants, bone graft history and loading time were determined with a Cox proportional hazard model based on logistic regression analysis. RESULTS: The seven-year cumulative survival rate of Osstem implants was 95.37%. The Cox proportional hazard model revealed that the following factors had a significant influence on survival rate; increased diameter, reduced prosthetic loading period and performance of bone grafting. CONCLUSION: The osstem implants showed satisfactory results over the seven-year study period.
Bone Transplantation ; Dental Implants ; Dentistry ; Humans ; Life Tables ; Logistic Models ; Proportional Hazards Models ; Seoul ; Survival Rate* ; Transplants

Purpose: The aim of this study is to demonstrate the association between recurrent atrial fibrillation (AF) and left ventricular (LV) adverse remodeling after catheter ablation and to evaluate the change of myocardial extracellular volume fraction (ECV) by catheter ablation outcomes. Materials and Methods: We retrospectively recruited 60 patients (44 men and 16 women) with a median age of 57 years (range, 32–78 years) who underwent cardiac MRI before and at 6–12 months after catheter ablation of AF. Cardiac MRI quantified myocardial ECV (%) in the left ventricle. Depending on myocardial ECV after catheter ablation, patients were divided into two groups: 1) LV adverse remodeling with ECV ≥ 28%; and 2) no adverse LV remodeling with ECV < 28%. Multivariable analysis was performed to assess the association between recurrent AF and LV remodeling. Results: Of 60 patients, 21 (35%) were in the LV adverse remodeling group (mean ECV ± standard deviation [SD]: 29.8% ± 1.4%) and 39 (65%) were in the no adverse LV remodeling group (mean ECV ± SD: 24.7% ± 1.5%). The incidence of recurrent AF was significantly greater in the LV adverse remodeling group than in the no adverse LV remodeling group (81% vs. 13%, p < 0.001). In patients with recurrent AF, mean myocardial ECV significantly increased from 27.7% ± 2.3% to 29.2% ± 2.3% (p = 0.004) after catheter ablation. In a multivariable analysis after adjusting sex, age, and myocardial ECV before catheter ablation, recurrent AF was independently associated with LV adverse remodeling after catheter ablation (odds ratio: 28.9, 95% confidence interval: 6.8–121.7, p < 0.001). Conclusion When monitoring with cardiac MRI, sustained AF was significantly associated with LV adverse remodeling through an increase in myocardial ECV after catheter ablation of AF.