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BACKGROUND:The spinal column is the most common site of cancer metastases. Most of the previous biomechanical experiments utilized models with defects only in the vertebral body or posterior elements, but the biomechanical changes of the thoracic vertebrae and posterior part with various locations of metastasis deserve further research. OBJECTIVE:To set up the three-dimensional (3D) finite element model to investigate biomechanical effects by simulating combined destruction of vertebral body and other posterior components. METHODS:Based on CT data, we constructed the 3D geometric models of the thoracic vertebrae (T9-11), including intervertebral discs, ligaments and ribs using the Mimics software. The 3D models of T9 vertebra and different parts of the posterior thoracic vertebrae related with the metastasis could be simulated, including the control group with the intact vertebrae, the group of the T10 vertebrae with the right defective hemi-vertebrae, the group of the defective hemi-vertebrae with the defective ipsilateral pedicle, the group of the defective hemi-vertebrae with the defective ipsilateral costovertebral joint, the group of the defective hemi-vertebrae with the defective ipsilateral pedicle and costovertebral joint, the group of the defective hemi-vertebrae with the defective ipsilateral pedicle, costovertebral joint and transverse process. The corresponding 3D finite element models were established using the Abaqus software. The displacement and Von Mises stress distribution of the models were analyzed when the anterior compressive flexure load was applied. RESULTS AND CONCLUSION:When the anterior compressive flexure load was applied, the entire stiffness was proportionaly decreased when the more posterior parts destroyed, especialy destruction of vertebral body and pedicle significantly decreased. The destruction of posterior structures such as the thoracic rib joints and transverse processes was not great. However, the maximal Von Mises stress increased significantly when the vertebral body and pedicle were destructed, but additional costovertebral joint destruction slightly decreased the maximal Von Mises stress because of the stress was re-distributed.
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Objective:To establish a reliable approach for measuring proximal femoral 3 dimensional anatomy, and to compare post-operative differences of proximal femoralanatomy in the inter-trochanter fractures with two kinds of antegrade nailings.Methods: Some computer assisted design ( CAD ) soft-wares, e.g.Mimics, were used to establish a reliable approach for measuring proximal femoral 3 dimen-sional (3D) anatomy.Intra-class correlation coefficient ( ICC) was used to test the reliability of intra-and inter-observers.The post-operative pelvic CT data of 19 cases of inter-trochanter fracture patients treated with InterTAN nailing and 21 cases of inter-trochanter fracture patients treated with proximal femo-ral nail anti-rotation ( PFNA) were retrospectively analysed and used to measure bilateral proximal femo-ral anatomical parameters, including 2D and 3D femoral neck-shaft ( NS) angle and femoral neck ante-version (NA) angle, and 2D and 3D anteversion angles of the intramedullary (IM) nailings.ICC was used to test the consistency of the NA angles in the different groups, and the paired student T-test was used to test the differences of the paired quantitative data.Results:The established measurement method hasdexcellent consistency within the intra-and inter-observers, with all the ICCs higher than 0.9.The paired student T-test showed no significant difference between the post-operative bilateral 2D or 3D NA angles.The ICCs results showed that there were no consistency between the post-operative bilateral 2D or 3D NA angles (P values were 0.099 and 0.055, respectively), but the excellent consistency between the 2D injured side NA angle and 2D IM nailing’ s NA angle, or between the 3D injured side NA angle and 3D IM nailing’s NA angle (the ICCs were 0.81 and 0.8, respectively, P values <0.001).In PF-NA group, 57%of the differences between the 2D post-operative injured side’s and intact side’s NA an-gles were higher than 15°, which was more than 15.78%in InterTAN group.The paired student T-test showed no significant difference between the post-operative injured side’ s 2D or 3D NS angles and the in-tact side’s respective 2D or 3D angles in PFNA group (P values were 0.925 and 0.367, respectively), but in InterTAN group, the post-operative injured side’s 2D or 3D NS angles were significantly smaller than the intact side’s respective angles (P values were 0.033 and 0.009, respectively).Conclusion:By analyzing and comparing bilateral proximal femoral anatomical parameters after two kinds of IM nailings procedures, the differences between the bilateral post-operative NA angles in PFNA group were significantly larger than those in InterTAN group.There was significant correlation between the NA angles of the injured sides and NA angles of IM nailings in both the groups.
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Objective To establish a 3D atlas of Letournel-Judet classifications of acetabular fractures which provides remote access on the web through hypertext markup language (HTML) and virtual reality modeling language (VRML) for efficient remote diagnosis. Methods Firstly,different Letournel-Judet classifications of acetabular fracture were simulated based on 3D reconstruction models of healthy volunteers via Mimics software.The files of VRML format were exported after geometry modeling.Secondly,The.wrl files were edited by adding nodes of Sensor,Route,and Script to the files to make the static scene respond to users' interaction.Finally,the homepage of 3D atlas was established with the Dreamweaver software.Results The 3D atlas of Letournel-Judet classifications of acetabular fractures was established which can be accessed online.These virtual worlds can be browsed via the Internet and hyperlinked with the World Wide Web. Conclusion The 3D atlas of Letournel-Judet classifications of acetabular fractures can be easily and convenicntly used by surgeons for consultation in clinical diagnosis of an acetabular fracture.
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Objective To compare the diagnostic values of 3D CT and 2D CT imaging for tibial plateau fractures. Methods A retrospective study was performed to evaluate 21 tibial plateau fractures. Four experienced orthopaedists were asked To make assessmem of fracture classifications and characteristics using 3D CT and 2D CT images.Agreement test Was performed to evaluate interobserver and intraobserver reliability for fracture classification and criteria validity for fracture characteristics(intraoperative findings were taken as the golden standard).Furthermore,MeNemar test was used to compare the agreement of 3D CT results and 2D CT results respectively with the golden standard for fracture characteristics.Results When 3D CT images were used.interobserver reliability and intraobserver reliability for fracture elassiftcation increased to"almost perfect agreement".The agreement of golden standard with 3D CT results for fracture characteristics Was significantly higher than that with 2D CT results. Condmiou Since 3D CT imaging can improve the reliability and accuracy of preoperative assessment oftibial plateau fractures,it is helpful and valuable for tibial plateau fractures.
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Objective This article aimed to describe an interactive segmenting method for serial anatomical cross-sectional image of Chinese Digital Human(CDH) using commercially available software,Photoshop CS(Adobe;San Jose,CA,Corel KnockOut 2.0 plug-in) and Matlab 7.0(Math Works;Worcester,MA). Methods First,the interesting region was segmented from the image interactively utilizing the Knochout menu of Adobe Photoshop which had a powerful masking function.And then smooth contour was acquired precisely by morphological operation function and edge detection operator(the Sobel method) in Matlab. Results The segmentation and classification of bone,muscle and main vascular nerve were fulfilled successfully and the smooth contour lines were acquired with precise details and accurate localization.Conclusion This local clustering segmenting method might segment and classify the colored image of Chinese Digital Human quickly and precisely.