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<p><b>OBJECTIVE</b>To analyze the data of angle variation on traction based on a finite element model of complete cervical spine with straight physiological curvature, and try to give experimental reference and suggestion in treating cervical spondylosis.</p><p><b>METHODS</b>A 43-year-old female patient with straight cervical spine was chosen and the CT scan data were collected. By using specially designed modeling system, a high quality finite element model of complete cervical spine with straight physiological curvature is generated,which included ligament and muscle according to anatomy. After the model was confirmed, traction was loaded with angle 0 degree, anterior 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, to observe the data of distance change on between adjacent intervertebral foramen, processus articularis, uncovertedral joint, intervertebral discs, and stress of anulus fibrosus and nucleus pulposus.</p><p><b>RESULTS</b>When the angle was 0 degrees-15 degrees, the distance between intervertebral foramen, Luschka joint and processus articularis posterioris was enlarged, the tensile stress was adequate and compressive stress was small. It met the clinical requests.</p><p><b>CONCLUSION</b>0 degree-15 degrees anterior position is suggested for the treatment of cervical spondylosis.</p>
Subject(s)
Adult , Female , Humans , Biomechanical Phenomena , Cervical Vertebrae , General Surgery , Finite Element Analysis , Spondylosis , General Surgery , Traction , MethodsABSTRACT
Objective To evaluate the influence of different insertion torque values on stress and strain distributions at implant-bone interface. Methods The three-dimensional finite element model of the whole mandible with dental implants for immediate loading was created by CT scanning and self-developed USIS (universal surgical integration system) software. The insertion torque values of dental implants were supposed to be 0、15、25 N•cm3, respectively. The values of Von Mises stress and strain at implant-bone interface were calculated with ANSYS software, when the dental implants were loaded with vertical and buccolingual force at a 45°oblique angle of 150 N. Results When the dental implants under the three insertion torques were loaded with the vertical force, the maximum Von Mises stress was 33.6, 56.4, 69.6 MPa and the maximum strain was 5 157, 8 645, 15 630 με, respectively, while loaded with the buccolingual force, the maximum Von Mises stress was 95.3, 100.6, 108.3 MPa and the maximum strain was 17 110, 18 690, 21 380 με, respectively. Conclusions With the increased torque value of dental implants, the stress and strain at the implant-bone interface were both increased, but the increase was much slower under buccolingual loading than that under vertical loading.
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Objective To establish patient-specific hexahedral finite element mesh model for the maxillofacial surgery. Methods A standard and common hexahedral finite element mesh model for the face soft tissue was first built by semi-automatic procedure, and the an individual facial hexahedral mesh was then generated by an example learning method based on volumetric mapping. Results It was convenient to generate a high quality patient-specific hexahedral mesh with geometric shape feature and mesh element quality preserved as much as possible with this method. Conclusions The new hexahedral mesh modeling method can provide high quality hexahedral mesh input for biomechanics analysis with good application prospect in many fields such as oral and maxillofacial surgery.
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Objective Creating a 3D finite element model of a full pelvis with sacroiliac joint fracture. Comparing the biomechanical properties of the model where the fracture part was fixated by using a new sacroliliac anatomy type Bar-plate internal fixation system to iliosacral screw fixation and front reconstruction plate fixation. Methods A specially designed biomechanical semi-automatic mesh generator was employed to generate the complete pelvis finite element model from CT datas. Then, one side of sacroiliac joint related ligaments was deleted to simulate the case of sacroiliac joint fracture. Using a new sacroliliac bar-plate internal fixation system with anatomic plate (SABP) to fix the fracture part, and the comparing models using iliosacral screw fixation (SS) and front reconstruction plate fixation (SP) were also generated. Finally, all models were simulated under same loading conditions. Results Using SABP fixation, the maximal displayment of the sacroiliac joint decreases about 40% and 42% compared to SS fixation and SP fixation, respectively. The minimal value of maximal stress for main loading transfer regions was reached by SABP fixation and t he maximal stress of SABP decreases about 33%-70% compares to SS in regions of fracture hip cortical bone and cartilages bone, and decreases about 60%-75% to SP in regions of sacral cortical bone and fracture hip cortical bone. Conclusion The new sacroliliac anatomy type Bar-plate internal fixation system has better biomechanical properties than other internal fixations, and deserves to be put into clinical application.
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<p><b>OBJECTIVE</b>To establish anisotropic mandible model with dental implants and to investigate the effect of anisotropy material on stress and strain distribution of implant-bone interface.</p><p><b>METHODS</b>Three-dimensional finite element models of whole mandible with anisotropic and equivalent isotropic material were created by CT scanning and universal surgical integration system (USIS) software developed by the authors. Two ITI threaded implants were implanted in the posterior teeth area. The values of principal stress and principal strain on the bone around dental implants were calculated in two different finite element models with buccolingual load.</p><p><b>RESULTS</b>In the anisotropic mandible model, nearly all values of the principal stress and principal strain on cortical and cancellous bone increased compared with the equivalent isotropy model, 2.1%-74.1% for principal stress and 4.7%-57.3% for principal strain, but 10. 3%-71.4% for principal stress and 19.5%-63.4% for principal strain on cancellous bone.</p><p><b>CONCLUSIONS</b>In the three-dimensional finite element analysis, anisotropic mandible model with dental implants has an apparent effect on the stress and strains of the implant-bone interface. Anisotropic mechanical properties of mandible should be emphasized in biomechanical study.</p>