摘要
OBJECTIVE@#To compare the biomechanical stability of three cross-bridge headless compression screws and locking plates in the fixation of Mason type Ⅲ radial head fractures by finite element method.@*METHODS@#Using reverse modeling technology, the radial CT data and internal fixation data of a healthy 25-year-old male were imported into the relevant software. Three-dimensional finite element model of 3 cross-bridge headless compression screws and locking plates for MasonⅢ radial head fractures were established, and the radial head was loaded with 100 N axial loading. The maximum displacement, maximum Von Mises stress and stress distribution of the two groups were compared.@*RESULTS@#The maximum displacements of the three cross-bridge screws group and locking plate group were 0.069 mm and 0.087 mm respectively, and the Von Mises stress peaks were 18.59 MPa and 31.85 MPa respectively. The stress distribution of the three screws group was more uniform.@*CONCLUSION@#Both internal fixation methods can provide good fixation effect. CoMPared with the locking plate fixation method, the 3 cross-bridge headless compression screws fixation is more stable and the stress distribution is more uniform.
Subject(s)
Male , Humans , Adult , Finite Element Analysis , Radial Head and Neck Fractures , Bone Screws , Biomechanical Phenomena , Radius Fractures/surgery , Fracture Fixation, Internal/methods , Bone Plates , Fractures, Comminuted摘要
Objective@#To explore the effect of different miniscrew placement heights on the distribution of biological forces produced by clear aligner combined with intramaxillary traction for mandibular molar distalization, to identify the miniscrew location that is conducive to the protection of lower anterior tooth anchorage and to provide a reference that can be used when designing clinical treatments.@*Methods@#Mimics, GeomagicStudio 2017, SolidWorks 2016, and Ansys workbench were used to establish finite element analysis models and perform mechanical analysis under the following six working conditions: working condition 1 was the control group without miniscrews; working conditions 2 to 5 had miniscrew in the buccal bone cortex between the first and second molars of the lower jaw 10 mm, 7 mm, 4 mm, and 1 mm from the top of the alveolar crest, respectively; working condition 6 had the miniscrew in the center of the buccal tongue at the anterior edge of the ascending branch of the lower jaw 5 mm above the occlusal plane.@*Results@#On the sagittal axis, miniscrew anchorage caused distal displacement of all teeth. Compared to the control group, in the miniscrew group, the displacement of the anterior molars exceeded that of the second molars. On the vertical axis, the result in the control group was similar to backward bending; the results in the miniscrew groups resembled the effect of a lever, lowering the lateral incisors and canines and raising the central incisors and first premolars. On the coronal axis, the second premolars and the first molars showed lingual displacement in the control group, and only the premolars and first molars showed lingual displacementin the miniscrew groups. The canines were the teeth that were most strongly affected by the change in miniscrew placement height.@*Conclusion@#The higher the miniscrew position is, the stronger the protective effect on the anterior anchorage. According to the miniscrew placement height, the mandibular arch should be properly narrowed, the central incisors and first premolars should be lowered, and the lateral incisors and canines should be raised when designing clinical treatments.
摘要
Vascular biomechanics mainly explores how vascular cells perceive mechanical stimuli,how mechanics affects the development of diseases,and the exploitation of various mathematical models to analyze the effects of mechanical factors on diseases.In recent years,researches in the field of vascular biomechanics are developing rapidly,and various research teams have analyzed the mechanical and biological processes of blood vessels from different directions,in order to gain a deeper understanding of the regulatory mechanisms of vascular biomechanical factors affecting the progression of various vascular diseases,and provide a theoretical basis based on the mechanobiology for the prevention and treatment of cardiovascular and cerebrovascular diseases.This article summarizes and discusses the recent research hotspots and emerging trends in the field of vascular mechanobiology based on domestic and foreign expert teams and combined with the work of this research team,thus providing a systematic framework for grasping hotspots and exploring new research directions in the field of vascular mechanobiology.
摘要
Objective To explore the dynamic process of fluid-structure interaction(FSI)between venous blood and valves and the physiological mechanism that guarantees unidirectional blood reflux back to the heart.Methods A three-dimensional(3D)numerical model of the venous system was established using the immersed boundary/finite element method.In the simulation,information from medical images of human lower-extremity veins and the anatomical structure and size of the bovine great saphenous vein were applied.Moreover,a hyperelastic constitutive model was used to describe the incompressible,nonlinear,and hyperelastic mechanical responses of the venous valve under physiological conditions.Results The simulations visualized the process of venous blood transport and the function of venous valves in preventing reflux.The periodic characteristics of venous valve motion and blood flow were reproduced,and important physiological data during the entire cardiac cycle were discussed and quantified,including the pressure,velocity,and flow rate of venous blood;opening area of the venous valve;and stress and strain distributions on the valve surface.Conclusions The 3D FSI model numerically reproduces the physiological dynamic process within veins and potentially provides important references and guidance for revealing the pathological mechanism of venous diseases.
摘要
Objective For patient-specific open-wedge high tibial osteotomy(OWHTO),a novel anatomical fixation plate was designed,and the effects of geometric parameters and material selection on biomechanical fixation were studied.Methods A patient-specific OWHTO anatomical fixation plate was designed and constructed,and the effects of design parameters(thickness,width,and length of the fixation plate)and four different materials(stainless steel,titanium alloy,magnesium alloy,and PEEK)on the biomechanics of the OWHTO fixation system were studied using finite element analysis.The biomechanical differences between the anatomical fixation plate and TomoFix fixation plate were also compared.Results The thickness had a greater effect on the micromotion of the osteotomy space than the length and width of the fixation plate did.Titanium alloy or magnesium alloy fixation plates were more conducive than stainless steel and PEEK materials in obtaining reasonable stability and mechanical transfer simultaneously.Compared with that of the TomoFix plate,the maximum von Mises stress of the anatomical fixation plate was reduced by 13.5%;the maximum von Mises stress of the screws and tibia was increased by 9.8%and 18.4%,respectively;and the micromotion at the maximum osteotomy space cc was increased by 49.3%.Conclusions Anatomical fixation plates have a positive effect on reducing the stress-shielding effect and improving biomechanical properties under the premise of ensuring stability.This study provides a reference for the development of OWHTO anatomical fixation plates.
摘要
Objective To establish a smooth three-dimensional(3D)geometric model of the maxilla based on CT data using four dif-ferent software packages,to mimic the modified Le Fort Ⅰ osteotomy and its fixation scheme,and to perform a finite element analysis of the postoperative occlusion.Methods CT data were preliminarily processed using Mimics software to produce an STL 3D model.The model was then imported into Inspire Studio software to create a smoothed PolyNURBS geometric model.SpaceClaim software was used to model the surgical osteotomy and fixation schemes.Finally,ANSYS Workbench was used to conduct a 3D finite element analysis simu-lating the patient's occlusion after surgery.Results The simulation results showed that the connection relationship of the finite element model was accurately established under the molar occlusion condition.Under a total occlusal force of 6 N,the maximum equivalent stress of the titanium plate was 73 MPa.Conclusion The maxillary modeling and analysis method used in this study can produce a smooth geometric model suitable for finite element simulation.The results of this study can provide reference for various fixation schemes in orthognathic surgery.
摘要
Objective:To characterize the biomechanics of distal dynamic locking and distal static locking of proximal femur bionic nails (PFBN) in fixation of intertrochanteric fractures by a finite element analysis.Methods:The CT image data from the hip to the upper tibia from an adult male volunteer were used to establish a three-dimensional model of the femur by Mimics 20.0 and Geomagic 2013 which was processed further into a model of Evans type I intertrochanteric fracture by software NX 12.0. With reference to the internal fixation parameters commonly used, 4 models of PFBN fixation were established: distal single transverse nail dynamic locking (model A), single oblique nail dynamic locking (model B), single nail static locking (model C) and double nail dynamic locking (model D). Abaqus 6.14 software was used to load and analyze the internal fixation stresses and displacements of fracture ends.Results:Under a 2100N loading, the peak stress was located upon the main nail in the 4 models. The smallest peak stress upon the main nail was in Model D (161.9 MPa), decreased by 15.9% compared with model A (192.5 MPa), by 15.6% compared with model B (191.9 MPa), and by 0.9% compared with model C (163.3 MPa). The peak stress upon the fixation screw was the largest in model A (95.3 MPa), the smallest in model B (91.5 MPa), and 91.5 MPa and 92.2 MPa in models C and D, respectively. The overall displacements of the implants, in a descending order, were 10.14 mm in model A, 10.10 mm in model B, 10.09 mm in model C, and 10.05 mm in model D. Similarly, the displacements of fracture ends were 0.125 mm in model A, 0.121 mm in model B, 0.110 mm in model C, and 0.098 mm in model D.Conclusion:Compared with dynamic locking, distal static locking of PFBN provides a better mechanical stability and reduces stress concentration upon internal fixation.
摘要
Objective:A three-dimensional (3D) finite element model of the ankle joint of marathon runners was constructed to simulate the changes of the lateral collateral ligament (LCL) injury on the stability of the ankle joint and the force distribution of talar talus cartilage during exercise.Methods:The 3D MRI images of the right ankle joint of one marathon runner were acquired and imported into Mimics software in DICOM format for preliminary 3D model reconstruction of the images. The boundary conditions and loads were loaded on the model using Ansys Workbench software, and the ankle joint forces were analyzed by Ansys Workbench for marathon runners in the sports condition, and four kinds of ankle LCL injury finite element models were established, i.e., the normal model of LCL, the injury model of anterior talofibular ligament (ATFL), the injury model of AFTL merged with the calcaneofibular ligament (CFL), and the injury model of AFTL merged with the CFL and the posterior talofibular ligament (PTFL). The peak talus slide cartilage stress and its distribution were observed under the four models, and one-way ANOVA was used to compare the values of talus advancement, and the SNK- q test was used for two-by-two comparisons. Results:In the LCL normal model, the maximum stress peak of the talar slide was 0.21 MPa, which was mainly distributed in the junction area of the anterior medial (MA) and anterior lateral (LA) parts and part of the LA region. In ATFL injury, the peak stress of talar cartilage increased compared with the normal model, with a maximum value of 0.65 MPa, which was mainly distributed in the MA region. In ATFL combined with CFL injury, the peak stress increased, and the peak was mainly distributed in the MA region, and was shifted from the MA to the LA region. In ATFL combined with CFL and PTFL injuries, the peak cartilage stress in the talus slide was up to 2.29 MPa, and the maximum stress was mainly distributed in MA and LA, which had a comparable range of distribution. The anterior talar displacement values were (3.2±0.4), (3.4±0.4), (3.7±0.5), and (6.5±0.7) mm for normal LCL, AFTL injury, AFTL combined with CFL injury, ATFL combined with CFL, PTFL injuries, respectively, with a statistically significant difference ( F=109.08, P<0.001). The anterior talar displacement of ATFL combined with CFL, PTFL injuries was larger than those of normal LCL, AFTL injury, and AFTL combined with CFL injury ( P<0.05). Conclusions:A 3D finite element model is successfully constructed based on 3D MRI of the ankle joint in marathon runners. The peak and range of cartilage stresses in the talar glide change during LCL injury, and the talar glide displaces anteriorly.
摘要
Objective:To evaluate the mechanical performance of customized metal prosthesis with tibia stems of varying lengths for tibial bone defects reconstruction.Methods:Morphologically matched postoperative finite element models of bone defect revision were developed, with three gradients (15 mm, 30 mm, and 45 mm) according to the degree of bone defect and were reconstructed with 3D printed tantalum metal prosthesis using three tibial stem lengths (80 mm, 120 mm, and 150 mm), respectively. Conventional static and dynamic (walking gait) loading was performed to analyze the peak tibial stress distribution and accumulated sliding distance at the prosthetic interface, and to assess the effects of the three tibial stems of different lengths on the stability of the customized tibial defect restorations and the internal tibial stress state.Results:The peak accumulated sliding distance of the dynamically loaded morphologically matched restorations ranged from 17.94 to 21.31 mm with static loading, which were 68% to 84.3% higher than those of 10.26 to 11.69 mm with static loading. The peak tibial stresses in the dynamically loaded model were greater than those in the statically loaded model, with an increase of 28%-49.2%, including 132.94-143.88 MPa in the statically loaded model and 170.41-200.14 MPa in the dynamically loaded model. The overall accumulated sliding distance of the tibia prosthetic model gradually decreased from the tibial osteotomy surface, and the accumulated peak sliding distances ranged from 10.26 to 11.69 mm for static loading, and from 17.94 to 21.31 mm for dynamic loading. The bone tissue stresses in the anterolateral and medial-posterior tibia increased gradually from top to bottom, and the maximum stress value in each section was in the posterior medial tibia (the maximum value was 200.14 MPa). The highest bone tissue stress in the lateral tibia was affected by the tibial stem length, which resulted in a different location, and it was the area most affected by stress shielding (maximum value of 170.65 MPa).Conclusion:For stability assessment of morphologically matched tantalum customized prosthesis, physiological gait dynamic loading studies are more reliable than static loading; the choice of tibial stem length depends on a combination of accumulated peak sliding distances and tibial bone stress distribution factors.
摘要
Objective:To investigate the stability and feasibility of using absorbable screws during Bernese periacetabular osteotomy.Methods:A retrospective analysis was conducted on a 36 year-old woman diagnosed with developmental dysplasia of the hip, who had undergone Bernese periacetabular osteotomy. Finite element analysis was used to simulate the stability of the acetabulum under loads of 10%, 20%, 50%, and 100% of the patient's weight. The structural stiffness of the pelvis and the maximum equivalent stress on the absorbable screws were observed under different conditions, including whether the acetabular bone block and the ilium were in contact, whether 3 or 4 screws were used, and whether a graft (including fibular cortical bone and PEEK grafts) was used.Results:The structural stiffness of the pelvis fixed with four screws increased by 67%-94% compared to that with three screws. After using a graft, the structural stiffness of the pelvis increased by 50%-83%. As the load increased, the maximum equivalent stress on the screws also increased. When the acetabular bone block and the ilium had no contact, no graft was used, and only three screws were used for fixation, the maximum equivalent stress could reach 518.9 MPa, while this value dropped to 61% when four screws were used (318.7 MPa). When the acetabular bone block and the ilium were in contact, the maximum equivalent stress was about 12% of that when there was no contact, regardless of the number of screws used. When a cortical bone graft or a PEEK graft was used, the maximum equivalent stress could drop to 21%-26% of that without a graft. When the screw strength was 130 MPa, a load of 20% of body weight was applied, and only three screws were used without a graft, the equivalent stress could exceed the strength of the screw; if four screws were used, the equivalent stress was slightly higher than the strength of the screw when a load of 50% of body weight was applied. However, when a graft was used (either cortical bone or PEEK), even when a load of 100% of body weight was applied, the equivalent stress was slightly lower than the strength of the screw.Conclusion:Absorbable screws can provide sufficient stability for Bernese periacetabular osteotomy. The contact between the acetabular bone block and the ilium, an increase in the number of screws, and the use of grafts (cortical bone and PEEK grafts) can further improve stability. Therefore, absorbable screws have broad application prospects in Bernese periacetabular osteotomy.
摘要
Objective To design a search and rescue UAV that is portable and user-friendly in order to meet the needs of rescue personnel on the battlefield.Methods Three-dimensional design software CATIA was used to complete the structural design of the UAV body.In order to make full use of the internal space of the UAV body,folding wings were adopted to reduce the volume of the UAV.By using ABAQUS,the finite elements of the key parts of the UAV were analyzed before the modal analysis of the whole vehicle was conducted to verify the reliability of the structure.The robot simulation software Webots was used for motion simulation of the UAV.Results Simulation analysis and test verification suggested that the structural design of the UAV was well-grounded.It could be quickly and properly deployed by means of hand launch or barrels,which made it easier for rescuers to use the UAV.Conclusion The design and simulation research of UAVs with portable folding wings for search and rescue is of great significance for the research and development of physical prototypes.This study is expected to stimulate new ideas for the development of rescue equipment in the PLA,and contribute to miniaturization of UAVs.
摘要
Objective To explore the effects of four extralevator abdominoperineal excision (ELAPE) procedures on the biomechanics of female pelvic floor through finite element analysis. Methods Six finite element models of the female pelvic floor were established, including a normal model, an ELAPE model, and four individual models. The maximum stress in each model was measured under the same pressure, and the stress distribution was observed. Results The maximum stress of non-levator ani muscle tissues on the partially reserved side and totally removed side of the levator ani muscle were 3.101±0.133 and 4.868±0.123 MPa in individual model 1, respectively, which were lower than the maximum stress in the ELAPE model (5.111±0.081 MPa; both P<0.01). The maximum stress in the non-levator ani muscle tissue were 5.138±0.091 MPa on both sides in individual model 2, which were not significantly different from that in the ELAPE model (P>0.05). The maximum stress of non-levator ani muscle tissues were 4.700±0.105 and 3.653±0.156 MPa in individual models 3 and 4, respectively, which were lower than the maximum stress in the ELAPE model (both P<0.01). Conclusion Three ELAPE procedures, including ELAPE with unilateral levator ani muscle resection plane close to the rectum, and the bilateral pubococcygeal muscle lateral resection of levator ani muscle and levator ani muscle in front of the rectum preserved could decrease stress in the non-levator ani muscle tissue on both sides. The effect is evident on the levator ani muscle partially reserved side of ELAPE with unilateral levator ani muscle resection plane close to the rectum. ELAPE with unilateral levator ani muscle resection plane close to the pelvic wall has no significant reduction effect on the non-levator ani muscle tissue on either side.
摘要
BACKGROUND:The proximal femoral nail antirotation is the preferred treatment for reverse osteoporotic intertrochanteric fractures.Bone cement enhancement can reduce the probability of proximal femoral nail antirotation cut-out and cut-through,but there are no relevant biomechanical studies demonstrating the effect of bone cement content and location on the stress and displacement of the fracture end. OBJECTIVE:To investigate the effects of different contents and locations of bone cement in cement-reinforced proximal femoral nail antirotation on stress,strain,and displacement of reverse osteoporotic femoral intertrochanteric fractures in the elderly by finite element analysis. METHODS:A healthy adult female right femur model was extracted by Mimics software and smoothed in Geometric software.Five types of internal fixation methods of proximal femoral nail antirotation(cementless,cephalic spherical 1 mL,cephalic spherical 2 mL,cephalic spherical 3.4 mL,and cylindrical 5 mL around spiral blade)and femoral intertrochanteric fracture(AO subtype 31-A3.1 type)model were established in Solidworks software.After assembly,the total stress distribution,peak stress and displacement of the five models of implants with the femur were compared in Ansys software. RESULTS AND CONCLUSION:(1)The peak stresses of proximal femoral nail antirotation with head-end spherical 1 mL,head-end spherical 2 mL,head-end spherical 3.4 mL,and cylindrical 5 mL enhanced proximal femoral nail antirotation around the spiral blade respectively were 571.07 MPa(located at the junction of the spiral blade and the main nail),495.45 MPa(located at the junction of the spiral blade and the main nail),467.20 MPa(located at the junction of the main nail and the distal screw connection),642.70 MPa(located at the junction of the main nail and distal screw connection),and 458.58 MPa(located at the junction of the spiral blade and the main nail).(2)The maximum displacements of proximal femoral nail antirotation with head end sphere 1 mL,head end sphere 2 mL,head end sphere 3.4 mL,and with cylindrical 5 mL enhancement around the spiral blade were 9.260 5,7.589 1,7.316 8,6.790 7,and 6.615 7 mm,respectively,all of which were located at the proximal end of the femoral head.(3)These findings revealed that for reverse femoral intertrochanteric fractures treated with proximal femoral nail antirotation,the bone cement enhancement had significant mechanical stability compared with no enhancement,and the enhancement of the spiral blade 5 mL around the perimeter was the best,which is more preferable for aged unstable intertrochanteric fractures.
摘要
BACKGROUND:In the treatment of edentulous maxillary implants supported fixed repair,the selection of upper scaffold structure materials and the design of different distal implant implantation methods have a close influence on the long-term stability of the whole mouth implant repair. OBJECTIVE:To comprehensively explore the influence of three different materials of upper scaffold and two implant fixation designs on the biomechanics of the fixed maxillary implant repair based on the three-dimensional finite element method. METHODS:Based on the conical beam CT data of a healthy adult with normal jaws,the Mimics software was used to separate the maxillary and maxillary dentin three-dimensional solid models,and the Geomagic Studio software was used to construct the three-dimensional finite element model of denture with denture implant and fixed maxillary arch combined with specific model parameters.According to the different designs of distal implants in the maxillary posterior region,two scheme models were established.Scheme 1(Design 1)was designed in accordance with the"All-on-4"design used in clinical practice.Two implants were vertically implanted in the bilateral incisor region of the maxilla,and the other two implants were implanted in the bilateral second premolar region at a 30° angle.In scheme 2(Design 2),two implants were vertically implanted in the lateral incisor region of the maxilla,and two short implants were vertically implanted in the posterior region of the maxilla in the bilateral second premolar region.Three materials(titanium,zirconia and polyether ether ketone)were used to assign values to the upper scaffold structure in the two designs,and six different models were obtained.The biomechanical effects of the implant,surrounding bone tissue and the upper scaffold structure were compared and analyzed in the oblique loading direction. RESULTS AND CONCLUSION:(1)The maximum stress peaks of all models were distributed in the neck region around the posterior implant and the cortical bone under the two edentulous implant fixed restoration schemes,regardless of the material of the upper scaffold.(2)Compared with the alternative design of Design 2,which adopted vertical implantation of short implants,Design 1 showed a more ideal stress distribution on the maxilla.(3)The scaffold model constructed by polyether ether ketone material transferred higher stress to the implant and surrounding bone tissue close to the loading zone of the upper jaw bone,followed by titanium and zirconia.As for the support itself,the peak stress of the upper scaffold of polyether ether ketone was significantly lower than that of the zirconia and titanium scaffolds.Zirconia scaffolds were used among the three upper scaffolds to disperse the stress distribution of implant and bone tissue.(4)The results suggest that both designs can be applied to clinical practice.However,from the perspective of biomechanics,the stress distribution of the implant,surrounding bone tissue and upper scaffold in Design 1 is more rational,which is more conducive to the long-term prognosis of fixed implant repair in patients with edentulous jaws.The upper scaffold material has a certain influence on the stress distribution of the implant-bone interface.
摘要
BACKGROUND:For dislocation of acromioclavicular joint induced by coracoclavicular ligament fracture,single EndoButton Plate reconstruction and double EndoButton Plates reconstruction are common repair methods.Further study on the stress distribution and fracture risk of the two repair methods is of great significance. OBJECTIVE:To study the biomechanical properties of the coracoclavicular ligament,and compare the fixation effect,stress distribution and failure mode of single and double EndoButton Plates reconstruction. METHODS:(1)Finite element simulation analysis:Mimics,Wrap and SolidWorks were used to establish normal coracoclavicular ligament,single EndoButton Plate reconstruction and double EndoButton Plates reconstruction.Ansys software was used to analyze the stress and deformation of the scapula and clavicle of each model under vertical load.(2)Sample experiment:Fifteen intact scapular-clavicle specimens were randomly grouped into five groups,with three specimens in each group.In group A,the acromioclavicular ligament was severed and the coracoclavicular ligament remained intact.In group B,acromioclavicular ligaments and trapeoid ligaments were severed,leaving intact conical ligaments.In group C,acromioclavicular ligaments and conical ligaments were cut off,and the intact traprex ligaments were retained.In group D,acromioclavicular and coracoclavicular ligaments were severed,and coracoclavicular ligaments were repaired by single EndoButton Plate reconstruction.In group E,acromioclavicular and coracoclavicular ligaments were severed,and the coracoclavicular ligaments were repaired by double EndoButton Plates reconstruction.The mechanical experiment was carried out by a mechanical testing machine to analyze the biomechanical status,stress distribution and failure patterns of the scapular-clavicle and clavicle. RESULTS AND CONCLUSION:(1)Finite element simulation analysis:The average stress of coracoclavicular ligament attached specimens was the lowest,and the risk of coracoclavicular fracture was less than that of single and double EndoButton Plates reconstruction.The mean stress of the coracoid process was similar in single and double EndoButton Plates reconstruction,and the fracture risk was similar.(2)Sample experiment:In groups A,B,C,D and E,the stiffness of specimens was(26.4±3.5),(19.8±2.8),(21.3±3.2),(57.7±4.1),and(46.2±2.8)N/mm,respectively;the ultimate loads were(545.5±53.7),(360.1±42.1),(250.9±44.4),(643.5±39.1),and(511.9±31.7)N,respectively;global stiffness in groups D and E was higher than that in group A(P=0.000 06,0.000 3);ultimate load in group D was higher than that in group A(P<0.05);the ultimate load was not significantly different between the group E and group A(P>0.05).Ligament fracture was observed in groups A,B and C and coracoid process fracture was found in groups D and E.(3)These results suggest that from the biomechanical analysis,Single EndoButton Plate reconstruction and double EndoButton Plates reconstruction are effective treatment techniques for coracoclavicular ligament fracture in acromioclavicular joint dislocation,but increase the risk of fracture.The double EndoButton Plates reconstruction dispersed the stress of the steel plate and reduced the contact force between the steel plate and bone,but slightly reduced the ultimate bearing capacity.Single and double EndoButton Plates reconstruction should be selected according to the actual clinical situation.
摘要
BACKGROUND:Due to the treatment of cervical spondylosis,the Zero-P system of the anterior cervical interbody fusion system will have problems such as screw loosening and fracture after operation,so a novel Low-P system has been developed. OBJECTIVE:To compare the effects of the novel Low-P and Zero-P anterior cervical intervertebral fusion systems on the biomechanical properties of adjacent segments of the cervical spine and to perform stress analysis on the internal fixation system,so as to provide a theoretical reference for clinical treatment. METHODS:A complete model of the C1-C7 segment of the cervical spine was established.Based on the effectiveness of the model,a finite element model of Low-P(type Z Low-P and type H Low-P)and Zero-P system implanted in C4-C5 segments was established.The stress distribution of implanted devices and adjacent vertebral nucleus pulposus,fibrous rings and end plates was analyzed under the conditions of forward flexion,posterior extension,lateral bending and rotation. RESULTS AND CONCLUSION:(1)After implantation of Low-P and Zero-P internal fixation devices,the range of motion of the type H Low-P system was large;the maximum stress value of type Z Low-P system was small;the maximum stress of Zero-P on the nucleus pulposus of adjacent segments was large;the maximum stress of end plate was small.(2)The influence of three internal fixation systems on adjacent segment fiber rings was close.(3)The screw stress of the Zero-P internal fixation system was much greater than that of the Low-P system.(4)It is indicated that compared with Zero-P type internal fixation system,the novel Low-P system reduces the stress value of steel plate and screw,which can reduce screw loosening and internal fixation system failure.The Low-P system has less stress on the nucleus pulposus of adjacent discs and reduces disc degeneration in adjacent segments.This paper provides a theoretical basis for the clinical study of a Low-P type internal fixation system.
摘要
BACKGROUND:Among the pathogenic factors of cervical spondylosis,herniation of the intervertebral disc,dislocation of the facet joint and the stenosis of the intervertebral foramen are important factors leading to symptoms in patients.Moreover,inappropriate manipulation may aggravate the possibility of cervical disc rupture,leading to exacerbation of symptoms in patients. OBJECTIVE:To compare the effect between sagittal cervical manipulation and traditional cervical rotation manipulation on the area of the intervertebral disc,facet joint and intervertebral foramen at the operative segment by the finite element analysis. METHODS:The neck CT data of a male volunteer with a normal neck were selected and imported into Mimics 17.0 three-dimensional reconstruction software.Geo-magic Studio 12.0,Solidworks 2017 and Ansys Workbench 17.0 software were used for the construction of the finite element model of cervical vertebrae(C3-6)including intervertebral disc and articular cartilage.The lower end plate of the C5 vertebral body was fixed.A uniformly distributed vertical downward 50 N load was applied on the upper surface of the upper vertebral body(C3).The stress,deformation and deformation direction of the C4-5 intervertebral disc,joint capsule stress,the displacement of facet joints and the area of bilateral intervertebral foramen were compared between sagittal cervical manipulation and traditional rotation reduction. RESULTS AND CONCLUSION:(1)When using the rotation technique,the maximum normal equivalent stress(von Mises stress)of the C4-5 disc was 8.06 MPa;the total deformation was 1.05 mm,and the fiber ring expanded to the left and outside.When using the sagittal tip lifting technique,the maximum normal equivalent stress(von Mises stress)of the C4-5 disc was 2.60 MPa;the total deformation was 0.90 mm,and the fiber ring expanded to the left and back.Compared with the rotation technique,the pressure of the cervical manipulation technique on the disc was less(about 32.3%of the rotation technique),and the deformation degree of the disc was also light(about 85.7%of the rotation technique).(2)When the rotation technique was used,the maximum stresses of the left and right articular capsule ligaments were 0.37 MPa and 1.69 MPa,respectively.The overall displacement of the facet joint was 2.21 mm.The area of the right intervertebral foramen decreased by about 3.8%and the area of the left intervertebral foramen increased by about 0.9%.When the sagittal end lifting manipulation was performed,the maximum stresses of the left and right articular capsule ligaments were 0.27 MPa and 1.70 MPa,respectively;the overall displacement of the facet joint was 1.63 mm;the area of the right intervertebral foramen increased by about 2.6%,and the area of the left intervertebral foramen decreased by about 0.9%.Compared with rotation manipulation,sagittal end lifting manipulation had fewer changes in the displacement of facet joint,joint capsule stress and intervertebral foramen area,so it was safer to operate.(3)In conclusion,compared with cervical rotation manipulation,sagittal end lifting manipulation has fewer changes in facet joint displacement,intervertebral disc stress/deformation degree,joint capsule stress,and foraminal area.In clinical practice,more appropriate manipulation should be selected based on biomechanical results after an accurate assessment of patients'conditions.
摘要
BACKGROUND:Endoscopic treatment of lumbar disc herniation has obvious advantages over traditional open surgery.Endoscopic surgery involves the implantation of a working cannula,which requires only partial bone removal,and there are no studies on the effects of two types of intraoperative foraminoplasty and laminoplasty on the mechanical properties of the local structure of the lumbar spine. OBJECTIVE:To compare the effect of foraminoplasty and laminoplasty on the biomechanical properties of disc and isthmus of the responsible segment. METHODS:The lumbosacral CT images of a healthy male volunteer were taken,and a finite element model M0 of the L3 to sacral vertebrae was established,on which the primary and secondary foraminoplasty models M1 and M2 of the L5/S1 and the laminoplasty model M3 were built.The same load was applied to compare the intervertebral motion range,disc Von Mises stress and equivalent stress characteristics of L5 vertebral isthmus with each model. RESULTS AND CONCLUSION:(1)Compared with M0,M1 and M2 motion range in L5/S1 segment did not change significantly in all directions;M2 overall motion range increased by 8.60%in flexion;M3 increased by 8.23%and 8.26%in L5/S1 right bending and right torsion,and 5.39%and 5.67%in overall motion range in flexion and right bending,with no significant changes in motion range in the rest of working conditions.(2)Compared with M0,M1 showed no significant change in the extremes of Von Mises stress at L5/S1 disc;M2 increased 11.06%,12.50%,18.32%,and 15.48%in flexion,extension,left torsion,and right torsion;M3 increased 12.22%,19.54%,10.05%,and 9.97%in flexion,extension,left torsion,and right torsion,and the rest working conditions and L4/5 disc maximum Von Mises stress did not change significantly.(3)Compared to M0,the maximum Von Mises stress in the left isthmus of L5 of M1 increased by 12.43%in left bending,18.38%,13.29%,13.62%,and 40.00%in the right isthmus in extension,right bending,left torsion,and right torsion.The maximum Von Mises stress in the left isthmus of L5 of M2 increased by 38.87%,42.63%,16.95%,and 19.35%,and that in the right isthmus increased by 12.58%,33.70%,12.92%,and 17.42%in flexion,extension,left bending,and left torsion.The maximum Von Mises stress in the left isthmus of L5 of M3 increased 67.07%,78.14%,32.33%,62.94%,and 89.99%in flexion,extension,left and right bending,and right torsion.(4)The results suggest that foraminoplasty and laminoplasty have a small effect on spinal motion range;there is a mild increase in the extreme values of disc Von Mises stress in the segments operated by interbody laminoplasty and secondary foraminoplasty;there is no significant change in the extreme values of disc Von Mises stress in adjacent segments,and there is a significant increase in the Von Mises stress in the ipsilateral isthmus operated by the interbody laminoplasty model.
摘要
BACKGROUND:Ankylosing spondylitis is a chronic inflammatory disease with chronic rheumatic immunity.Soft tissue ossification and fusion and spinal stiffness can cause biomechanical changes. OBJECTIVE:To reconstruct the lumbar-sacral intervertebral disc in ankylosing spondylitis patients with lumbar kyphosis by finite element analysis,and to study the range of motion of each segment of T11-S1 and the biomechanical characteristics of annulus fibrosus and nucleus pulposus. METHODS:The imaging data were obtained from an ankylosing spondylitis patient with lumbar kyphosis.The original CT image data of continuously scanned spine were imported into Mimics 21.0 in DICOM format,and T11-S1 was reconstructed respectively.The established model was imported into 3-Matic software in the format of"Stl"to reconstruct the intervertebral disc,and the fibrous intervertebral disc model was obtained.The improved model was further imported into Hypermesh software,and the vertebra,nucleus pulposus,annulus fibrosus and ligament were mesh-divided.After the material properties were given,the model was imported into ABAQUS software to observe the range of motion of each vertebral body in seven different working conditions of T11-S1,and analyze the biomechanical characteristics of each segment of annulus fibrosus and nucleus pulposus. RESULTS AND CONCLUSION:(1)The range of motion of L1 vertebrae was higher than that of other vertebrae under six different working conditions:extension,forward flexion,rotation(left and right),and lateral flexion(left and right).The maximum range of motion was 2.18° during L1 vertebral flexion,and the minimum range of motion was 0.12° during L5 vertebral extension.(2)The annular fiber flexion at L2-L3 segments was greater than the extension(P<0.05),and the annular fiber flexion at L3-L4 and L4-L5 segments was less than the extension(P<0.05).The left rotation of L1-L2 annular fibers was greater than the right rotation(P<0.05).The left flexion of the annulus was greater than the right flexion in L1-L2,L2-L3,L3-L4,L4-L5 and L5-S1 segments(P<0.05).(3)The nucleus pulposus stresses of T11-L12,L1-L2,L2-L3,L3-L4 and L4-L5 segments in forward flexion were greater than in extension(P<0.05).The left rotation of T12-L1 and L3-L4 segments was smaller than the right rotation(P<0.05),and that of T11-T12,L1-L2,and L2-L3 segments was larger than the right rotation(P<0.05).The left flexion was larger than the right flexion in the T11-S1 segment.(4)It is concluded that in ankylosing spondylitis patients with lumbar kyphosis,the minimum range of motion of the vertebral body is located at the L5 vertebral body in extension.To prevent fractures,it is recommended to avoid exercise in the extension position.During the onset of lumbar kyphosis in patients with ankylosing spondylitis,the maximum stress of the annulus fibrosus and nucleus pulposus is located in the L1-L2 segment,which is fixed and will not alter with the change of body position.The late surgical treatment and correction of deformity should focus on releasing the pressure of the annulus fibrosus and nucleus pulposus in this segment to avoid the rupture of the annulus fibrosus and the injury of the nucleus pulposus.
摘要
BACKGROUND:Intramedullary nail has achieved a good clinical result in the treatment of femoral shaft fractures,but some patients still have aseptic nonunion due to mechanical instability.The femur is the longest and largest bone in the human body,but there are few studies on whether the fracture of the femur has different biomechanical results in different areas and the influence of different inserting methods on the stability of fracture fragments in different areas. OBJECTIVE:To analyze the biomechanical characteristics of anterograde and retrograde intramedullary nails in the treatment of different areas of femoral shaft fractures,and to evaluate the best way of insertion to reduce the incidence of nonunion. METHODS:CT data of a healthy volunteer were selected to import into the software of Mimics 19.0 and Geomagic studio 2017 to extract and optimize the three-dimensional model of the right femur.The anterograde and retrograde intramedullary nail models were built with Solidworks 2017 software and assembled with femoral shaft fracture models at different fracture areas according to standard surgical techniques.The models were imported into Abaqus 2017 software in STEP format to set material attribute parameters,boundary conditions,load and submit calculation,and the results were viewed in the visualization module.Among them,the antegrade and retrograde intramedullary nails of the upper femoral shaft fracture were A1 and A2 models,B1 and B2 models in the middle segment,and C1 and C2 models in the lower segment. RESULTS AND CONCLUSION:(1)In models A1,B1 and C2,the overall stress distribution of the femur was more uniform,and the placement,the displacement and angle of the fracture site,and inversion angle of the proximal femoral bone fragment were smaller.(2)For the upper and middle femoral shaft fractures,the anterograde intramedullary nail has a better biomechanical effect.For lower femoral shaft fractures,a retrograde intramedullary nail is preferable.