Effects of acetabular resurfacing component material and fixation on the strain distribution in the pelvis

2002 ◽  
Vol 216 (4) ◽  
pp. 237-245 ◽  
Author(s):  
M S Thompson ◽  
M D Northmore-Ball ◽  
K E Tanner
Keyword(s):  
Cancellous Bone ◽  
Reaction Force ◽  
Hip Resurfacing ◽  
Heel Strike ◽  
Bone Strain ◽  
Fe Model ◽  
Joint Reaction Force ◽  
Cortical Shell ◽  
Von Mises ◽  
Von Mises Stresses

A 3D finite element (FE) model of an implanted pelvis was developed as part of a project investigating an all-polymer hip resurfacing design. The model was used to compare this novel design with a metal-on-metal design in current use and a metal-on-polymer design typical of early resurfacing implants. The model included forces representing the actions of 22 muscles as well as variable cancellous bone stiffness and variable cortical shell thickness. The hip joint reaction force was applied via contact modelled between the femoral and acetabular components of the resurfacing prosthesis. Five load cases representing time points through the gait cycle were analysed. The effect of varying fixation conditions was also investigated. The highest cancellous bone strain levels were found at mid-stance, not heel-strike. Remote from the acetabulum there was little effect of prosthesis material and fixation upon the von Mises stresses and maximum principal strains. Implant material appeared to have little effect upon cancellous bone strain failure with both bonded and unbonded bone-implant interfaces. The unbonded implants increased stresses in the subchondral bone at the centre of the acetabulum and increased cancellous bone loading, resembling behaviour obtained previously for the intact acetabulum.

scholarly journals Reconstruction of Severe Acetabular Bone Defect with 3D Printed Ti6Al4V Augment: A Finite Element Study

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Jun Fu ◽  
Ming Ni ◽  
Jiying Chen ◽  
Xiang Li ◽  
Wei Chai ◽  
...  
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Bone Defect ◽  
Cancellous Bone ◽  
Acetabular Bone ◽  
Fea Model ◽  
Acetabular Bone Defect ◽  
3D Printed ◽  
Von Mises ◽  
Von Mises Stresses

Purpose. The purpose of this study was to establish the finite element analysis (FEA) model of acetabular bone defect reconstructed by 3D printed Ti6Al4V augment and TM augment and further to analyze the stress distribution and clinical safety of augments, screws, and bones.Methods. The FEA model of acetabular bone defect reconstructed by 3D printed Ti6Al4V augment was established by the CT data of a patient with Paprosky IIIA defect. The von Mises stresses of augments, screws, and bones were analyzed by a single-legged stance loading applied in 3 increments (500 N, 2000 N, and 3000 N).Results. The peak von Mises stresses under the maximal loading in the 3D printed augments, screws, and cortical bone were less than the yield strength of the corresponding component. However, the peak stress in the bone was greater than the yield strength of cancellous bone under walking or jogging loading. And under the same loading, the peak compressive and shear stresses in bone contact with TM augment were larger than these with 3D printed augment.Conclusions. The FEA results show that all the components will be intact under single-legged standing. However, partial cancellous bone contacted with 3D printed augment and screws will lose efficacy under walking or jogging load. So we recommend that patients can stand under full bearing, but can not walk or jog immediately after surgery.

A Finite Element Analysis of the Human Temporomandibular Joint

1994 ◽  
Vol 116 (4) ◽  
pp. 401-407 ◽  
Author(s):  
J. Chen ◽  
Liangfeng Xu
Keyword(s):  
Finite Element ◽  
Temporomandibular Joint ◽  
Reaction Force ◽  
Element Model ◽  
Contact Stresses ◽  
Element Analysis ◽  
Tensile Stresses ◽  
Reaction Forces ◽  
Von Mises ◽  
Von Mises Stresses

A 2-D finite element model of the human temporomandibular joint (TMJ) has been developed to investigate the stresses and reaction forces within the joint during normal sagittal jaw closure. The mechanical parameters analyzed were maximum principal and von Mises stresses in the disk, the contact stresses on the condylar and temporal surfaces, and the condylar reactions. The model bypassed the complexity of estimating muscle forces by using measured joint motion as input. The model was evaluated by several tests. The results demonstrated that the resultant condylar reaction force was directed toward the posterior side of the eminence. The contact stresses along the condylar and temporal surfaces were not evenly distributed. Separations were found at both upper and lower boundaries. High tensile stresses were found at the upper boundaries. High tensile stresses were found at the upper boundary of the middle portion of the disk.

THE BIOMECHANICAL EFFECTS OF CEMENT AUGMENTATION AND PARTIAL VERTEBRAL HEIGHT RESTORATION ON THE LOAD TRANSFER CHANGE OF ADJACENT VERTEBRAE IN VERTEBROPLASTY

2015 ◽  
Vol 15 (03) ◽  
pp. 1550025 ◽  
Author(s):  
CHIEN-YU LIN ◽  
WENG-PIN CHEN ◽  
PO-LIANG LAI ◽  
SHIH-YOUENG CHUANG ◽  
DA-TONG JU ◽  
...  
Keyword(s):  
Load Transfer ◽  
Cement Augmentation ◽  
Erector Spinae ◽  
Von Mises Stress ◽  
Fe Model ◽  
Vertebral Height ◽  
Adjacent Disc ◽  
Before And After ◽  
Von Mises ◽  
Von Mises Stresses

Vertebroplasty is commonly used to treat vertebral wedge fractures (VWFs). However, differing degrees of vertebral height restoration (VHR) have been reported after vertebroplasty, and little is known about how grades (steepness) of VWF deformities affect loadings on the fractured and adjacent unfractured vertebrae. Therefore, the goal of this study was to create a non-linear finite element (FE) model of the T10–L2 thoracolumbar segments. With this model, we aimed to evaluate the biomechanical outcomes of three different collapse models (25%, 50%, and 75%) at the T12 vertebra before and after cement augmentation (CA) and with and without VHR. In these VWF simulations, the forces of the erector spinae, the intradiscal pressure, and the maximum von Mises stresses in the endplates and vertebral bodies increased as vertebral deformation increased. Performing CA alone, without restoring vertebral height for the fractured vertebra, did not change the stiffness of multiple spinal segments or the pressures on the adjacent disc, but it did decrease stresses on the endplates and the vertebral bone. A 10% restoration of vertebral height after CA reduced the maximum von Mises stress in the endplates and bone structures more than when CA did not restore vertebral height (no VHR). These results suggest that achieving partial VHR during vertebroplasty may help prevent postvertebroplasty fractures in the fractured and adjacent vertebrae.

Evaluation of Optimal Taper of Immediately Loaded Wide-Diameter Implants: A Finite Element Analysis

2013 ◽  
Vol 39 (2) ◽  
pp. 123-132 ◽  
Author(s):  
Momen A. Atieh ◽  
Reza A. Shahmiri
Keyword(s):  
Finite Element ◽  
Cancellous Bone ◽  
Strain Distribution ◽  
Immediate Loading ◽  
Stress Strain ◽  
Wide Diameter ◽  
Mandibular Molar ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Molar Extraction

This study aimed to evaluate the effects of different tapering angles of an immediately loaded wide-diameter implant on the stress/strain distribution in bone and implant after implant insertion in healed or fresh molar extraction sockets. A total of 10 finite element (FE) implant-bone models, including 8.1-mm diameter implant, superstructure, and mandibular molar segment, were created to investigate the biomechanical behavior of different implant taper angles in immediate and delayed placement conditions. The degrees of implant taper ranged from 2° to 14°, and the contact conditions between the immediately loaded implants and bone were set with frictional coefficients (μ) of 0.3 in the healed models and 0.1 in the extracted models. Vertical and lateral loading forces of 189.5 N were applied in all models. Regardless of the degree of implant tapering, immediate loading of wide-diameter implants placed in molar extraction sockets generated higher stress/strain levels than implants placed in healed sockets. In all models, the von Mises stresses and strains at the implant surfaces, cortical bone, and cancellous bone increased with the increasing taper angle of the implant body, except for the buccal cancellous bone in the healed models. The maximum von Mises strains were highly concentrated on the buccal cortical struts in the extracted models and around the implant neck in the healed models. The maximum von Mises stresses on the implant threads were more concentrated in the non-tapered coronal part of the 11° and 14° tapered implants, particularly in the healed models, while the stresses were more evenly dissipated along the implant threads in other models. Under immediate loading conditions, the present study indicates that minimally tapered implants generate the most favorable stress and strain distribution patterns in extracted and healed molar sites.

scholarly journals The sensitivity of contact stresses in the mandibular premolar region to the shape of Zirconia dental implant: A 3D finite element study

2018 ◽  
Vol 24 (2) ◽  
pp. 55-63 ◽  
Author(s):  
Duraisamy Velmurugan ◽  
Masilamany Santha Alphin ◽  
Benedict Jain AR Tony
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Cortical Bone ◽  
Transition Region ◽  
Dental Implant ◽  
Cancellous Bone ◽  
Contact Stresses ◽  
Thread Profile ◽  
Von Mises ◽  
Von Mises Stresses

Abstract Background: Implant thread profile plays a vital role in magnitude and distribution of contact stresses at the implant-bone interface. The main goal of this study was to evaluate the biomechanical effects of four distinct thread profiles of a dental implant in the mandibular premolar region. Methods: The dental implant represented the biocompatible Zirconia material and the bone block was modelled as transversely isotropic and elastic material. Three-dimensional finite element simulations were conducted for four distinct thread profiles of a dental implant at 50%, 75%, and 100% osseointegration. An axial static load of 500 N was applied on the abutment surface to estimate the stresses acting within the bones surrounding the implant. Results: Regions of stress concentration were seen mostly along the mesiodistal direction compared to that in the buccolingual direction. The cortical bone close to the cervical region of the implant and the cortical bone next to the first thread of the implant experienced peak stress concentration. Increasing the degree of osseointegration resulted in increased von-Mises stresses on the implant-cortical transition region, the implant-cancellous transition region, the cortical bone, and the cancellous bone. Conclusion: The results show that the application of distinct thread profiles at different degrees of osseointegration had significant effect on the stresses distribution contours in the surrounding bony structure. Comparing all four thread profiles, a dental implant with V-thread profile induced lower values of von-Mises stresses and shear stresses on the implant-cortical transition region, implant-cancellous transition region, cortical bone, and cancellous bone.

Effect of Bone Material Properties on the Initial Stability of a Cementless Hip Stem: A Finite Element Study

2005 ◽  
Vol 219 (4) ◽  
pp. 265-275 ◽  
Author(s):  
A S Wong ◽  
A M R New ◽  
G Isaacs ◽  
M Taylor
Keyword(s):  
Finite Element ◽  
Bone Quality ◽  
Cancellous Bone ◽  
Bone Ingrowth ◽  
Clinical Results ◽  
Relative Effect ◽  
Bone Strain ◽  
Fe Model ◽  
Initial Stability ◽  
Hip Stems

In previous finite element studies of cementless hip stems reported in the literature, the effect of bone quality on the initial micromotion and interface bone strain has been rarely reported. In this study, the effect of varying cortical and cancellous bone modulus on initial stem micromotion and interface bone strain was examined and the potential consequence of these changes on bone ingrowth and implant migration was reported. A finite element (FE) model of a total hip replacement (THR) was created and the Young's moduli of cortical and cancellous bone were systematically varied to study the relative effect of the quality of both types of bone on the initial stability of a cementless THR. It was found that the initial micromotion and interface bone strain in a THR was significantly affected by the overall stiffness of the femur. In other words, both the reduction of the modulus of cortical and cancellous bone caused an increase in the initial micromotion and interface bone strain. This suggests that for FE studies to be truly predictive, a range of bone quality must be examined to study the performance envelope of a particular stem and to allow comparison with clinical results.

EFFECT OF ANTERIOR IMPLANT POSITION ON BIOMECHANICAL PERFORMANCE IN THE MAXILLARY ALL-ON-FOUR TREATMENT: A 3-D FINITE ELEMENT ANALYSIS

2021 ◽  
Author(s):  
Taygun SEZER ◽  
Kerem Kilic ◽  
Emir Esim
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Bone Tissue ◽  
Cancellous Bone ◽  
Principal Stresses ◽  
Element Analysis ◽  
Central Tooth ◽  
Von Mises ◽  
Von Mises Stresses

In the all-on-four concept, the positions of both posterior and anterior implants can affect stress distribution. The aim of this study was to examine the effect of the position of anterior implants on stress distribution in the implant, the bone around the implant, and prosthetic components in the resorbed maxilla using the all-on-four concept. All-on-four designs were prepared with three different anterior implant positions in a fully edentulous maxilla. Anterior implants were placed axially in the central incisor area in model 1, in the lateral incisors area in model 2, and in the canine area in model 3, forming three groups. The von Mises and principal stresses in the bone tissue and the von Mises stresses in the implant and prosthetic components were evaluated by three-dimensional finite element analysis. There were more stresses on the cortical bone than cancellous bone. The stresses on the bone tissue and implant components were generally concentrated around the posterior implant, whereas the stresses on the prosthetic components were generally concentrated in the anterior region. Changing the anterior implant positions from the central tooth to the canine tooth reduced the stress on the bone around the implant. The highest von Mises stresses occurred in the prosthetic superstructure in all models, whereas the lowest stresses occurred in the cancellous bone. Changing the position of the anterior implants from the central tooth to the canine area in the maxillary all-on-four concept created a favourable stress distribution.

Study of Different Biomaterials for Artificial Lumbar Disc Prosthesis Using FEM

2015 ◽  
Vol 799-800 ◽  
pp. 483-487
Author(s):  
Fátima Somovilla Gómez ◽  
Ruben Lostado Lorza ◽  
Marina Corral Bobadilla ◽  
Luis María López González ◽  
José Antonio Gómez Cristobal ◽  
...  
Keyword(s):  
Finite Element ◽  
Lumbar Disc ◽  
Fe Model ◽  
Disc Prosthesis ◽  
Artificial Disc ◽  
Cocrmo Alloy ◽  
Suitable Material ◽  
Flexion Moment ◽  
Von Mises ◽  
Von Mises Stresses

The purpose of this study was to analyze the behavior of a lumbar spine disc prosthesis with different materials. The study was performed at L4-L5 lumbar motion segment using the finite element method (FEM). A healthy Finite Element (FE) model was used as a reference with which to compare the results of the FE simulations of the artificial discs. The healthy and the artificial FE models were subjected to a combination of 0.5 MPa Compression pre-load and 10Nm of Flexion moment. The artificial FE models were based on Maverick artificial disc, and the three materials proposed for study the artificial disk were Titanium, Ceramic and CrCoMo alloy. The most suitable material for developed the artificial disc was the CoCrMo alloy due to: The von Mises stresses on the bone with which this artificial disc was in contact were reduced as much as possible and also, were very similar to the von Mises stresses obtained in the bones from the healthy disc.

scholarly journals Finite element simulations of the effects of an extraoral device, RAMPA, on anterosuperior protraction of the maxilla and comparison with gHu-1 intraoral device

2021 ◽  
Author(s):  
Mohammad Moshfeghi ◽  
Yasushi Mitani ◽  
Bumkyoo Choi ◽  
Peiman Emamy
Keyword(s):  
Finite Element ◽  
Fe Model ◽  
Maxillary Expansion ◽  
Lateral Direction ◽  
Positive Effects ◽  
Intraoral Device ◽  
Nodal Displacements ◽  
Von Mises ◽  
External Forces ◽  
Von Mises Stresses

ABSTRACT Objectives To investigate the effects of an extraoral device, right-angle maxillary protraction appliance (RAMPA), combined with a semi-rapid maxillary expansion intraoral device (gHu-1) on the anterosuperior protraction of maxillary bone. Materials and Methods The finite element (FE) model included craniofacial bones and all sutures. The linear assumption was assumed for the FE simulations and the material properties of bones and sutures. The gHu-1 was simulated under screw activations equal to Δx = 0.25 and 0.5 mm in the lateral direction with and without RAMPA under a set of external forces {F1 = 2.94, F2 = 1.47, F3 = 4.44} N. Results Displacement contours, nodal displacements of 12 landmarks, and von Mises stresses were compared. Combining RAMPA and gHu-1 (with Δx = 0.25 mm) resulted in changes in the displacement of the front part of the maxilla near the mid-palatal suture from (0.02, −0.1, −0.02) mm to (0.02, 0.3, 0.8) mm. For gHu-1 with Δx = 0.5 mm, the displacement of the same part changed from (0.04, −0.04, −0.2) mm to (0.04, 0.3, 0) mm. Similar trends were found in other locations. Conclusions The findings are in agreement with the previous cephalometric clinical data of an 8-year-old patient and prove the positive effects of RAMPA on the anterosuperior protraction of the maxilla when it is combined with the intraoral device gHu-1. In addition, RAMPA does not interfere with the lateral expansion generated by the intraoral device.

scholarly journals The biomechanical effect of preexisting different types of disc herniation in cervical hyperextension injury

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Jian-jie Wang ◽  
Meng-lei Xu ◽  
Hui-zi Zeng ◽  
Liang-dong Zheng ◽  
Shi-jie Zhu ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Disc Herniation ◽  
Cervical Spinal Cord ◽  
Neutral Position ◽  
Fe Model ◽  
Diffuse Type ◽  
Local Type ◽  
Different Types ◽  
Von Mises ◽  
Von Mises Stresses

Abstract Objective Preexisting severe cervical spinal cord compression is a significant risk factor in cervical hyperextension injury, and the neurological function may deteriorate after a slight force to the forehead. There are few biomechanical studies regarding the influence of pathological factors in hyperextension loading condition. The aim of this study is to analyze the effects of preexisting different types of cervical disc herniation and different degrees of compression on the spinal cord in cervical hyperextension. Method A 3D finite element (FE) model of cervical spinal cord was modeled. Local type with median herniation, local type with lateral herniation, diffuse type with median herniation, and diffuse type with lateral herniation were simulated in neutral and extention positions. The compressions which were equivalent to 10%, 20%, 30%, and 40% of the sagittal diameter of the spinal cord were modeled. Results The results of normal FE model were consistent with those of previous studies. The maximum von Mises stresses appeared in the pia mater for all 32 loading conditions. The maximum von Mises stresses in extension position were much higher than in neutral position. In most cases, the maximum von Mises stresses in diffuse type were higher than in local type. Conclusion Cervical spinal cord with preexisting disc herniation is more likely to be compressed in hyperextension situation than in neutral position. Diffuse type with median herniation may cause more severe compression with higher von Mises stresses concentrated at the anterior horn and the peripheral white matter, resulting in acute central cord syndrome from biomechanical point of view.

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