scholarly journals Finite Element Analysis of Custom Shoulder Implants Provides Accurate Prediction of Initial Stability

Mathematics ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 1113
Author(s):  
Jonathan Pitocchi ◽  
Mariska Wesseling ◽  
Gerrit Harry van Lenthe ◽  
María Angeles Pérez
Keyword(s):  
Finite Element ◽  
Bone Ingrowth ◽  
Mechanical Test ◽  
Fe Analysis ◽  
Patient Specific ◽  
Rank Test ◽  
Bench Test ◽  
Initial Fixation ◽  
Initial Stability ◽  
The Stability

Custom reverse shoulder implants represent a valuable solution for patients with large bone defects. Since each implant has unique patient-specific features, finite element (FE) analysis has the potential to guide the design process by virtually comparing the stability of multiple configurations without the need of a mechanical test. The aim of this study was to develop an automated virtual bench test to evaluate the initial stability of custom shoulder implants during the design phase, by simulating a fixation experiment as defined by ASTM F2028-14. Three-dimensional (3D) FE models were generated to simulate the stability test and the predictions were compared to experimental measurements. Good agreement was found between the baseplate displacement measured experimentally and determined from the FE analysis (Spearman’s rank test, p < 0.05, correlation coefficient ρs = 0.81). Interface micromotion analysis predicted good initial fixation (micromotion <150 µm, commonly used as bone ingrowth threshold). In conclusion, the finite element model presented in this study was able to replicate the mechanical condition of a standard test for a custom shoulder implants.

Computer assisted evaluation of plate osteosynthesis of diaphyseal femur fracture considering interfragmentary movement: a finite element study

2017 ◽  
Vol 62 (3) ◽  
Author(s):  
Claudia Wittkowske ◽  
Stefan Raith ◽  
Maximilian Eder ◽  
Alexander Volf ◽  
Jan S. Kirschke ◽  
...  
Keyword(s):  
Finite Element ◽  
Plate Osteosynthesis ◽  
Computation Time ◽  
Fe Analysis ◽  
Patient Specific ◽  
Osteoporotic Bone ◽  
Computer Assisted ◽  
Efficient Computation ◽  
User Input ◽  
Patient Specific Modeling

AbstractA semi-automated workflow for evaluation of diaphyseal fracture treatment of the femur has been developed and implemented. The aim was to investigate the influence of locking compression plating with diverse fracture-specific screw configurations on interfragmentary movements (IFMs) with the use of finite element (FE) analysis. Computed tomography (CT) data of a 22-year-old non-osteoporotic female were used for patient specific modeling of the inhomogeneous material properties of bone. Hounsfield units (HU) were exported and assigned to elements of a FE mesh and converted to mechanical properties such as the Young’s modulus followed by a linear FE analysis performed in a semi-automated fashion. IFM on the near and far cortex was evaluated. A positive correlation between bridging length and IFM was observed. Optimal healing conditions with IFMs between 0.5 mm and 1 mm were found in a constellation with a medium bridging length of 80 mm with three unoccupied screw holes around the fracture gap. Usage of monocortical screws instead of bicortical ones had negligible influence on the evaluated parameters when modeling non-osteoporotic bone. Minimal user input, automation of the procedure and an efficient computation time ensured quick delivery of results which will be essential in a future clinical application.

CEMENTLESS MIS MINI-KEEL PROSTHESIS REDUCES INTERFACE MICROMOTION VERSUS STANDARD STEMMED TIBIAL COMPONENTS

2016 ◽  
Vol 16 (05) ◽  
pp. 1650070 ◽  
Author(s):  
DESMOND Y. R. CHONG ◽  
ULRICH N. HANSEN ◽  
ANDREW A. AMIS
Keyword(s):  
Finite Element ◽  
Bone Ingrowth ◽  
Stair Climbing ◽  
Fixation Strength ◽  
Knee Prostheses ◽  
Periprosthetic Bone ◽  
Design Change ◽  
Initial Stability ◽  
Better Than

Fixation strength of the cementless knee prostheses is dependent on the initial stability of the fixation and minimal relative motion across the prosthesis–bone interface. Broad mini-keels have been developed for tibial components to allow minimally invasive knee arthroplasty, but the effect of the change in fixation design is unknown. In this study, bone–prosthesis interface micromotions of the mini-keel tibial components (consisting of two designs; one is stemless and another with a stem extension of 45[Formula: see text]mm) induced by walking and stair climbing were investigated by finite element modeling and compared with standard stemmed design. The prosthesis surface area amenable for bone ingrowth for the mini-keel tibial components (both stemmed and unstemmed) was predicted to be at least 67% larger than the standard stemmed implant, thereby reducing the risk of long-term aseptic loosening. It was also found that while different load patterns may have led to diverse predictions of the magnitude of the interface micromotions and the extent of osseointegration onto the prosthesis, the outcome of design change evaluation in cementless tibial fixations remains unchanged. The mini-keel tibial components were predicted to anchor onto the periprosthetic bone better than the standard stemmed design under all loading conditions investigated.

Influence of Implant Surface Texture Design on Peri-Acetabular Bone Ingrowth: A Mechanobiology Based Finite Element Analysis

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Kaushik Mukherjee ◽  
Sanjay Gupta
Keyword(s):  
Finite Element ◽  
Acetabular Component ◽  
Surface Texture ◽  
Bone Ingrowth ◽  
Patient Specific ◽  
Implant Surface ◽  
Acetabular Bone ◽  
Bead Diameter ◽  
Bead Height ◽  
Texture Design

The fixation of uncemented acetabular components largely depends on the amount of bone ingrowth, which is influenced by the design of the implant surface texture. The objective of this numerical study is to evaluate the effect of these implant texture design factors on bone ingrowth around an acetabular component. The novelty of this study lies in comparative finite element (FE) analysis of 3D microscale models of the implant-bone interface, considering patient-specific mechanical environment, host bone material property and implant-bone relative displacement, in combination with sequential mechanoregulatory algorithm and design of experiment (DOE) based statistical framework. Results indicated that the bone ingrowth process was inhibited due to an increase in interbead spacing from 200 μm to 600 μm and bead diameter from 1000 μm to 1500 μm and a reduction in bead height from 900 μm to 600 μm. Bead height, a main effect, was found to have a predominant influence on bone ingrowth. Among the interaction effects, the combination of bead height and bead diameter was found to have a pronounced influence on bone ingrowth process. A combination of low interbead spacing (P = 200 μm), low bead diameter (D = 1000 μm), and high bead height (H = 900 μm) facilitated peri-acetabular bone ingrowth and an increase in average Young's modulus of newly formed tissue layer. Hence, such a surface texture design seemed to provide improved fixation of the acetabular component.

scholarly journals Finite Element Analysis of Patient-Specific Condyle Fracture Plates: A Preliminary Study

2015 ◽  
Vol 8 (2) ◽  
pp. 111-116 ◽  
Author(s):  
Peter Aquilina ◽  
William C. H. Parr ◽  
Uphar Chamoli ◽  
Stephen Wroe
Keyword(s):  
Finite Element ◽  
Internal Fixation ◽  
Material Properties ◽  
Mechanical Performance ◽  
Mandibular Condyle ◽  
Patient Specific ◽  
Element Analysis ◽  
Subcondylar Fracture ◽  
The Stability ◽  
Condyle Fracture

Various patterns of internal fixation of mandibular condyle fractures have been proposed in the literature. This study investigates the stability of two patient-specific implants (PSIs) for the open reduction and internal fixation of a subcondylar fracture of the mandible. A subcondylar fracture of a mandible was simulated by a series of finite element models. These models contained approximately 1.2 million elements, were heterogeneous in bone material properties, and also modeled the muscles of mastication. Models were run assuming linear elasticity and isotropic material properties for bone. The stability and von Mises stresses of the simulated condylar fracture reduced with each of the PSIs were compared. The most stable of the plate configurations examined was PSI 1, which had comparable mechanical performance to a single 2.0 mm straight four-hole plate.

scholarly journals Oblique Lateral Interbody Fusion Combined With Different Internal Fixations in The Treatment of Degenerative Lumbar Spine Disease: A Finite Element Analysis

2021 ◽  
Author(s):  
ShuYi Zhang ◽  
Zhengpeng Liu ◽  
Chenshui Lu ◽  
Li Zhao ◽  
Chao Feng ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Finite Element ◽  
Internal Fixation ◽  
Pedicle Screw ◽  
Interbody Fusion ◽  
Three Dimensional ◽  
Fe Analysis ◽  
The Other ◽  
The Stability ◽  
Unilateral Pedicle Screw

Abstract Little is known about the biomechanical performance of various internal fixations in oblique lumbar interbody fusion (OLIF). In this study, finite element (FE) analysis was used to describe the biomechanical findings of various different internal fixations to compare and explore the stability of each fixation.METHODS: Six validated FE models of the L3-S1 segment were reconstructed from computed tomography images, including (1) an intact model, (2)a stand-alone (SA) model with no instrument (3) a unilateral pedicle screw model (UPS), (4) a unilateral pedicle screw contralateral translaminar facet screw model (UPS-CTLFS), (5) a bilateral pedicle screw (BPS) model, and (6) a cortical bone trajectory screw (CBT).Three-dimensional model was performed by computed tomography data, and 150N static force and 10N.m moments in different directions were applied to the models to analyze the validation of the models in comparison with previous studies. Models of the OLIF cage was created with three-dimensional scanning to improve the accuracy of the FE analysis. Range of motion (ROM) of the surgical segment stresses, stress of the cage, and stress of fixation were evaluated in the different models.RESULTS:ROM increased from least to greatest as follows: BPS, UPS-CTFS, CBT, UPS, SA. The SA group had the greatest ROM and the SA group had the greatest ROM and stresses on the CAGE. The ROM of the BPS and UPS-CTFS was not significantly different for all motion loadings. Compared with the other three models, the BPS model had lower stresses in internal fixation for all loading conditions and the CBT screw internal fixation had the highest stresses for different loads Compared with the other groups.CONCLUSIONSThe BPS model provided the best biomechanical stability for OLIF. The SA model was relatively less stable. The UPS-CFTS group reduced the ROM of the fusion segments, but the stresses on the internal fixation and CAGE were relatively higher in the UPS-CFTS Compared with the BPS group; and the CBT group had lower ROM in flexion and extension Compared with the BPS, but its ROM in rotation and lateral flexion was relatively higher. The stability of the CBT was poorer than that of the BPS and LPS-CTFS groups. The stress on the CAGE and internal fixation was greater in the CBT group.

scholarly journals A Study on the Mechanical Characteristics and Self-Preservation Performance of a Deployment Mechanism with a Large Exhibition Ratio during Its Gathering Process

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1650
Author(s):  
Ning Kong ◽  
Jinyu Li ◽  
Congfa Zhang ◽  
Jie Zhang ◽  
Hongbo Li ◽  
...  
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Mechanical Test ◽  
Surface Friction ◽  
Axial Direction ◽  
Theoretical Development ◽  
Experimental Result ◽  
Unstable State ◽  
Finite Element Software ◽  
The Stability

In order to study the stress state and stability of a spiral tube and actuator for controlled extension and retraction (STACER) during the launching process of a satellite, finite element software was applied to establish a finite element model of STACER via the explicit dynamics analysis method. The influence of top rod’s radius on the gathering or so called packaging process of STACER was analyzed. The effects of surface friction coefficient and acceleration on the stability were studied during the gathering process. It was found that the top rod radius directly affects the gathering load and the deformation around the rivet of the STACER. When the spring reel is gathered, the friction coefficient between contact surfaces, and the acceleration, work on the stability of STACER. The stability of STACER can be maintained by a friction coefficient with small fluctuations. An unstable state occurs after the STACER is gathered when the direction of acceleration is parallel to the axial direction of the rivet. A mechanical test on the STACER is conducted to verify the reliability and accuracy of the model. The force trend is similar between the finite element result and experimental result. This work will contribute to the theoretical development for designing the radius of the top rod of the spring reel, the surface friction coefficient of the STACER and the position of the spring reel during the launch process of satellites.

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.

Finite element simulation and statistical investigation of an orthodontic mini-implant’s stability in a novel screw design

2021 ◽  
pp. 095441192110236
Author(s):  
Vahid Pouyafar ◽  
Ramin Meshkabadi ◽  
Amir Hooman Sadr Haghighi ◽  
Ali Navid
Keyword(s):  
Finite Element ◽  
Lateral Displacement ◽  
Experimental Tests ◽  
Statistical Investigation ◽  
Internal Diameter ◽  
Fe Model ◽  
Initial Stability ◽  
Conical Section ◽  
The Stability ◽  
Screw Threads

One of the essential aspects of the mini-implant’s successful application is its stability after being installed in the bone. The stability of the mini-implant affected the most by its geometry. In the present research, the effect of the geometry-related parameters of the mini-implant on its lateral displacement is investigated by Finite Element (FE) modeling using ABAQUS software. The parameters studied include length, diameter, pitch, and depth of the screw threads; besides, length and angle of the conical section. The Taguchi method was used to prevent many experiments. The mesh convergence tests and experimental tests confirmed the FE model quantitatively and qualitatively. Mean of means and variance analysis determined the parameters significance and their contribution on the stability. The screw diameter and length have the most contribution to mini-implant’ displacement. The effect of screw pitch was less than that for length and diameter. The conical section improved the initial stability by creating compressive stress and additional friction in its surrounding bone. No significant effects on the stability of the mini-implant have been observed for the non-threaded part. By examining the effect of thread depth on its stability by defining the ratio of thread depth to the internal diameter and to maintain the strength of the screw the optimal value for internal to external ratio is set at about 0.7.

Experimental and Finite Element Comparaison of Various Joint Fixation Designs

1999 ◽  
Author(s):  
O. Patenaude ◽  
A. Shirazi-Adl ◽  
M. Dammak
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Bone Ingrowth ◽  
Element Model ◽  
Bone Implant ◽  
Combined Loads ◽  
Pull Out ◽  
Initial Fixation ◽  
Fixation Stability ◽  
Friction Models

Abstract The short- and long-term success of tibial cementless implants depends on the initial fixation stability provided primarily by posts and screws. Excessive relative motions at the bone-implant interface are known to inhibit bone ingrowth and, hence, biologic fixation. In this work, the performance of a number of fixation configurations under static and fatigue combined loads (i.e., compression plus shear) is investigated both experimentally and numerically. These results will permit both to compare different fixation types and to serve to validate a 3D finite element model that incorporates the measured nonlinear bone-implant friction and posts/screws pull-out tests. Once validated, the finite element model is also used to study the effect of different bone-implant friction models for porous coated posts and plate and of loading order of application on predictions.

A Novel Dynamic Bone Stress Evaluation Method of Postoperative Proximal Femur During Gait by Using Elastic Multi Body Analysis Based on Finite Element Analysis

2017 ◽  
Author(s):  
Yukiko Nakamura ◽  
Kazuhiko Adachi ◽  
Nungna Wi ◽  
Mitsuaki Noda
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Boundary Conditions ◽  
Hip Joint ◽  
Proximal Femur ◽  
Dynamic Stress ◽  
Fe Analysis ◽  
Patient Specific ◽  
Time Varying ◽  
Multi Body

A proximal femur fracture due to osteoporosis is one of serious health care problems in aging societies. Osteosynthesis with pin or screw type of implants, such as Hansson pin (HP), Dual SC Screw (DSCS), is widely used for femoral neck fracture treatment in Japan. Unfortunately, some complications such as secondary fractures, especially peri-prosthetic fractures, may occur during postoperative rehabilitation period. In order to reveal the potential cause of the postoperative fracture from the viewpoint of the biomechanics, authors had already performed the dynamic stress analysis of the treated proximal femur based on finite element (FE) analysis. The final goal of our project is to establish the reliable postoperative bone fracture risk assessment method in response to the daily activity including mainly walking. The aim of this study is to propose a novel elastic multi body analysis method based on FE analysis for proximal femur biomechanics. Patient-specific 3D left hip joint FE model was constructed from an elderly female volunteer’s CT images. The model consists of the pelvis, proximal femur, cartilage and DSCS, as multi bodies. The dynamic loading and boundary conditions were applied to the model for simulating a gait motion. Direction and magnitude of the loads varies in response to the gait motion. The time dependent loading forces; hip contact, gluteus medius, gluteus maximus, tensor fasciae latae and adductor, acting around the hip joint was obtained by inverse dynamic analysis of a human gait using in-house lower-limb musculoskeletal model. These loading and boundary conditions for simulating the gait motion are the major technical advantages of the proposed multi body analysis comparing with the conventional static FE analysis. Time varying stress distribution during the gait was evaluated by using dynamic explicit method via ABAQUS. In order to visually demonstrate dynamic stress distribution, we examined the time varying von Mises stresses at the representative points located on the cortical surface of the proximal femur; femoral head, fracture surface and around the lateral insertion holes. The results indicate significant increase of the stresses around the proximal lateral insertion holes for DSCS treatment. Maximum stress values are good agreement with the previous static FE analysis, on the other hand, these biomechanical discussions based on the stress time histories are only obtained from the proposed method. It is indicated that the proposed method is feasible to support the better pre- and postoperative clinical decisions, which is the main contribution of this study.

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