The Effect of Boundary Condition on the Biomechanics of a Human Pelvic Joint Under an Axial Compressive Load: A Three-Dimensional Finite Element Model

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Zhixiu Hao ◽  
Chao Wan ◽  
Xiangfei Gao ◽  
Tao Ji
Keyword(s):  
Boundary Condition ◽  
Finite Element ◽  
Stress Distribution ◽  
Strong Correlation ◽  
Compressive Load ◽  
Femoral Stem ◽  
Anatomical Location ◽  
Fe Model ◽  
Biomechanical Behavior

The finite element (FE) model of the pelvic joint is helpful for clinical diagnosis and treatment of pelvic injuries. However, the effect of an FE model boundary condition on the biomechanical behavior of a pelvic joint has not been well studied. The objective of this study was to study the effect of boundary condition on the pelvic biomechanics predictions. A 3D FE model of a pelvis using subject-specific estimates of intact bone structures, main ligaments and bone material anisotropy by computed tomography (CT) gray value was developed and validated by bone surface strains obtained from rosette strain gauges in an in vitro pelvic experiment. Then three FE pelvic models were constructed to analyze the effect of boundary condition, corresponding to an intact pelvic joint, a pelvic joint without sacroiliac ligaments and a pelvic joint without proximal femurs, respectively. Vertical load was applied to the same pelvis with a fixed prosthetic femoral stem and the same load was simulated in the FE model. A strong correlation coefficient (R2=0.9657) was calculated, which indicated a strong correlation between the FE analysis and experimental results. The effect of boundary condition changes on the biomechanical response depended on the anatomical location and structure of the pelvic joint. It was found that acetabulum fixed in all directions with the femur removed can increase the stress distribution on the acetabular inner plate (approximately double the original values) and decrease that on the superior of pubis (from 7 MPa to 0.6 MPa). Taking sacrum and ilium as a whole, instead of sacroiliac and iliolumber ligaments, can influence the stress distribution on ilium and pubis bone vastly. These findings suggest pelvic biomechanics is very dependent on the boundary condition in the FE model.

scholarly journals Biomechanical assessment of different fixation methods in mandibular high sagittal oblique osteotomy using a three-dimensional finite element analysis model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Charles Savoldelli ◽  
Elodie Ehrmann ◽  
Yannick Tillier
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Three Dimensional ◽  
Von Mises Stress ◽  
Analysis Model ◽  
Element Analysis ◽  
Fixation Methods ◽  
Oblique Osteotomy ◽  
Von Mises

AbstractWith modern-day technical advances, high sagittal oblique osteotomy (HSOO) of the mandible was recently described as an alternative to bilateral sagittal split osteotomy for the correction of mandibular skeletal deformities. However, neither in vitro nor numerical biomechanical assessments have evaluated the performance of fixation methods in HSOO. The aim of this study was to compare the biomechanical characteristics and stress distribution in bone and osteosynthesis fixations when using different designs and placing configurations, in order to determine a favourable plating method. We established two finite element models of HSOO with advancement (T1) and set-back (T2) movements of the mandible. Six different configurations of fixation of the ramus, progressively loaded by a constant force, were assessed for each model. The von Mises stress distribution in fixations and in bone, and bony segment displacement, were analysed. The lowest mechanical stresses and minimal gradient of displacement between the proximal and distal bony segments were detected in the combined one-third anterior- and posterior-positioned double mini-plate T1 and T2 models. This suggests that the appropriate method to correct mandibular deformities in HSOO surgery is with use of double mini-plates positioned in the anterior one-third and posterior one-third between the bony segments of the ramus.

Biomechanical in Vitro and Finite Element Study On Different Sagittal Alignment Postures of the Lumbar Spine During Multiaxial Daily Motion

2021 ◽  
Author(s):  
Nadja Wilmanns ◽  
Agnes Beckmann ◽  
Luis Fernando Nicolini ◽  
Christian Herren ◽  
Rolf Sobottke ◽  
...  
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Planning Process ◽  
Axial Rotation ◽  
Intervertebral Discs ◽  
Fe Model ◽  
Bending Moments ◽  
Sagittal Spinal Alignment ◽  
Biomechanical Response

Abstract Lumbar Lordotic correction (LLC), the gold standard treatment for Sagittal Spinal malalignment (SMA), and its effect on sagittal balance have been critically discussed in recent studies. This paper assesses the biomechanical response of the spinal components to LLC as an additional factor for the evaluation of LLC. Human lumbar spines (L2L5) were loaded with combined bending moments in Flexion (Flex)/Extension (Ex) or Lateral Bending (LatBend) and Axial Rotation (AxRot) in a physiological environment. We examined the dependency of AxRot range of motion (RoM) on the applied bending moment. The results were used to validate a Finite Element (FE) model of the lumbar spine. With this model, the biomechanical response of the intervertebral discs (IVD) and facet joints under daily motion was studied for different sagittal spinal alignment (SA) postures, simulated by a motion in Flex/Ex direction. Applied bending moments decreased AxRot RoM significantly (all P<0.001). A stronger decline of AxRot RoM for Ex than for Flex direction was observed (all P<0.0001). Our simulated results largely agreed with the experimental data (all R2>0.79). During daily motion, the IVD was loaded higher with increasing lumbar lordosis (LL) for all evaluated values at L2L3 and L3L4 and posterior Annulus Stress (AS) at L4L5 (all P<0.0476). The results of this study indicate that LLC with large extensions of LL may not always be advantageous regarding the biomechanical loading of the IVD. This finding may be used to improve the planning process of LLC treatments.

scholarly journals Finite element analysis to assess the biomechanical behavior of a finger model gripping handles with different diameters

2019 ◽  
Vol 11 (1) ◽  
pp. 69-79 ◽  
Author(s):  
Benedict Jain A.R. Tony ◽  
Masilamany S. Alphin
Keyword(s):  
Finite Element ◽  
Contact Pressure ◽  
Subcutaneous Tissue ◽  
Fe Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Biomechanical Behavior ◽  
Biomechanical Response ◽  
Human Finger ◽  
Finger Model

SummaryStudy aim: Interactions between the fingers and a handle can be analyzed using a finite element finger model. Hence, the biomechanical response of a hybrid human finger model during contact with varying diameter cylindrical handles was investigated numerically in the present study using ABAQUS/CAE.Materials and methods: The finite element index finger model consists of three segments: the proximal, middle, and distal phalanges. The finger model comprises skin, bone, subcutaneous tissue and nail. The skin and subcutaneous tissues were assumed to be non-linearly elastic and linearly visco-elastic. The FE model was applied to predict the contact interaction between the fingers and a handle with 10 N, 20 N, 40 N and 50 N grip forces for four different diameter handles (30 mm, 40 mm, 44mm and 50 mm). The model predictions projected the biomechanical response of the finger during the static gripping analysis with 200 incremental steps.Results: The simulation results showed that the increase in contact area reduced the maximal compressive stress/strain and also the contact pressure on finger skin. It was hypothesized in this study that the diameter of the handle influences the stress/strain and contact pressure within the soft tissue during the contact interactions.Conclusions: The present study may be useful to study the behavior of the finger model under the static gripping of hand-held power tools.

Shape Optimization of Femoral Components of an Artificial Hip Prosthesis Using the Three-Dimensional P-Version Finite Element Study and the In Vitro Measurement of Strain in the Bone Cement

2002 ◽  
Author(s):  
Masaru Higa ◽  
Ikuya Nishimura ◽  
Kazuhiro Matsuda ◽  
Hiromasa Tanino ◽  
Yoshinori Mitamura
Keyword(s):  
Finite Element ◽  
Shape Optimization ◽  
Bone Cement ◽  
Femoral Component ◽  
Three Dimensional ◽  
Femoral Stem ◽  
Cement Mantle ◽  
Optimum Shape ◽  
Shear Stresses

Though Total Hip Arthroplasty (THA) is being performed with greater frequency every year for patients with endstage arthritis of hip, mechanical fatigue of bone cement leading to damage accumulation is implicated in the loosening of cemented hip components. This fatigue failure of bone cement has been reported to be the result of high tensile and shear stresses at the bone cement. The aim of this study is to design the optimum shape of femoral component of a THA that minimizes the peak stress value of maximum principal stress at the bone cement and to validate the FEM results by comparing numerical stress with experimental ones. The p-version three-dimensional Finite Element Method (FEM) combined with an optimization procedure was used to perform the shape optimization. Moreover the strain in the cement mantle surrounding the cemented femoral component of a THA was measured in vitro using strain gauges embedded within the cement mantle adjacent to the developed femoral stem to validate the optimization results of FEM.

Effect of a Degenerated C5-C6 Disc on the Biomechanics of Adjacent Levels: A Poroelastic Finite Element Investigation

2007 ◽  
Author(s):  
Mozammil Hussain ◽  
Raghu N. Natarajan ◽  
Gunnar B. J. Andersson ◽  
Howard S. An
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Morphological Changes ◽  
Axial Strain ◽  
Fe Model ◽  
Fe Method ◽  
Regional Effect ◽  
In Vitro Techniques

Degenerative changes in the cervical spine due to aging are very common causes of neck pain in general population. Although many investigators have quantified the gross morphological changes in the disc with progressive degeneration, the biomechanical changes due to degenerative pathologies of the disc and its effect on the adjacent levels are not well understood. Despite many in vivo and in vitro techniques used to study such complex phenomena, the finite element (FE) method is still a powerful tool to investigate the internal mechanics and complex clinical situations under various physiological loadings particularly when large numbers of parameters are involved. The objective of the present study was to develop and validate a poroelastic FE model of a healthy C3-T1 segment of the cervical spine under physiologic moment loads. The model included the regional effect of change in the fixed charged density of proteoglycan concentration and change in the permeability and porosity due to change in the axial strain of disc tissues. The model was further modified to include various degrees of disc degeneration at the C5-C6 level. Outcomes of this study provided a better understanding on the progression of degeneration along the cervical spine by investigating the biomechanical response of the adjacent segments with an intermediate degenerated C5-C6 level.

Comparison Between DEXA and Finite Element Studies in the Long-Term Bone Remodeling of an Anatomical Femoral Stem

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
A. Herrera ◽  
J. J. Panisello ◽  
E. Ibarz ◽  
J. Cegoñino ◽  
J. A. Puértolas ◽  
...  
Keyword(s):  
Finite Element ◽  
Bone Density ◽  
Bone Mass ◽  
Simulation Model ◽  
Load Transfer ◽  
Fe Simulation ◽  
Femoral Stem ◽  
Mineral Density ◽  
Biomechanical Behavior

The implantation of a cemented or cementless femoral stem changes the physiological load transfer on the femur producing an effect on the bone called adaptative remodeling. The patterns of this remodeling are attributed to mechanical and biological factors, and those changes in bone mineral density have been determined in long-term densitometry studies. This technique has proved to be a useful tool able to quantify small changes in bone density in different femoral areas, and it is considered to be ideal for long-term studies. On the other hand, the finite element (FE) simulation allows the study of the biomechanical changes produced in the femur after the implantation of a femoral stem. The aim of this study was to contrast the findings obtained from a 5 year follow-up densitometry study that used a newly designed femoral stem (73 patients were included in this study), with the results obtained using a finite element simulation that reproduces the pattern of load transfer that this stem causes on the femur. In this study we have obtained a good comparison between the results of stress of FE simulation and the bone mass values of the densitometry study establishing a ratio between the increases in stress (%) versus the increases in bone density (%). Hence, the changes in bone density in the long term, compared with the healthy femur, are due to different load transfers after stem implantation. It has been checked that in the Gruen zone 7 at 5 years, the most important reduction in stress (7.85%) is produced, which coincides with the highest loss of bone mass (23.89%). Furthermore, the simulation model can be used with different stems with several load conditions and at different time periods to carry out the study of biomechanical behavior in the interaction between the stem and the femur, explaining the evolution of bone density in accordance to Wolff’s law, which validates the simulation model.

scholarly journals Determination of the biomechanical effect of an interspinous process device on implanted and adjacent lumbar spinal segments using a hybrid testing protocol: a finite-element study

2015 ◽  
Vol 23 (2) ◽  
pp. 200-208 ◽  
Author(s):  
Deniz U. Erbulut ◽  
Iman Zafarparandeh ◽  
Chaudhry R. Hassan ◽  
Ismail Lazoglu ◽  
Ali F. Ozer
Keyword(s):  
Finite Element ◽  
Range Of Motion ◽  
Hybrid Approach ◽  
Load Sharing ◽  
Intradiscal Pressure ◽  
Fe Model ◽  
Bone Implant ◽  
Control Approach ◽  
Adjacent Segments

OBJECT The authors evaluated the biomechanical effects of an interspinous process (ISP) device on kinematics and load sharing at the implanted and adjacent segments. METHODS A 3D finite-element (FE) model of the lumbar spine (L1–5) was developed and validated through comparison with published in vitro study data. Specifically, validation was achieved by a flexible (load-control) approach in 3 main planes under a pure moment of 10 Nm and a compressive follower load of 400 N. The ISP device was inserted between the L-3 and L-4 processes. Intact and implanted cases were simulated using the hybrid protocol in all motion directions. The resultant motion, facet load, and intradiscal pressure after implantation were investigated at the index and adjacent levels. In addition, stress at the bone-implant interface was predicted. RESULTS The hybrid approach, shown to be appropriate for adjacent-level investigations, predicted that the ISP device would decrease the range of motion, facet load, and intradiscal pressure at the index level relative to the corresponding values for the intact spine in extension. Specifically, the intradiscal pressure induced after implantation at adjacent segments increased by 39.7% and by 6.6% at L2–3 and L4–5, respectively. Similarly, facet loads at adjacent segments after implantation increased up to 60% relative to the loads in the intact case. Further, the stress at the bone-implant interface increased significantly. The influence of the ISP device on load sharing parameters in motion directions other than extension was negligible. CONCLUSIONS Although ISP devices apply a distraction force on the processes and prevent further extension of the index segment, their implantation may cause changes in biomechanical parameters such as facet load, intradiscal pressure, and range of motion at adjacent levels in extension.

scholarly journals Comparative analysis of stress distribution in one-piece and two-piece implants with narrow and extra-narrow diameters: A finite element study

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0245800
Author(s):  
Fabricia Teixeira Barbosa ◽  
Luiz Carlos Silveira Zanatta ◽  
Edélcio de Souza Rendohl ◽  
Sergio Alexandre Gehrke
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Three Dimensional ◽  
In Vitro Study ◽  
Von Mises Stress ◽  
Axial Loads ◽  
Three Dimensional Model ◽  
The One ◽  
Von Mises

Objectives The aim of this in vitro study was to evaluate the stress distribution on three implant models with narrow and extra-narrow diameters using the finite element method (FEA). Materials and methods Dental implants of extra-narrow diameter of 2.5 mm for a one-piece implant (group G1), a narrow diameter of 3.0 mm for a one-piece implant (group G2) and a narrow diameter of 3.5 mm for a two-piece implant with a Morse taper connection (group G3). A three-dimensional model was designed with cortical and cancellous bone, a crown and an implant/abutment set of each group. Axial and angled (30°) loads of 150 N was applied. The equivalent von Mises stress was used for the implants and peri-implant bone plus the Mohr-Coulomb analysis to confirm the data of the peri-implant bone. Results In the axial load, the maximum stress value of the cortical bone for the group G1 was 22.35% higher than that the group G2 and 321.23% than the group G3. Whereas in angled load, the groups G1 and G2 showing a similar value (# 3.5%) and a highest difference for the group G3 (391.8%). In the implant structure, the group G1 showed a value of 2188MPa, 93.6% higher than the limit. Conclusions The results of this study show that the extra-narrow one-piece implant should be used with great caution, especially in areas of non-axial loads, whereas the one- and two-piece narrow-diameter implants show adequate behavior in both directions of the applied load.

scholarly journals Material property and boundary condition effects on stresses in avalanche snow-packs

1974 ◽  
Vol 13 (67) ◽  
pp. 99-108 ◽  
Author(s):  
J. O. Curtis ◽  
F. W. Smith
Keyword(s):  
Boundary Condition ◽  
Finite Element ◽  
Stress Distribution ◽  
Computer Program ◽  
Material Properties ◽  
Shear Failure ◽  
Stress Distributions ◽  
Snow Pack ◽  
Snow Layer ◽  
Linear Elastic

A linear elastic finite element computer program was applied to determine the stress distributions in multi-layered snow-packs typical of those found at Berthoud Pass, Colorado. The effect on stress distribution of wide variations in elastic material properties was examined. Also, an attempt was made to model the shear failure of a weak sub-layer in the snow-pack by relaxing the condition that the bottom snow layer be firmly attached to the ground.

scholarly journals Three-Dimensional Finite Element Analysis to Evaluate Stress Distribution in Tooth and Implant-Supported Fixed Partial Denture–An In Vitro Study

2020 ◽  
Vol 8 (03) ◽  
pp. 084-091
Author(s):  
Himani Jain ◽  
Tarun Kalra ◽  
Manjit Kumar ◽  
Ajay Bansal ◽  
Deepti Jain
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Alveolar Bone ◽  
Three Dimensional ◽  
In Vitro Study ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Three Dimensional Finite Element

Abstract Introduction This study was undertaken to assess the influence of different superstructure materials, when subjected to occlusal loading, on the pattern of stress distribution in tooth-supported, implant-supported, and tooth implant-supported fixed partial prostheses, using the finite element analysis with a comparative viewpoint. Materials and Methods The geometric models of implant and mandibular bone were generated. Three models were created in accordance with the need of the study. The first model was given a tooth-supported fixed partial prosthesis. The second model was given tooth implant-supported fixed partial prosthesis, and the third model was given implant-supported fixed partial prosthesis. Forces of 100 N and 50 N were applied axially and buccolingually, respectively. Results The present study compared the stresses arising in the natural tooth, implant, and the whole prostheses under simulated axial and buccolingual loading of three types of fixed partial dentures, namely, tooth-supported, tooth implant-supported, and implant-supported fixed partial dental prostheses using three different types of materials. Conclusion The pattern of stress distribution did not appear to be significantly affected by the type of prosthesis materials in all models. The maximum stress concentrations were found in the alveolar bone around the neck of the teeth and implants.

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