scholarly journals Finite element modeling of proximal femur with quantifiable weight-bearing area in standing position

2020 ◽  
Author(s):  
Yang Peng ◽  
Tian-Ye Lin ◽  
Jing-Li Xu ◽  
Hui-Yu Zeng ◽  
Da Chen ◽  
...  
Keyword(s):  
Finite Element ◽  
Femoral Head ◽  
Proximal Femur ◽  
Physical Phenomenon ◽  
Weight Bearing ◽  
Positional Distribution ◽  
Standing Position ◽  
Fe Model ◽  
X Ray ◽  
Weight Bearing Area

Abstract BackgroundThe positional distribution and size of the weight-bearing area of femoral head in the standing position as well as the direct active surface of joint force can directly affect the result of finite element (FE) stress analysis, however in most studies related separate FE models of femur, the division of this area is vague, imprecise and un-individualized. The purpose of this study was to quantify the positional distribution and size of the weight-bearing area of femoral head in standing position by a set of simple methods, to realize individualized reconstruction of proximal femur FE model.MethodsFive adult volunteers were recruited for X-ray and CT examination in the same simulated bipedal standing position with a specialized patented device. We extracted these image data, calculated the 2D weight-bearing area on X-ray image, reconstructed the 3D model of proximal femur based on CT data, and registered them to realize the 2D weight-bearing area to 3D transformation as the quantified weight-bearing surface. One of the 3D models of proximal femur was randomly selected for finite element analysis (FEA), and we defined three different loading surfaces, and compared their FEA results.ResultsA total of 10 weight-bearing surfaces in 5 volunteers were constructed, they were mainly distributed on the dome and anterolateral of femoral head with crescent shape, in the range of 1,218.63mm2 - 1,871.06mm2. The results of FEA showed stress magnitude and distribution in proximal femur FE models among three different loading conditions were significant differences, the loading case with quantized weight-bearing area was more in accordance with the physical phenomenon of the hip.ConclusionThis study confirmed an effective FE modeling method of proximal femur, which can quantify weight-bearing area to define more reasonable load surface setting without increasing the actual modeling difficulty.

scholarly journals Finite element modeling of proximal femur with quantifiable weight-bearing area in standing position

2020 ◽  
Author(s):  
Peng Yang ◽  
Tian-Ye Lin ◽  
Jing-Li Xu ◽  
Hui-Yu Zeng ◽  
Da Chen ◽  
...  
Keyword(s):  
Finite Element ◽  
Femoral Head ◽  
Proximal Femur ◽  
Physical Phenomenon ◽  
Weight Bearing ◽  
Positional Distribution ◽  
Standing Position ◽  
Fe Model ◽  
X Ray ◽  
Weight Bearing Area

Abstract Background The positional distribution and size of the weight-bearing area of femoral head in the standing position as well as the direct active surface of joint force can directly affect the result of finite element (FE) stress analysis.However,the division of this area was vague, imprecise and un-individualized in most studies related separate FE models of femur. The purpose of this study was to quantify the positional distribution and size of the weight-bearing area of femoral head in standing position by a set of simple methods, to realize individualized reconstruction of proximal femur FE model. Methods Five adult volunteers were recruited for X-ray and CT examination in the same simulated bipedal standing position with a specialized patented device. We extracted these image data, calculated the 2D weight-bearing area on X-ray image, reconstructed the 3D model of proximal femur based on CT data, and registered them to realize the 2D weight-bearing area to 3D transformation as the quantified weight-bearing surface. One of the 3D models of proximal femur was randomly selected for finite element analysis (FEA), and we defined three different loading surfaces, and compared their FEA results. Results A total of 10 weight-bearing surfaces in 5 volunteers were constructed, they were mainly distributed on the dome and anterolateral of femoral head with crescent shape, in the range of 1,218.63mm2 − 1,871.06mm2. The results of FEA showed stress magnitude and distribution in proximal femur FE models among three different loading conditions were significant differences, the loading case with quantized weight-bearing area was more in accordance with the physical phenomenon of the hip. Conclusion This study confirmed an effective FE modeling method of proximal femur, which can quantify weight-bearing area to define more reasonable load surface setting without increasing the actual modeling difficulty.

scholarly journals Biomechanical Analysis of Fibular Graft Techniques for Nontraumatic Osteonecrosis of Femoral Head: A Finite Element Analysis

2020 ◽  
Author(s):  
Jian Xu ◽  
Shi Zhan ◽  
Ming Ling ◽  
Dajun Jiang ◽  
Hai Hu ◽  
...  
Keyword(s):  
Finite Element ◽  
Femoral Head ◽  
Healthy Subject ◽  
Proximal Femur ◽  
Weight Bearing ◽  
Biomechanical Properties ◽  
Patient Specific ◽  
Structural Stiffness ◽  
Osteonecrosis Of Femoral Head ◽  
Weight Bearing Area

Abstract Background: Free vascularized fibula graft (FVFG) technique has achieved the most consistent successful therapeutic effect on young patients diagnosed as nontraumatic osteonecrosis of femoral head (NONFH), of which the Core Track Technique (CTT) has been the most commonly used. As an alternative to CTT, the modified Light Bulb Technique (LBT) was reported to have a higher success rate. However, its biomechanical characters have been poorly understood. This study aimed to investigate the biomechanical properties of modified LBT in treating NONFH by comparing with CTT.Methods: Two types (C1 and C2) of NONFH finite element models were established from a healthy subject according to the Japanese Investigation Committee (JIC) classification, and CTT and LBT procedures were simulated in each type of the models. The average Von Mises stresses and stiffness of the proximal femur were calculated by applying 250% body weight loading on femoral head to simulate walking condition. In addition, two patient-specific models were built and simulated under the same boundary condition for the further validation of LBT.Results: In the healthy subject-derived models, both LBT and CTT resulted in reduced stresses in the weight-bearing area, central femoral head, femoral neck, and trochanteric and subtrochanteric regions, and increased structural stiffness after surgery. In the weight-bearing area, CTT reduced more stresses than LBT (36.19% vs 31.45%) for Type C1, while less reduction (23.63% vs 26.76%) for Type C2. In patient-specific models, stiffness and stresses of before and after surgery were also increased and reduced respectively, which is consistent with healthy subject-derived models.Conclusion: LBT and CTT have different biomechanical performance on different JIC type of NONFH. In terms of preventing the collapse of femoral head, LBT may be more effective for JIC Type C2, which could alternatively be chosen, while for JIC Type C1, CTT is still a better choice. Both techniques can improve biomechanical properties of NONFH with patients’ proximal femur stress reduced and structural stiffness enhanced.

scholarly journals Allograft Fibula Combined with Cannulated Screw for Femoral Head Necrosis: A Finite Element Analysis

2021 ◽  
Author(s):  
Gan Zhao ◽  
Ming Liu ◽  
Bin Li ◽  
Tianye Lin ◽  
JingLi Xu ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Femoral Head ◽  
Cortical Bone ◽  
Maximum Stress ◽  
Weight Bearing ◽  
Cannulated Screw ◽  
Element Analysis ◽  
Osteonecrosis Of Femoral Head ◽  
Weight Bearing Area

Abstract Background: Osteonecrosis of femoral head (ONFH) is characterized by high incidence and disability. Allograft fibula combined with cannulated screw has been extensively applied for treating Osteonecrosis of femoral head. However, its biomechanical outcomes remain unclear. The present study aimed to investigate the optimal placement of the allograft fibula and cannulated screw for treating ONFH.Methods: Two types (C1 and C2) of NONFH finite element models were built based on a healthy subject and the Japanese Investigation Committee (JIC) classification system. The allograft fibula combined with cannulated screw was simulated in the respective type of the model. Different models were built by complying with the different positions of allograft fibula and cannulated screw (below model, posteriorly below model, anteriorly below model and anteriorly above model). Furthermore, a comparison was drawn on the maximum stress value and the mean stress value of the subchondral cortical bone of femoral head weight-bearing area.Results: As indicated from the finite element analysis, normal femoral head, necrotic femoral head and postoperative femoral head achieved the different maximum stress values, and the maximum stress value achieved by necrotic femoral head significantly reached over that of normal femoral head. After the operation, the maximum stress value of subchondral cortical bone in the weight-bearing area of the femoral head was noticeably down-regulated compared with that before the operation (necrotic femoral head). When the cannulated screw was directly below the fibula, subchondral cortical bone in the weight bearing area of femoral head achieved the smallest maximum stress value and average stress value, which showed a statistical difference from those of other models (P<0.05).Conclusion: Allograft fibula combined with cannulated screw is capable of significantly reducing the stress of subchondral cortical bone in the weight-bearing area of the ONFH femoral head, as well as down-regulating the stress concentration in the ONFH weight-bearing area. For JIC C1 and C2 osteonecrosis of the femoral head, when administrated with allograft fibula combined with cannulated screw, the optimal biomechanics was the cannulated screw located just directly below the fibula.

Failure mechanics analysis of AISI 4340 steel using finite element modeling of the milling process

2021 ◽  
pp. 030932472110580
Author(s):  
Muhammed Muaz ◽  
Sanan H Khan
Keyword(s):  
Finite Element ◽  
Failure Analysis ◽  
End Milling ◽  
Physical Phenomenon ◽  
Machining Process ◽  
Fe Model ◽  
Dissipation Energy ◽  
Damage Initiation ◽  
Milling Operation ◽  
Cutting Operation

A slot cutting operation is studied in this paper using a rotating/translating flat end milling insert. Milling operation usually comprises up-milling and down-milling processes. These two types of processes have different behaviors with opposite trends of the forces thus making the operation complex in nature. A detailed Finite Element (FE) model is proposed in this paper for the failure analysis of milling operation by incorporating damage initiation criterion followed by damage evolution mechanism. The FE model was validated with experimental results and good correlations were found between the two. The failure criteria field variable (JCCRT) was traced on the workpiece to observe the amount and rate of cutting during the machining process. It was found that the model was able to predict different failure energies that are dissipated during the machining operation which are finally shown to be balanced. It was also shown that the variation of these energies with the tool rotation angle was following the actual physical phenomenon that occurred during the cutting operation. Among all the energies, plastic dissipation energy was found to be the major contributor to the total energy of the system. A progressive failure analysis was further carried out to observe the nature of failure and the variation of stress components and temperature occurring during the machining process. The model proposed in this study will be useful for designers and engineers to plan their troubleshooting in various applications involving on-spot machining.

Development and Validation of a Finite Element Model of Wear in Uhmwpe Liner Using Experimental Data From Hip Simulator Studies

2021 ◽  
Author(s):  
Nihal Kottan ◽  
Gowtham N H ◽  
Bikramjit Basu
Keyword(s):  
Finite Element ◽  
Femoral Head ◽  
Wear Rate ◽  
Contact Pressure ◽  
Correction Factor ◽  
Linear Wear ◽  
Maximum Relative Error ◽  
Fe Model ◽  
3D Point Clouds ◽  
Dynamic Wear

Abstract The wear of acetabular liner is one of the key factors determining the longevity and osseointegration of Total Hip Replacement (THR) implants. The long-term experimental measurements of wear in THR components are time and cost-intensive. A finite element (FE) model of a 32 mm Ceramic on Polymer system consisting of ZTA (Zirconia-toughened Alumina) femoral head and UHMWPE (Ultrahigh molecular weight polyethylene) liner was developed to predict the dynamic wear response of the liner. Archard-Lancaster equation, consisting of surface contact pressure, wear rate, and sliding distance, was employed to predict the wear in the liner. The contact pressure and wear at the articulating surface were found to decrease over time. A new computational method involving 3D point clouds from the FE analyzed results were used to construct wear maps. The model was able to predict the linear wear with relative errors ranging from 9% to 36% over 2 million cycles when compared to the published results. The increasing error percentage occurring primarily from the use of a constant wear rate was reduced to a maximum of 17% by introducing a correction factor. Volumetric wear rate was predicted with a maximum relative error of 7% with the implementation of the correction factor. When the model was implemented to study liners of diameters ranging from 28 mm to 36 mm, the linear wear was seen to decrease with an increase in femoral head diameter, which is in agreement with the clinical data.

scholarly journals Degradation of subchondral bone collagen in the weight-bearing area of femoral head is associated with osteoarthritis and osteonecrosis

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Zongyi Wu ◽  
Bingzhang Wang ◽  
Jiahao Tang ◽  
Bingli Bai ◽  
Sheji Weng ◽  
...  
Keyword(s):  
Femoral Head ◽  
Trabecular Bone ◽  
Subchondral Bone ◽  
Weight Bearing ◽  
Collagen Fibers ◽  
Bone Collagen ◽  
Control Group ◽  
Neck Fracture ◽  
Hematoxylin And Eosin ◽  
Weight Bearing Area

Abstract Background The aim of the study was to evaluate the change of subchondral bone collagen and trabecular bone in the weight-bearing area of femoral head from patients with osteoarthritis (OA) or osteonecrosis of femoral head (ONFH), and discuss the effect of collagen degradation on OA and ONFH. Methods Femoral heads from patients with femoral neck fracture (FNF) were collected as control group. All collected samples were divided into OA group (N = 10), ONFH group (N = 10), and FNF group (N = 10). Differences of subchondral bone collagen were compared through scanning electron microscope (SEM) observation, immunohistochemistry staining, and Masson’s trichrome staining. Alteration of subchondral bone was displayed through hematoxylin and eosin (H&E) staining and gross morphology. Results SEM results showed that collagen fibers in OA and ONFH group appeared to be thinner, rougher, sparser, and more wizened. Immunohistochemistry and Masson’s trichrome staining results demonstrated that the content of collagen fibers in the OA and ONFH group was obviously less than the FNF group. H&E staining results showed that trabecular bone in OA and ONFH group appeared to be thinner and ruptured. Gross morphology results showed that the degeneration and destruction of cartilage and subchondral bone in OA and ONFH group were severer than FNF group. The characteristics mentioned above in ONFH group were more apparent than OA group. Conclusions This study revealed that degradation of collagen fibers from subchondral bone in the weight-bearing area of femoral head was associated with OA and ONFH, which may help to find new therapeutic strategies of the diseases.

scholarly journals Three-dimensional finite element analysis of silk protein rod implantation after core decompression for osteonecrosis of the femoral head

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Liangta Huang ◽  
Feiyan Chen ◽  
Siqun Wang ◽  
Yibing Wei ◽  
Gangyong Huang ◽  
...  
Keyword(s):  
Finite Element ◽  
Femoral Head ◽  
Surface Stress ◽  
Weight Bearing ◽  
Three Dimensional ◽  
Core Decompression ◽  
Silk Protein ◽  
Head Weight ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Abstract Background Several methods are available for the treatment of early-stage osteonecrosis of the femoral head. Core decompression with implantation is a widely-used treatment. However, no single implant is recognized as the most effective way to prevent disease progression. Silk has high strength and resiliency. This study explored the possibility of a strong and resilient silk protein biomaterial as a new alternative implant. Methods We investigated the biomechanical properties of the silk protein material by regular compression, torsion, and three-point bending tests. We established three-dimensional finite element models of different degrees of femoral head osteonecrosis following simple core decompression, fibula implantation, porous tantalum rod implantation, and silk protein rod implantation. Finally, we compared the differences in displacement and surface stress under load at the femoral head weight-bearing areas between these models. Results The elastic modulus and shear modulus of the silk protein material was 0.49GPa and 0.66GPa, respectively. Three-dimensional finite element analyses demonstrated less displacement and surface stress at the femoral head weight-bearing areas following silk protein rod implantation compared to simple core decompression (p < 0.05), regardless of the extent of osteonecrosis. No differences were noted in the surface deformation or surface stress of the femoral head weight-bearing areas following silk protein rod, fibula or tantalum rod implantation (p > 0.05). Conclusions When compared with simple core decompression, silk protein rod implantation demonstrated less displacement and surface stress at the femoral head weight-bearing area, but more than fibula or tantalum rod implantation. Similar effects on the surface stress of the femoral head between the silk rod, fibula and tantalum rod implantations, combined with additional modifiable properties support the use of silk protein as a suitable biomaterial in osteonecrosis surgery.

scholarly journals Microstructural Modeling of Rheological Mechanical Response for Asphalt Mixture Using an Image-Based Finite Element Approach

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2041 ◽  
Author(s):  
Wenke Huang ◽  
Hao Wang ◽  
Yingmei Yin ◽  
Xiaoning Zhang ◽  
Jie Yuan
Keyword(s):  
Finite Element ◽  
Mechanical Response ◽  
Micromechanical Model ◽  
Asphalt Mixture ◽  
Simulation Software ◽  
Fe Model ◽  
Finite Element Approach ◽  
X Ray ◽  
Element Approach ◽  
Asphalt Mortar

In this paper, an image-based micromechanical model for an asphalt mixture’s rheological mechanical response is introduced. Detailed information on finite element (FE) modeling based on X-ray computed tomography (X-ray CT) is presented. An improved morphological multiscale algorithm was developed to segment the adhesive coarse aggregate images. A classification method to recognize the different classifications of the elemental area for a confining pressure purpose is proposed in this study. Then, the numerical viscoelastic constitutive formulation of asphalt mortar in an FE code was implemented using the simulation software ABAQUS user material subroutine (UMAT). To avoid complex experiments in determining the time-dependent Poisson’s ratio directly, numerous attempts were made to indirectly obtain all material properties in the viscoelastic constitutive model. Finally, the image-based FE model incorporated with the viscoelastic asphalt mortar phase and elastic aggregates was used for triaxial compressive test simulations, and a triaxial creep experiment under different working conditions was conducted to identify and validate the proposed finite element approach. The numerical simulation and experimental results indicate that the three-dimensional microstructural numerical model established can effectively analyze the material’s rheological mechanical response under the effect of triaxial load within the linear viscoelastic range.

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