scholarly journals Reducing Contact Stress of the Surface by Modifying Different Hardness of Femoral Head and Cup in Hip Prosthesis

2021 ◽  
Vol 7 ◽  
Author(s):  
Eko Saputra ◽  
Iwan Budiwan Anwar ◽  
J. Jamari ◽  
Emile van der Heide
Keyword(s):  
Femoral Head ◽  
Contact Stress ◽  
Hip Prosthesis ◽  
Hip Prostheses ◽  
Wear Process ◽  
Element Simulation ◽  
Static Contact ◽  
Surface Contact ◽  
The Difference ◽  
Wear Law

The wear of hip prosthesis due to applied load and sliding distance during the patient's daily activity cannot be avoided. Wear causes osteolysis or metallosis due to the wear debris produced by the wear process. Several methods were used to reduce wear in metal-on-metal hip prostheses. One of the efforts performed to reduce wear was the differential-hardness concept. Based on the literature, the fine surface roughness of the femoral head are the reason why the hip prosthesis with differential-hardness reduces wear. Besides, the differential-hardness will contribute to the difference of modulus elasticity then influenced the contact stress on the surface contact. According to Archard's wear law, wear on the material pair is affected by contact stress. Therefore, the analysis of contact stress on the hip prosthesis with differential-hardness is important to investigate. The investigation performed by the static contact of two-dimensional axisymmetric with frictionless by using finite element simulation. The simulated models are the alumina vs. alumina, alumina vs. SS316L, CoCr vs. CoCr, CoCr vs. SS316L, and SS316L vs. UHMWPE. The purpose of this study is to determine the contact stress on the surface contact due to differential-hardness of the femoral head and cup. The results of simulations show that the differential-hardness marked by differences in the modulus of elasticity can reduce the contact stress on the surface contact if compare with the similar hardness.

Study of Unipolar and Bipolar Hip Prostheses Using Finite Element Simulation: Contact Stress Analysis

2017 ◽  
Vol 739 ◽  
pp. 96-102 ◽  
Author(s):  
Eko Saputra ◽  
Iwan Budiwan Anwar ◽  
Rifky Ismail ◽  
J. Jamari ◽  
Emile van der Heide
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Contact Interaction ◽  
Contact Stress ◽  
Analytical Method ◽  
Hip Prosthesis ◽  
Hip Prostheses ◽  
Element Simulation ◽  
Liner Surface ◽  
Maximum Contact

One of phenomena which cannot be avoided in the hip prosthesis due to sliding contact as a product of human activity is wear on the surface of contact interaction Wear in the bipolar model is more complicated than the unipolar model. There are two contact interaction in the bipolar model, while the unipolar model has only one contact interaction. Wear on the liner and cup surfaces of the bipolar model itself can be early estimated by investigation the contact stresses due to their contact interactions. The contact stress on the liner surface of unipolar model can be estimated using analytical method. However, the estimation of contact stress on the liner and cup surface of the bipolar model using analytical method still need to consider. The aiming of this paper is to study the contact stresses on the liner and cup surfaces in the bipolar model of hip prosthesis using the finite element simulation. There are three model of hip prostheses which are simulated in this research, i.e. the unipolar, bipolar and big head unipolar models. The result showed that the maximum contact stress on the liner surface of bipolar model is higher than the unipolar model. The maximum contact stress on the cup surface of the bipolar model is lower than the big head unipolar model. Based on this results, it can be concluded that the contact stress on the liner and cup surfaces of the bipolar model cannot be estimated using analytical method.

scholarly journals Two-dimensional finite element simulation of fracture and fatigue behaviours of alumina microstructures for hip prosthesis

2011 ◽  
Vol 225 (12) ◽  
pp. 1158-1168 ◽  
Author(s):  
K Kim ◽  
B Forest ◽  
J Geringer
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Contact Stress ◽  
Hip Prosthesis ◽  
Scale Effects ◽  
Crack Density ◽  
Contact Stresses ◽  
Two Dimensional ◽  
Acetabular Cup ◽  
Element Simulation

This paper describes a two-dimensional (2D) finite element simulation for fracture and fatigue behaviours of pure alumina microstructures such as those found at hip prostheses. Finite element models are developed using actual Al2O3 microstructures and a bilinear cohesive zone law. Simulation conditions are similar to those found at a slip zone in a dry contact between a femoral head and an acetabular cup of hip prosthesis. Contact stresses are imposed to generate cracks in the models. Magnitudes of imposed stresses are higher than those found at the microscopic scale. Effects of microstructures and contact stresses are investigated in terms of crack formation. In addition, fatigue behaviour of the microstructure is determined by performing simulations under cyclic loading conditions. It is shown that crack density observed in a microstructure increases with increasing magnitude of applied contact stress. Moreover, crack density increases linearly with respect to the number of fatigue cycles within a given contact stress range. Meanwhile, as applied contact stress increases, number of cycles to failure decreases gradually. Finally, this proposed finite element simulation offers an effective method for identifying fracture and fatigue behaviours of a microstructure provided that microstructure images are available.

scholarly journals Assessment of the contact stress distribution dependent on functional and design parameters after total hip arthroplasty

2009 ◽  
pp. 43-53
Author(s):  
Emmanuel Rixrath ◽  
Sylvie Wendling-Mansuy ◽  
Patrick Chabrand
Keyword(s):  
Stress Distribution ◽  
Contact Stress ◽  
Hip Prosthesis ◽  
Distribution Model ◽  
Design Parameters ◽  
Geometrical Parameters ◽  
Hip Prostheses ◽  
Total Hip ◽  
Dynamic Loading Conditions ◽  
Contact Stress Distribution

A numerical model was developed to assess the contact stress distribution in total hip prosthesis as a function of geometrical parameters such as the clearance between the bearing surfaces, the inclination and thickness of the UHMWPE cup. The contact stress distribution model proposed is submitted to static loading considering the maximal force during gait and jogging. The results shows that the magnitude of the maximal contact stress remains constant for inclination values in the range of [0-35°] and increase significantly with the cup clearance and liner thickness for inclination values in the range of [35°-65°]. This model could be improved by considering other factors such as friction and dynamic loading conditions. This approach would permit to bring new perspectives for studying the long-term behaviour of total hip prostheses.

Modularity of total hip prosthesis and its tribological implications

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Liliana-Laura Badita ◽  
Virgil Florescu ◽  
Constantin Tiganesteanu ◽  
Lucian Capitanu
Keyword(s):  
Femoral Head ◽  
Hip Prosthesis ◽  
Femoral Stem ◽  
Fretting Wear ◽  
Fretting Corrosion ◽  
Content Type ◽  
Hip Prostheses ◽  
Total Hip ◽  
Starting Point ◽  
Modular Prostheses

Purpose The study aims to analyze the fretting phenomenon, manifested at the taper junctions of modular total hip prostheses (THP). Modularity of prostheses implies the micro-movement occurrence. Fractures can arise as a result of the fretting cracking of the prostheses components, affecting durability of modular THPs. Fretting corrosion is associated with the decrease in the clinical acceptance of hip modular implants. Design/methodology/approach Starting from the fretting phenomenon influence on modularity, monoblock THPs and prostheses with modular femoral head recovered from some review surgeries were investigated. Modular prostheses have a taper junction femoral head – femoral stem neck. Investigation consisted in the analysis of fretting wear and fretting corrosion, of the femoral heads’ taper and of the femoral stems’ trunnions. Findings The main result was that the micro-movement that provokes the fretting of the femoral head-femoral stem taper junction analyzed does not have the same direction. It is manifesting in the direction of the axis of the femoral head taper, around this axis or as a composed movement. The authors suspect that this is due to the different design of the taper. In this way, the inclination of the stem’s trunnion into the head hole has a different angular misalignment and may cause greater damages of the taper. Originality/value This result can be a starting point from the improvement of the future taper junctions design that will improve the quality, durability and modularity of THPs.

scholarly journals A Computational Analysis of Squeaking Hip Prostheses

2015 ◽  
Vol 10 (2) ◽  
Author(s):  
Ehsan Askari ◽  
Paulo Flores ◽  
Danè Dabirrahmani ◽  
Richard Appleyard
Keyword(s):  
Femoral Head ◽  
Hip Prosthesis ◽  
Angular Speed ◽  
Initial Position ◽  
Force Model ◽  
Stick Slip ◽  
Hip Prostheses ◽  
Continuous Contact ◽  
Joint Friction ◽  
Implant Size

A ceramic-on-ceramic (CoC) hip prosthesis with clearance is modeled as a multibody dynamics system for the purpose of studying hip squeaking. A continuous contact force model provides the intrajoint forces developed at the hip joint. Friction effects due to the relative motion are also considered. A FFT analysis of the audible sounds from CoC hip acceleration is carried out to analyze hip squeaking. The effects of friction, hip implant size, and the head initial position on hip squeaking and the trajectory of femoral head are analyzed and discussed. It was shown that the causes of hip squeaking are stick/slip, friction-induced vibration, and the femoral head angular speed and force changes.

scholarly journals Analysis of Tooth Surface Contact Stress of Involute Spur Gear

2021 ◽  
Vol 2133 (1) ◽  
pp. 012037
Author(s):  
Yusheng Zhai ◽  
Jie Mu ◽  
Ruiguang Yun ◽  
Siran Jia ◽  
Jianfeng En ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Contact Stress ◽  
Simulation Analysis ◽  
Spur Gear ◽  
Tooth Surface ◽  
Analysis Model ◽  
Element Analysis ◽  
Element Simulation ◽  
Surface Contact

Abstract Through the establishment of a pair of spur gear contact models, based on Hertz contact theory, the tooth surface contact stress is calculated; then the Ansys finite element analysis software is used to simulate and analyse the stress distribution. Through the analysis and comparison of the two results, it is proved that the contact stress calculated by Hertz theory is relatively small, which is close to the results of the finite element simulation analysis. Theoretical calculation can verify the accuracy of the finite element simulation analysis model, and the finite element simulation analysis provides an effective way to accurately calculate the contact stress of the tooth surface.

scholarly journals Analysis and Optimization of Static Contact Characteristics of Heavy-Duty Tracked Vehicle Rollers

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
He Tian ◽  
Yi Fang ◽  
Shuai Wang ◽  
Zeren Chen ◽  
Chuliang Yan
Keyword(s):  
Contact Stress ◽  
Contact Structure ◽  
Kriging Model ◽  
Heavy Duty ◽  
Tracked Vehicle ◽  
Maximum Contact Stress ◽  
Static Contact ◽  
The Difference ◽  
Design And Manufacture ◽  
Maximum Contact

The static contact characteristics of heavy-duty tracked vehicle roller and track plate contact structure are analyzed, and the influence mechanism of the roller’s shape parameters on the contact stress is studied. According to the Hertz contact theory, a mathematical model of the roller and track plate contact is established. The contact structure model is established in ANSYS software, and the simulation results are compared with the Hertz theory results to verify each other. In the parameter optimization section for the roller and track plate, based on the Hertz stress calculation formula, a new method is proposed to establish a roller and track plate Kriging model and to globally optimize the model by the genetic algorithm (GA). After that, the relationship among the track roller radius R 1 , the track roller rim radius r 1 , and the track plate rim radius r 2 is analyzed. The results show that the difference between the radius of the rim of the roller and the track plate and the radius of the roller rim both affect the maximum contact stress. Changing the plane contact into the curved surface contact can reduce the maximum contact stress by 33%. This study can provide a reference for the design and manufacture of supporting track rollers and track plates.

The Function of Bipolar Hip Prostheses—A Laboratory Study Using Cadaveric Acetabula

1992 ◽  
Vol 206 (1) ◽  
pp. 37-42 ◽  
Author(s):  
R G Wetherell ◽  
A Unsworth ◽  
A A Amis
Keyword(s):  
Femoral Head ◽  
Laboratory Study ◽  
Hip Prosthesis ◽  
Weight Bearing ◽  
The Self ◽  
Head Size ◽  
Separate Study ◽  
Hip Prostheses ◽  
Hip Simulator

Cadaveric acetabula were mounted in a hip simulator and the friction developed in each during articulation with a series of metal femoral head prostheses of differing sizes was measured. In a separate study, assembled Hastings bipolar hip prostheses were subjected to weight-bearing forces in the same acetabula and their self-righting mechanism was observed. The self-righting mechanism was found to function efficiently, in most cases overcoming the combined friction of the inner and outer articulations of the Hastings hip. However, during motion in the hip simulator a wide variation of friction was observed between different acetabula and within the same acetabulum with differing head size. In several cases this acetabular friction was found to be less than the friction in the inner articulation of the Hastings bipolar hip prosthesis, and this may explain some cases of reported failure of biarticular function.

Novel methods for demonstrating osseointegration of hydroxylapatite-coated titanium hip prostheses

1991 ◽  
Vol 49 ◽  
pp. 34-35 ◽  
Author(s):  
P. Frayssinet ◽  
J. Hanker ◽  
D. Hardy ◽  
B. Giammara
Keyword(s):  
Hip Prosthesis ◽  
Ethanol Concentration ◽  
Bone Matrix ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
Hip Prostheses ◽  
Cellular Inclusions ◽  
Microscopic Studies ◽  
Diamond Saw ◽  
Plasma Sprayed

Prostheses implanted in hard tissues cannot be processed for electron microscopic examination or microanalysis in the same way as those in other tissues. For these reasons, we have developed methods allowing light and electron microscopic studies as well as microanalysis of the interface between bone and a metal biomaterial coated by plasma-sprayed hydroxylapatite(HA) ceramic.An HA-coated titanium hip prosthesis (Corail, Landos, France), which had been implanted for two years, was removed after death (unrelated to the orthopaedic problem). After fixation it was dehydrated in solutions of increasing ethanol concentration prior to embedment in polymethylmethacrylate(PMMA). Transverse femur sections were obtained with a diamond saw and the sections then carefully ground to a thickness of 200 microns. Plastic-embedded sections were stained for calcium with a silver methenamine modification of the von Kossa method for calcium staining and coated by carbon. They have been examined by back-scatter SEM on an ISI-SS60 operated at 25 KV. EDAX has been done on cellular inclusions and extracellular bone matrix.

Analysis of 18F-FDG uptake patterns in PET for diagnosis of septic and aseptic loosening after total hip arthroplasty

2003 ◽  
Vol 42 (06) ◽  
pp. 234-239 ◽  
Author(s):  
T. Mumme ◽  
P. Reinartz ◽  
D. Wirtz ◽  
F. U. Niethard ◽  
U. Büll ◽  
...  
Keyword(s):  
Aseptic Loosening ◽  
Femoral Component ◽  
Hip Prosthesis ◽  
Prosthetic Infection ◽  
Clinical Value ◽  
Septic Loosening ◽  
Hip Prostheses ◽  
Fdg Uptake ◽  
Positron Emission ◽  
Painful Hip

Summary Aim: Identification of typical patterns for fluorodeoxyglucose (FDG) uptake in positron emission tomography (PET) to detect aseptic loosening of hip prosthesis (ace-tabular and/or femoral component) and prosthetic infection. Methods: 18 patients with painful hip prosthesis underwent PET using a dedicated full ring scanner after application of 200-300 MBq FDG. The interface between bone and surrounding soft tissue or bone as displayed on coronal slices was divided into 12 segments in accordance with the classifications of Delee and Gruen. FDG uptake in each of the segments was scored (0-3) by two independent observers. Intraoperative findings were regarded as the gold standard. Results: After surgical revision 14 acetabular components and 9 femoral components were found to be loose and prosthetic infection was present in 7 prostheses. Loosening of the acetabular component was correlated to enhanced uptake in the middle of the acetabular interface, while loosening of the femoral component was correlated to enhanced uptake in the proximal and middle segment of the lateral femoral interface and the proximal segment of the medial femoral interface. A similar pattern was found in prosthetic infection with high uptake along the middle portion of the lateral fe-moral interface. In 6 of 7 infected prostheses loosening of the acetabular and of the femoral component was present. Taking the typical uptake patterns as criteria for loosening and grade 3 uptake as an additional criterion for septic loosening the accuracy of PET imaging in the detection of loosening of the acetabular or the femoral component and of prosthetic infection was 72, 78 and 89%, respectively. Conclusion: This pilot study presents FDG-PET as a promising diagnostic tool for patients with painful hip prostheses. Its clinical value should be evaluated in a larger patient population.

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