Contact Mechanics of Soft Layer Artificial Hip Joints: Part 2: Application to Joint Design

1994 ◽  
Vol 208 (4) ◽  
pp. 206-215 ◽  
Author(s):  
J Q Yao ◽  
T V Parry ◽  
A Unsworth ◽  
J L Cunningham
Keyword(s):  
Shear Stress ◽  
Aspect Ratio ◽  
Coefficient Of Friction ◽  
Hip Joint ◽  
Contact Area ◽  
Hip Joints ◽  
Soft Layer ◽  
Physiological Loading ◽  
Artificial Hip ◽  
Artificial Hip Joints

In this paper, the general solutions previously obtained for the contact mechanics of a soft layer artificial hip joint have been applied to the design of such joints. In particular, simple power-law design formulae have been generated for the prediction of the contact radius and the maximum Tresca shear stress within the elastomeric layer, when the aspect ratio varied from 1 to 20 (which covered the entire range of the aspect ratio for soft layer artificial hip joints). The effects of the layer thickness, Young's modulus of the layer and the equivalent radius of the joint upon the contact area and the maximum Tresca shear stress have all been examined for physiological loading conditions which would be experienced by hip joint prostheses in the body. Furthermore, the shear strain field was calculated so that the level of strain expected for such joints under physiological loading conditions can be estimated. With these data, relevant fatigue tests can be devised to assess the long-term performance of any particular design of soft layer hip joint. Finally, the effect of the friction between articular surfaces upon the stress field within soft layers has been examined using a newly developed asymptotic analytical theory. It was shown that, for a low coefficient of friction, the maximum Tresca shear stress occurred at layer-substrate bonding interface. With an increase in the coefficient of friction, however, the maximum Tresca shear stress increased its magnitude and moved towards the centre of the contact area along the articular surface.

Alumina–alumina artificial hip joints. Part II: Characterisation of the wear debris from in vitro hip joint simulations

Biomaterials ◽  
2002 ◽  
Vol 23 (16) ◽  
pp. 3441-3448 ◽  
Author(s):  
J.L. Tipper ◽  
A. Hatton ◽  
J.E. Nevelos ◽  
E. Ingham ◽  
C. Doyle ◽  
...  
Keyword(s):  
Hip Joint ◽  
Wear Debris ◽  
Hip Joints ◽  
Artificial Hip ◽  
Artificial Hip Joints

scholarly journals The impact of surface and geometry on coefficient of friction of artificial hip joints

2017 ◽  
Vol 72 ◽  
pp. 192-199 ◽  
Author(s):  
Dipankar Choudhury ◽  
Martin Vrbka ◽  
Azuddin Bin Mamat ◽  
Ian Stavness ◽  
Chanchal K. Roy ◽  
...  
Keyword(s):  
Coefficient Of Friction ◽  
Hip Joints ◽  
Artificial Hip ◽  
Artificial Hip Joints ◽  
The Impact

scholarly journals Measurement and evaluation of specific absorption rate and temperature elevation caused by an artificial hip joint during MRI scanning

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Youngseob Seo ◽  
Zhiyue J. Wang
Keyword(s):  
High Temperature ◽  
Hip Joint ◽  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Rf Heating ◽  
Temperature Elevation ◽  
Hip Joints ◽  
Specific Absorption ◽  
Artificial Hip ◽  
Artificial Hip Joints

AbstractA primary safety concern in a magnetic resonance imaging environment is heating of metallic implants by absorbing radiofrequency (RF) energy during MRI scanning. Experimental measurement in conjunction with computational modeling was used to evaluate the risk of biological tissue injury from the RF heating of artificial hip joints by obtaining both specific absorption rate (SAR) and temperature elevation at 1.5 T and 3 T MRI systems. Simulation result showed that high SAR and high temperature appeared near both head and tail sections of the artificial hip joints. For five different 1.5 T and 3 T MRI systems, measured temperature location showed that high temperature rises occurred near both head and tail regions of the metallic hip joints. Measured SAR value of 24.6 W/kg and the high temperature rise (= 4.22 °C) occurred in the tail region of the hip joint at 1.5 T, which was higher than the limits for temperature required by the international electrotechnical commission 60601-2-33. We have demonstrated the feasibility of evaluating RF heating of metallic hip joints during MRI scans.

A Simulated Synovial Fluid for Wear Characterization of Artificial Hip Joints by a Hip Joint Simulator

2006 ◽  
Vol 309-311 ◽  
pp. 1273-1276 ◽  
Author(s):  
Hiroaki Takadama ◽  
Mineo Mizuno
Keyword(s):  
Hip Joint ◽  
Bovine Serum ◽  
Calf Serum ◽  
Major Constituent ◽  
Wear Property ◽  
Hip Joints ◽  
Artificial Hip ◽  
Artificial Hip Joints ◽  
Wear Characterization

The calf serum solution was defined as the international standard lubricant for wear characterization of artificial hip joints. It is, however, known that its composition varies according to age, manufacturing processes or production areas of bovine cattle, and that the difference in composition has large effect on the wear characterization. It was difficult to compare the results obtained by different laboratories. Therefore, it is desirable to develop an artificial lubricant whose composition can be always set to a specified value as an alternative to bovine serum. In the present study, the effect of each major constituent in bovine serum on wear property was studied by hip simulator. As a result, transparent and stable lubricant solutions were prepared. It showed quite similar wear property to bovine serum by controlling the composition. These results serve as a guide to propose the new lubricant suitable for the wear characterization of hip joint.

Contact Mechanics of Soft Layer Artificial Hip Joints: Part 1: General Solutions

1994 ◽  
Vol 208 (4) ◽  
pp. 195-205 ◽  
Author(s):  
J Q Yao
Keyword(s):  
Fluid Film ◽  
Contact Radius ◽  
Lubrication Mechanism ◽  
Hip Joints ◽  
Soft Layer ◽  
Synovial Joints ◽  
Artificial Hip ◽  
Artificial Hip Joints ◽  
Film Lubrication ◽  
Fluid Film Lubrication

Unlike natural synovial joints, which are lubricated with a full fluid film lubrication mechanism, conventional artificial hip joints are lubricated with a mixed lubrication mechanism. Recently, however, a new generation of artificial hip joints employing compliant layers to mimic the compliance of articular cartilage in natural synovial joints have been developed to provide fluid film lubrication in these joints. While satisfactory lubrication can be achieved by employing soft layers, compliant thin layers are susceptible to the debonding between the soft layer and its stiffer substrate and long-term mechanical fatigue failure. Stress analyses for different designs of such joints are therefore important. In the present paper, the circular contact between a rigid sphere and an elastomeric layer bonded on to a rigid substrate has been analysed with a novel semi-analytical approach. The detailed contact parameters (the contact radius, the maximum surface deformation, the contact pressure and the contact stress inside the layer) have been examined for a wide range of aspect ratios (0 ≤ a/ht ≤ 100).

Elasto-Hydrodynamic Lubrication Modelling of Spherical Metal-on-Metal Artificial Hip Joints

2005 ◽  
Author(s):  
F. C. Wang ◽  
Z. M. Jin ◽  
I. J. Udofia
Keyword(s):  
Hip Joint ◽  
Hydrodynamic Lubrication ◽  
Hip Joints ◽  
Hip Implant ◽  
Metal On Metal ◽  
Artificial Hip ◽  
Joint Implants ◽  
Artificial Hip Joints

A full numerical methodology was developed for the elasto-hydrodynamic lubrication analysis of hip joint implants for the lubrication problem in spherical and conformal contacts. Typical results of a metal-on-metal hip implant were obtained to illustrate the applicability of the numerical methodology developed in the present study.

Lubrication Modelling of Artificial Hip Joints: From Fluid Film to Boundary Lubrication Regimes

Volume 1 ◽  
2004 ◽  
Author(s):  
Fengcai Wang ◽  
Zhongmin Jin
Keyword(s):  
Contact Area ◽  
Direct Contact ◽  
Fluid Film ◽  
Acetabular Cup ◽  
Hip Joints ◽  
Lubrication Regimes ◽  
Artificial Hip ◽  
Dry Contact ◽  
Artificial Hip Joints ◽  
Ultra High Molecular Weight

A full numerical methodology was developed for the mixed lubrication analysis of hip implants, covering a continuous spectrum from full fluid film to boundary (dry contact) lubrication regimes. The methodology was applied to a typical hip implant employing an ultra high molecular weight polyethylene (UHMWPE) acetabular cup in articulation with a metallic femoral head. It was shown that as the viscosity decreased, direct contact was initiated at the exit regions both in the entraining and side-leakage directions where the minimum film thickness occurred. As the viscosity decreased further, the direct contact area increased and until eventually became similar to the dry contact area.

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