scholarly journals A Mixed Elasto-Hydrodynamic Lubrication Model for Wear Calculation in Artificial Hip Joints

Lubricants ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 72 ◽  
Author(s):  
Alessandro Ruggiero ◽  
Alessandro Sicilia
Keyword(s):  
Hydrodynamic Lubrication ◽  
Acetabular Cup ◽  
Hip Joints ◽  
Total Hip Replacements ◽  
Artificial Hip ◽  
Hip Replacements ◽  
Volume Wear ◽  
Wear Calculation ◽  
Artificial Hip Joints

The aim of this paper was to propose a novel in silico mixed elasto-hydrodynamic lubrication model with the purpose of wear prediction in Total Hip Replacements (THRs). The model considers the progressive wear contribution in the calculation of the meatus filled by the non-Newtonian synovial fluid. The results were referred to the gait cycle kinematics, calculated by using musculoskeletal multibody software, while the loading was assumed by literature in vivo measurements. The simulations allow evaluating the fluid and the contact pressure fields and the acetabular cup wear over the time. The results were obtained considering a Ultra High Molecular Weight PolyEthylene, UHMWPE, cup and were compared with results from the literature, showing a good agreement in terms of total volume wear of the cup.

A Novel Elastic Squeeze Film Total Hip Replacement

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
S. Boedo ◽  
J. F. Booker
Keyword(s):  
Gait Cycle ◽  
Squeeze Film ◽  
Surface Geometry ◽  
Hip Joints ◽  
New Approach ◽  
Total Hip ◽  
Total Hip Replacements ◽  
Artificial Hip ◽  
Hip Replacements ◽  
Artificial Hip Joints

This paper describes a new approach to the design of total hip replacements with the goal of enhancing lubrication and reducing wear. Elastic elements and ellipsoidal cup surface geometry are incorporated into the new design to promote and enhance ‘squeeze-film’ action over ‘wedge-film’ action employed in conventional artificial hip joints. Employing an established finite element lubrication model with a realistic gait cycle and realistic ball-to-cup clearance specifications, it is found that significantly larger minimum film thicknesses and significantly smaller maximum film pressures are predicted over the stance-phase portion of the gait cycle when compared with conventional designs.

Rationalizing the In Vivo Degradation of Metal-on-Metal Artificial Hip Joints Using Tribocorrosion Concepts

CORROSION ◽  
10.5006/2514 ◽  
2017 ◽  
Vol 73 (12) ◽  
pp. 1510-1519 ◽  
Author(s):  
Shoufan Cao ◽  
Anna Igual Muñoz ◽  
Stefano Mischler
Keyword(s):  
Hip Joints ◽  
Metal On Metal ◽  
Artificial Hip ◽  
Artificial Hip Joints ◽  
In Vivo Degradation

Wear and deformation of ceramic-on-polyethylene total hip replacements with joint laxity and swing phase microseparation

2003 ◽  
Vol 217 (2) ◽  
pp. 147-153 ◽  
Author(s):  
S Williams ◽  
M Butterfield ◽  
T Stewart ◽  
E Ingham ◽  
M Stone ◽  
...  
Keyword(s):  
Volume Change ◽  
Swing Phase ◽  
Joint Laxity ◽  
Acetabular Cup ◽  
Hip Joints ◽  
Wear Rates ◽  
Ceramic Femoral Head ◽  
Artificial Hip ◽  
Artificial Hip Joints

Wear of polyethylene and the resulting wear debris-induced osteolysis remains a major cause of long-term failure in artificial hip joints. There is interest in understanding engineering and clinical conditions that influence wear rates. Fluoroscopic studies have shown separation of the head and the cup during the swing phase of walking due to joint laxity. In ceramic-on-ceramic hips, joint laxity and microseparation, which leads to contact of the head on the superior rim of the cup, has led to localized damage and increased wear in vivo and in vitro. The aim of this study was to investigate the influence of joint laxity and microseparation on the wear of ceramic on polyethylene artificial hip joints in an in vitro simulator. Microseparation during the swing phase of the walking cycle produced contact of the ceramic head on the rim of the polyethylene acetabular cup that deformed the softer polyethylene cup. No damage to the alumina ceramic femoral head was found. Under standard simulator conditions the volume change of the moderately crosslinked polyethylene cups was 25.6 ± 5.3 mm3/million cycles and this reduced to 5.6 ± 4.2 mm3/million cycles under microseparation conditions. Testing under microseparation conditions caused the rim of the polyethylene cup to deform locally, possibly due to creep, and the volume change of the polyethylene cup when the head relocated was substantially reduced, possibly due to improved lubrication. Joint laxity may be caused by poor soft tissue tension or migration and subsidence of components. In ceramic-on-polyethylene acetabular cups wear was decreased with a small degree of joint laxity, while in contrast in hard-on-hard alumina bearings, microseparation accelerated wear. These findings may have significant implications for the choice of fixation systems to be used for different types of bearing couples.

Elastohydrodynamic Lubrication Modeling of Artificial Hip Joints Under Steady-State Conditions

2005 ◽  
Vol 127 (4) ◽  
pp. 729-739 ◽  
Author(s):  
F. C. Wang ◽  
Z. M. Jin
Keyword(s):  
Steady State ◽  
External Rotation ◽  
Elastohydrodynamic Lubrication ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Acetabular Cup ◽  
Hip Joints ◽  
General Applicability ◽  
Flexion Extension ◽  
Artificial Hip ◽  
Artificial Hip Joints

A general steady-state elastohydrodynamic lubrication model was developed for artificial hip joints, with particular reference to the effect of the anatomical position of the cup and the three-dimensional physiological loading and motion experienced during walking. Appropriate spherical coordinates and mesh grids were employed to facilitate the numerical solution. A specific hip implant employing an ultrahigh molecular-weight polyethylene acetabular cup against a metallic femoral head was chosen to demonstrate the general applicability of the lubrication model and the effects of both the cup inclination angle and the combined flexion-extension and internal-external rotation on the lubrication were analyzed.

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.

Frictional Properties of Artificial Hip Joints

1988 ◽  
Vol 17 (3) ◽  
pp. 101-104 ◽  
Author(s):  
A Unsworth ◽  
M J Pearcy ◽  
E F T White ◽  
G White
Keyword(s):  
Complete Separation ◽  
Hip Joints ◽  
Frictional Properties ◽  
Compliant Surfaces ◽  
Artificial Hip ◽  
Hip Replacements ◽  
Order Of Magnitude ◽  
Hip Function ◽  
Artificial Hip Joints ◽  
New Generation

A new generation of hip replacements has been designed incorporating compliant layers to promote fluid film lubrication when the joints are implanted in patients. Tests in the Durham hip function simulator show that the friction in these joints is up to an order of magnitude lower than in currently used prostheses, and because this is due to complete separation of the rubbing surfaces, wear ought to be vastly reduced. Experiments have shown that the best results are achieved with compliant surfaces of hardness between 4 and 8 N/mm2. Such surfaces produce coefficients of friction of the order of 5 × 10-3.

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