Edge‐loading severity as a function of cup lip radius in metal‐on‐metal total hips—A finite element analysis

Elkins, Jacob M.; Kruger, Karen M.; Pedersen, Douglas R.; Callaghan, John J.; Brown, Thomas

doi:10.1002/jor.21524

Cited by 34 publications

(42 citation statements)

References 36 publications

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“…To accurately predict the stress concentration and plastic strain, the present FE analysis required the element size < 0.06 mm for contact surfaces to attain a converged contact solution. This element size is approximately 10 times lower than the 0.5 mm used for the elastic model as obtained from the previous FE studies 32. This result demonstrates that both an elastoplastic model and a substantially fine FE mesh are needed for the rim contact model under microseparation conditions.…”

Section: Discussionmentioning

confidence: 75%

“…Computational models using motion and load inputs determined from kinematic and inverse dynamic data from human‐subject optoelectronic motion capture can provide an alternative approach to the physical simulation 32. A fluoroscopic technique has been developed to detect the translational displacement of the cup and head bearings under dynamic conditions 16, 17.…”

Section: Discussionmentioning

confidence: 99%

“…A full analysis of the dynamic contact is required with an advanced dynamic contact model to incorporate all the factors involved for which a preliminary dynamic model is to be reported 45. The cup version angle was not included which may complicate the variation in contact location at the cup rim and lead to varied trends in contact stress as indicated in the elastic model study 32. The present elastic‐perfectly plastic model is an improved approximation of the material properties of CoCr in MoM bearings, and the contact modeling was based on the original bearing geometry without considering the loading history.…”

Section: Discussionmentioning

confidence: 99%

“…Scifert et al29 developed a contact model to study factors that can influence hip dislocation; Elkin et al30, 31, 32 extended the model to investigate the effect of subluxation and impingement for MoM bearings and fracture for CoC implants; Mak et al18, 24 calculated contact stress for edge loading due to microsepartion in CoC hip joints; Sariali et al33 also carried out similar predictions for CoC bearings. Experimentally, Sanders and Brannon34 developed a method to predict contact area on cup edge and compared with the Hertzian contact theory.…”

Section: Introductionmentioning

confidence: 99%

“…For MoM bearings, all the present contact analyses have been based on the assumption of elastic materials as a first approximation. With microseparation rim contact, the resulting high stress can exceed the yield strength of the bearing materials32 which requires a model that can incorporate plasticity. In addition, to capture the highly concentrated stress, a substantially fine mesh is needed to improve the accuracy of prediction 18…”

Section: Introductionmentioning

confidence: 99%

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Effect of microseparation on contact mechanics in metal‐on‐metal hip replacements—A finite element analysis

2014

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Some early failures of metal‐on‐metal (MoM) hip replacements associated with elevated wear have caused concerns for the use of this bearing combination. Simulator studies have shown that microseparation and its associated rim contact and edge loading may produce the most severe wear in MoM bearings. It is generally recognized that this high wear can be attributed to the high contact stress of the head on the rim of the cup. In this study, an improved finite element contact model that incorporates an elastic‐perfectly plastic material property for cobalt‐chrome alloy of the metal bearing was developed in an attempt to provide an accurate prediction of the stress and strain for the rim contact. The effects of the microseparation displacement (0.1−2 mm), cup inclination angle (25−65°) and cup rim radius (0.5−4 mm) on the contact stress/strain were investigated. The results show that a translational displacement >0.1 mm under a load >0.5 kN can produce a highly concentrated contact stress at the surface of the cup rim which can lead to plastic deformation. This study also suggests that the magnitude of translational displacement was the major factor that determined the severity of the contact conditions and level of stress and strain under microseparation conditions. Future studies will address the effect of surgical translational and rotational malposition and component design on the magnitude of microseparation, contact stress and strain and severity of wear. © 2014 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B: 1312–1319, 2015.

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Section: Discussionmentioning

confidence: 75%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effect of microseparation on contact mechanics in metal‐on‐metal hip replacements—A finite element analysis

2014

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Reducing stress concentration on the cup rim of hip implants under edge loading

Uddin

Chan

2018

Numer Methods Biomed Eng

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High stress concentration under edge loading on the cup rim contact due to micro-separation causes accelerated striping wear, fracture, and fatigue in hip implant components. While continuous effort is devoted into improving bearing design and surgical procedure to tackle the problem, the concern still has remained forcing biomedical engineers to seek for new and alternative solutions. The current paper aims to investigate the effect of a new geometry "spline" introduced at the cup's rim corner to minimise stress concentration under edge loading. Three-dimensional finite element modelling of a metal-on-metal hip implant is developed, where contact pressure, von Mises stress, and strain are predicted for three spline geometries, ie, equivalent characteristic arc radius (R = 0.5, 1.0, and 1.5 mm) at four micro-separations (of 1.0, 1.5, 2.0, and 2.5 mm) simulating edge loading on the rim contact via the application of a constant vertical load of 3 kN. The efficacy of the spline is compared with that of circular arc and sharp corner (ie, no arc) geometries. Overall, the spline outperforms both sharp corner and circular arc in reducing contact pressure, stress, and strain. The benefit of the spline over the circular arc is quite promising at larger micro-separation but fairly marginal at smaller arc radius and micro-separation. The findings indicate that, as an alternative to the circular fillet, the spline can be considered a potential geometry to be incorporated at the rim corner of the cup.

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The effect of femoral head size on edge loading in metal‐on‐metal hip joint replacement under dynamic separation conditions

Lian

Li³

et al. 2019

J Biomed Mater Res

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Edge loading that occurs in hip joint replacements due to dynamic separation of the joint bearings has been shown to cause severe wear for meal-on-metal bearings. In the present study, the multibody dynamics model for metal-on-metal (MoM) hip joints with a medial-lateral translational mismatch in the centers of rotation of the cup and head has been developed to predict the dynamic separation and contact force of edge loading under gait loading conditions. The effects of larger head diameters (28-55 mm), in combination with the translational mismatch (0-4 mm) and varied cup inclination angles (45 -65 ), on edge loading of MoM bearings have been computationally investigated. For the given translational mismatch, increasing head diameters results in negligible effects on the dynamic separation, contact force and severity of edge loading. Increasing head size also leads to increased offset loading torque which has been found to reach at the level that may cause cup loosening under larger translational mismatch at 4 mm. The result highlights the importance of the cup inclination angle of 45 and a lower translational mismatch to avoid severe edge loading. K E Y W O R D Sedge loading, hip joint replacement, metal-on-metal, multibody dynamics, wear

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Edge‐loading severity as a function of cup lip radius in metal‐on‐metal total hips—A finite element analysis

Cited by 34 publications

References 36 publications

Effect of microseparation on contact mechanics in metal‐on‐metal hip replacements—A finite element analysis

Effect of microseparation on contact mechanics in metal‐on‐metal hip replacements—A finite element analysis

Reducing stress concentration on the cup rim of hip implants under edge loading

The effect of femoral head size on edge loading in metal‐on‐metal hip joint replacement under dynamic separation conditions

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