Effect of Tapered Geometry on the Load Transfer of an Idealized Cemented Hip Implant

2002 ◽  
Author(s):  
N. Nun˜o
Keyword(s):  
Residual Stresses ◽  
Bone Cement ◽  
Chemical Bond ◽  
Load Transfer ◽  
Hip Implants ◽  
Implant Loosening ◽  
Cement Interface ◽  
Grouting Material ◽  
Surrounding Bone ◽  
Causes Of Failure

Implant loosening of cemented hip implants is one of the major causes of failure of the arthroplasty. In cemented hip implants, the polymethyl methacrylate (PMMA), also called bone cement, is used as grouting material between the stem and the surrounding bone. During polymerisation of the cement, residual stresses are generated in the bulk cement. The bone cement does not have a chemical bond with the stem nor the bone; however, it fills completely the space between the two and serves to distribute the load being transferred from the stem to the bone. Numerical analyses on the load transfer of cemented hip implants usually do not include the residual stresses due to cement curing at the stem-cement interface [1–2].

Effect of Tapered Geometry on the Load Transfer of an Idealized Cemented Hip Implant

2002 ◽  
Author(s):  
N. Nun˜o
Keyword(s):  
Residual Stresses ◽  
Bone Cement ◽  
Chemical Bond ◽  
Polymethyl Methacrylate ◽  
Load Transfer ◽  
Hip Implants ◽  
Cement Interface ◽  
Grouting Material ◽  
Surrounding Bone ◽  
Causes Of Failure

Implant looseining of cemented hip implants is one of the major causes of failure of the arthroplasty. In cemented hip implants, the polymethyl methacrylate (PMMA), also called bone cement, is used as grouting material between the stem and the surrounding bone. During polymerisation of the cement, residual stresses are generated in the bulk cement. The bone cement does not have a chemical bond with the stem nor the bone; however, it fills completely the space between the two and serves to distribute the load being transferred from the stem to the bone. Numerical analyses on the load transfer of cemented hip implants usually do not include the residual stresses due to cement curing at the stem-cement interface [1–2].

Bone-Cement Interface Micromechanical Model under Cyclic Loading

2011 ◽  
Vol 488-489 ◽  
pp. 391-394
Author(s):  
J.A. Sanz-Herrera ◽  
H. Esteban ◽  
M.P. Ariza
Keyword(s):  
Bone Cement ◽  
Hip Replacement ◽  
Mechanical Characterization ◽  
Micromechanical Model ◽  
Volume Element ◽  
Implant Loosening ◽  
Cement Interface ◽  
Causes Of Failure ◽  
Interface Geometry

Total hip replacement is one of the most common techniques in orthopaedic surgery, and one of the most important surgical advances of the last XX century. Normally, implant is fixed to bone by means of a polymer material known as bone cement, building an interface between implant and bone regions. Microscopically, two interfaces can be distinguished, namely, bone-cement and implant-cement interfaces. One of the main causes of failure is implant loosening due to fatigue of one of the two microscopic interfaces. In this work, a micromechanical analysis of bone-cement interface under cyclic forces is introduced. Both bone and cement are considered using different models based on fatigue damage over a statistically representative volume element (RVE) of the microstructure. This technique allows to homogenize mechanical stresses of the RVE yielding the effective macroscopic behavior of the bone-cement interface, avoiding experimental fitting case to case, once the interface geometry and mechanical characterization of the involved phases are known.

Transient and Residual Stresses and Displacements in Self-Curing Bone Cement—Part II: Thermoelastic Analysis of the Stem Fixation System

1982 ◽  
Vol 104 (1) ◽  
pp. 28-37 ◽  
Author(s):  
A. M. Ahmed ◽  
R. Nair ◽  
D. L. Burke ◽  
J. Miller
Keyword(s):  
Adverse Effects ◽  
Residual Stresses ◽  
Bone Cement ◽  
Cancellous Bone ◽  
Thermal Stresses ◽  
Curing Process ◽  
Hardening Material ◽  
Cement Interface ◽  
Fixation System ◽  
Curing Cement

In this second part of a two-part report, an idealized model of the stem fixation system is analyzed to determine the adverse effects of the thermal stresses and displacements of bone cement during its curing process. The Shaffer-Levitsky stress-rate strain-rate law for chemically hardening material has been used. The results show that if the cement is surrounded by cancellous bone, as opposed to cortical bone, then transient tensile circumferential stresses in the cement and similar radial stresses at the stem/cement interface are generated. The former may cause flaws and voids within the still curing cement, while the latter may cause gaps at the interface.

MODELLING THE BONE-CEMENT INTERFACE IN CEMENTED HIP IMPLANTS

2008 ◽  
Vol 41 ◽  
pp. S68
Author(s):  
M.A. Pérez ◽  
J.M. García-Aznar ◽  
M. Doblaré
Keyword(s):  
Bone Cement ◽  
Hip Implants ◽  
Cement Interface

scholarly journals Damage of the Bone-Cement Interface in Finite Element Analyses of Cemented Orthopaedic Implants

2018 ◽  
Author(s):  
Toufik Bousnane ◽  
Smail Benbarek ◽  
Abderahmen Sahli ◽  
Boualem Serier ◽  
Bel Abbes Bachir Bouiadjra
Keyword(s):  
Bone Cement ◽  
Load Transfer ◽  
Cement Mantle ◽  
Damage Scenario ◽  
Cement Interface ◽  
Total Hip ◽  
Long Term Stability ◽  
Prosthetic Implants ◽  
Cement Penetration

In orthopedic surgery and particularly in total hip arthroplasty, fixation of femoral implant is generally made by the surgical cement. Bone–cement interface has long been implicated in failure of cemented total hip replacement (THA), it is actually a critical site that affect the long-term stability and survival of prosthetic implants after implantation. The main purpose of this study is to investigate the effect of cement penetration into the bone on damage scenario at the interface. Previously most researchers have been performed to study damage accumulation in the cement mantle for different amount of cement penetration. In this work, bone–cement interface integrity has been studied for different mechanical properties. Cohesive traction separation law is used to detect contact damage between cement and bone. Results showed that a larger debonded area was predicted proximally and distally. Adhesion between bone and cement is affected mainly by cement penetration into the bone. Higher cement penetration into the bone leads to a good load transfer. A lower strength of the bone–cement interface due to a lower mechanical property results in faster interface damage. So we advise surgeons to well perpetrate the bone for long-term durability of cemented THA.

Measurements of the Residual Stresses Due to Cement Polymerization for Cemented Hip Implants

2003 ◽  
Author(s):  
Natalia Nun˜o ◽  
Dominic Plamondon
Keyword(s):  
Residual Stresses ◽  
Bone Cement ◽  
Normal Stresses ◽  
Liquid Form ◽  
Synthetic Bone ◽  
Press Fit ◽  
Grouting Material ◽  
Solidification Phenomenon ◽  
Outside Diameter

In cemented hip implant, the polymethyl methacrylate (PMMA) also called bone cement is used as grouting material between the implant and the bone. During the operation, the bone cement still in a liquid form is inserted between the femoral component and the bone. During polymerisation of the cement, residual stresses are generated in the bulk cement. The process of cement curing is a complex solidification phenomenon where transient stresses are generated and the residual stresses vary with different boundary conditions during curing (Ahmed et al., 1982). In particular, normal stresses are generated at the implant-PMMA interface resulting in a press-fit problem. The cement does not have a chemical bond with the stem nor the bone, however it fills completely the space between the two and serves to distribute the load being transferred from the stem to the bone. An experiment has been devised to measure directly the residual stresses of the bone cement to reproduce the in-vivo behaviour of the prosthesis. An idealized prosthesis (19-mm diameter) is used. A subminiature load cell (9.5-mm diameter) is inserted inside the stem to measure directly the radial residual stresses of the PMMA on the stem. Bone cement polymerizes between the stem and the synthetic bone (40-mm outside diameter). The tests are conducted at body temperature of 37°C.

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