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.

Transient and Residual Stresses and Displacements in Self-Curing Bone Cement—Part I: Characterization of Relevant Volumetric Behavior of Bone Cement

1982 ◽  
Vol 104 (1) ◽  
pp. 21-27 ◽  
Author(s):  
A. M. Ahmed ◽  
W. Pak ◽  
D. L. Burke ◽  
J. Miller
Keyword(s):  
Thermal Expansion ◽  
Residual Stresses ◽  
Bone Cement ◽  
Coefficient Of Thermal Expansion ◽  
Stress Generation ◽  
Curing Process ◽  
Cooling Phase ◽  
Volumetric Behavior ◽  
Fixation System

In this first part of a two-part report, some aspects of the volumetric behavior of bone cement during its curing process are examined as a prelude to an analysis for the transient and residual stresses and displacements in stem fixation systems. Experiments show that stress generation in the cement is associated with its temperature while curing and that during the cooling phase, the stresses are mainly due to thermal as opposed to bulk shrinkage. The appropriate coefficient of thermal expansion of bone cement has been evaluated from measurements in a simulated fixation system in conjunction with a thermoelastic analysis.

THE INFLUENCE OF TIBIAL PROSTHESIS DESIGN FEATURES ON STRESSES RELATED TO ASEPTIC LOOSENING AND STRESS SHIELDING

2011 ◽  
Vol 11 (01) ◽  
pp. 55-72 ◽  
Author(s):  
DESMOND Y. R. CHONG ◽  
ULRICH N. HANSEN ◽  
ANDREW A. AMIS
Keyword(s):  
Bone Resorption ◽  
Bone Cement ◽  
Aseptic Loosening ◽  
Cancellous Bone ◽  
Stress Shielding ◽  
Cement Mantle ◽  
Shear Stresses ◽  
Knee Prostheses ◽  
Design Features ◽  
Cement Interface

Aseptic loosening caused by mechanical factors is a recognized failure mode for tibial components of knee prostheses. This parametric study investigated the effects of prosthesis fixation design changes, which included the presence, length and diameter of a central stem, the use of fixation pegs beneath the tray, all-polyethylene versus metal-backed tray, prosthesis material stiffness, and cement mantle thickness. The cancellous bone compressive stresses and bone–cement interfacial shear stresses, plus the reduction of strain energy density in the epiphyseal cancellous bone, an indication of the likelihood of component loosening, and bone resorption secondary to stress shielding, were examined. Design features such as longer stems reduced bone and bone–cement interfacial stresses thus the risk of loosening is potentially minimized, but at the expense of an increased tendency for bone resorption. The conflicting trend suggested that bone quality and fixation stability have to be considered mutually for the optimization of prosthesis designs. By comparing the bone stresses and bone–cement shear stresses to reported fatigue strength, it was noted that fatigue of both the cancellous bone and bone–cement interface could be the driving factor for long-term aseptic loosening for metal-backed tibial trays.

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].

Reduced Modulus Acrylic Bone Cement

1985 ◽  
Vol 55 ◽  
Author(s):  
Alan S. Litsky ◽  
Robert M. Rose ◽  
Clinton T. Rubin
Keyword(s):  
Bone Cement ◽  
Cancellous Bone ◽  
Property Testing ◽  
Acrylic Bone Cement ◽  
Material Interfaces ◽  
Cement Interface ◽  
Reduced Modulus ◽  
Endoprosthesis Loosening

ABSTRACTLoosening is the dominant long-term problem facing joint replacement surgeons and patients. A probable cause of endoprosthesis loosening is the strain singularity at the material interfaces. The concentration of shear at the bone-cement interface leads to micromotion which precipitates a soft-tissue membrane and resorption of the cancellous bone.A more compliant cement would substantially reduce the interfacial stresses and serve as a “pillow” between the prosthetic stem and the cancellous bone. We have developed a surgically-workable formulation of a reduced modulus acrylic bone cement — polybutylmethylmethacrylate (PBMMA) — to test this hypothesis. Materials property testing and in vivo implantation are discussed.

Measurement of Shrinkage Stresses in PMMA Bone Cement

2004 ◽  
Vol 1-2 ◽  
pp. 127-132 ◽  
Author(s):  
J.F. Orr ◽  
N.J. Dunne
Keyword(s):  
Bone Cement ◽  
Thermal Stresses ◽  
Hole Drilling ◽  
Full Field ◽  
Thermally Induced ◽  
Closed Form Solutions ◽  
Cement Interface ◽  
Pmma Bone Cement ◽  
Hip Replacements ◽  
Methacrylate Monomer

Polymethyl methacrylate (PMMA) bone cement comprises liquid methyl methacrylate monomer and PMMA beads, the former encapsulating the beads and polymerising within 10 minutes of mixing. Up to 7% volumetric shrinkage accompanies the exothermic polymerisation reaction and subsequent cooling induces residual thermal stresses when the cement is restrained around implant components. The authors have measured shrinkages, calculated residual stresses by closed form solutions and measured stresses by a range of methods. Full field optical displacement measurement has been used to derive strains and stresses in rings of cement cooling by 50oC under representative restraints and the hole drilling technique has been applied to cured PMMA cement. A strain gauged transducer developed to measure shrinkage forces in cement rings for derivation of contact stresses. The theoretical results predict stresses in the range 10-25MPa for a range of curing temperatures. These results are supported by the experimental methods and also by subsequent finite element models. The acquisition of these results required experimental characterisation of proprietary PMMA cements, particularly in terms of elastic modulus (up to 2.65GPa) and Poisson’s Ratio (0.455). It is concluded that the thermally induced stresses are sufficient to cause cracking around hip replacement femoral stems at the stem/cement interface, in the immediate post-curing phase and prior to functional loading of the implant. Cracks of this type have been reported from clinical studies and the authors have reproduced such cracks in laboratory models of hip replacements. It is proposed that the cracks are likely to propagate by the mechanism of fatigue under cyclic loading. It is concluded that thermal stresses are important in failure of hip replacements by aseptic loosening, the most common reported indicator for implant revision. There are few references in literature that address this issue directly, however the results of this work are supportive of the measurements and observations reported and provide an explanation and understanding of the initiation of failures.

Flow characteristics of curing polymethyl methacrylate bone cement

1998 ◽  
Vol 212 (3) ◽  
pp. 199-207 ◽  
Author(s):  
N J Dunne ◽  
J F Orr
Keyword(s):  
Shear Rate ◽  
Bone Cement ◽  
Polymethyl Methacrylate ◽  
Cancellous Bone ◽  
Power Index ◽  
Flow Characteristics ◽  
Flow Index ◽  
Shear Stresses ◽  
Bone Cements ◽  
Cement Interface

During polymerization, polymethyl methacrylate bone cements have complex viscoelastic characteristics. Within a short working time they transform from dough-like consistencies to solid cements. Therefore, the time at which a cement is introduced to cancellous bone surfaces and subjected to pressure is important, to achieve optimum flow and mechanical interdigitation. Achieving adequate mechanical interlock increases the area for load transfer and reduces localized bone-cement interface stresses. The aim of this study was to measure the flow characteristics for commercial bone cements as a function of time and calculate the apparent viscosities for the curing bone cements The capillary extrusion method was used to measure the rate of flow of the curing cement, by means of a melt flow index apparatus, which was manufactured in-house. The tests were conducted using nozzles of different lengths and under two loads. This enabled the power index value, n, and the pressure at the die entry, Po, to be calculated for each material with respect to time. Once the flow characteristics were determined, a series of formulae were used to calculate the shear rates, y, the shear stresses, r, and the apparent viscosities, na, of the curing bone cements. The results indicated that acrylic bone cements are non-Newtonian, pseudoplastic materials, since the power index values are less than 1.0 during the curing stage. The consistency indices, K, were calculated from the shear stress versus shear rate data. The apparent viscosities of the cements were found to increase with respect to increases in time. Clinically, it was considered desirable to inject and pressurize the cement into the medullary canal while its viscosity is relatively low in order to obtain maximum interdigitation into cancellous bone, provided adequate containment and a means of pressurization can be achieved. The pseudoplastic character of bone cements is responsible for their reduction in viscosity with increased shear rate, a property that may be exploited to enhance penetration with appropriate delivery.

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].

A Model of Tension and Compression Cracks With Cohesive Zone at a Bone-Cement Interface

1985 ◽  
Vol 107 (2) ◽  
pp. 175-182 ◽  
Author(s):  
J. P. Clech ◽  
L. M. Keer ◽  
J. L. Lewis
Keyword(s):  
Bone Cement ◽  
Uniaxial Tension ◽  
Cancellous Bone ◽  
Cohesive Zone ◽  
Stress Singularity ◽  
Continuum Theory ◽  
Strengthening Mechanism ◽  
Bimaterial Interface ◽  
Cement Interface ◽  
Crack Faces

This paper gives an insight about compression and tension cracks as encountered at a bone-cement interface. Within the context of continuum theory of fracture, an analytical solution is presented for the problem of a bimaterial interface edge crack under uniaxial tension or compression, assuming no tangential slip along the crack faces since cement pedicles penetrate into the cancellous bone several millimeters. Also essential to the solution are cohesive zone effects that account for a strengthening mechanism over the crack faces. The solution provides a methodological framework for quantifying the influence of the cohesive zone on the magnitude of the stress singularity. Mode I crack tip stress intensity factors are calculated at different stages of the loading and unloading phases under uniaxial tension or compression. Finally, an inelastic mechanism is presented that gives theoretical support to explain the formation of interfacial compression cracks, a phenomenon that was not previously appreciated and that arises from the rigid cement being forced into the more compliant cancellous bone.

scholarly journals Does Additive Pressurized Carbon Dioxide Lavage Improve Cement Penetration and Bond Strength in Cemented Arthroplasty?

2021 ◽  
Vol 10 (22) ◽  
pp. 5361
Author(s):  
Kevin Knappe ◽  
Christian Stadler ◽  
Moritz M. Innmann ◽  
Mareike Schonhoff ◽  
Tobias Gotterbarm ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Bone Cement ◽  
Cancellous Bone ◽  
Failure Load ◽  
Testing Machine ◽  
Safe Procedure ◽  
Cement Interface ◽  
Cement Penetration ◽  
Cemented Arthroplasty

The modern cementing technique in cemented arthroplasty is a highly standardized and, therefore, safe procedure. Nevertheless, aseptic loosening is still the main reason for revision after cemented total knee or cemented total hip arthroplasty. To investigate whether an additional carbon dioxide lavage after a high-pressure pulsatile saline lavage has a positive effect on the bone–cement interface or cement penetration, we set up a standardized laboratory experiment with 28 human femoral heads. After a standardized cleaning procedure, the test implants were cemented onto the cancellous bone. Subsequently, the maximum failure load of the bone–cement interface was determined using a material testing machine to pull off the implant, and the cement penetration was determined using computed tomography. Neither the maximum failure load nor cement penetration into the cancellous bone revealed significant differences between the groups. In conclusion, according to our experiments, the additive use of the carbon dioxide lavage after the high-pressure pulsatile lavage has no additional benefit for the cleaning of the cancellous bone and, therefore, cannot be recommended without restrictions.

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