Long‐term compressive creep deformation and damage in acrylic bone cements

Chwirut, Daniel J.

doi:10.1002/jbm.820180105

Cited by 53 publications

(29 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A more probable explanation for this phenomenon is the occurrence of creep of the acrylic cement. Earlier studies have indicated that cement creeps [12][13]. Creep of the cement mantle, which is a timedependent phenomenon, would facilitate the subsidence of the taper with time without generating cement fractures.…”

Section: Discussionmentioning

confidence: 99%

Surface roughness of debonded straight-tapered stems in cemented THA reduces subsidence but not cement damage

Verdonschot

Huiskes

1998

Biomaterials

View full text Add to dashboard Cite

Although stress analyses have shown that the mechanical endurance of cemented femoral THA reconstructions is served by stems that firmly bond to their cement mantles, retrieval studies suggest that this may be difficult to achieve. Clinical studies with roentgen stereophotogrammetric analyses have shown that stems may gradually debond from their cement mantle. Accepting the fact that stem debonding is unavoidable, stem subsidence and cement stresses can be reduced by increasing stem-cement friction, as indicated by finite element stress analyses. Hence, it can be hypothesized that debonded stems with high surface roughness values would damage the cement mantle to a lesser extent as compared to polished ones. To confirm this hypothesis, tapered stems with polished and rough surface finishes were implanted in cement mantles and cyclically loaded for 1.7 million times. It was investigated how surface roughness affected the damage in the cement mantle, and how it was related to prosthetic subsidence.The polished taper subsided considerably more than the rough one (630 vs. 270 m at the end of the experiments). In addition, it was found that the polished taper displayed step-wise subsidence, which is probably due to the interaction of stick-slip processes at the interface, associated with creep of the acrylic cement. The rough taper subsided monotonously. Scanning Electron Microscopic (SEM) analysis of the taper-cement structures showed that the rough taper was completely debonded from the cement mantle, creating a gap at the interface, and that many large cement cracks and particles were created. Around the polished taper, only a few cracks were found and the taper-cement interface seemed undamaged.It was concluded that an increased surface roughness does not necessarily lead to a reduction in cement damage. On the contrary, compared to polished ones, debonded rough stems may produce more cement cracks and acrylic cement debris, and provide routes to transport these wear products. Hence, after failure of the stem-cement interface, straight-tapered stems with an increased surface roughness accelerate the failure process due to inferior fail-safe features. Consequently, in vivo subsidence patterns at the stem-cement interface should be considered in combination with the surface finish of the implant. An amount of post-operative subsidence of a rough stem may be much more damaging for the reconstruction than the same amount for a polished stem.

show abstract

Section: Discussionmentioning

confidence: 99%

Surface roughness of debonded straight-tapered stems in cemented THA reduces subsidence but not cement damage

Verdonschot

Huiskes

1998

Biomaterials

View full text Add to dashboard Cite

show abstract

“…Experimental creep data were based on uniaxial tests, which considered the presence of only one stress component (Chwirut, 1984;Huiskes, 1994, 1995a). For this reason, the uniaxial creep laws could not be applied directly to structures with threedimensional stress states.…”

Section: The Finite Element Simulationsmentioning

confidence: 99%

“…Another problem which obstructed the direct use of the creep laws was the fact that they were determined assuming stress conditions which were either purely static (Chwirut, 1984), or cyclic dynamic Huiskes, 1994,1995a). However, assuming friction at the taper-cement interface, the stress state was neither purely static, nor cyclic dynamic (Fig, 3).…”

Section: The Finite Element Simulationsmentioning

confidence: 99%

“…To determine the creep strain due to the residual stress component, the creep law determined by Chwirut (1984) was used; Sstat = 1.798 X 1 0 '6íO,283(7r Ief 58) (5) the where t is the loading time in seconds, and ffres residual stress level in MPa. The structure was dynam ically loaded, which makes it convenient to rewrite equa tion (5) in terms of the number of loading cycles, instead of loading time.…”

Section: The Finite Element Simulationsmentioning

confidence: 99%

“…It is also unclear to what extent cement creeps when exposed to the stress levels that typically occur in a cement mantle, and what the effects on load transfer and the endurance of the reconstruction would be. Several investigators have measured the creep properties of bone cement under static loading condi tions (Chwirut, 1984 to establish the relationships among creep strain, load level, and the number of loading cycles Huiskes, 1994,1995a). As a result of these investiga tions, the creep behavior of acrylic cement under un idirectional static and dynamic loading conditions is now well established.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Subsidence of tha stems due to acrylic cement creep is extremely sensitive to interface friction

Verdonschot

1996

Journal of Biomechanics

View full text Add to dashboard Cite

Abstract-Acrylic cement, used to fixate total hip arthroplasty (THA), creeps under dynamic and static loading conditions. As a result, THA stems which are debonded from the cement, may gradually subside, depending on their shape and surface roughness. The purpose of this study was to evaluate the relationship among dynamic load, creep characteristics, interface friction, and subsidence patterns.A laboratory model consisting of a metal tapered cone, surrounded by a cement mantle, was developed. The cone was gradually compressed in the cement by a dynamic, sinusoidal axial force, cycling between 0 and 7 kN for 1.7 million cycles at a frequency of 1 Hz. Subsidence and cement strain were monitored. Two tapers were tested in this way. The relationships among subsidence, creep properties and interface friction were evaluated from a finite element (FE) model, used to simulate the experiments. In this model, the creep properties obtained in dynamic and static, tension and compression experiments measured earlier, were used.The subsidence patterns of both tapers were similar, but one subsided more than the other (380 vs 630 /an). Both subsided stepwise instead of continuous, with a frequency much smaller than that of the applied load. The characteristics of the subsidence and cement-strain patterns could be reproduced by the FE model, but not with great numerical precision. The stepwise subsidence could be explained by slip-stick mechanisms at the interface starting distally and gradually working towards proximal, Variations in friction from 0.25 to 0,50 reduced the total subsidence and the step frequency by about 50%.It was concluded that FE-models used to simulate the mechanical endurance characteristics of THA reconstruc tions, extended to incorporate cement creep, produce realistic results. These results showed that prosthetic subsidence under dynamic loads occurs due to cement creep. The extent of the subsidence is extremely sensitive to interface friction, hence to small variations in surface roughness and cement constitution, This may explain the relatively large variation of in vivo prosthetic subsidence rates reported in the literature.

show abstract

Effects of cement creep on stem subsidence and stresses in the cement mantle of a total hip replacement

McKellop

1997

J. Biomed. Mater. Res.

View full text Add to dashboard Cite

In cemented total hip prostheses, the role of creep of the acrylic cement (polymethyl methacrylate, [PMMA]) in increasing or decreasing the chance of failure of the cement mantle is a subject of ongoing controversy. In the present study we used a three-dimensional finite-element model of a cemented stem to assess the influence of cement creep on subsidence of the stem, and on the stress and strain in the cement under cyclic load, both in the short and long term. The cement layer was assigned the shear and bulk creep moduli of Zimmer regular PMMA cement, which were obtained experimentally. The stem-cement interface was modeled either as (1) completely bonded, (2) completely debonded with friction, or (3) completely debonded and frictionless. Under the cyclic load some cement creep occurred with all three bonding conditions, allowing additional subsidence of the stem and a decrease in the stress components within the cement. During the unloaded period the full recovery of the preload conditions could be reached with the completely bonded and with the frictionless interfaces. With the frictional interface there was residual cement creep, residual stresses within the cement, and residual subsidence of the stem during the unloaded period; however, the reduction of the stress was at most 13% and the subsidence was about 0.46 mm. The much larger subsidence of debonded stems that is often observed clinically might be attributed to the factors which were not included in the present model, such as circumferential bone remodeling.

show abstract

Long‐term compressive creep deformation and damage in acrylic bone cements

Cited by 53 publications

References 10 publications

Surface roughness of debonded straight-tapered stems in cemented THA reduces subsidence but not cement damage

Surface roughness of debonded straight-tapered stems in cemented THA reduces subsidence but not cement damage

Subsidence of tha stems due to acrylic cement creep is extremely sensitive to interface friction

Effects of cement creep on stem subsidence and stresses in the cement mantle of a total hip replacement

Contact Info

Product

Resources

About