Some failure modes of four clinical bone cements

Abstract

The fracture or failure behaviours of four commercial acrylic-based bone cements have been examined in tensile, bending and compression modes, and their mechanical properties are reviewed. It was found that Palacos R-40 bone cement had high radiopaque agent concentration, with high surface hardness. It exhibited a much lower bending strength and bending modulus compared with the other three bone cements (CMW1, CMW2000 and Simplex P). The textures of tensile fracture surfaces produced were similar for the four bone cements studied. The fracture surface was fragmented by crevices, which developed through the matrix and around large undissolved polymethylmethacrylate (PMMA) beads. Three bands with different features existed on the bending fracture surfaces, with an abrupt transition between them. It appears that the agglomerates of zirconium dioxide particles are implicated in Palacos R-40 bone cement fracture surface. The examination of compressive failed specimens revealed that a 'yielded crack band' existed across the transverse section. Plastic deformation resulted in the PMMA beads being squashed in the longitudinal direction and dilated in the transverse direction.

Effect of iodixanol particle size on the mechanical properties of a PMMA based bone cement

“…The largest shift in UTS takes place between the 5 µm group and the 8 µm group, the change in either compressive strength or maximum flexural strength is more gradual and takes place at a larger particle size. The results from the flexural test and the tensile test indicate that the material undergoing tensile stress is more sensitive to the filler than a material undergoing compressive stress, in accordance with the results of [15] and [16]. Under tension the failure will occur at the filler-cement interface, whereas compressive failure will occur in the cement matrix, that is the composite matrix which is the same for all the materials tested.…”

“…The reason for the difference in mechanical strength between the cements that contain small particles and the cement that contain larger particles can possibly be explained by two processes; firstly, small particles tend to agglomerate, as was shown by Liu et al [16] who reported that BaSO 4 is prone to form agglomerates within the polymer matrix, thereby acting both as stress concentrators degrading the mechanical properties of the bone cement, and, by being agglomerates, they are themselves mechanically weak, thus intra agglomerate failure can occur. Secondly, the small size of the powders can result in them covering the individual polymer beads, and that there are a large number of these particles and thus they affect the polymerisation between the co-polymer and the monomer.…”

Chemical structure of methylmethacrylate-2-[2′,3′,5′-triiodobenzoyl]oxoethyl methacrylate copolymer, radio-opacity, in vitro and in vivo biocompatibility

“…One well-known solution, especially in the case of dental and bone cements, is the incorporation of inorganic additives, such as barium sulphate or zirconium dioxide particles. In the case of methacrylic bone cements, it has been reported that these particles diminish the mechanical properties (especially fatigue life) due to the creation of interfaces between the polymeric matrix and the inorganic radio-opacifying particles [1,[7][8][9][10][11][12]. In addition, the release of such particles has been found to be deleterious to bone since they activate bone resorption [13].…”

Evaluation of damage progression and mechanical behavior under compression of bone cements containing core–shell nanoparticles by using acoustic emission technique

“…Therefore, it is possible to postulate that the signals detected at this strain level, during the quasi-static compression test, occurred because some significant damage has initiated; this process is caused mainly for the presence of core-shell nanoparticles in the bone cement formulations as the reference bone cement did not emit AE signals of high amplitude and energy (seeFigure 5a). The absence of AE signals in the reference formulation (bone cement without core-shell nanoparticles)does not imply the inexistence of damage signs in the material Liu et al (2001). reported that the bone cements subjected to a compressive load undergo yield but they do not break or fracture; authors also observed "yield crack bands" crossing the transverse section of the yield specimens.The fact that the presence of particles induces some effect in cements when these are subjected to external forces is not unusual;Vila et al (1999) studied the influence of mixing the elastomeric acrylonitrile-butadiene-styrene (ABS) copolymer into a bone cement matrix on the mechanical properties and concluded that rubber particles have a double effect in the failure of cements.…”