Untitled

Abstract

The addition of contrast media such as BaSO4 or ZrO2 to bone cement has adverse effects in joint replacements, including third body wear and particle-induced bone resorption. Ground PMMA containing particles of the non-ionic water-soluble iodine-based X-ray contrast media, iohexol (IHX) and iodixanol (IDX), has, in bone tissue culture, shown less bone resorption than commercial cements. These water-soluble non-ceramic contrast media may change the mechanical properties of acrylic bone cement. The static mechanical properties of bone cement containing either IHX or IDX have been investigated. There was no significant difference in ultimate stress between Palacos R (with 15.0 wt % of ZrO2) and plain cement with 8.0 wt % of IHX or IDX with mass median diameter (MMD) of 15.0 or 16.0 microm, while strain to failure was higher for the latter (p < 0.02). The larger particles (15.0 or 16.0 microm) gave significantly higher (p < 0.001) ultimate tensile strengths and strains to failure than smaller sizes (2.4 or 3.6 microm). Decreasing the amount of IHX from 10.0 wt % to 6.0 wt % gave a higher ultimate tensile strength (p < 0.001) and strain to failure (p < 0.02). Scanning electron microscopy (SEM) showed the smaller contrast media particles attached to the surface of the polymer beads, which may prevent areas of the acrylate bead surface from participating in the polymerization. In conclusion, the mechanical properties of bone cement were influenced by the size and amount of contrast medium particles. By choosing the appropriate amount and size of particles of water-soluble non-ionic contrast media the mechanical properties of the new radio-opaque bone cement can be optimized, thus reaching and surpassing given regulatory standards.

A Three-Parameter Weibull Distribution Method to Determine the Fracture Property of PMMA Bone Cement

“…The calculated average tensile strength f t of PMMA bone cement was 43.23MPa. It is located in the range of 33.0 MPa~51.4 MPa for tensile strength f t which has been reported in related literature [17][18][19][20][21]. The average value of fracture toughness K IC was 1.77 MPa • m 1/2 , which likewise falls within the range of 1.0 MPa • m 1/2 ~2.7 MPa • m 1/2 as reported by related literature [10][11][12][13][14][15][16][17].…”

“…Wedge-splitting specimens (WS) [11,13], three-point bending specimens [10], and chevron-notched short-rod specimens [14][15][16] are commonly used in laboratory testing to examine the fracture parameters of PMMA bone cement. The tensile strength of PMMA bone cement was obtained through four-point bending specimens [19] and dumb-bell specimens [18,21]. A large number of experiments are required to obtain the necessary parameters, which increases costs and the time required for the experiments.…”

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

“…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. During mixing, the particles could remain as a layer over the individual cement beads, rather than becoming thoroughly mixed with the monomer liquid and being fully incorporated during polymerisation [11]. Since the polymer beads are usually in the particle size ~150 µm and the contrast media particle size down to <1 µm, the surface of the individual polymer beads are covered by the small contrast media particles to such a high degree that they can interfere with the polymerisation process leading to shorter interconnecting polymer chains between the polymer beads, which would again decrease the mechanical properties of the bulk material [20].…”

“…The batches had Mass Median Diameters (MMDs) of 3, 5, 8, 15 and 20 µm. Also included are two batches from a previous study [11] where 8 wt% IDX was used in two particle sizes, 4 and 15 µm. The data from the 15 µm batch from the previous study has been combined with the 15 µm batch from this study.…”

“…The release of contrast media from bone cement has been investigated and the water uptake profile studied [10], limited opacifier release from the IDX cement was detected. The tensile properties of cement containing IDX have been previously reported [11] for a few particle sizes of contrast media, and it was hypothesized that the mechanical strength of cement with IDX varies depending on the particle size, and that the use of smaller contrast media particles reduces the tensile strength of the bone cement. It was argued that the smaller particles inhibit, to some extent, the polymerisation process, due to the large number of contrast media particles on each individual polymer bead; and that the tensile strength of the bone cement increased with particle size up to a threshold where the strength again goes down, due to stress concentrations.…”