Strength of polymethylmethacrylate increased by vacuum mixing

Mixing does not improve mechanical properties of all bone cements

“…Manual mixing of polymethyl methacrylate (PMMA) bone cements has been miscredited, because voids and microporosities make the cement more susceptible to mechanical failure. Supplementary mixing methods, such as centrifuging (Burke et al 1984, Davies et al 1987a, 1989a, prechilling, and vacuum mixing (Lidgren et al 1984, Wixson et al 1987, or vacuum mixing and precompression after chilling of the cement compounds (Draenert 1986), have been advocated.…”

Interface gap after implantation of a cemented femoral stem in pigs

“…Vacuum mixing of bone cement has been shown to reduce porosity and increase the mechanical strength (Lidgren et al 1984, Wang et al 1993. How much porosity reduction, by centrifugation or vacuum mixing, will influence the shrinkage of bone cement has been debated for a long time (Rimnac et al 1986, Connelly et al 1987, Jay et al 1987, Hamilton et al 1988, Davies and Harris 1995.…”

The effect of mixing on gentamicin release from polymethylmethacrylate bone cements

“…The porosity can be increased, for instance, by inclusion of soluble dextran (Kuechle et al 1991) or of a second antibiotic (Penner et al 1996), but adverse effects on the mechanical properties of the cement limit the extent to which this can be done. In fact, to avoid the inclusion of air in bone cements, that may act as foci for initiation of a crack, polymer powder and monomer liquid are often mixed under lower than atmospheric pressure (Lidgren et al 1984, Wixson et al 1987, Bishop et al 1996, Fritsch 1996. Vacuum-mixing reduces the porosity of bone cement with a concurrent increase in mechanical properties, but it is not known to what extent this procedure affecs the release of antibiotics from the cement.…”