Clinical influences on bone cement monomer release.

Monomer losses for two self-curing acrylic cements were similar via laboratory serial weighing experiments. Both the P/L ratio and mixing duration substantially influenced subsequent monomer losses, but ambient temperature variation during mixing had little effect. Greater losses were encountered during the mixing and setting intervals than during the molding interval. Patient potential exposure to monomer occurs during the molding and setting intervals; therefore, handling procedures reducing losses in these intervals are important to the surgeon. The least monomer loss during both molding and setting occurred at the manufacturers' recommended P/L ratio, which strongly indicated the need to mix all contents supplied. Mixing loss increased with amount of spatulation. However, once the mass was well mixed (about 300 steady spatulations), no further decreases in the molding and setting interval losses were promoted by overmixing. Because of the lower monomer loss rate during the molding interval, postponed cement insertion may not be warranted in light of losing mechanical locking efficiency. The actual ramifications of a threefold reduction in potential patient exposure (3.5 down to 1.2 wt% of total monomer) via modified handling techniques have not yet been clinically evaluated.