MIXING DOES NOT IMPROVE MECHANICAL-PROPERTIES OF ALL BONE CEMENTS - MANUAL AND CENTRIFUGATION-VACUUM MIXING COMPARED FOR 10 CEMENT BRANDS

Contemporary mixing methods-centrifugation, vacuum mixing with or without precompression-were compared with manual mixing by testing strength characteristics in accordance with a proposed revision of the international standard for bone cements as applied to 10 cement brands. Simplex(R) brands and low-viscosity cements were the strongest, and were not improved by any of the vacuum-mixing procedures. Centrifuging was found unsuitable for low-viscosity cements. Without attaining the strength of the former, the cements best suited for auxiliary mixing methods were CMW-1(R) and Palacos(R) brands, which improved 6-11 percent by either of the methods. The Sterivac(R) system was generally found unacceptable, because about 20 percent of a cement package was retained in the mixing gear, and the application of precompression had no additional effect on compressive and bending strengths.