[In vitro studies on various PMMA bone cements: a first comparison of new materials for arthroplasty]

Two clinically established PMMA bone cements (Refobacin Palacos R and Palacos R + G) and two newer cements not yet in widespread clinical use (Refobacin Bone Cement R and SmartSet GHV) were tested in vitro for practically relevant differences.

The tests included chemical analyses, handling properties and testing according to the ISO standard for PMMA bone cements.

The results obtained indicate clearly that the copolymers used in Refobacin Bone Cement R and SmartSet GHV differ from those used in the Palacos cements. There were also significant differences in viscosity behaviour and waiting time (p < 0.01 for Palacos cements versus Refobacin Bone Cement R) as an expression of different handling properties. The hardening times under ISO 5833 conditions also differed significantly (p < 0.01 and p < 0.05 for Palacos cements compared with Refobacin Bone Cement R and p < 0.01 for Refobacin Bone Cement R compared with SmartSet GHV).

In view of these differences in material properties, the clinical data from long-term use of the bone cements Refobacin Palacos R and Palacos R + G cannot be extrapolated to the newly developed PMMA cements Refobacin Bone Cement R and Smart GHV. Before broad clinical use of these cements, prospective clinical studies using RSA or DEXA and, as a second step, statistically powerful prospective comparative studies should be performed. Until these data are available, patients in whom Refobacin Bone Cement R and SmartSet GHV are used should be informed that the material employed deviates from the standard procedures for cemented joint replacement in the Scandinavian arthroplasty registers and that the long-term consequences cannot, in the final instance, be foreseen. This is essential in order to avoid later malpractice claims on the grounds of inadequate information.