Influence of load type on flexural strength of a bone cement based on PMMA

The Weibull cumulative distribution function, which is commonly used in the characterisation of brittle materials, was used to describe the wide data scatter observed in the strength of a PMMA-based bone cement. A commercial additive-free bone cement was tested in flexure and the degree of fit of the flexural strength data with the Weibull distribution was assessed. The Weibull model gave a good representation of the results with regression coefficients of at least 0.98. Cements tested in three-point bending resulted in a higher flexural strength than cement tested in four-point bending. The ratio of mean strength measured in the different load arrangements, as well as the specimen size effect, were satisfactorily predicted by the Weibull model. The failure strengths of bone cements based on PMMA are governed by the severest flaw and may hence be treated by the Weibull statistics. (C) 2002 Elsevier Science Ltd. All rights reserved.