Poly(methylmethacrylate) is used as a grouting agent in total joint arthroplasty. Fracture toughness of the relatively brittle bone cement is an important property determining the reliability and defect tolerance capability of the material. In the present study, fracture toughness of bone cement and commercial PMMA has been determined using a short bar chevron-notch test method. Chevron-notched short bar specimens were prepared with a notch molded-in during the polymerization process or by machining techniques. Specimen size and other test parameters were varied to determine variability of the results. In addition, parameters were also varied to simulate clinical practices.
A peak load test method following ASTM E 1304-89 was used to estimate fracture toughness. The load-displacement curves obtained were independent of the displacement rates within the recommended peak load time range. Wide variation of displacement rates had no effect on the fracture toughness values. No plasticity-induced effects on fracture toughness were evident in the slow rate regime up to a peak load time of 300 s for 12.7-mm-thick short bar specimens. The results of this study indicate that the ASTM Test Method E 1304-89 can be successfully used in determining fracture toughness of bone cements.