Fracture characteristics of acrylic bone cements. I. Fracture toughness

Abstract

The vital first phase of the overall materials study to protract the life of the total joint replacements is the identification of the fracture toughness and fatigue properties of bone cements. Information gained from fatigue testing, performed in a manner which simmulates in vivo conditions, and fracture toughness, which is a measure of the propensity of a crack to propagate, is the first step towards the prediction of the life of the total joint replacement. This study is concerned with the fracture toughness of Zimmer and Simplex-P cold-curing bone cements. Following cement fabrication conditions which closely approximate clinical procedures, fracture toughness testing was conducted on cement specimens which were immersed in bovine serum at 37 degrees C in order to simulate in vivo conditions. In addition, a similar study was completed on specimens, tested in air at ambient temperature for purposes of comparison. Results of this procedure, when analyzed by a Student's t-test at the 95% confidence level with eight degrees of freedom, indicate that both Zimmer and Simplex-P exhibit a higher fracture toughness in the simulated physiological environment. In order to determine whether the addition of barium sulfate to these cements compromises the fracture toughness, the above described testing rationale was repeated, indicating the existence of a complicated relationship between the different testing environments and barium sulfate. The importance of these results lies in the fact that an increased fracture toughness indicates that a cement will inherently exhibit a greater degree of resistance to the propagation of cracks, which could contribute to the ultimate failure of the total joint replacement.

The effect of adding 10% of barium sulphate radiopacifier on the mechanical behaviour of acrylic bone cement

“…In that study 22 no significant differences were found between K IC of cement with and without BaSO 4 . Conversely, the above described negative effect has also been reported previously 19 . This indicates that, although the presence of BaSO 4 may slow down the stable crack propagation, a critical stress value is reached faster in this material because of the weakened matrix.…”

“…All specimens were stored in water at 37 °C for at least 14 d to assure a complete polymerization of the material before testing. The test environment was air at 23 ± 1 °C, representing an environmentally more critical condition than simulated physiological conditions (37 °C temperature in saline solution), for cement fatigue and fracture testing 16,19,23 …”

The effect of post-curing chemical changes on the mechanical properties of acrylic bone cement

“…There is also considerable literature on the fracture properties of acrylic bone cement [9][10][11][12][13][14][15][16]. Yet it is obvious when reviewing this literature that there had been no standardization of the fracture test procedures.…”

Characterization of self‐curing acrylic bone cements

“…Fracture energies, measured on bone cements by Freitag and Cannon,57 are in good agreement with the range of 1.1-4.9 X lo5 erg/cm2 reported by all test methods for pure molding grade acrylic.27,28,32,37,62-66 Although y should be independent of test method at about 1.1-1.5…”