FRACTURE CHARACTERISTICS OF ACRYLIC BONE CEMENTS .2. FATIGUE

Part I of this study identified the fracture toughness characteristics of two acrylic bone cements, while the present work has been concerned with determining the fatigue behavior by means of tests conducted in a rotating bending fatigue apparatus. Fatigue specimens were fabricated under conditions which approximated clinical procedures and then tested while immersed in bovine serum at 37 degree C in order to simulate in vivo conditions. Results of this phase of the study, when analyzed by a Student t-test at the 90% confidence level with four degrees of freedom, indicate that the fatigue life of specimens tested in bovine serum at 37 degree C is superior to that of specimens tested in air at ambient temperature. The addition of BaSO//4 to Simplex-P cement, while not significant at the 90% confidence level, was significant in increasing the fatigue life in air at the 80% confidence level; however, this effect was not noticeable when testing in bovine serum at 37 degree C. Examination of the fracture surfaces enabled calculations of the critical stress intensity factor which when compared with values from an earlier work showed good agreement.