INVESTIGATION OF FRACTURE IN AN INTERFACE CRACK BETWEEN BONE CEMENT AND STAINLESS STEEL

Abstract

INTERFACE STRENGTH IS CONSIDERED AS ONE OF THE MOST INFLUENTIAL FACTORS IN THE LONG-TERM DURABILITY OF THE REPLACED JOINT IN CEMENTED TOTAL HIP REPLACEMENT. SEVERAL RESEARCHERS HAVE SUGGESTED THAT THE DAMAGE INITIATION IN A REPLACED JOINT IS A MECHANICAL PHENOMENON PRIMARILY TAKING PLACE IN THE VICINITY OF CEMENT-PROSTHESIS INTERFACE. IN THIS STUDY, THE FRACTURE BEHAVIOR OF A CRACK AT THE INTERFACE OF CEMENT-PROSTHESIS WAS INVESTIGATED BOTH EXPERIMENTALLY AND THEORETICALLY UNDER STATIC LOADING CONDITIONS. THE FINITE ELEMENT METHOD, AND THEN THE MAXIMUM TANGENTIAL STRESS (MTS) AND THE GENERALIZED MTS (GMTS) CRITERIA WERE USED FOR THEORETICAL STUDY OF INTERFACE FRACTURE. SOME EXPERIMENTS WERE ALSO CARRIED OUT TO INVESTIGATE THE EFFECT OF CEMENT MIXING METHODS (HAND MIXING AND VACUUM MIXING) ON CRACK GROWTH PATTERN. THE RESULTS SHOWED THAT THE VACUUM-MIXED CEMENT LED TO SELF-SIMILAR CRACK GROWTH ALONG THE CEMENT-PROSTHESIS INTERFACE, WHILE THE CRACK KINKED INTO THE CEMENT IN THE SAMPLES PREPARED BY HAND-MIXED CEMENT. THEN SOME EXPERIMENTS WERE PERFORMED TO VERIFY THE THEORETICAL RESULTS OBTAINED FOR MIXED MODE FRACTURE ANGLES IN THE SAMPLES PREPARED BY HAND-MIXED CEMENT. THE SANDWICH BRAZILIAN DISK MODEL WAS USED IN BOTH FINITE ELEMENT AND EXPERIMENTAL APPROACHES TO SIMULATE THE CEMENT-PROSTHESIS INTERFACE. THE EXPERIMENTAL RESULTS WERE FOUND TO BE IN GOOD AGREEMENT WITH THOSE PREDICTED BY THE GMTS CRITERION.