Fracture analysis of ceramic femoral head in hip arthroplasty based on microdamage monitoring using acoustic emission

Damage accumulation during compression testing of the alumina femoral head used in hip arthroplasty was monitored using an acoustic emission (AE) technique. Because a number of mechanical noises due to friction disturbed the AE measurement during the test using a conventional testing configuration standardized in ISO 7206, the testing apparatus was modified so that AE signals from microdamage were detected successfully. During the compression tests of femoral heads, a rapid increase in AE energy was observed before the final fracture. Dye penetration observations demonstrated that the rapid increase in AE energy correlated with the formation of maincrack which leads to the final fracture. The stress distribution in femoral heads was analyzed using finite element analysis (FEA). The critical stress for maincrack formation and the final fracture strength were determined. Finally, fundamental insights into the development of a technique for assessing the long-term reliability of ceramic femoral heads were obtained.