Orthopedic applications of silicon nitride ceramics

Silicon nitride (Si3N4) is a ceramic material developed for industrial applications that demand high strength and fracture resistance under extreme operating conditions. Recently, Si3N4 has been used as an orthopedic biomaterial, to promote bone fusion in spinal surgery and to develop bearings that can improve the wear and longevity of prosthetic hip and knee joints. Si3N4 has been implanted in human patients for over 3 years now, and clinical trials with Si3N4 femoral heads in prosthetic hip replacement are contemplated. This review will provide background information and data relating to Si3N4 ceramics that will be of interest to engineering and medical professionals.