Biocompatibility of surgical-grade dense polycrystalline alumina

This article reviews the knowledge about biocompatibility of alumina since its introduction as a material for use in joint replacements. Alumina is a hydrophilic material with high wettability allowing very low friction with negligible wear. Macrophages loaded with alumina particles show no morphologic alteration and do not lose their chemotactic ability. The host response has been studied for bulk and particulate alumina in soft tissues, as well as in human and animal bone under loaded and nonloaded conditions. The soft-tissue response to bulk alumina exhibits minimal fibrosis, and direct bone contact is achieved at compression-loaded interfaces. Examination of human biopsies from failed total hip prostheses reveals a foreign-body reaction containing predominantly macrophages loaded with alumina particles. No lymphocyte or plasma-cell infiltration is observed because of the absence of soluble component release. The amount of necrosis and fibrosis was lower than that associated with metal or polyethylene debris. In summary, alumina exhibits greater bioinertness than all other implant materials currently available for joint replacement.