An evaluation of inert and resorbale ceramics for future clinical orthopedic applications

Abstract

Abstract The compatibility of implanted ceramic materials with autogenous bone, and the subsequently noted influence of the ceramic on the rate of new bone formation, were investigated to evaluate such materials for use in orthopedic implants. Three ceramic materials, aluminium oxide (Al 2 O 3 ), zirconium oxide (ZrO 2 ), and calcium aluminate (yCaO · xAl 2 O 3 ) were tested. These were placed in the femurs of rhesus monkeys for periods of 50, 100, and 350 days. Definite compatability between the autogenous bone and the materials was exhibited for the implant time periods evaluated. No toxicogenic activity was noted in any of the biochemical, biomedical, and ceramographic evolutions. An added benefit resulted from the calcium aluminate composition, which was fabricated as a two‐phase oxide material to make it slightly soluble in the body fluids. In the 50‐ and 100‐ day implants, the bone penetrated the ceramic for distances up to 100 μ while the ceramic dissolved and the pores enlarged. In addition, the mineralization in the area of the calcium aluminate was greater than that found around the other ceramics. Radiographs over the entire 350‐day implant period confirmed the increased callus formation around all of the materials with no signs of rejection evident in the surrounding osseous or soft tissues. After 350 days the entire pore area of the calcium aluminate ceramic was infiltrated with a columnar substance which on the basis of scanning electron microscope procedures was considered to be mineralized osteoid.