PREPARATION, CHARACTERIZATION, AND USE OF REPLAMINEFORM CERAMICS AND A METAL AS BIOMATERIALS (ALUMINA, SEM, TITANIA, IMAGE ANALYSIS)

A significant need has been identified in the biomaterials field for porous orthopaedic implant materials that are both biologically inert and that are infiltrated during bone growth. This research was undertaken to develop prosthetic ceramic and metal materials with the porous macro-structures obtained from certain coral species using replamineform. Advancement of these materials would aid the long term attachment of prosthetic devices that could restore lost or give never possessed function.;Characterizations of the starting materials (ceramic powders and corals), the sintered macro-porous ceramic bodies (solid and void frameworks), and the micro-porosity of the solids were made using the automated scanning electron microscope image analysis system. The ultimate goal of this characterization is the ability to relate the properties of the final sintered ceramic to the starting materials properties and processing conditions.;In vivo testing in both rabbits and dogs showed that these materials are well tolerated and are ingrown with calcified tissues when implanted in bone.;A positive structure of CaO is obtained from the direct heat treatment of the CaCO(,3) of the coral. This porous refractory network provides an ideal "mold" in which to cast desired metals. The first successful conversion of the carbonate structure for use as a porous metal mold resulted from this work. The CaO is then hydrated and removed from the casting leaving a porous, negative replica of the carbonate precursor.;The preparative procedures to make ceramic materials with positive replamineform porosity were developed for both alumina and titania. The macro-pores of the ceramics are stable during sintering while the micro-pores are unstable and are nearly eliminated.;An NIH-sponsored research study in cooperation with personnel and facilities at the Hershey Medical Center was successfully completed; and required the design and fabrication of a segmental femoral replacement from a Co based Cr-Mo surgical grade alloy. A porous overlay on the ends of the cylindrically shaped implant was used as the fixation sites for new bone. Techniques for forming and sintering a CaO mold were developed that permitted a single pour casting. Characterizations of the starting materials, intermediate CaO macro-porous "mold," and cast alloy micro- and macro-structures were made to aid in future development work.