Potential of ceramic materials as permanently implantable skeletal prostheses

The feasibility of the use of porous ceramic materials in the permanent repair of skeletal defects was studied from the standpoint of physiological compatibility and in growth of natural bone. High‐fired calcium aluminate samples in the form of quarter‐inch diameter cylindrical pellets containing interconnecting porous networks were implanted in vivo into canine femurs for 4‐, 11‐, and 22‐week periods. The implants had 65% porosity with pore size falling within one of five distinct ranges from less than 45 μ to about 200 μ in diameter.

Thin sections were prepared by grinding (poly) methyl methacrylate‐mounted cross sections of the femurs containing the implanted ceramic samples and adjacent soft tissues. Tissue‐prosthetic compatibility was determined using standard histological thin section procedures, electron microbeam probe examinations, autoradiographic techniques, microfadiographic techniques, microchemistry techniques, and ultra‐violet fluorescent techniques. Optical microscopic evaluations of each section showed the ceramic samples to be bound lightly by natural bone and gave no detectable signs of tissue incompatibility. Minimum pore size for significant ingrowth of natural bone was indicated to be between 75 and 100 μ.