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 ingrowt,h 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 p to about 200 p 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, microradiographic 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 p.

No abstract

SummaryIn this investigation, ceramics were studicd to determine their role as rigid, abrasive implants in soft, living tissue. Discs and tubes of three ceramics, CaO .A1,0?, CaO . TiO,, and CaO . ZrO,, were introduced as porous and non-porous structures into muscle and Connective tissue sites in rabbits. The animals were observed grossly to determine the duration of redness and swelling following surgery, and samples were retrieved at 1 week, 3 months, 6 months, and 9 months after implantation. A mild, acute inflammatory response immediately followed the implantation of all three materials in both the porous and non-porous forms. Histological sections of the ceramics and surrounding tissue, cut and stained for light microscopy, demonstrated the absence of inflammatory cells and revealed the normal morphology and organization of the cells present around all types of implants tested. Tissue around discs of porous ceramics healed faster and exhibited thinner fibrous encapsulations than with impervious discs of the same material. Healthy fibrous connective tissue with an ample blood supply occupied those implants with pores of 45-100 mp, and even more rapidly filled the samples with a 100-to 150-p pore size. The tissue ingrowth and tight adherence to the porous samples was believed responsible for the more moderate response to porous implants. No adverse responses of any kind were observed, except in a very few, atypical specimens.

No abstract

The purpose of this investigation was to study bone growth into porous polyethylene rods as a function of time and pore structure. Previous studies have indicated the biocompatibility of solid polyethylene materials which are currently being used clinically. Porous polyethylene rods were implanted in the femurs of mongrel dogs which are sacrificed four, eight, and 16 weeks postoperatively. The implants were then sectioned and examined histologically and microadiographically. Quantitative techniques were employed to determine the amount of bone ingrowth as a function of time and pore size. The pore structures of the materials were evaluated using optical microscopy and mercury intrusion porosimetry. The results of this investigation have demonstrated that porous polyethylene is capable of accepting bone growth into pores as small as 40 mum. The optimum rate of bone ingrowth was observed in pore sizes of approximately 100 to 135 mum, with no increase in the rate of bone ingrowth observed in samples possessing larger pore sizes. No adverse tissue response was found at implant times up to 16 weeks in pore sizes of 100 mum or larger.