Abstract

Many properties of porous calcium phosphate ceramics have been described, but how pore size influences bony integration of various porous ceramics remains unclear. This study was performed to quantify the bony ingrowth and biodegradability of two porous calcium phosphate ceramics with four different pore size ranges (45-80 µm, 80-140 µm, 140- 200 µm, and 200-250 µm). Hydroxyapatite (HA) and b-tricalcium phosphate (TCP) cylinders were implanted into the femoral condyles of rabbits and were left in situ for up to 12 months. The percentage of bone ingrowth and the depth of ingrowth within the pores were determined. Biodegradability of the implants was also evaluated. Bone ingrowth occurred at a higher rate into the TCP than into the HA ceramics with the same pore size ranges. The amount of newly formed bone was statistically smaller (p < 0.05) into ceramics with 45- 80 µm pore size than with larger pore size, whatever the implantation time for HA and until four months for TCP. No statistical difference was noted between the three highest pore size ranges. No implant degradation was noted up to four months. Our results suggest that a pore size above 80 µm improves bony ingrowth in both HA and TCP ceramics. Bone formation was higher in the TCP than in the HA implants.