Comparative study of porous hydroxyapatite and tricalcium phosphate as bone substitute

Abstract

This study was performed to quantitate the bone ingrowth and biodegradability of porous calcium phosphate. Two kinds of coralline hydroxyapatite (CHA), along with sintered triculcium phosphate (TCP), were evaluated. All implants had totally interconnecting pores. These pores measured 260–600 μ for CHA‐Goniopora (CHAG), 190–230 μm for CHA‐Porites (CHAP), and 100–300 μm fot TCP. Cylindrical implants (3 mm in diameter by 8 mm in length) were implanted into the diaphyses of rabbit tibias for 3 to 24 weeks. The quantity of regeneration bone, remaining implant, nonmineralized space, and the middle two quarters of the cortical area were measured by a computerized operator‐assisted anaylsis for bone, histomorphometry. At 3 weeks after implantation, 17.3% of CHAG, 11.3% of CHAP, and 7.0% of TCP were infiltrated by regenerated bone. At 24 weeks, 56.1% of CHAG, 52.7% of CHAP, and 44.7% of TCP were occupied by lamellar‐type bone. Implant degradation was noted to be 46.4% for TCP and 27.5% for CHAP. In contrast, CHAG did not show appreciable degradation until 24 weeks.