Previous studies have demonstrated the induction of bone in coral-deri
ved porous hydroxyapatite when implanted intramuscularly in baboons. T
his hydroxyapatite-induced bone differentiation model was used to stud
y the effect of different animal species on heterotopic bone formation
. Porous hydroxyapatite, obtained after hydrothermal conversion of the
calcium carbonate exoskeleton of coral (genus Goniopora), was implant
ed in the rectus abdominis of adult rabbits, dogs and baboons (Papio u
rsinus). Specimens were harvested on day 90 after implantation and sub
jected to histological and histomorphometrical analysis. Minimal amoun
ts of bone formed in hydroxyapatite specimens harvested from rabbits a
nd dogs. Substantial bone differentiation did occur, however, in hydro
xyapatite specimens harvested from the rectus abdominis of the baboons
. In primates, the porous hydroxyapatite, as used in this study, may a
ct as a solid matrix for adsorption, storage and controlled release of
circulating or locally produced bone morphogenetic proteins, which lo
cally initiate bone formation. The results of this study on heterotopi
c bone formation in porous hydroxyapatite underscore the importance of
primate models in biomaterial research, which should be exploited for
the formulation of porous substrata with intrinsic osteoinductive act
ivity.