Tissue reaction to collagen-coated porous hydroxyapatite.
To give tenacity to high porosity (80%-90%) hydroxyapatite (HA) and to make a stronger bone substitute, a collagen-coated porous HA (C-HA) was prepared, and its compressive strength was examined. By implanting C-HA into the femoral condyle of adult rabbits, the capacity for new bone formation and foreign-body reactivity were quantitatively compared with those of HA alone. The compressive strength of C-HA was 4.3 times greater than HA. At four weeks after implantation, the mean areal ratio of the newly formed bone in the C-HA block in each rabbit was 9.9%, which was somewhat less than the 13.7% in the HA block; the mean number of multinucleated giant cells (MGC) per visual field at x25 in the C-HA-implanted specimens in each rabbit was 14.4, significantly larger than the 6.1 in the HA specimens. However, 12 weeks after C-HA implantation, the areal ratio of new bone increased to 32.7%, the number of MGC decreased to 9.4, and the differences compared to the values in HA cases, 31.5% and 6.8, disappeared. These results showed that C-HA is mechanically stronger than HA and that there is no difference between HA and C-HA in capacity for new bone formation or foreign-body reaction.
Iwano
T
T
Department of Orthopaedic Surgery, Faculty of Medicine, University of Tokyo, Japan.
Kurosawa
H
H
Murase
K
K
Takeuchi
H
H
Ohkubo
Y
Y
D000818:Animals; D001846:Bone Development / Q000187:drug effects*; D003094:Collagen / Q000008:administration & dosage*; D005549:Foreign-Body Reaction; D006882:Hydroxyapatites / Q000008:administration & dosage*; D008855:Microscopy, Electron, Scanning; D016062:Porosity; D011312:Pressure; D011817:Rabbits; D013718:Tensile Strength
D006882:Hydroxyapatites; D003094:Collagen