Bone graft proteins influence osteoconduction: A titanium chamber study in rats

Abstract
Although it is often emphasized that the matrix of bone grafts contains several growth factors, it is not known if these factors become activated and play a role in bone grafting. We therefore compared ground defatted bone which had or had not been deproteinized by heating with water to 270 °C at an autogenic pressure of 55 bar. This is a careful ceramic procedure which leaves the mineral unchanged. Depro-teinized and non-deproteinized bone granulae derived from cortical rat bone were placed in titanium bone conduction chambers implanted bilaterally in rat tibiae. in growing bone could enter the cylindrical interior of the chamber only at one end. It then penetrated the material in the chamber, but due to the length of the cylinder, it never reached the other end. the mean distance which the ingrown bone had reached in the material was then measured on histological slides. the bone formation activity was measured by TcMDP scintimetry. With the protein-containing granulae, the mean bone in growth distance and the scintimetric activity were increased by 41 % and 31%, respectively (p < 0.01). We conclude that there is a limited favorable effect of proteins in a graft. Our grounded material had a large fracture surface area with no osteoid lining. the leakage of growth factors from such areas may explain the extraordinarily good clinical incorporation of mor-selized compacted allografts.