Increased bone ingrowth distance into lipid-extracted bank bone at 6 weeks. A titanium chamber study in allogeneic and syngeneic rats.

In previous rabbit chamber experiments, lipid extraction has been shown to increase bank bone incorporation, as measured by scintimetric activity at 3 weeks. In the present study, the new bone ingrowth distance was measured by histomorphometry at 6 weeks using a titanium chamber model in rats. By insertion into bilateral bone conduction chambers, frozen grafts were compared with grafts that had been processed by lipid extraction. To evaluate the effects of lipid extraction further, the group of 26 rats was divided into three subgroups according to MHC haplotype, namely a heterogeneous group (outbred Sprague-Dawley rats), a mismatched group, and a syngeneic group. In the total material, defatted grafts showed a 58% greater new bone ingrowth distance and a 31% higher scintimetric activity over controls. The effect of defatting was not shown to be due to immunologic factors. In general, rats with a lower capacity to incorporate bone grafts showed a larger positive effect of defatting.