Similarity of bone ingrowth in rats and goats: A bone chamber study

Bone ingrowth has been studied extensively in rats by use of bone chambers. However, it is not known whether results in small animals, with respect to bone ingrowth processes, are similar in large animals, in which more reali stic models are often used. Since the metabolic rate in small animals is, i n general, higher than that in larger species, we hypothesized that bone in growth in chambers develops more rapidly in small animals. Therefore, ident ical bone chambers were placed in the tibias of rats and goats. After 6 and 12 weeks, histologic and histomorphometric examinations were carried out t o measure bone and tissue ingrowth distances. Bone ingrowth was higher in both species at 12, compared with 6 weeks (P < 0.01). Tissue ingrowth in general (including soft tissue) was less in rats than in goats at both time periods (P < 0.001). However, bone ingrowth did not differ between species. Thus, when differences in size of an osseous de fect are corrected for, there seems to be only little influence of differen ces in body size.