Cellular basis of inflammation-induced osteopenia in growing rats.

Local nonosseous inflammation provoked by four subcutaneous talc powder injections induced a marked trabecular bone loss in rats within 7 days. The disturbance included suppression of bone elongation, inefficiency and decreased number of trabecular osteoblasts, decreased osteoprogenitor cell number in tibial metaphyses, and bone marrow expansion. Neither the appearance and function of osteoblasts in the vicinity of the cortical bone nor the number of osteoclasts in the metaphysis were found to be altered. The loss of trabecular bone in granulomatosis was based on a suppression of bone elongation and a failure of osteoblasts to form normal secondary spongiosa.