THE RESPONSE OF OSTEOCYTES TO A LIPID CLEARING AGENT IN STEROID-TREATED RABBITS

We studied the effect of a lipid clearing agent (dlinofibrate) on the osteocytes of rabbits treated with corticosteroids. Thirty-one rabbits were divided into four groups: (A) steroid-treated with a normal diet, (B) steroid-treated and on a diet with added clinofibrate, (C) non-steroid-treated, on a diet with clinofibrate; and (D) non-steroid-treated on a normal diet. All the steroid-treated animals demonstrated hyperlipidaemia and fatty degeneration of the liver. Lipid-containing osteocytes were seen in the femoral heads of these animals. However, those which received clinofibrate (group B) had less severe lipidaemia, and less severe degeneration of the liver. In them, only the osteocytes around the haversian canals exhibited lipid inclusions. Clinofibrate appears to modify lipid metabolism, diminishing the steroid induced accumulation of lipids within osteocytes. This effect may protect against steroid-mediated osteonecrosis. One of the most disabling side effects of systemic corticosteroid therapy is osteonecrosis. The pathogenesis of this disorder is uncertain and among the several hypotheses that have been proposed are osteoporosis leading to microfractures (Freiberger and Swanson 1965; Solomon 1973), coagulation abnormalities (Boettcher et al 1970), fat embolisation (Jones and Sakovich 1966