DEPRESSED OSTEOBLAST ACTIVITY AND INCREASED OSTEOCYTE NECROSIS AFTER CLOSED BONE-FRACTURE AND HEMORRHAGIC-SHOCK

Background: Although bone facture and hemorrhagic shock are frequent c omplications in trauma patients, it remains unknown whether hemorrhagi c shock after bone fracture produces any deleterious effects on osteob last function and osteocyte necrosis. Methods: Sham-operation, closed bone fracture (right tibia) with and without hemorrhagic shock (mean a rterial blood pressure 35 +/- 5 mm Hg for 90 minutes followed by fluid resuscitation) were induced in 18 male C3H/HeN mice (25 g body weight ). Aa 72 hours after the experiment, all animals were killed, whole bl ood was obtained by cardiac puncture, and plasma assayed for circulati ng levels of osteocalcin. Results: Plasma osteocalcin levels were foun d to be significantly depressed after closed bone fracture in conjunct ion with hemorrhagic shock. Closed bone fracture alone increased plasm a osteocalcin. Histologic analysis of the fracture sites revealed that hemorrhagic shock after closed bone fracture significantly increased osteocyte necrosis adjacent to the fracture site, when compared to ani mals with closed bone fracture alone. Conclusions: These findings sugg est that severe hemorrhage after closed bone fracture depresses osteob last activity and increases osteocyte necrosis, which should compromis e fracture healing under those conditions.