Fracture healing : the effects of local insulin delivery via calcium sulfate and tricalcium phosphate

Previous studies have documented the major role played by insulin in osseous healing. This is the first study to examine local intramedullary insulin delivery to the fracture site and its effect upon the normal fracture healing process. Preceding results show that when administered at the fracture site of the impaired fracture healing model of the diabetic BB Wistar rat, insulin will regulate early cellular proliferation and chondrogenesis and late mineralized tissue, cartilage content and mechanical strength. In this study, two novel delivery vehicles have been evaluated for sustained insulin release in the normal fracture model of the BB Wistar rat. Calcium sulfate and tn-calcium phosphate have osteoconductive properties that support bone growth. These materials served as carriers to provide continuous insulin release at the fracture site. The vehicles were evaluated for insulin content at days 2, 4 and 7 and normalized to the total systemic protein content of the animal. Calcium sulfate shows an early burst of insulin release and sustained amounts of insulin throughout the 7 day study. The local treatment of insulin does not affect the animals’ systemic insulin levels. Histomorphometric analysis shows a significant difference in new bone content in the fracture calluses that received insulin treatment as compared to control groups. The study concludes that calcium sulfate could be a promising vehicle for local insulin delivery and improvement of the fracture healing process in healthy patients