Infected Femoral Segmental Defect Model: Effects of Nanosilver in Re-Establishing BMP-2 Osteoinductivity in Infected Wounds

INTRODUCTION: Bone graft materials are placed in a variety of skeletal defects to promote bony union. Infection of bone graft devices are devastating complications that require multiple debridement surgeries, systemic antibiotic treatment, and may result in osseous non-union. Besides significant medical costs, there are also high costs from lost productivity and function. It is therefore critical to develop a systematic approach to study and treat bone graft infections. The aim of this study is to establish an infected segmental defect model to simulate acute bacterial infections in the setting of a critical-sized, segmental bone loss, and to use this model to test BMP2 efficacy with antibactericidal treatment. Staphylococcus aureus (S. aureus) was used in this model because it is the bacterial pathogen responsible for ~80% of all cases of human osteomyelitis. Silver in nano particle size (nanosilver; Ag), rather than an antibiotic, was used in this study because antiseptics such as silver are broad spectrum, potentially low cytotoxicity agents that nonselectively target many bacterial cellular activities and are thus less likely to promote bacterial resistance. We hypothesize that S. aureus can effectively create an acute osteomyelitic model without use of sclerosing agents and that nanosilver can restore BMP2 efficacy in osteomyelitic bone defects.