Antimicrobial Bone Graft Substitutes1

Open fractures account for approximately 20% of all combat-related injuries in soldiers. Because of the severity of wounding mechanisms and high rates of wound infection, open fractures from combat pose greater problems to surgeons and result in higher morbidity than similar injuries suffered by civilians. Standard care for open fractures requires multiple procedures, including irrigation, débridement, stabilization, and antibiotic therapy. A commonly used method to provide local antibiotics through elution and to fill dead space is the application of polymethylmethacrylate (PMMA) combined with a broad-spectrum antibiotic, rolled into beads, and placed in the bone defect. Although effective for treating infection, these cement beads are not bioabsorbable and will eventually retard bone growth if not removed during a second surgical procedure. Yet a third procedure for bone autografting is often required for definitive treatment. Current standard care with multiple procedures and delayed definitive treatment results in high patient morbidity and increased cost of treatment. To evaluate potential alternatives to current standard care we have developed a large animal open fracture model in goats. Thus far we have tested different osteoconductive or osteoinductive bone graft substitutes impregnated with antibiotics to determine the ability of each product to reduce infection rates. All products have been as effective as standard care treatment in preventing infection in this contaminated bone defect model. Current research is evaluating the use of similar, but commercially available products that have been approved, or are pending approval, by the United States Food and Drug Administration. The use of antimicrobial bone graft substitutes may reduce morbidity, the number of surgical interventions, and associated medical costs for military personnel and civilians alike.