Implant-associated post-traumatic osteomyelitis.: Bacterial biofilms and the immune defence as protagonists of the local inflammatory process

Background. Formation of bacterial biofilms on implants is a severe complication following orthopaedic surgery. In the present study we addressed the role of the immune response, particularly with regard to the pathogenesis of the disease. Methods. In a prospective study comprising 74 patients with implant-associated posttraumatic osteomyelitis, peripheral blood cells as well as cells recovered from the infected site during surgery were characterised phenotypically and functionally. Results. We found massive infiltration of polymorphonuclear neutrophils (PMN), which were highly activated, particularly regarding their bactericidal potential, such as increased production of superoxides and upregulation of activation-associated surface receptors. Conclusion. PMN are activated in response to the implant-associated osteomyelitis; they also infiltrate the infected tissue, but cannot control the infection. By release of their cytotoxic entities they could contribute to tissue destruction and eventually to osteolysis.