The importance of early diagnosis and management in total knee arthroplasty infection

The infection of a knee prosthesis is a serious complication often characterized by a complex and prolonged diagnostic procedure and the treatment of which, even if could gain a healing of the septic process, not always results in a satisfactory functional result.1 Difficulties in the treatment of a knee prosthetic infection deal with the presence of the prosthesis which acts as a foreign body, feeding the persistence of the infection itself2. Microorganisms usually considered as nonpathogenic or poorly resistant to common antibiotic therapy could determine the clinical conditions in which the healing can be achieved only with the removal of the prosthetic implant3. There are particular situations at the base of the onset and persistence of so-called “foreign body” infections: the host organism reacts against biomaterials filling them with a thin film made of proteinaceous material. Some of these proteins have receptors specific for Staphylococcus Aureus and Epidermidis, determining contact that at least initially, is reversible. This condition can become irreversible through the production of a gelatinous substance (exopolysaccharides) by certain bacterial species as coagulase-negative staphylococci (St. Epidermidis, Capitis, Haemolyticus), Enterobacteriaceae, Pseudomonacee, Aciteobacter (Figure 1). Formation of a matrix glycoprotein then acts, defined by Gristina and Costeron, as “glycocalyx”.2 The action of the glycocalyx is manifold: it forms a barrier against antibiotics and inhibits macrophage phagocytosis.3