A practical definition of pin site infection.

Pin Site Infection (PSI) is the most common complication of external fixation treatment. Several classifications and diagnostic approaches have been used with reported incidences varying widely from 1 to 100 %. The quality of the existing literature is limited by the absence of a definition. This renders comparing literature and developing evidence-based algorithms for prevention, diagnostics, and treatment difficult to impossible. Similar problems were identified with prosthetic joint infection (PJI) and fracture-related infection (FRI) in recent years, resulting in new, validated definitions. PSI is complicated by the complexity of the issue. Numerous factors in PSI need consideration. Factors may be related to the patient, the surgical technique, the pin-bone interface, the pin-skin interface, the choice of external fixation device and/or the material used and its properties. Reliably diagnosing PSI is one of the most pressing issues. New definitions for FRI or PJI have diagnostic criteria which can be either confirmatory or suggestive. Any positive finding of a confirmatory criterion constitutes an infection. Although PSI resembles PJI and FRI, distinct differences are present. The skin is never closed, and bacterial colonization is inevitable along the treatment duration. The external fixator is only temporarily in place; thus, the goal of all measures is to continue the external fixator until the intended indication is reached. This paper proposes the principles of a definition of PSI. This definition is not designed to guide any treatment of PSI. Its purpose is to create common ground for clinical investigations and publishing further research.