Terminology of bone and joint infection.

Musculoskeletal infections are common and often difficult to treat. Their diagnostics and treatment are an integral part of the daily clinical routine of every orthopaedic and trauma surgeon. Diagnostics and first treatment approaches are often initiated prior to referrals to a specialized centre. Treatment algorithms in the field of musculoskeletal infections, based on clinical and experimental empiricism, promise successful treatment courses in many cases, although a considerable proportion of bone and joint infections are characterized by treatment failure, for a variety of reasons.

The basic prerequisite for the initiation of correct diagnostics, and thus consecutive best possible therapy, is the correct terminology of individual bone and joint infections. A variety of terms exists to describe bone and joint infections. Osteomyelitis, implant-associated infection, fracture-related infection (FRI), and infected nonunion denote bone infections. Joint infections are described by periprosthetic joint infection (PJI) and septic arthritis, with its synonyms of supportive and infectious arthritis. In the spine, a distinction can be made between implant-associated vertebral osteomyelitis and hematogenous spondylodiscitis according to the aetiology. Even among experts in the field, terms are interchanged and used synonymously. It often appears to be difficult to arrive at exact definitions, which naturally limits the understanding of optimal treatment. For FRI and PJI, diagnostic criteria have been developed, and in the case of PJI those criteria have been continuously improved and are still the subject of scientific discussion.

To lay the foundation for optimal therapy using the correct terminology of the underlying condition, this infographic presents the hallmarks of bone and joint infections and diagnostic criteria.