Low-grade infection. Are biopsies of every non-union really necessary?

Low-grade infections and infected non-unions are a therapeutic challenge. They are difficult to diagnose and extensive to treat. The actual incidence of low-grade infections is unknown but there is evidence in the current literature that low-grade infections and infected non-unions are more common than previously assumed. An accurate diagnosis as well as the identification of the pathogen are required for a successful therapy. Biopsies of the tissue are the gold standard and a swab or puncture is not sufficient. In addition to the standard tissue cultures there are more recent diagnostic methods, such as sonication or the polymerase chain reaction (PCR). They seem to have a higher sensitivity, particularly with respect to pathogens with biofilms or previous antibiotic therapy. Histological investigations can also verify an osteomyelitis but a big drawback of this method is the missing pathogen identification. The significance of very high rates of positive pathogen detection using PCR or sonication has to be investigated in the future. In summary, low-grade infections and infected non-unions seem to be more common than previously assumed; therefore, biopsies should be taken of every non-union before surgery. In addition to standard tissue cultures, other diagnostic methods, e.g. sonication, seem to be useful to improve the diagnostic accuracy, particularly in cases of missing clinical signs of infection.