Advances in the laboratory diagnosis of prosthetic joint infection

Prosthetic joint implant surgery (arthroplasty) provides restoration of movement to almost half a million people each year in the USA, with major health and economic benefits. While the majority of recipients experience dramatic relief of preoperative pain at the arthroplasty site, some prostheses fail to achieve this result. This is most commonly the result of aseptic biomechanical failure or prosthetic joint infection (PJI), both of which are associated with significant morbidity. Because the management of PJI differs from that of aseptic failure, it is important to accurately differentiate these two entities. Current laboratory methods for diagnosis of PJI depend on isolation of a pathogen by culture from a clinical specimen (e.g., synovial fluid, periprosthetic tissue). However, as PJI is typically a low organism burden and focal infection caused by commensal micro-organisms, these methods have neither ideal sensitivity nor ideal specificity. Therefore, culture-independent molecular methods have been used to improve the diagnosis of PJI. In the research setting, detection of 16S ribosomal DNA (rDNA) by polymerase chain reaction has been the prime focus of the molecular diagnosis of PJI. In this article, advantages and limitations of conventional and molecular methods for the laboratory diagnosis of PJI are reviewed, as is the use of methods that may improve detection of organisms in the biofilm environment. The diagnosis of PJI remains challenging and a rapid, sensitive and specific method is needed for appropriate surgical and medical treatment decisions in the growing arthroplasty population.