The assessment of neutrophil cd64 count as an early warning marker of joint replacement infection

120,000 hip and knee replacements are performed each year in the UK and more than 1 % of these require revision surgery due to infection. Current diagnostic tests used to diagnose infection of joint replacements, including the current gold standard C-reactive protein, which offers poor specificity when diagnosing infection in the post-operative period. In the post-operative period these tests are unable to differentiate between physiological inflammation and infection of the replacement. Early treatment through antibiotic and washout therapy is essential to eradicate infection, saving the patient and the NHS the stress of revision surgery, which offers a much poorer prognosis than the original operative procedure. Thus, a superior marker is required and CD64 has been proposed to fulfil the necessary requirements of an effective marker. Data from several studies utilising a flow cytometer support the view that CD64 is firstly, a good marker of systemic infection and secondly, when studied in conjunction with musculoskeletal infections alone, is a sensitive and specific marker of this type of infection. However, meta-analysis of studies in this field concludes that more highly powered studies are needed before definite conclusions can be drawn. Despite this, the studies do portray a strong case for CD64 being the future of diagnosis of post-operative infection.