Joint aspiration in suspected infected implants is a validated diagnostic method in establishing the diagnosis of prosthetic joint infection (PJI). Cut-off values for synovial leukocyte counts and differentials are well described for patients with hip and knee PJI. In 19 failed shoulder implants, a leucocyte count of >12.2 G/L had a sensitivity and specificity of 92% and 100% respectively; A differential of >54% neutrophils had a sensitivity of 100 % and a specificity of 75%.
Keywords: cell count; prosthetic joint infection; shoulder arthroplasty; synovial fluid.