TC-99(M)-POLYCLONAL IGG SCINTIGRAPHY IN THE DETECTION OF INFECTED HIPAND KNEE PROSTHESES

We investigated the usefulness of Tc-99(m)-polyclonal human IgG (Tc-99 (m)-HIG) scintigraphy in the diagnosis of infected hip and knee prosth eses. Twenty-nine scintigraphic studies were performed in 27 patients (17 females, 10 males) with a suspected prosthetic infection. As some patients had bilateral prostheses, a total of 35 prostheses were evalu ated. There were 25 hip replacements and 10 knee prostheses. The image s were analysed both visually and quantitatively. The scintigraphic re sults were compared with the culture results of surgical specimens and also with clinical follow-up after 3 months. Increased uptake was obs erved in 22 prostheses, of which 12 were true-positive and 10 were fal se-positive results. Staphylococci were the agents most commonly isola ted. In all false-positive patients, aseptic inflammation was diagnose d. Based on quantitative analysis, no statistically significant differ ence was found between the true-positive and false-positive cases. For the prostheses as a whole, the sensitivity, specificity, positive pre dictive value and negative predictive value were 100%, 41%, 54% and 10 0% respectively. For the hip prostheses alone, these values were 100%, 53%, 57% and 100% respectively. Taking its high sensitivity and predi ctive value into consideration, Tc-99(m)-HIG scintigraphy can be used as a screening test to help eliminate prosthetic infection.