Serial diagnosis of septic loosening of hip-endoprosthesis using laboratory parameters and antigranulocytescintigraphy.

Aim: The value of serial diagnosis of septic loosening of hip endoprosthesi s using laboratory parameters and antigranulocytes scintigraphy was investi gated and compared to joint aspiration. Method: In 35 patients with intraop erative verification of infection, we calculated sensitivity, specifity and prevalence dependent positive and negative predictive values for antigranu locyte scintigraphy, laboratory tests and the most suitable combination of both. We also calculated predictive values of joint aspiration using sensit ivity and specifity values given in the literature. Results: From negative and positive predictive values, of the sedimetation rate and leukocyte coun t provided no increase of information. We found the same result for positiv e predictive values of C-reactive protein. For antigranulocyte scintigraphy alone, we found a distinct but still unsatisfying increase of information. Nevertheless, in both cases infection could be excluded definitely. Theref ore, the combination of C-reactive protein and antigranulocyte, scintigraph y was suitable and the positive predictive values of this combination were only about 5% lower than those of joint aspiration. But with joint aspirati on, infection could not be excluded. Conclusion: A positive result in seria l diagnosis using C-reactive protein and antigranulocyte scintigraphy leads to an distinct increase in the probability of infection which is comparabl e to that of joint aspiration. The additional advantages of this procedure are the certain exclusion of infection and the absence of invasiveness.