Diagnostic value of triple-phase bone scintigraphy for the diagnosis of infection around antibiotic-impregnated cement spacers

INTRODUCTION Two-stage revision arthroplasty is today considered as the gold standard for control of chronic deep prosthetic infection. Although the revision arthroplasty should only be considered when infection is eliminated, the diagnosis of residual infection prior to the revision remains a challenging problem. MATERIALS AND METHODS We evaluated triple-phase bone scintigraphy as a useful diagnostic test for the detection of residual infection around the antibiotic-impregnated cement spacer in patients waiting for the second-stage revision hip or knee arthroplasty. Increased uptake of radioisotope in all three phases was considered positive for infection. The final diagnosis was based on histopathological results in addition to microbiologic examinations of surgical specimens. RESULTS Histopathological examination showed positive in 17 and negative in 13 out of 30 examinations. Among 17 samples positive for histopathology, there were only 4 samples positive for bacterial culture. All samples negative for histopathology showed negative for bacterial culture. The positive and negative predictive values of triple-phase bone scintigraphy for the presence of infection were 80% and 90%, respectively. The diagnostic sensitivity was 94% and the specificity was 69%. CONCLUSION Triple-phase bone scintigraphy was useful in the diagnosis of infection around the articulating cement spacer. In particular, when triple-phase bone scintigraphy shows negative, the residual infection around the cement spacer is unlikely.