Frozen sections of samples taken intraoperatively for diagnosis of infection in revision hip surgery

Background The diagnosis of a suspected infected prosthesis is often difficult, but is important for the choice of treatment. Even at surgery, it is not easy to assess whether the prosthesis is infected or not-even though this may be important for the choice of surgical procedure. Patients and methods We assessed the sensitivity, specificity, predictive value, and reliability of the results of the analysis of frozen sections from samples of tissues taken during revision hip surgery of 136 probably infected prostheses. Samples of tissues were taken to be analyzed immediately from frozen sections, to be processed on a routine basis later, and: to be referred for bacteriological cultures. A finding of 5 or more polymorphormclear leukocytes per field at a magnification of 400x was considered positive for infection. Results The analysis of frozen sections for infection was in agreement with the results of routine histopathology in 134 of 136 cases. Comparison with the results of culture showed a sensitivity of 85%, a specificity of 87%, a PPV of 79 %, an NPV of 91 %, and a Kendall's tau correlation coefficient of 0.72. I Interpretation We believe that the method we have tested is of value in revision surgery when infection cannot be ruled out.