PAPER 142: FROZEN SECTION ANALYSIS AT THE TIME OF REVISION TO A TOTAL JOINT ARTHROPLASTY IN THE TREATMENT FOR NON-UNION OF FRACTURES ABOUT THE HIP: A USEFUL TEST?

Purpose: Intraoperative frozen section analysis in which the number of cells per high powered field (CPHF) are used to predict the presence or absence of infection has been found to be a very useful test in the setting of revision total joint arthroplasty. The purpose of this retrospective review was to determine the usefulness of this same test at the time of implantation of a total hip arthroplasty (THA) following the failure of hip fracture fixation. Method: A retrospective review from 1999 – 2007 of twenty-two consecutive patients who had THA performed as a result of failed hip fracture fixation. The mean age of patients was seventy-two years. The number of CPHF was correlated with the results of intraoperative cultures, and other pre-operative and post-operative parameters. The mean duration of follow-up was 14 months. Results: Two patients had a culture-proven infection (Staphylococcus aureus in one patient, and staphylococcus epidermidis and propionibacterium acnes in the other.) Both of these patients had a positive test for infection based on the frozen section having greater than ten CPHF by the pathologist. (100% agreement) Four out of the six specimens that were graded as 10 CPHF by the pathologist had negative intra-operative cultures (33% agreement). With the CPHF limit set at 10 CPHF, the sensitivity of frozen section analysis in this clinical setting was 100%, while the specificity was 19%. The positive predictive value was calculated to be 33%, and the negative predictive value was 100%. With the cutoff of 5 CPHF or greater, the sensitivity of 100% and a specificity of 52% as well as a positive predictive value of 17% and a negative predictive value of 100%. Conclusion: Although the results are preliminary, and further study is warranted, it seems that CPHF is a useful test to rule out the presence of infection when revising failed fracture fixation to Total Hip Replacement..