Application of core biopsy in revision arthroplasty for deep infection.

A preliminary core biopsy was performed in 168 consecutive joint arthroplasties (141 hips and 27 knees) before revision for suspected deep infection. Data of the core biopsy and subsequent revision procedures were available for 159 cases. Biopsies and revisions were all performed by one surgeon, and the exchange procedures were all undertaken in an ultra clean air enclosure. Biopsy material was cultured both aerobically and anaerobically and the results compared to that of the specimens obtained at the subsequent exchange procedure. In 116 patients (70%), the culture and sensitivity results were identical in samples from core biopsy and samples obtained during revision procedure (either no growth or growth of same organisms). When compared to intraoperative specimen report, 25 biopsies (15%) gave an apparently false-positive result. In 16 instances, a false-negative result was seen, but repeat biopsy in 4 of these cases was positive. The final diagnosis of infection was made using all available clinical and investigative data. When compared to final diagnosis, the sensitivity of core biopsy was 88%, the specificity was 91%, and the accuracy was 89%. Core biopsy was successful in identifying the organisms with the sensitivities to antibiotics in 80% of the disease-positive cases, hence, offering the opportunity to add the most appropriate antibiotic to bone cement during the exchange procedure.