Role of core biopsy in diagnosing infection before revision hip arthroplasty.

A prerevision core biopsy from a failed hip joint was performed in 41 hips (38 patients) with a high index of suspicion for sepsis to determine its efficacy in diagnosing sepsis. Seven hips were known septic failures, and core biopsy was undertaken to confirm resolution of sepsis. Forty hips were revised, whereas 1 hip had excision of heterotopic bone. Cultures and permanent histologic sections were obtained during subsequent surgeries, and findings were compared with the results of core biopsy. The commonest organisms isolated were coagulase-negative staphylococci and Propionibacterium acne. In patients without a history of sepsis, core biopsy diagnosed infection with sensitivity of 80%, specificity of 100%, accuracy of 97%, and positive predictive value of 100% using histologic evidence of sepsis at revision as the standard. Core biopsy, however, had low sensitivity and accuracy in establishing resolution of infection in patients with a history of septic failure. Cultures from the aspirate had 44% sensitivity and positive predictive value of 57%. Core biopsy is useful for investigating failed arthroplasties with suspected sepsis. It has advantages of hip aspiration and allows examination of periprosthetic tissue histology. Its role in diagnosing resolution of infection in previously septic failures, however, is limited.