Unexpected positive intraoperative cultures and gram stain in revision total hip arthroplasty for presumed aseptic failure.

No method to determine aseptic versus septic failure provides 100% sensitivity and specificity. An algorithmic approach nears 100%. In cases where preoperative suspicion is low and the septic workup is negative, intraoperative cultures can still be positive. The importance of unexpected positive results is unknown. We investigated the incidence of positive intraoperative gram stain and cultures in 103 revision total hips. Seven positive gram stains or cultures were observed. No subsequent infections were observed. All positive results were treated as significant. Unexpected positive culture results or gram stain in an otherwise low suspicion revision total hip arthroplasty should be treated as significant. It is now recommended that multiple cultures be obtained and that a single isolate may not be a significant finding.