FINE-NEEDLE ASPIRATION IN INFECTED HIP REPLACEMENTS

Ninety painful prosthetic hips from 88 consecutive patients underwent fine needle aspiration and the results compared with clinical progress , operative findings and culture. Fourteen of the 15 cases proven to b e infected at operation were correctly identified by fine-needle aspir ation. The one hip with a false negative aspirate had an arthrogram wh ich showed a cavity suggesting infection. There were three false posit ive aspirates, One grew a different organism at surgery from the origi nal aspirate. The other two had no growth on surgical culture. Both ha d had pre-operative antibiotics. Eleven cultures of doubtful significa nce were repeated or regarded as negative and the patients carefully f ollowed-up. One repeat culture confirmed infection emphasizing the imp ortance of repeating doubtful aspirates. The sensitivity of aspiration is 93%, specificity is 96%. The accuracy is 95% confirming that aspir ation is a simple and reliable method of diagnosing infection in hip p rostheses.