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Aug 16, 2023

‘Dry tap’ may not reliably predict absence of infection after THA

Treu E, et al. Paper 1077. Presented at: Musculoskeletal Infection Society Annual Meeting; Aug. 4-5, 2023; Salt Lake City (hybrid meeting). Treu E, et al. Paper 1077. Presented at: Musculoskeletal

Treu E, et al. Paper 1077. Presented at: Musculoskeletal Infection Society Annual Meeting; Aug. 4-5, 2023; Salt Lake City (hybrid meeting).

Treu E, et al. Paper 1077. Presented at: Musculoskeletal Infection Society Annual Meeting; Aug. 4-5, 2023; Salt Lake City (hybrid meeting).

Results presented here showed a “dry tap,” which occurs when little to no synovial fluid is able to be aspirated, may not be a reliable predictor for the absence of infection after total hip arthroplasty.

“We conclude, based on the results of our study, that a dry tap is not synonymous with the absence of infection,” Emily Treu, MD, a fourth-year orthopedic surgery resident at the University of Utah, said in her presentation at the Musculoskeletal Infection Society Annual Meeting.

“Based on these results, we recommend a re-aspiration when there is clinical concern for [periprosthetic joint infection] PJI,” she added.

In a retrospective review of 100 dry taps and 175 successful total hip aspirations from 2014 to 2021, Treu and colleagues compared patient and aspiration characteristics between the two groups. Researchers also evaluated re-aspirations and revision surgeries performed within 90 days of each initial dry tap and documented intraoperative culture results to determine whether a dry tap may be a reliable predictor for the absence of infection.

Researchers defined infection by a single organism having two or more positive intraoperative cultures.

Results showed a dry tap rate of 36.4%, with no significant patient demographic differences in age, BMI or gender between the dry tap and successful aspiration groups. In addition, Treu said that fluoroscopic-guided aspirations were more likely to yield a dry tap than ultrasound.

Treu said 15 patients in the dry tap group underwent re-aspiration, of which six were successful. In addition, she said 48 patients with a dry tap underwent revision surgery. She noted two of the successful re-aspirations had positive cultures and 15 of the revisions had positive cultures at any point within 90 days of revision.

“The success rate in our cohort of re-aspiration was 40%, which we feel is significant enough to offer a good next step in this challenging patient population,” Treu said.