A "Dry Tap" in Prosthetic Joint Infection Workup of Total Hip Arthroplasty Is Not Reassuring
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Updated: Jul 10, 2026
Novel Diagnostics in Revision Arthroplasty: Implant Sonication and Multiplex Polymerase Chain Reaction
Published on: December 3, 2017
Emily A Treu1, Nathan F Behrens1, Brenna E Blackburn1
1Department of Orthopaedics, University of Utah, Salt Lake City, Utah.
Background:
Synovial fluid analysis is important in diagnosing prosthetic joint infection (PJI). The rate of culture-positive PJI in patients who have a dry tap of a total hip arthroplasty (THA) is not well described.
Methods:
We reviewed all image-guided THA aspirations, performed from 2014 to 2021 at a single academic institution. Aspirations were categorized as successful (≥ 0.5 mL) or unsuccessful (< 0.5 mL, "dry tap"). We analyzed culture data on all repeat aspirations and revision surgeries performed within 90 days of the initial dry tap.
Results:
We reviewed 275 consecutive attempted THA aspirations of which 100 (36.4%) resulted in a dry tap. The dry tap cohort had a significantly higher percentage of fluoroscopic-guided aspirations (64%) and fewer ultrasound-guided aspirations (36%) compared to the successful aspiration cohort (48.9% fluoroscopic, 53.1% ultrasound, P = .0061). Of the 100 patients who have dry taps, 48 underwent revision surgery within 90 days of the initial dry tap, and 15 resulted in 2 or more positive cultures. The rate of PJI defined by MusculoSkeletal Infection Society major criteria in the dry tap cohort was 16.0%.
Conclusions:
Attempted aspiration of a THA resulted in a dry tap 36.4% of the time. Of those patients who had a dry tap, 16.0% were subsequently found to have PJI based on MusculoSkeletal Infection Society major criteria. Therefore, a "dry tap" does not exclude the diagnosis of infection and should not be considered reassuring for the absence of PJI.
Insights
A dry tap during total hip arthroplasty (THA) aspiration occurred in 36.4% of cases. Importantly, 16.0% of these dry tap patients were later diagnosed with prosthetic joint infection (PJI), indicating a dry tap does not rule out infection.
Area of Science:
- Orthopedic surgery
- Infectious disease diagnostics
- Arthroplasty care
Background:
- Synovial fluid analysis is crucial for diagnosing prosthetic joint infection (PJI).
- The diagnostic yield of a
Purpose of the Study:
- To determine the rate of culture-positive prosthetic joint infection (PJI) in patients with a "dry tap" during total hip arthroplasty (THA) aspiration.
- To evaluate the clinical significance of unsuccessful arthrocentesis in the context of suspected PJI.
Main Methods:
- Retrospective review of 275 image-guided THA aspirations (2014-2021).
- Aspirations classified as successful (≥0.5 mL) or unsuccessful ("dry tap", <0.5 mL).
- Analysis of culture data from repeat aspirations and revision surgeries within 90 days of initial dry tap.
Main Results:
- A "dry tap" occurred in 100 of 275 (36.4%) THA aspirations.
- The dry tap cohort showed a higher rate of fluoroscopic guidance (64%) versus ultrasound (36%).
- In the dry tap cohort, 16.0% were diagnosed with PJI based on Musculoskeletal Infection Society major criteria.
Conclusions:
- A "dry tap" during THA aspiration is common, occurring in over a third of cases.
- A significant proportion (16.0%) of patients with a dry tap were subsequently diagnosed with PJI.
- A "dry tap" should not be considered reassuring and does not exclude the possibility of prosthetic joint infection.
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