Clinical Study
Synovial Fluid Aspiration Should Not Be Routinely Performed during the Two-Stage Exchange of the Knee
Table 4
Comparison of results for sensitivity and specificity for interstage aspiration by different authors.
| Author | Definition of persistent infection | Joints | SFC | SWBCC | Sensitivity | Specificity | Cut-off | Sensitivity | Specificity |
| Hoell et al. 2016 | at least two identical tissue cultures at SES | 56 Hip- and 59 Knee-Spacers | 0.05 | 0.99 | 970 | 0.313 | 0.391 |
| Newman et al. 2017 | modified MSIS at SES | 77 Hip-Spacers | 0.30 | 1.00 | 1166 | 0.76 | 0.78 |
| Zmistowski et al. 2017 | positive tissue culture at SES, and/or subsequent surgery for PJI after reimplantation | 40 Hip- and 88 Knee-Spacers | - | - | 1234 | 0.444 | 0.755 |
| Muhlhofer et al. 2018 | 2 positive tissue cultures at SES | 92 Hip- and Knee- Spacers (60 for SWBCC) | 0.06 | 0.92 | - | 0.10 | 0.81 |
| Boelch et al. 2018 | modified IDSA criteria at SES | 92 Hip-Spacers | 0.05 | 0.94 | 2000 | 0.25 | 0.969 |
| this study | histopathologic sign of infection persistence at SES | 62 Knee-Spacers (28 for SWBCC) | 0.03 | 1.00 | 3250 | 0.357 | 0.929 | at least two identical tissue cultures at SES or growth of a virulent microorganism | 94 Knee-Spacers (39 for SWBCC) | 0.00 | 0.99 | 4450 | 0.50 | 0.865 |
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SFC: synovial fluid culture; SWBCC: synovial white blood cell count; SES: second stage; PJI: periprosthetic joint infection; MSIS: Musculoskeletal Infection Society.
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