Table 4: Comparison of results for sensitivity and specificity for interstage aspiration by different authors.

AuthorDefinition of persistent infectionJointsSFCSWBCC
SensitivitySpecificityCut-offSensitivitySpecificity

Hoell et al. 2016at least two identical tissue cultures at SES56 Hip- and 59 Knee-Spacers0.050.999700.3130.391

Newman et al. 2017modified MSIS at SES77 Hip-Spacers0.301.0011660.760.78

Zmistowski et al. 2017positive tissue culture at SES, and/or subsequent surgery for PJI after reimplantation40 Hip- and 88 Knee-Spacers--12340.4440.755

Muhlhofer et al. 20182 positive tissue cultures at SES92 Hip- and Knee- Spacers (60 for SWBCC)0.060.92-0.100.81

Boelch et al. 2018modified IDSA criteria at SES92 Hip-Spacers0.050.9420000.250.969

this studyhistopathologic sign of infection persistence at SES62 Knee-Spacers (28 for SWBCC)0.031.0032500.3570.929
at least two identical tissue cultures at SES or growth of a virulent microorganism94 Knee-Spacers (39 for SWBCC)0.000.9944500.500.865

SFC: synovial fluid culture; SWBCC: synovial white blood cell count; SES: second stage; PJI: periprosthetic joint infection; MSIS: Musculoskeletal Infection Society.