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Poor diagnostic validity found with synovial PMMA spacer aspiration for detection of PJI
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Synovial polymethylmethacrylate spacer aspiration had poor diagnostic validity in detecting persistent periprosthetic joint infection before total knee arthroplasty reimplantation, according to results.
To detect periprosthetic joint infection (PJI) in 73 patients who underwent second-stage septic revision total knee arthroplasty, researchers determined the sensitivity and specificity of the synovial polymethylmethacrylate-spacer joint aspiration and referenced this against microbiologic and histologic samples obtained at second-stage surgery.
Results showed synovial spacer aspiration detected persistent PJI in seven patients before second-stage surgery. Researchers noted false-negative results in 27 cases in reference to the intraoperative samples of the second-stage surgery. Bacterial species detected in four of the seven cases of culture-positive synovial spacer aspiration were in agreement with the bacterial species found during explantation. However, researchers found the other three cases of persistent PJI had bacterial species were different from those found during first-stage surgery. – by Casey Tingle
Disclosures: Preininger reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.
Perspective
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Thorsten Gehrke, MD
The strict diagnostic and therapeutic protocol of the ENDO-Klinik in Hamburg makes it possible to perform, in 80% to 85% of our cases, a single-stage septic exchange. In culture-negative PJI, a two-stage procedure is performed with the use of an antibiotic spacer. Timing of second-stage surgery is a key issue, and the evidence of infection control is subject of scientific debate.
We follow the postoperative levels of C-reactive protein (CRP) and clinical signs, like wound healing, pain and body temperature. If all of these parameters are turning normal (CRP of less than 15 mg/L), the infection is considered being under control and re-implantation can be planned. The interval between stages can be kept between 2 weeks and 6 weeks.
Another aspiration is not necessary, as demonstrated in this retrospective study from the Charité (Berlin); the low sensitivity of 21% for detection of persistent PJI makes this diagnostic step unreasonable. As shown at the International Consensus Meeting on PJI in 2013, there was no conclusive evidence regarding the ideal duration of antibiotic therapy. However, a period between 2 weeks to 6 weeks was recommended.
A combination of clinical signs and symptoms, and biochemical markers may be employed for proper timing. There was no evidence supporting an antibiotic holiday prior to reimplantation as a means of ensuring eradication of infection.
References:
Ghanem E, et al. Clin Orthop Relat Res. 2009;doi:10.1007/s11999-009-0742-9.
Kusuma SK, et al. Clin Orthop Relat Res. 2011;doi:10.1007/s11999-010-1619-7.
Parvizi J, et al. Proceedings of the International Consensus Meeting on Periprosthetic Joint Infection; Data Trace Publishing, 2013.
Vielgut I, et al. Int Orthop. 2015;doi:10.1007/s00264-015-2751-5.
Zahar A, et al. Clin Orthop Relat Res. 2016;doi:10.1007/s11999-015-4408-5.
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