Paper of the Week: Poor performance of open incisional biopsy for the microbiological diagnosis of periprosthetic knee joint infection

Jan Schwarze, Burkhard Moellenbeck, Georg Gosheger, Tom Schmidt-Braekling, Lukas Lampe, Sebastian Klingebiel, Thomas Ackmann & Christoph Theil

Sci Rep 11, 10989 (2021)

Summary by Nicholas Siegel, BS

Periprosthetic joint (PJI) infection is a rare but serious complication following total knee arthroplasty (TKA) [1]. Low-grade PJIs can be difficult to diagnose because they do not fulfill the criteria for infection [2–4]. Joint biopsy is one potential option for patients in whom PJI is suspected, but the preoperative workup is inconclusive. Prior studies have shown high sensitivity and specificity for synovial biopsies in the diagnosis of low-grade PJI [5,6]. However, there is a dearth of studies on open synovial biopsies in cases of inconclusive PJI preoperative scoring and the subsequent need for intraoperative findings.

Schwarze et al. investigated the usefulness of open synovial biopsies in patients with suspected PJI and inconclusive preoperative serum and synovial markers. They retrospectively reviewed 63 patients with painful or radiographically loosened TKA who underwent incisional biopsy after inconclusive diagnostics for PJI from 2010 to 2018. A biopsy was performed prior to revision surgery. Primary outcome was cultures of five diagnostic biopsies compared against 3-5 intraoperative deep tissue sample cultures from the subsequent revision surgery. Sensitivity and specificity of the incisional biopsy was calculated by diagnosis of PJI based on ICM criteria from findings of the revision surgery.

The study found 27 patients (43%) had a positive culture taken during biopsy. Based on these results, 19 patients (30%) were diagnosed with PJI. The most frequent microbiological findings were coagulase-negative staphylococci in 18 cases (67%) and Cutibacterium acnes in 8 cases (30%). Of the 19 patients diagnosed with PJI based on the incisional biopsy, the diagnosis of PJI was confirmed in 9 cases using the samples taken during the revision surgery. Biopsies had a sensitivity of 47% and a specificity of 77% for PJI. 

The authors concluded that open biopsy following inconclusive diagnostics for low grade PJI may be considered but should be combined with additional diagnostic markers and histological investigation. The primary limitations of the study were its retrospective nature with low numbers, lack of histological analysis of tissue, and inconsistent serum analysis due to changing guidelines during the study period.


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