Protein Profiling Assays Diagnose Periprosthetic Joint Infection

Molecular markers found in the protein in synovial fluid may aid in the diagnosis of patients undergoing revision arthroplasty for septic or aseptic failure.

Proteomic analysis has the potential as highly sensitive diagnostic tool for periprosthetic joint infection (PJI) that occur during surgical reconstruction or replacement of a malformed or degenerated joint.

Doctors at the Thomas Jefferson University Hospital (Philadelphia, PA, USA) collected synovial fluid specimens from selected patients in the operating room at the time of revision surgery and before incision into the joint (arthrotomy). Samples were assayed to determine the concentration of inflammatory proteins according to MultiAnalyte profiling (MAP) protocols established by Rules-Based Medicine (RBM; Austin, TX, USA). The samples were shipped to RBM for Human Inflammation MAP analysis, which quantifies concentrations of 46 inflammatory proteins in fluid samples using a multiplex enzyme-linked immunosorbent assay (ELISA) protocol.

The scientists analyzed 74 synovial fluid samples: 31 infected and 43 uninfected, based on clinical and laboratory criteria. Proteomics analysis and receiver operating characteristic curve analyses were conducted on 46 inflammatory proteins for each sample. Of the 46 proteins, 5 including interleukin 6, interleukin 8, alpha (2)-macroglobulin, C-reactive protein, and vascular endothelial growth factor had an area under the curve greater than 0.90, indicating their importance in infected joints. Of the infected cases, purulence was identified intraoperatively in 22 cases, and an organism was isolated preoperatively or intraoperatively in 16 cases. The organisms isolated included primarily Staphylococcus and Streptococcus species.

The study demonstrated that inflammatory proteins can be detected in synovial fluid and their concentrations ascertained, and these varying concentrations align well with the presence or absence of PJI. The study was published in September 2011, in the Journal of Arthroplasty.

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Thomas Jefferson University Hospital
Rules-Based Medicine