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Updated: Jan 12, 2026
Novel Diagnostics in Revision Arthroplasty: Implant Sonication and Multiplex Polymerase Chain Reaction
Published on: December 3, 2017
Low Synovial Lymphocyte Percentage as a Novel Diagnostic Marker of Periprosthetic Joint Infection
Assil-Ramin Alimy1, Jonah Sijakov1, Nico Maximillian Jandl1
1Department of Trauma and Orthopedic Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Objectives:
Correctly diagnosing periprosthetic joint infection (PJI) remains a major clinical challenge. While acute PJI is straightforward to identify because of its pronounced clinical presentation, chronic infections remain challenging to detect since clinical signs are subtle and standard criteria lack sensitivity. By analyzing a wide range of serum and synovial parameters in patients undergoing revision arthroplasty, we sought to identify the most accurate diagnostic PJI markers.
Methods:
A retrospective analysis of 400 patients undergoing knee or hip revision arthroplasty, including 145 patients who had PJI and 255 patients who had aseptic failure, was conducted. Diagnosis of PJI was established using the 2018 International Consensus Meeting criteria. A comprehensive evaluation of medical records, serum, and synovial biomarkers was performed. For each marker, receiver operating characteristic curves, calculating the area under the curve and optimal cutoff values, were determined.
Results:
Synovial biomarkers such as alpha-defensin and C-reactive protein did not demonstrate superior diagnostic performance compared with polymorphonuclear neutrophil (PMN) count and percentage. Importantly, low synovial lymphocyte percentage (<34.7%) emerged as the most accurate marker for PJI diagnosis (area under the receiver operating characteristic curve [AUC] = 0.96, sensitivity = 0.85, specificity = 0.96), independent of location or infection subtype (acute and chronic). This was further supported by a conditional inference tree model for diagnosing chronic PJI, which identified synovial lymphocyte percentage and PMN count as key decision nodes and demonstrated excellent diagnostic performance (AUC = 0.95; sensitivity = 0.93; specificity = 0.91).
Conclusions:
Our study provides evidence that low synovial lymphocyte percentage is a reliable diagnostic marker of PJI. Integrating the assessment of synovial lymphocytes into clinical practice could enable more timely diagnosis and, therefore, effective treatment, ultimately improving patient outcomes. However, as this was a single-center study limited to hip and knee revision, external validation is warranted to confirm the generalizability of our findings.
Level Of Evidence:
Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.
Insights
Low synovial lymphocyte percentage is a highly accurate marker for diagnosing periprosthetic joint infection (PJI). This finding could lead to earlier detection and improved treatment for patients with chronic PJI.
Area of Science:
- Orthopedic surgery
- Infectious diseases
- Biomarker research
Background:
- Periprosthetic joint infection (PJI) diagnosis is challenging, especially for chronic cases with subtle clinical signs.
- Current diagnostic criteria for PJI lack sufficient sensitivity for chronic infections.
Purpose of the Study:
- To identify accurate diagnostic markers for periprosthetic joint infection (PJI) in patients undergoing revision arthroplasty.
- To evaluate serum and synovial fluid parameters for PJI detection.
Main Methods:
- Retrospective analysis of 400 patients (145 with PJI, 255 with aseptic failure) undergoing hip or knee revision.
- Diagnosis confirmed using 2018 International Consensus Meeting criteria.
- Evaluation of serum and synovial biomarkers, including polymorphonuclear neutrophil (PMN) count and lymphocyte percentage, using receiver operating characteristic curves.
Main Results:
- Synovial alpha-defensin and C-reactive protein were not superior to PMN count/percentage.
- Low synovial lymphocyte percentage (<34.7%) showed high diagnostic accuracy for PJI (AUC=0.96, sensitivity=0.85, specificity=0.96).
- A conditional inference tree model identified synovial lymphocyte percentage and PMN count as key for chronic PJI diagnosis (AUC=0.95).
Conclusions:
- Low synovial lymphocyte percentage is a reliable diagnostic marker for PJI.
- Incorporating synovial lymphocyte assessment may improve timely PJI diagnosis and treatment.
- External validation is needed due to the single-center, hip/knee-specific nature of the study.
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