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Updated: Nov 6, 2025
Novel Diagnostics in Revision Arthroplasty: Implant Sonication and Multiplex Polymerase Chain Reaction
Published on: December 3, 2017
Diagnosis of knee prosthetic joint infection; aspiration and biopsy
Omer Salar1, Jonathan Phillips1, Robert Porter2
1Department of Trauma and Orthopaedics, Exeter Knee Reconstruction Unit, Princess Elizabeth Orthopaedic Centre, Royal Devon and Exeter Hospitals, Barrack Road, EX2 5DW, United Kingdom.
Background:
Prosthetic joint infection (PJI) is a significant cause of morbidity and mortality following knee replacement surgery. The diagnosis can be challenging and is based on a combination of clinical suspicion, radiographic findings and also biochemical/ microbiological investigations. Our Aim was to review the role of aspiration and biopsy in the diagnosis of PJI in Total Knee Arthroplasty (TKA).
Method/Results:
Aspirated synovial fluid should be analysed by direct culture, via blood culture bottles, EDTA bottles for cell count and 'point of care' testing such as leucocyte esterase or alpha defensin. Synovial WCC and PMN cell percentage are important steps in diagnosis of both acute and chronic PJI. A minimum of 5 deep samples using a 5 clean instrument technique should be obtained and sent for tissue culture done either blind or arthroscopic. Formal fluoroscopic guided interface biopsy has also been described with excellent results. In a recent series of 86 TKRs preoperative arthroscopic biopsy group had a sensitivity of 100%, specificity of 94.7%, positive predictive value of 87.4% and a negative predictive value of 100%.
Conclusion:
In the presence of clinical suspicion with raised biomarkers, it is recommended that aspiration +/- biopsy with synovial fluid testing is performed. Direct culture and cell count are recommended. 'Point of care tests' such as Leucocyte Esterase testing should be considered. Duration of culture, including pathogen and host factors, should be discussed with a local microbiology/ID department in the context of a formal multi-disciplinary team.
Insights
Diagnosing prosthetic joint infection (PJI) after knee replacement requires synovial fluid analysis. Aspiration and biopsy, along with cell counts and point-of-care tests, are crucial for accurate PJI diagnosis.
Area of Science:
- Orthopedic Surgery
- Infectious Diseases
- Diagnostic Medicine
Background:
- Prosthetic joint infection (PJI) is a serious complication of knee replacement surgery.
- Diagnosing PJI is challenging, relying on clinical, radiographic, and laboratory findings.
- This review focuses on the diagnostic utility of aspiration and biopsy in Total Knee Arthroplasty (TKA).
Purpose of the Study:
- To review the role of aspiration and biopsy in diagnosing PJI in Total Knee Arthroplasty (TKA).
Main Methods:
- Analysis of aspirated synovial fluid includes direct culture, cell counts (WCC, PMN), and point-of-care tests (leukocyte esterase, alpha defensin).
- Collection of at least 5 deep tissue samples using sterile technique for culture.
- Evaluation of fluoroscopic-guided interface biopsy and arthroscopic biopsy.
Main Results:
- Synovial fluid white cell count (WCC) and polymorphonuclear cell (PMN) percentage are key diagnostic indicators.
- Preoperative arthroscopic biopsy in one series showed 100% sensitivity and 94.7% specificity for PJI detection.
- Interface biopsy techniques have demonstrated excellent diagnostic results.
Conclusions:
- Aspiration and synovial fluid testing are recommended when PJI is clinically suspected and biomarkers are elevated.
- Direct culture and cell count of synovial fluid are essential diagnostic steps.
- Consider point-of-care tests like Leucocyte Esterase; consult microbiology for optimal culture duration.
