Portable Point-of-Care Synovial Fluid pH Measurement for Rapid Diagnosis of Periprosthetic Joint Infection

Judl T., Jahoda D., Daniel M., Tomšík E., Hrubý M., Fojt J., Mazura M., Barták V., Melicherčík P., Tabačko Š., Beneš M.

Background
Periprosthetic joint infection (PJI) is a serious complication of total joint arthroplasty. Synovial fluid pH reflects the local inflammatory microenvironment and has shown promise as a rapid adjunctive biomarker for infection diagnosis.

Clinical Study
Prospective observational cohort.
190 patients: THA 103, TKA 87.
PJI: 60 (31.6%); non-infected: 130 (68.4%).
PJI classified according to MSIS 2018 criteria.
Synovial fluid pH measured intraoperatively or by aspiration.

Key Findings
Mean pH: 7.07 in PJI vs 7.74 in aseptic/non-infected.
Median pH: 7.11 vs 7.78.
Cut-off: 7.4.
Sensitivity: 90.0%.
Specificity: 96.2%.

Lower synovial fluid pH is strongly associated with periprosthetic joint infection. A cut-off of 7.4 shows high sensitivity and specificity for PJI detection.

From Biomarker to Point-of-Care Device
The concept consists of a portable point-of-care platform designed for rapid measurement using a small-volume synovial fluid sample and single-use disposable sensors. The intended workflow includes aspiration or sample collection, application of a small synovial fluid sample, portable pH measurement, and immediate digital readout.

The platform is intended for bedside, outpatient and intraoperative use and represents a translational step toward routine clinical implementation.

Current Status
The portable prototype has already been tested on a small sample set. However, the number of samples is still insufficient for statistically meaningful validation.

The diagnostic performance shown on this poster reflects synovial fluid pH as a biomarker and should not be interpreted as validated performance of the prototype device.

Why It Matters
Potentially faster decision support.
Simple adjunct to current diagnostic algorithms.
May facilitate wider access to synovial pH testing.

Next Steps
Analytical verification of the prototype.
Prospective clinical testing.
Multicenter validation.
Integration into future smart orthopaedic solutions.

Conclusion
Synovial fluid pH provides a rapid and biologically plausible adjunctive marker for the diagnosis of PJI, with clear separation between PJI and aseptic/non-PJI cases in this cohort. Translation into a portable point-of-care platform could support faster clinical decision-making from small synovial samples at the bedside, outpatient clinic or operating room. Further analytical verification, prospective clinical testing and multicenter validation are required before routine implementation.

Clinically evaluated biomarker. Prototype under validation.

Reference
Judl T, Popelka S, Tomšík E, Hrubý M, Daniel M, Fojt J, Melicherčík P, Landor I, Jahoda D. Acidity Is an Excellent Marker of Infection in Hip and Knee Arthroplasty. J Clin Med. 2024;13(3):688. doi: 10.3390/jcm13030688. PMID: 38337382.

Paper No. 414 – Category: Diagnosis