More severe joint disease and lower patient oxygenation are associated with less corrosive in vivo synovial fluid in patients with knee osteoarthritis.

Aims: Electrochemical properties of synovial fluid are variable among patients and can lead to implant corrosion, negatively impacting their longevity. The purpose of this study was to explore the relationships between electrochemical properties of synovial fluid of knee osteoarthritic (OA) patients undergoing total knee arthroplasty (TKA) and their clinical and demographic data. Methods: Knee OA patients undergoing TKA were enrolled in this study, and samples of their synovial fluid were collected during surgery and immediately injected into a three-electrode electrochemical cell to measure their electrochemical properties, including open circuit potential, polarization resistance, and cathodic current density. Synovial fluid samples from 43 patients were collected (25 females; mean age 69.9 years (SD 7.6); mean BMI 27.6 kg/m Results: Significant correlations were found between disease severity and both the polarization resistance and the cathodic current density, between WOMAC stiffness scores and polarization resistance, and between KSS knee scores and both open circuit potential and cathodic current density. Finally, patients with a history of oxygen-reducing medical conditions had larger open circuit potential than patients without this kind of medical history. Conclusion: For the first time, correlations between patients' characteristics clinical and an in vivo electrochemical measurement have been obtained. The results showed that patients with more severe disease and more symptoms had less corrosive synovial fluid. Moreover, this study showed lower corrosive properties of synovial fluid in patients with a history of oxygen-reducing medical conditions, highlighting the critical role of oxygen in corrosion.