Exploring Freeze-Drying as a Method for Diagnostic Optimization of Synovial Fluid Spectroscopic Data: An ATR-FTIR Analysis on Primary Osteoarthritic Patients

The need for cost-efficient, simple and radiation free technologies in clinical diagnostics has orientated the scientific community in the investigation of techniques such as vibrational spectroscopy. Vibrational spectroscopy due to its simplicity both in sample preparation as well as friendly use combined with the technological evolution in data processing and storage could play a promising role in diagnostics even for multifactorial diseases such as osteoarthritis via biofluid analysis. However, despite the related works aiming in synovial fluid there is not a common line in terms of sample preparation. Hence, it is important to establish an effective sample pretreatment protocol to avoid subjectivity and provide the possibility of reliable comparisons among results. In this work, freeze drying preprocessing technique was compared with natural drying in terms of diagnostic performance in 35 knee synovial fluids aspirated from primary osteoarthritic patients with 2 and 4 Kellgren-Lawrence scores. Principal component analysis combined with mean spectra analysis was implemented for this diagnostic purpose. Results have shown that natural drying technique tends to generate more distinct enhanced interclass variations among synovial dried samples compared to freeze drying, despite the latest potential in other biological samples.