Synovial fluid studies in navicular disease.
Authors: Viitanen, Bird, Makela, Schramme, Smith, Tulamo, May
Journal: Research in veterinary science
Summary
# Editorial Summary: Synovial Fluid Biomarkers in Navicular Disease Viitanen and colleagues investigated whether biochemical changes in navicular bursal fluid could be reliably detected through distal interphalangeal (DIP) joint synovial sampling, comparing 18 affected navicular bursae and 35 DIP joints from horses with navicular disease against healthy controls (16 joints). Using cartilage oligomeric matrix protein (COMP) as an internal standardiser to account for dilution effects, the researchers measured glycosaminoglycans (GAG), hyaluronan (HA), and matrix metalloproteinases (MMP-2 and MMP-9) across both synovial compartments. Navicular disease was characterised by significantly depleted GAG levels in both the bursa and DIP joint, whilst HA and both MMPs were markedly elevated, indicating concurrent cartilage degradation and increased collagenolytic activity. Critically, COMP concentrations remained consistent between bursal and DIP fluid in diseased horses, suggesting that DIP joint sampling could serve as a non-invasive diagnostic proxy for navicular bursal pathology when standardised against COMP values. These findings provide clinicians with a potential diagnostic framework for detecting the biochemical hallmarks of navicular disease through readily accessible joint fluid sampling, though further validation of clinical utility in field conditions would strengthen translation to practice.
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Practical Takeaways
- •Synovial fluid biomarkers, particularly elevated MMPs and reduced GAG levels, may aid in diagnosing navicular disease in clinical practice
- •DIP joint fluid sampling may serve as a non-invasive alternative to navicular bursa aspiration for assessing some biochemical markers of navicular disease, though not all markers correlate between sites
- •COMP appears to be a reliable internal standard for normalizing other synovial fluid measurements across different joint compartments in navicular disease evaluation
Key Findings
- •COMP levels in synovial fluid showed no significant difference between navicular bursa and DIP joint in navicular disease, making it suitable for standardizing other measurements
- •Horses with navicular disease showed significantly lower absolute GAG concentration and GAG/COMP ratio compared to healthy horses in both navicular bursa and DIP joint
- •HA concentration, HA/COMP ratio, and MMP-2/COMP and MMP-9/COMP ratios were significantly elevated in DIP joint fluid from navicular disease horses
- •MMP-2 and MMP-9 relative activity levels and their respective COMP ratios were increased in navicular bursal fluid of affected horses compared to controls