The association between collagen and bone biomarkers and radiographic osteoarthritis in the distal tarsal joints of horses.
Authors: Coppelman E B, David F H, Tóth F, Ernst N S, Trumble T N
Journal: Equine veterinary journal
Summary
# Distal Tarsal Osteoarthritis: Synovial Biomarkers Show Promise for Grading Disease Severity Osteoarthritis of the distal intertarsal and tarsometatarsal joints represents a significant clinical problem in horses, yet identifying early or progressive changes remains challenging in practice. Coppelman and colleagues investigated whether synovial fluid biomarkers reflecting collagen breakdown and bone turnover could provide objective measures of disease presence and severity by collecting joint fluid from 16 affected joints (mild to moderate radiographic changes) and 13 control joints in adult horses, then measuring four biomarkers via ELISA: CPII and C2C (collagen markers), BAP (bone metabolism), and CS846 (chondroitin sulfate). All three collagen and bone markers showed strong positive correlations with radiographic osteoarthritis scores—CPII demonstrated the strongest relationship (R = 0.84)—with affected joints exhibiting substantially elevated concentrations across the board; for instance, CPII levels in arthritic joints averaged nearly four times higher than controls (2174 versus 595 ng/mL). Whilst radiographic examination only was performed rather than lameness assessment, and age differences between groups may have influenced results, these findings suggest that synovial fluid biomarker analysis could potentially serve as a more sensitive early detection tool or objective severity gauge for tarsal osteoarthritis than radiography alone, offering farriers and veterinarians a quantifiable complement to standard diagnostic imaging when evaluating chronic distal limb problems.
Read the full abstract on PubMed
Practical Takeaways
- •Synovial fluid biomarkers (CPII, C2C, CPII/C2C ratio) may help detect early radiographic OA in distal tarsal joints when radiographs are inconclusive or monitoring disease progression
- •CPII appears more sensitive than other markers for mild OA, potentially offering an earlier diagnostic signal than bone turnover markers (BAP) or chondroitin sulfate epitopes
- •Age must be considered when interpreting biomarker results, as CPII and C2C naturally increase with age independent of OA status
Key Findings
- •CPII, C2C, BAP, and CPII/C2C ratios positively correlated with radiographic OA severity (R = 0.41–0.84, all P ≤ 0.03)
- •CPII, C2C, and CPII/C2C were significantly elevated in joints with radiographic OA compared to controls (e.g., CPII 2174 ± 1064 vs 595 ± 463, P < 0.001)
- •CPII distinguished even mild radiographic OA from controls (1515 ± 585 vs 658 ± 417, P = 0.04), whereas CS846 showed no difference
- •Age positively correlated with CPII and C2C concentrations but controls were not age-matched to OA groups