Correlation of dickkopf-1 concentrations in plasma and synovial fluid to the severity of radiographic signs of equine osteoarthritis

Summary

Objective: The purpose of this study was to determine whether there was a correlation between circulating and intra-synovial Dkk-1 and radiographic signs of equine osteoarthritis.

Methods: Circulating and intra-synovial Dkk-1 levels were measured in clinical cases using a commercially available human Dkk-1 ELISA. Radiographs were performed of the joints from which fluid was collected and these were assessed and scored by a boarded radiologist for joint narrowing, subchondral bone sclerosis, subchondral bone lysis, and periarticular modelling. Comparisons were made between radiographic scores and the concentrations of Dkk-1 using a Kruskal-Wallis one-way ANOVA. Correlations were calculated using Kendall’s statistic.

Results: A total of 42 synovial fluid samples from 21 horses were collected and used in the analysis. No significant correlation was identified between Dkk-1 concentrations and radiographic signs of osteoarthritis. Intrasynovial Dkk-1 concentrations were significantly greater (p <0.001) in low motion joints (mean concentration, 232.68 pg/mL; range, 109.07–317.17) when compared to high- motion joints (28.78 pg/mL; 0.05–186.44 pg/mL) (p <0.001).

Clinical significance: Low motion joints have significantly higher concentrations of Dkk-1 compared to high motion joints. Further research is needed to establish the importance of this finding and whether potential diagnostic or therapeutic applications of Dkk-1 exist in the horse.

Supplementary material for this article is available at https://doi.org/10.3415/VCOT-16-11-0157

Keywords

Dickkopf-1 - osteoarthritis - radiography - joint motion - equine lameness

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