Gundogdu G, et al. - The aim of the researchers was to investigate adropin and tumor necrosis factor alpha (TNF-α) levels and the association between adropin in subjects having knee osteoarthritis (OA) classified by Kellgren-Lawrence (KL). In the knee OA patients vs the healthy controls, lower adropin level and higher TNF-α level were detected. However, parallel to the increase in the KL grade, a significant decrease in adropin level and an increase in TNF-α level was seen. Overall, it was suggested that serum adropin level could be used as a new biomarker indicating the early grade of knee OA.