Erturk C, et al. - This study was undertaken to shed light on the link between serum oxidized low-density lipoprotein (ox-LDL), oxidative stress, and paraoxonase-1 (PON1) in knee osteoarthritis (OA), using radiological and clinical parameters. An association was evident, between the levels of various serum markers of oxidative injury, especially ox-LDL, and increasing severity of knee OA; indirect evidence for their regulation by PON1 was also found. In the initial course of OA as well as during progression, oxLDL seemed to play a critical role, and hence, serum oxLDL levels may be of help as a biomarker to assess the severity of knee OA.