To determine the content and sulfation pattern of keratan sulfate (KS) in synovial fluid (SF) from patients with hip osteoarthritis (OA) and investigate its significance as a marker of cartilage matrix metabolism.
Hip SF samples were aspirated from 50 patients with OA. KS in the samples was digested to 2 disaccharide isomers, beta-galactosyl-(1-4)-6-0-sulfo-N-acetylglucosamine (L2) and beta-6-0-sulfo-galactosyl-(I-4)-6-0-sulfo-N-acetylglucosamine (LA) by keratanase II. Concentrations of these disaccharide isomers were determined by high performance liquid chromatography (HPLC), and their levels were investigated in relation to radiological stage of disease.
Analysis of covariance (age as covariate) showed that the L2 levels in advanced stage OA were significantly lower than in early stage OA (p < 0.0001). L2 levels in terminal stage OA were also significantly lower than in early stage OA (p < 0.0001); however, no significant difference was observed between the L2 levels in advanced and terminal stage OA (p = 0.516). There were no significant differences in the levels of L4, L2 + L4, or the ratio of L4 to L2 at each disease stage.
The levels of KS related disaccharide isomer vary with severity of disease in hip OA. Analysis of these KS related disaccharide isomers by HPLC provides information on both the content and sulfation pattern of KS in SF, reflecting the metabolism of cartilage aggrecan.