Viscosupplementation of synovial fluid with xanthan gum for treatment of osteoarthritis and its clearance kinetics in the rabbit knee joint.

BACKGROUND: Injection of xanthan gum (XG) has been demonstrated to reduce the symptoms and progression of osteoarthritis (OA) in experimental models. Due to its high viscosity and stability, it may restore the rheological homeostasis of osteoarthritic synovial fluid (SF), and avoid numerous intra-articular injections.

OBJECTIVE: The present study investigated the effect of XG on the rheological properties of SF, and determined its residence time in the rabbit joint cavity.

METHODS: Rabbit knees were subject to intra-articular injection with XG or XG labeled with green fluorescence, and the SF was collected at different time. Rheological properties of SF with XG injected were compared with those with sodium hyaluronate injected. Resistance to oxidant damage was tested by adding H2O2 to the viscosupplement. Fluorescence intensity was measured for the SF with XG labeled with green fluorescence.

RESULTS: Results showed that XG could significantly improve the SF viscosity at 24, 96, 168 h, and increase the storage moduli (G') and loss moduli (G″) tested at frequency of 0.5 and 2.5 Hz. SF with XG injection exhibited a gel-like behavior at 24 h, in that G' exceed G″ over the entire oscillation frequency range. XG preparation had a high resistance to oxidant damage. Half-life of XG in the joint cavity was 35.9 h, with clearance obeying first-order kinetics.

CONCLUSIONS: Intra-articular injection of XG could improve the rheological properties of SF, and this effect could last for several days.