Although there are many nonsurgical therapies available for the treatment of pain
associated with osteoarthritis (OA), their long-term use and safety have not been
systematically followed. Intra-articular (IA) hyaluronan therapy has been used in the
treatment of symptoms associated with OA of the knee with a very favorable safety
profi le (Pagnano and Westrich 2005). In this connection, the physiological and pharmacological
characteristics of HA have recently been reviewed. The high concentration
of HA in spinal fl uid (SF) is essential for normal joint function. The altered properties
of the synovial fl uid in OA, the decrease in molecular size and concentration of
HA leads to reduced rheologic properties, which affect the lubrication and protection
mechanism of action of IA hyaluronan and is probably more complex than previously
thought (Maneiro et al 2004).