Synvisc is a gel-like solution that is very similar in composition to the natural joint fluid usually produced by the knee.

It is used for intra-articular injection into the knee in patients with osteoarthritis (and is given as a single injection).

When injected into the knee joint, it has been shown to reduce pain and improve knee function in up to 80% of patients and the effect can last for 6 to 12 months. The magnitude and duration of this effect tends to be greater in those with milder arthritis. Top-up injections can be done at regular intervals, but there is an increased risk of hypersensitivity reactions with repeated exposure.