Injections of hyaluronic acid, also known as viscosupplementation are aimed at reducing joint pain and improving the functional condition of the osteoarthritic joint, in particular, the knee.
Hyaluronic acid is a viscous and elastic substance that is normally produced by the joint and that makes up joint fluid(or "synovial fluid"). The latter is rich in hyaluronic acid in its normal state, and its viscous properties lubricate the cartilage surfaces while its elastic properties protect them from shocks. In osteoarthritis the synovial fluid is depleted in hyaluronic acid making the cartilage more vulnerable to forces of friction and compression.
Injections of hyaluronic acid act more slowly than corticosteroid injections but their effect is longer lasting, reaching up to 8 months to 1 year. Some scientific studies suggest that they may slow the progression of osteoarthritis.
The injection, which is not very painful, is performed by a rheumatologist in a medical surgery. Generally, a very fine needle is used for it.
In the event of persistent local painful reactions, consult your doctor.