Hyaluronic acid is a protein which is found naturally in all living organisms. In humans it is found in the skin and also in the articular cartilage and synovial fluids within joints such as the knee. It's role is to help with lubrication of the joint.
As we get older, the body produces less hyaluronic acid. This explains much of why the skin becomes wrinkly and less elastic and why joint movement becomes stiffer and sometimes painful.
Hyaluronic acid is important for the homeostatis (maintenance of a constant level) of synovial joints. It helps to maintain synovial fluid viscosity, as well as stimulating cell function in the articular cartilage which lines the joint.
What are Hyaluronic Acid Injections?
Hyaluronic acid injections are sometimes used for those with osteoarthritis, especially in the knee joint. This treatment is sometimes also known as viscosupplementation.
In cases of OA, the articular cartilage has started to wear away which in turn reduces the concentration of hyaluronic acid within the joint. This can account for the increase in susceptibility to knee cartilage injuries, as well as the deterioration of existing conditions.
Hyaluronic acid injections are used to supplement the bodies own stores. The acid used for the injection is obtained from either animals (Rooster's combs) or humans, or can be genetically engineered.
What to Expect
When you go for your injection, the Doctor will start by cleaning the knee with an alcohol solution to kill any bacteria on the skin and reduce the risk of infection.
If there is lots of fluid on the knee they may drain this off first. They will then inject the hyaluronic acid directly into the knee joint. After the injection you should try to avoid any heavy weight bearing or impact for up to 48 hours. After this period you can resume as normal.
A course of treatment is usually recommended which ranges from 3-5 injections, at weekly intervals.
How Effective are Hyaluronic Acid Injections?
Hyaluronic acid injections appear to be more effective in some people than others. They tend not to work as well in severe cases of osteoarthritis, or in older people.
Generally though HA injections are comparable in effectiveness to Corticosteroids and NSAID's (non-steroid anti-inflammatories) such as ibuprofen. The main benefit of HA injections is the reduced systemic side-effects. The only side effects tend to be soreness at the injection site and initial knee swelling.