Hyaluronic acid is a naturally occurring substance found in synovial fluids that lubricate the joints. With osteoarthritis, this substance can rapidly break down and lead to worsening of the condition. Intra-articular injections have been used to increase lubrication, reduce pain, and improve the range of motion in a joint.

Hyaluronic acid injections are used to treat  osteoarthritis and improve the functions of the knee joint. This treatment method is called viscosupplementation.During a hyaluronic acid injection (viscosupplementation), a small amount of hyaluronic acid, often just 2 mL, is injected directly into the knee joint capsule.

The goals of treating knee osteoarthritis with hyaluronic acid injections are to:

• Reduce pain
• Improve joint movement by increasing joint lubrication and reducing joint friction and inflammation
• Perhaps slow osteoarthritis progression
• Hyaluronic acid injections are usually given at a doctor’s office. Depending on the brand used, this treatment involves 1, 3, 4, or 5 injections. If more than one injection is needed, injections are given one week apart.

A healthy knee joint contains up to 4 mL of joint fluid. 3 Hyaluronic acid is a key component of the joint fluid. It gives the joint fluid its viscous, slippery quality, which does the following:

Enables the bones’ cartilage-covered surfaces to glide against each other, thereby reducing joint friction
Adds cushion to protect joints during impact (e.g. weight-bearing activity)

Joints affected by osteoarthritis typically have a lower concentration of hyaluronic acid in their joint fluid than healthy joints, and therefore less protection against joint friction and impact. 4 Experts believe this further accelerates the joint degeneration process, setting in place a vicious cycle.

Who Can Get Hyaluronic Acid Injections for Knee Osteoarthritis?

Hyaluronic acid injection is not a first-line treatment for knee osteoarthritis. This treatment may be considered for those who:

• Have moderate knee osteoarthritis with symptoms that affect daily living.
• See Knee Osteoarthritis Symptoms

Do not take pain medication because they:

Have little or no benefit from pain relieving medications, such as non-steroidal anti-inflammatory drugs (NSAIDs), and/or steroids (tablets or injectable). Some people may also choose to avoid these medications.
Are at a risk of side effects such as kidney damage, heart problems, and/or abdominal bleeding with long-term use of NSAIDs.
Have other conditions, such as diabetes or high blood pressure, and cannot take medications such as steroids.