Hyaluronic acid injections, also called viscosupplementation or gel injections, are a nonsurgical treatment for knee osteoarthritis. They supplement the joint’s natural lubricating fluid, which deteriorates as arthritis progresses.
In a healthy knee, synovial fluid is rich in hyaluronic acid, a molecule that gives the fluid its viscosity and shock-absorbing properties. In an arthritic knee, the concentration and quality of hyaluronic acid decline. The fluid becomes thinner and less protective, contributing to pain and stiffness.
Viscosupplementation aims to restore some of that lost cushion and lubrication.
The injection delivers a purified hyaluronic acid gel directly into the knee joint. Once inside, it mixes with the existing synovial fluid, increasing viscosity and improving the joint’s ability to absorb shock during movement.
Beyond simple lubrication, hyaluronic acid may also reduce pain through anti-inflammatory effects and by interacting with pain receptors in the joint lining. The exact mechanisms are still being studied, but many patients report meaningful symptom improvement.
Hyaluronic acid injections tend to work best for:
Hyaluronic acid injections are less likely to provide meaningful relief for:
Several FDA-approved hyaluronic acid products are available. They differ in molecular weight, source, and dosing schedule:
The choice of product depends on insurance coverage, patient preference, and clinical judgment. Dr. Zalikha recommends the option best supported by evidence and appropriate for the individual patient.
Hyaluronic acid injections are performed in the office. The procedure is similar to a cortisone injection: the skin is cleaned, a needle is inserted into the joint space, and the gel is injected. The process takes a few minutes. If fluid (an effusion) is present in the knee, Dr. Zalikha may drain it before injecting the hyaluronic acid. This improves the effectiveness of the treatment by reducing dilution of the injected product.
Unlike cortisone, which typically provides fast relief within days, hyaluronic acid works more gradually. Most patients notice improvement over two to four weeks. The effect may continue to build for several weeks after that.
When effective, hyaluronic acid injections can provide relief lasting four to six months, and sometimes longer. The response varies by individual and by the severity of arthritis. Repeat courses can be given, typically every six to twelve months as needed.
| Feature | Corticosteroid | Hyaluronic Acid | PRP |
|---|---|---|---|
| Onset of relief | Days | 2 to 4 weeks | Weeks |
| Duration | Weeks to months | Months | Variable |
| Mechanism | Anti-inflammatory | Lubrication and cushioning | Growth factor stimulation |
| Best for | Acute flares, swelling | Mild to moderate arthritis | Mild to moderate arthritis |
| Insurance coverage | Typically covered | Typically covered | Usually not covered |
| Frequency limit | 3 to 4/year | Every 6 to 12 months | Variable |
