Hyaluronic acid injections are viscosupplementation treatments that involves injecting a lubricating fluid called hyaluronic acid into the knee. Hyaluronic acid is already present in the joint fluid in healthy knees, but it's found in lower concentrations in joints affected by osteoarthritis.
How viscosupplementation helps the knee
The goal of viscosupplementation is to:
• Reduce pain
• Reduce stiffness
• Improve range of motion
Additionally, the pain relief of viscosupplementation may make it easier to pursue a rehabilitation program of gentle, progressive knee exercises—exercises that may have been too painful to do pre-injection.
Injections like viscosupplementation may provide relief, but knee rehabilitation and exercise is recommended to reduce pain over the long term. These measures can improve knee function and muscle strength to support the knee.
Viscosupplementation is considered a safe procedure, but like any medical procedure it does carry some risks and side effects. Patients should talk to their doctors about these potential risks and complications, which are described below.
Viscosupplementation Side Effects
Patients who undergo viscosupplementation may have mild discomfort immediately after the procedure. Typical side effects at the injection site may include:
• Localised swelling
• Skin warmth and redness
• Joint stiffness
It is estimated that 1% to 3% of patients experience localised swelling and skin changes. Side effects are usually mild and go away in 1 to 2 days.
Aside from side effects, viscosupplementation carries a few risks, although rare.
- Swelling and inflammation. The most common side effects of viscosupplementation can be mild pain, swelling, and inflammation at the site of injection. Rarely, these symptoms are pronounced enough to require immediate medical care.
- Infection. While very uncommon, any injection into the knee carries a risk of infection.
- Allergic reaction. A small very number of people have an allergic reaction to the injected material. Patients should let their doctors know if they have allergies to eggs, bird-feathers, or other bird products, as some viscosupplementation injections may spur an allergic reaction.
- Bursitis. It is possible that a viscosupplementation injection will irritate or inflame a nearby bursa, and potentially cause bursitis symptoms.
These complications are uncommon. If patients experience signs or symptoms of these conditions they should seek medical care.