Viscosupplementation is a medical procedure during which lubricating fluid is injected into a joint. Also called hyaluronic acid injections or hyaluronan injections, viscosupplementation is most commonly used to treat symptoms of symptoms of knee osteoarthritis.
Hyaluronic acid is a key component of the joint fluid in healthy joints, but is found in lower concentrations in osteoarthritic joints
By adding hyaluronic acid to the existing joint fluid of an osteoarthritic knee, the goal is to:
- Facilitate better knee movement
- Reduce pain
- Perhaps slow osteoarthritis progression
Typical candidates for viscosupplementation are people with knee osteoarthritis who have failed to improve with other non-surgical treatments.
Following the injections, it is generally recommended that patients engage in a rehabilitation program that includes gentle, progressive knee exercise. The goals of rehabilitation are to improve range of motion and develop muscle strength to support the knee.
How Viscosupplementation Works
During viscosupplementation a small amount of hyaluronic acid, often just 2 mL, is injected directly into a joint capsule.
A healthy knee joint has up to 4 mL of joint fluid within the joint capsule. 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. Experts believe this further accelerates the joint degeneration process, setting in place a vicious cycle.
As its name implies, viscosupplementation artificially supplements the joint fluid’s natural viscosity. By injecting a man-made hyaluronan into the knee, doctors hope to temporarily lubricate the knee joint, thereby decreasing pain, improving function and perhaps even slowing the degeneration process.
When successful, viscosupplementation can provide knee osteoarthritis pain relief for 3 months or even a year, with the greatest pain relief typically found between 5 and 13 weeks.
While viscosupplementation works for some knee osteoarthritis patients, it is not an effective treatment for everyone. However, most physicians still consider it a useful treatment option, to be used when other methods of non-surgical pain relief have failed to provide sufficient pain relief.
Can Viscosupplementation Treatment be Repeated?
When the pain relief wears off, patients may get another series of injections. Doctors and insurance companies typically require at least 6 months in between the initial injection and the second round of injections, but some insurance companies will only approve it yearly.
Viscosupplementation treatments can be repeated one or more times but may not work indefinitely. Osteoarthritis is likely to progress, and over time a patient may find viscosupplementation injections no longer provide adequate pain relief.
If the initial knee injection series does not provide meaningful pain relief, subsequent injections are not likely to provide pain relief and are not recommended, although sometimes a physician will try a different name brand of the medication. Some common name brands used in our office are Synvisc, Synvisc One, Euflexxa, Gel-One, Monovisc, Orthovisc and Supartz.
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 include:
- Localized swelling
- Skin warmth and redness
- Joint stiffness
It is estimated that 1% to 3% of patients experience localized 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.
- Extreme swelling and inflammation. The most common side effects of viscosupplementation are pain, swelling, and inflammation at the site of injection. Occasionally, these symptoms are pronounced enough to require immediate medical care.
- Infection. While not common, any injection into the knee carries a risk of infection.
- Allergic reaction. A small 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.