These are commonly referred to as “shock absorbing” injections and are used to treat arthritic joints, most commonly knee joints. They do more than act as shock absorbers however. Joints normally contain small amounts of synovial fluid and this fluid is rich in a substance called hyaluronic acid. The fluid lubricates the joint and nourishes the articular cartilage.
Viscosupplementation agents, such as Synvisc, contain hyaluronic acid. It has been found that arthritic joints have reduced amounts of hyaluronic acid, hence the use of viscosupplementation injections. These injections act as shock absorbers, lubricants and also encourage the joint to produce normal amounts of hyaluronic acid.
The agent is injected directly into the joint under sterile conditions. Up to 3 injections may be necessary. Patients are often immediately aware of the joint feeling smoother when moved. Pain relief is not immediate, however, and can take some days or weeks. The pain relief lasts for a variable amount of time and cannot be predicted before the treatment. Some patients respond much more than others, and this may be a reflection of how well the agent favourably alters the joint environment.
We use these injections in preference to steroid injections in arthritic hip and knee joints because they do not contain steroid and steroid injections into arthritic joints have been shown to result in an increase in the rate of infection when the joint is subsequently replaced. We also use these injections in patients who are not fit for surgery.
The injections have no significant adverse effects. Some patients experience a slight flare-up of their symptoms for a few days after the injection, but this settles quickly.
These injections can be very helpful in relieving the pain of arthritis.
For further details about viscosupplementation as a treatment please click here to view an informative brochure.