Some people who have constant pain in their knees have a condition called osteoarthritis. Unlike the temporary pain and inflammation caused in a joint by an overactive immune system response, osteoarthritis is a degenerative joint disease.
Osteoarthritis mostly affects the cartilage. Cartilage is the tissue that covers the ends of bones in a joint. When healthy, cartilage allows bones to glide over one another and provides a "shock absorber" function. The normal knee joint also contains a small amount of fluid called synovial fluid, which is a thick, gel-like substance that cushions the joint and provides lubrication to reduce friction.
Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy
In osteoarthritis, the surface layer of cartilage breaks down and wears away. Adding to the problem, the synovial fluid in your knees loses its ability to lubricate the joint. This combination causes pain and stiffness, limitation of joint motion, and some inflammation in your knees.
Viscosupplementation is a procedure in which a thick fluid called hyaluronate is injected into the knee joint. There are no cures for osteoarthritis, so viscosupplementation will not cure osteoarthritis of the knee. However, it is thought that hyaluronate will improve the lubricating properties of the synovial fluid, reduce the pain from osteoarthritis of the knee, improve mobility, and provide a higher and more comfortable level of activity.
Viscosupplementation is usually reserved until other treatment options have been tried and have not relieved your pain. Three to five injections, each 1 week apart, are required.
Not all patients are helped by the injections. Of those who are, many report feeling some pain relief during the 3- to 5-week course of the injections, while pain relief is delayed in others. Most patients report the greatest pain relief 8 to 12 weeks after beginning treatment. The length of pain relief varies; some patients have reported benefits for more than 6 months following the injections.
The most commonly reported side effects associated with the injections are temporary injection-site pain; swelling, heat, or redness; rash and itching; bruising around the joint; and fluid accumulation in the injected knee. These reactions are usually mild and don't last long. As with steroid injections, infection and bleeding are also rare complications.
Talk to your doctor about viscosupplementation if you have osteoarthritis and have not found pain relief from other means such as exercise, physical therapy, weight loss, use of heat and cold, use of a cane or other product that relieves pressure on the knee, use of pain relievers, or steroid injections.
Last reviewed by a Cleveland Clinic medical professional on 11/04/2014.
Learn more about our editorial process.