Hyaluronan injections can relieve knee ailments

Q: I heard there's this goop that you can get injected into your knee that can ease pain. True?

Yes. The goop is hyaluronan, which is a thick lubricant and shock absorber in joint fluid. Hyaluronan injections - also called viscosupplements - are given to people with osteoarthritis.

Viscosupplementation began in Japan and Italy in 1987, in Canada in 1992, in Europe in 1995 and in the United States in 1997.

Some anatomy
The knee, which is the largest joint in the body, is made up of the thighbone (femur), shin bone (tibia) and the kneecap (patella). Surfaces of this joint are covered with cartilage, a smooth substance that cushions the bones and enables them to move easily. The lateral meniscus and medial meniscus are pads of cartilage that further cushion the joint, acting as shock absorbers between the bones.

In addition, surfaces of the knee are covered by a thin, smooth tissue liner called the synovial membrane. This membrane releases fluid that lubricates the knee and reduces friction.

Osteoarthritis is a degenerative joint disease which primarily affects cartilage. The cartilage erodes and the synovial fluid loses its ability to lubricate the joint.

This breakdown causes pain, stiffness and limited range of motion.

Hyaluronan is injected into the knee to improve lubrication and reduce the symptoms of osteoarthritis.

There are several versions of hyaluronan injections for osteoarthritis in knees. These include Euflexxa, Hyalgan, Orthovisc, Supartz, Synvisc and Nuflexxa.

Hyaluronan injections are recommended when conservative treatments - medications, physical therapy, heat/cold - aren't working. The injections produce their best results if the patient is in the early stages of osteoarthritis. Possible side effects of these injections include joint swelling and pain.

The course of treatment depends upon the drugs used. The injections are usually given weekly. Synvisc-One is a single- injection viscosupplement.

In an analysis of eight hyaluronan trials involving 971 patients, outcomes in patients treated with hyaluronan were superior to outcomes in patients treated with placebo.

The most significant pain relief occurred eight to 12 weeks after the first injection for most patients.

Studies have shown that Synvisc and Hyalgan provide pain relief from knee osteoarthritis for up to six months. Supartz was shown in studies to provide pain relief for up to four-and-a-half months after the fifth injection. Patients may be able to repeat the course of treatment with hyaluronan injections.

Medicare and most insurance companies now cover viscosupplementation with restrictions.