Joint injections for knee arthritis are of two main kinds:


Steroid (cortisone or similar) injections

These are often given into the joint cavity in order to decrease inflammation. There is frequently some symptomatic relief, but repeated steroid injections may actually harm the joint.

Viscosupplementation (lubricating) injections

These may be injected into the joint cavity to replace lost joint fluid, eg. Synvisc, Hyalgan. Usually an injection a week is given for a total of five weeks. Synvisc (Hylan G-F 20) is a product manufactured by the company, Genzyme Biosurgery. It is a mixture of two gels extracted from hyaluronan, which itself is extracted from chicken combs. Hyaluronan (also called sodium hyaluronate) exists naturally in the human body and acts as a joint lubricant and shock-absorber. Synvisc is administered as a course of injections, and it may be several weeks before maximum improvement is apparent. Some people may demonstrate an allergy to the substance, and it should probably be avoided if you are known to be allergic to poultry products.