A needle is inserted into a joint for two main indications: aspiration of fluid (arthrocentesis) for diagnosis or for relief of pressure, or injection of medications. In practical terms, most injections into joints consist of a glucocorticoid, a local anesthetic, or a combination of the two. Occasionally saline is injected into the joint to diagnose a joint injury.
This topic will review the basic technique of inserting a needle into a joint and the main indications for intraarticular steroid injections. The same techniques apply for injection of the less commonly used hyaluronate viscosupplementation agents into knees, hips, and perhaps shoulders.