Osteoarthritis (OA) is one of the most common forms of arthritis. The joint pain and stiffness caused by OA can make it difficult to work, play sports and perform daily activities. Anti-inflammatory and analgesic medications may help ease your pain. Your doctor may also recommend physical therapy. If these conservative measures don’t work, it may be time for a corticosteroid injection directly into your aching joint.

Corticosteroids are medications that mimic the effects of the hormone cortisol, which is produced naturally by the adrenal glands. Cortisol affects many parts of the body, including the immune system. It helps lower levels of prostaglandins and downplays the interaction between certain white blood cells (T-cells and B-cells) involved in the immune response. Corticosteroids stimulate this effect to control inflammation.

Not for Everyone

 “While the injections help some patients significantly, at least for a period of time, others do not get much relief at all,” says Jonathan Samuels, MD, assistant professor of rheumatology at New York University Langone Center for Musculoskeletal Care, New York City.

The purpose of the injection is to reduce the irritation caused by bone interacting with bone – which is what happens when the smooth, cartilage interface wears away. Dr. Samuels says there can be several reasons why these direct “steroid shots” sometimes don’t work.

“Some patients’ disease is too far advanced to respond to this approach, and in difficult and bulky knees it may be hard to locate the actual joint space,” Dr. Samuels says. That can result in the medication delivered to the wrong place. Ultrasound guidance, he says, can help put the corticosteroid where it needs to be.

In fact, researchers at the University of North Carolina School of Medicine found ultrasound guidance dramatically improved the accuracy of needle placement in one of the most common joints affected by OA, the knee. Their research showed an ultrasound accuracy of about 96 percent, versus about 78 percent for injections guided simply by anatomy.

No doubt, some patients feel remarkably better after a steroid shot. But Dr. Samuels says it is never the only answer to their pain. “Any candidate for a steroid injection should still receive physical therapy, supportive bracing and oral or topical medication to maximize the response to the injection.”

How Long Will it Last?

Relief from the injections generally does not last forever. Guidelines by American Family Physician put the duration of pain relief at no more than two months. Researchers at Washington University School of Medicine in St. Louis, Mo., pegged steroid shot therapy as “a short-term treatment of a chronic problem.”

Factors such as extent of inflammation and overall patient health can determine how long a steroid shot will last. But Roy Altman, MD, professor of medicine, rheumatology, at UCLA Medical Center, Los Angeles, says with an acute inflammation, single injections can provide very long-term relief – for a year or longer. “It’s so variable. It’s almost like patient selection makes a difference.”