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Q: I was going to ask my doctor for a steroid injection in my knee that has osteoarthritis, but I heard the steroid shots can do more harm than good. Is that true?

A: Osteoarthritis is a common and potentially debilitating condition. It’s a degenerative joint disease (often called the “wear-and-tear” type) in which the smooth lining of cartilage becomes thinned and uneven, exposing the bone beneath.

Medications, such as acetaminophen, ibuprofen or injections of steroids or hyaluronic acid (a type of lubricant), can help. However, they don’t always work well, don’t cure the condition and may be accompanied by side effects.

Non-medication approaches can also help, such as loss of excess weight, physical therapy or use of a cane or brace. Surgery is usually a last resort, reserved for people who have declining function, unrelenting pain or both despite trying these other treatments.

Steroid injections can quickly provide pain relief that lasts from several weeks to several months. But a new report of one medical center’s experience and a review of past research came to some concerning conclusions about joint injections for osteoarthritis of the hip or knee, including:

—a lack of compelling evidence that they work

—about 7% to 8% of people getting steroid injections seem to worsen

—unusual fractures may occur (in about 1% of people)

—bone damage may develop (in about 1% of people)

Other side effects include a temporary increase in blood sugar, bleeding into the joint and, rarely, infection. And the injection itself can be painful, although numbing medication is usually provided.

The findings of this report are disappointing, especially for those who have not improved with other treatments. Even if the average benefit of a treatment is small, some individuals do report significant improvement with steroid injections.

It’s also not entirely clear that the problems described in this study are actually caused by the steroid injections. And, from my own experience, these rates of complications seem high.

I think steroid injections still have a role in the treatment of osteoarthritis, but only after a careful review of the potential risks and benefits.

If one injection is not terribly helpful, I would not encourage repeated injections. On the other hand, if it works well, a limited number of injections (up to three or four per year is a common limit) may reduce pain and improve function and quality of life.

Restricting the injections to those who improve the most and limiting the number of injections each year may be a better strategy than eliminating steroid injections altogether.

By Robert H. Shmerling, M.D., associate professor of Medicine at Harvard Medical School, senior medical editor at Harvard Health Publishing, and former clinical chief of rheumatology at Boston’s Beth Israel Deaconess Medical Center.

Q: I started a new pain medication, and it seems to be helping. But I wonder if the improvement is just a placebo effect. Can a fake pill be that effective?

A: A placebo is commonly used in clinical trials to test the effectiveness of a specific therapy, especially when evaluating how well a drug works. For instance, people in one group get the tested drug, while the others receive a “fake” drug, or placebo, that they think is the real thing.

This way, the researchers can measure if the drug works by comparing how both groups react. If they both have the same reaction — improvement or not — the drug is deemed ineffective.

However, experts have concluded that reacting to a placebo is not proof that a certain treatment doesn’t work, but rather that another, non-pharmacological mechanism may be present.

How placebos work is still not quite understood. The placebo effect is more than positive thinking — believing a treatment or procedure will work. It involves a complex neurobiological reaction that includes everything from increases in feel-good neurotransmitters, like endorphins and dopamine, to greater activity in certain brain regions linked to moods, emotional reactions and self-awareness.

Results of a study published three years ago in PLOS Biology showed how brain activity differs when people respond to a placebo.

Researchers used functional magnetic resonance imaging to scan the brains of people with chronic pain from knee osteoarthritis. Then everyone was given a placebo and had another brain scan.

The researchers noticed that those who felt pain relief had greater activity in the middle frontal gyrus brain region of the frontal lobe.

Placebos often work because people don’t know they’re getting one. But what happens if they know it’s a placebo?

A 2014 study published in Science Translational Medicine explored this question by testing how people reacted to migraine pain medication. One group took a migraine drug labeled with the drug’s name, another took a placebo labeled “placebo” and a third group took nothing.

The researchers discovered that the placebo was 50% as effective as the real drug to reduce pain after a migraine attack.

The researchers speculated that a driving force beyond this reaction was the simple act of taking a pill. People associate the ritual of taking medicine as a positive healing effect. Even if they know it’s not medicine, the action itself can stimulate the brain into thinking the body is being healed.

By Howard LeWine, M.D., an internist at Brigham and Women’s Hospital in Boston and assistant professor at Harvard Medical School.

For additional consumer health information, visit www.health.harvard.edu.

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