But do all these biochemical changes relieve sore, stiff joints? In the largest study of its kind ever conducted, Dr. Berman and his colleagues recruited 570 men and women over 50 who had osteoarthritis of the knee. Some of the study subjects were placed in a group that received 23 acupuncture treatments over the course of a half year or so. For comparison, the researchers gave a control group of study participants a placebo, or phony treatment designed to simulate acupuncture; the investigators used specially designed fake needles that produced the sensation of pinpricks, but didn’t pierce the skin.

The 2004 trial, which was published in the Annals of Internal Medicine, found that after 26 weeks, patients receiving real acupuncture felt significantly less pain and functioned better (as measured by how far they could walk in six minutes) than their counterparts who received fake acupuncture.

The Trouble with Fake Acupuncture

Yet, many other studies comparing real acupuncture to fake or “sham” acupuncture for OA have found needle therapy to be much less effective, points out researcher Eric Manheimer, the lead author of a major 2010 review of the scientific literature on acupuncture and OA and a colleague of Dr. Berman’s at the University of Maryland. However, there are several reasons why trials using sham acupuncture as a placebo may produce disappointing – and misleading – results,  Manheimer explains.

Placebos used in clinical trials are supposed to be inert and have no medicinal value. Yet the fake needles used as placebos in some trials may have stimulated acupuncture points even if they didn’t penetrate the skin. In other trials, investigators have performed sham acupuncture by using real needles, but inserting them randomly – that is, they avoided traditional acupuncture points.

However, some scientists believe that any piercing of the skin could stimulate the neurochemical changes associated with acupuncture. In these scenarios, says Manheimer, unintended pain relief brought on by sham acupuncture may have distorted the study results, since in some cases the fake treatments behaved too much like real acupuncture.

Meanwhile, much greater benefits for OA have been found in research trials where sham acupuncture isn’t used as a placebo. In these studies, patients undergoing acupuncture have been compared to other patients who received only standard care such as pain relievers and physical therapy. Unlike placebo-controlled studies, in these trials patients in the treatment group knew they were receiving real acupuncture.

Some critics argue that these studies aren’t reliable, since patients who know they’re getting an active treatment may be biased, making them more inclined to report feeling less pain and disability. But Dr. Berman feels that these types of studies reflect how medicine works in the real world. “We’re people, and we have our expectations and beliefs. That can be a big part of the overall effect” of acupuncture or any therapy, he says.