Acetaminophen, a common over-the-counter pain reliever, does not work in the treatment of osteoarthritis, a joint disorder afflicting tens of millions of elderly people, according to a study released Friday.

When taken on its own to alleviate pain or enhance mobility, the drug was found to be only marginally -- and insignificantly -- better than a dummy pill, according to a broad survey of 74 clinical trials covering nearly 60,000 patients.

"Our results suggest that (acetaminophen) at any dose is not effective in managing pain in osteoarthritis," said Sven Trelle, the main architect of the meta-study and a researcher at the University of Bern in Switzerland.

Trelle and colleagues evaluated eight different non-steroid anti-inflammatory drugs, taken individually in different doses and in combination with other medications.

The drug that worked best for arthritis, they found, was diclofenac, sold in different countries under the brand names Voltaren, Aclonac and Cataflam.

The results were published in the medical journal The Lancet.

Osteoarthritis is the most common form of joint disease and the leading cause of pain among older people.It occurs when the protective cartilage on the ends of bones wears down over time, causing acute stiffness and pain. The most common joints affected are in the hands, knees, hips and spine.

The condition gradually worsens, and no cure exists. Among people over the age of 60, it affects about 18 per cent of women and 9.5 per cent of men.

"This finding is not entirely unexpected," noted Nicholas Moore and three colleagues from the department of pharmacology at the University of Bordeaux in southwestern France.

"(Acetaminophen) has been on the market for as long as most of us remember. It efficacy has never been properly established or quantified in chronic diseases," they wrote in a comment, also published in The Lancet.