Their study investigated whether the food supplement could prevent painful flare-ups in patients who had already been taking it for two years on average, with some signs of benefit.
The results showed that there was little difference with placebo: 42 per cent of placebo patients experienced flare-ups in the six-month follow-up, compared with 45 per cent in the glucosamine group.
In addition, subjects using glucosamine flared as quickly and as severely as those using a placebo, reported the researchers in this month's Arthritis and Rheumatism (15;51(5), pp738-45).
The study, which used medicinal grade glucosamine, a purified derivative from shellfish, follows a series of conflicting results on the benefit of glucosamine for osteoarthritis.
However the supplement continues to see annual growth of around 10 per cent in the joint health category, with consumption of between 4,000-6,000 tons annually.
This is driven by rising numbers of arthritis sufferers - more than 7 million adults in the UK or 15 per cent of the population have long-term health problems due to arthritis and related conditions, according to the Arthritis Research Campaign, and 550,000 have moderate to severe osteoarthritis in their knees.
Madeleine Devey, scientific advisor to the Arthritis Research Campaign in the UK, noted that trials on osteoarthrits pose significant challenges regarding the outcome measures.
"Researchers are very reliant on subjective things like pain and how you feel and there has been a lot of criticism of outcome measures. The big problem with glucosamine is that there is a massive placebo effect - you get episodes of pain and then it resolves," she told NutraIngredients.com.
"It think the jury is still out on glucosamine, it is a very controversial area," she said, adding that a major government-funded trial in the US, called GAIT, may help to clear up some of the confusion when it releases results next year.
The Canadian trial followed 137 patients, aged 44-88, living in four Canadian centres: Vancouver, Winnipeg, London and Saint John. All participants had reported at least moderate improvement with use of the supplement prior to the study.
Lead investigator Dr Jolanda Cibere, from the University of British Columbia, said: "Our study shows that even if the supplement was initially perceived by study participants to be helpful, it has no benefit for maintenance and continued use is not effective to control flare-ups."
European glucosamine suppliers were unavailable to comment on the study.