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MELBOURNE, Australia – A widely used and affordable diabetes medication, metformin, may offer significant pain relief to individuals suffering from knee osteoarthritis, particularly those who are overweight or obese, according to findings from a Monash University-led clinical trial. The study, published in the Journal of the American Medical Association (JAMA), suggests that metformin could provide a much-needed treatment option and potentially help patients delay knee replacement surgery.
The research focused on 107 participants (73 women, 34 men, mean age 60) diagnosed with symptomatic knee osteoarthritis (OA) and classified as overweight or obese. Importantly, none of the participants had diabetes. Conducted entirely via telehealth, the randomized clinical trial compared the effects of taking up to 2000 mg of metformin daily for six months against a placebo.
Results indicated a notable difference in pain reduction between the two groups. Using a 0-100 pain scale (where 100 represents the worst pain), participants taking metformin reported an average pain reduction of 31.3 points over the six-month period. In contrast, the placebo group experienced an average reduction of 18.9 points. The researchers classified this difference as a “moderate effect” on pain.
“These results support use of metformin for treatment of symptomatic knee osteoarthritis in people with overweight or obesity,” the study authors concluded, while also noting, “Because of the modest sample size, confirmation in a larger clinical trial is warranted.”
Lead researcher Professor Flavia Cicuttini, Head of Monash University’s Musculoskeletal Unit and The Alfred’s Head of Rheumatology, highlighted the significance of the findings. “Effective treatments that improved knee pain in osteoarthritis were limited,” she stated, explaining that current options like lifestyle changes (weight loss, exercise) can be difficult for patients, and existing medications often offer small benefits or carry safety concerns. No new drugs for OA have been approved in Australia since the late 1990s.
Professor Cicuttini pointed out that the lack of effective treatments often leads patients towards knee replacement surgery, sometimes earlier than necessary. This trend is problematic, given that patient dissatisfaction rates with knee replacements are already high (20-30%), particularly when performed for early-stage OA. Furthermore, early replacements increase the likelihood of needing a revision surgery later, which is significantly more expensive (around $70,000 AUD compared to $20,000 AUD for the initial procedure) and often yields less favourable results.
“The best outcome for patients is to delay the knee replacements until it is absolutely needed,” Professor Cicuttini emphasized.
Metformin, she explained, appears to work differently from existing treatments, potentially by affecting low-grade inflammation and other metabolic pathways involved in knee OA. As a drug GPs are highly familiar with, known for its safety profile and low cost, metformin could become a valuable addition to the OA management toolkit.
“It could be provided to patients in addition to other treatments they use and has the potential to delay people having knee replacements before they are absolutely needed,” said Professor Cicuttini. She noted its safe use in non-diabetes conditions like polycystic ovarian syndrome and the study’s success in delivering the treatment via telehealth, suggesting broad accessibility.
Professor Cicuttini and her team are now collaborating with healthcare professionals and consumers to explore integrating metformin into standard knee OA care pathways, potentially through ‘off-label’ prescription following careful discussion between doctors and patients.
The research received support from the National Health and Medical Research Council (NHMRC).
Disclaimer: This news article is based on findings from a single clinical trial with a modest sample size. While promising, the results require confirmation through larger studies before metformin can be widely recommended for knee osteoarthritis. Patients should not change their current treatment plans or consider starting metformin for knee pain without consulting their healthcare provider. Using medications ‘off-label’ requires careful consideration and discussion of potential risks and benefits with a qualified doctor.
