Taking weight-loss drugs for at least three years could prevent thousands of knee replacements a year, research suggests. A study published in Regional Anesthesia & Pain Medicine found that patients with knee arthritis who took medications such as semaglutide or tirzepatide for at least three years had a significantly reduced risk of needing knee replacement surgery.
Study details
Researchers at the University of Maryland School of Medicine examined data for 6.8 million adults diagnosed with knee osteoarthritis between 2010 and 2024. They identified a matched sample of 42,000 people who had taken any type of GLP-1 medication for at least one year and compared them with an equal number of similar patients who had not. They also analyzed data for just under 31,000 patients who had taken the drugs for three years. Patients were tracked at regular intervals for eight years after diagnosis to assess the need for knee replacement surgery.
Key findings
The study found that taking GLP-1 medications for one year was associated with a 1.4-percentage-point reduced risk of knee replacement surgery at the three-year follow-up point and a 2.8-percentage-point lower risk after eight years. However, the greatest reduction in risk was with newer weight-loss drugs and longer treatment. Taking semaglutide or tirzepatide for three years was associated with a nearly 5-percentage-point lower chance of needing knee replacement at the eight-year follow-up assessment.
Potential impact
The authors speculated that if all eligible patients with knee arthritis and obesity or metabolic disease took semaglutide or tirzepatide for three years, there could be up to 14,400 fewer knee replacements every year in the US and more than 1,500 a year fewer in the UK. They concluded that their findings align with evidence that GLP-1 receptor agonists may influence knee osteoarthritis through complementary anti-inflammatory and analgesic mechanisms.
Expert reactions
Mark Bowditch, a consultant knee surgeon and immediate past president of the British Orthopaedic Association, said there may be some direct anti-inflammatory and possibly cartilage-protective effects of GLP-1 receptor agonists that operate through weight-independent mechanisms. However, he urged caution, as the findings do not prove that these drugs prevent the need for surgery. He emphasized that GLP-1 receptor agonists are not approved for the treatment of osteoarthritis and strongly cautioned against their use for this purpose outside of clinical trials.
Prof Lucy Donaldson, director of research at Arthritis UK, said the findings could help better understand the potential impact of weight-loss medications to help some patients avoid or delay the need for joint replacement surgery. She noted that maintaining a healthy weight can play a vital role in managing osteoarthritis, particularly in weight-bearing joints such as the knees and hips, and that even a small amount of weight loss can improve symptoms and sometimes slow the progression of osteoarthritis.
