T he symptoms of osteoarthritis, the most common joint disorder, typically emerge at 55 years of age or thereabouts. People live with osteoarthritis, often in considerable pain, for an average of 26 years. 1,2 But the pathological processes that drive joint damage often rage for years before symptoms emerge. By the time a doctor diagnoses osteoarthritis, the joint destruction is typically progressive, often inexorable (although there may be periods of stability) and sometimes ends in disability.There's little healthcare professionals can do pharmacologically to stem the almost inevitable decline. Drug treatment focuses on controlling symptoms, especially pain. 3 But healthcare professionals' efforts are often in vain. For example, intra-articular corticosteroid injections do not effectively alleviate pain, even transiently, in 20% to 30% of people with knee osteoarthritis. 3 Even joint replacement does not guarantee freedom from pain and disability: up to 25% of patients still complain of pain and disability a year after total joint replacement. 4 In any case, analgesia closes the symptomatic door long after the degenerative horse has bolted. Unfortunately, unlike rheumatoid arthritis (RA), there is no disease-modifying drug (DMD) for osteoarthritis. 2 But that could be about to change. "For many years, researchers assumed that osteoarthritis was simple wear and tear," says David Miles, Chief Executive Officer, AKL Research and Development, a biotech company researching new osteoarthritis treatments (see Box 1). "We now know that osteoarthritis arises from alterations in numerous signalling pathways, which raises the prospect of developing DMDs that target specific molecules and modify the underlying processes that leads to joint destruction.""The view that osteoarthritis is a simple consequence of age, like rubber wearing down on a tyre, is incorrect," says Tonia Vincent, Professor of Musculoskeletal Biology, Director of the Centre for Osteoarthritis Pathogenesis Versus Arthritis and