Osteoarthritis (OA) is the most common form of arthritis, affecting nearly one and a half million Australians. It can appear at any age, but tends to occur more commonly in women and in people aged over 40 years. Two of the most common areas affected are the hips and knees. OA affects cartilage, the hard, slippery tissue that covers the ends of bones. In osteoarthritis, the surface layer of cartilage breaks down and wears away. When this happens,...