Here's some specialist advice from our physiotherapist Quinton Caulfield on how to maintain an active, healthy lifestyle into your advanced years. Osteoarthritis (OA) is very common in the UK, affecting around eight million people. The joints in the spine, knees, hips, and hands are the most commonly affected. If you have been diagnosed with OA, it doesn’t mean that you have to live with the pain and stiffness.