Credit: Pixabay/CC0 Public Domain Knee osteoarthritis is a complex disease that affects the whole joint, including bone, cartilage, ligaments and muscles. Osteoarthritis is a common cause of pain and movement difficulty, affecting 8.3% of people in Australia. When pain persists, many people look for quick, convenient options, such as injections. Clinics offer several types of knee injections, including: corticosteroids hyaluronic acid platelet-rich plasma stem cells.