Arthritis is relatively common and can affect people of all ages, however, it is most common in people over the age of 60. Arthritis may affect one or several joints and often affects the weight-bearing joints, such as knees and hips. There are over 100 kinds of arthritis and it is a progressive disease, meaning it cannot be cured and may worsen over time. Osteoarthritis is the most common form of arthritis and is caused by stress on the joints.
The knee is the largest joint in the body and is vital for movement. It connects the femur (thigh bone) and tibia (shin bone) and is covered with the patella (knee cap). The tibia also has a smaller bone running beside it called the fibula. The joint is stabilised by tendons, ligaments and muscles. Knee osteoarthritis occurs when the firm, rubbery tissue that coats the knee joint known as cartilage becomes worn away. Cartilage enables the smooth movement of the knee as well as providing a protective cushion to prevent the bones from rubbing together. Cartilage can repair itself to some extent, but it does not regenerate once lost. One of the first signs of osteoarthritis is often stiffness or pain in the knee joint.