Osteoarthritis (also known as wear and tear arthritis) is the most common form of arthritis which occurs when the cartilage and synovial fluid between the joints wears down, affecting the mobility of the joint.

As the body starts to try and repair the damaged cartilage, the joints swell and thicken, and new bone material can grow abnormally, forming bony spurs. 

Over time, if the condition becomes more severe, the cartilage wears away completely, causing the bones to rub together and the joints to move out of place.

Osteoarthritis (OA) can affect any joint but is most frequently found in the knees, hips and small joints of the hands, lower back and neck. Although it can happen at any age, it tends to start in your 50s most commonly.