There is no definitive test to diagnose osteoarthritis, so your GP will ask about your symptoms and examine your joints to help determine whether you have the condition.
If your symptoms are slightly different from those listed above, this may indicate that you have another joint condition. For example, prolonged joint stiffness in the morning can be a sign of rheumatoid arthritis.
Further tests – such as X-rays or blood tests – are not usually necessary to confirm a diagnosis of osteoarthritis, although they may be used to rule out other possible causes of your symptoms, such as rheumatoid arthritis or a fractured bone.
X-rays can also allow doctors to assess the level of damage to your joints, but this is rarely helpful as the extent of damage visible on an X-ray isn’t a good indicator of how severe your symptoms are.
Source: NHS UK