Quote:
"To help determine whether you have osteoarthritis, your GP will first ask you about your symptoms and examine your joints.
Your GP may suspect osteoarthritis if:
you're aged 50 or older
you have joint pain that gets worse the more you use your joints
you have stiffness in your joints in the morning that lasts less than 30 minutes, or no stiffness at all
If your symptoms are slightly different from those listed above, this may indicate another joint condition. For example, prolonged joint stiffness in the morning can be a sign of rheumatoid arthritis.
[i]Further tests – such as X-rays or blood tests – aren't usually necessary[i], but may be used to rule out other possible causes, such as rheumatoid arthritis or a fractured bone"
Source:
http://www.nhs.uk/conditions/osteoarthritis/Pages/Introduction.aspx