It took me a while to figure out that frozen shoulder and adhesive capsulitis are just two terms for the same condition. For ages when I was searching online I kinda figured that they were two similar conditions but not exactly the same.
Well they are … the same that is.
A medical friend of mines has explained it like this:
The suffix -ITIS on any word means inflammation. So TonsillITIS is inflamed tonsils. DermatITIS is inflamed skin and so on.
The Capsule is the name given to a bag of gristle that surrounds the shoulder – holding it snug in place and providing lubrication to the joint inside. If the capsule gets inflamed then a doctor will call it CAPSULITIS.
The last bit of the puzzle relates to the fact (seemingly) that inflammation fluid is sticky and acts like glue inside a joint. This causes the capsule to stick to the joint and the bone and to itself too.
So when a doctor looks inside a frozen shoulder he sees a:
Sticky mess of inflamed capsule or an ADHESIVE CAPSULITIS
Easy isn’t it.