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.