So what is Frozen Shoulder?

Actual Photos of Adhesive Capsulitis - Shoulder Information

What is a frozen shoulder ?

A frozen shoulder or shoulder stiffness is a disease of it´s own, which leads into a stiff shoulder. A typical symptom is a painful reduced movement. Using a microscope an inflammation of the synovia and the shoulder capsule will be recognized and as the disease progresses a thickening of the shoulder joint capsule as well as a shrinking of the capsule can be observed, histologically. 

Further questions can be answered on the listed website link above:

Signs and symptoms of a shoulder stiffness ?

Development of a frozen shoulder ?

Age and sex of a frozen shoulder

Who is affected by a shoulder stiffness ?

How to treat a shoulder stiffness