20/03/2026
The Anatomy of "Frozen Shoulder"
In a healthy shoulder, the joint capsule is a flexible sleeve of tissue that surrounds the ball-and-socket joint. As shown in the diagram:
Inflamed Joint Capsule: The connective tissue around the glenohumeral joint becomes thick, stiff, and inflamed.
Adhesions: Over time, tight bands of scar tissue (adhesions) develop. This leaves less room for the humerus (upper arm bone) to move, effectively "freezing" the joint in place.
Key Bones Involved: The interaction between the humerus, the scapula (shoulder blade), and the clavicle (collarbone) is restricted because the socket part of the scapula is tightly gripped by the inflamed capsule.
Stages of Progression
Frozen shoulder typically develops slowly and follows three distinct phases:
Freezing Stage: Any movement of the shoulder causes pain, and the shoulder's range of motion starts to become limited.
Frozen Stage: Pain may begin to diminish during this stage. However, the shoulder becomes stiffer, and using it becomes increasingly difficult.
Thawing Stage: The range of motion in the shoulder begins to improve.
Common Symptoms
As the bottom right of your image illustrates, the primary indicators are:
Limited Range of Motion: Difficulty reaching overhead, behind the back, or out to the side.
Dull or Achy Pain: Usually worse in the early stages and often intensified at night.
Note: Because frozen shoulder can sometimes be confused with a rotator cuff tear or bursitis, a clinical diagnosis by a healthcare professional is usually necessary to determine the best course of physical therapy or treatment.