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Frozen shoulder
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Frozen shoulder, which in medicine is called adhesive capsulitis, is the painful, progressive loss of shoulder motion caused by fibrosis of the joint capsule. The capsule is the sleeve of tissue that wraps the joint, and fibrosis means that tissue hardens.
What happens inside has two stages. First there is inflammation: pain shows up and the shoulder stops moving freely. Then the capsule turns fibrotic and contracts, because fibroblasts, the cells that build supporting tissue, multiply and lay down excess collagen, the fiber that gives strength. It is a sleeve that shrinks until there is no room left to turn.
The exact mechanism remains uncertain. It appears mostly in middle-aged adults, and it is associated with diabetes, with thyroid disorders, with keeping the shoulder still for a long time and with injuries to the shoulder itself.
In brief
Adhesive capsulitis, or frozen shoulder, is the painful, progressive loss of shoulder motion caused by fibrosis of the joint capsule.
Inflammation first causes pain and limits motion; the capsule then turns fibrotic and contracts, with more fibroblasts and excess collagen.
It is a sleeve that shrinks until there is no room left to turn.
Its exact mechanism remains uncertain; it appears mostly in middle-aged adults and is associated with diabetes, thyroid disorders, prolonged immobilization and shoulder injuries.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingAdhesive Capsulitis (Frozen Shoulder), StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated