Frozen shoulder occurs when the connective tissue enclosing the joint becomes thickened and tight.
Frozen shoulder, also known as adhesive capsulitis, is a condition characterized by stiffness and pain in your shoulder joint. Signs and symptoms typically begin gradually, worsen over time and then resolve, usually within one to three years.
Your risk of developing frozen shoulder increases if you're recovering from a medical condition or procedure that prevents you from moving your arm — such as a stroke or a mastectomy.
Treatment for frozen shoulder involves range-of-motion exercises and, sometimes, corticosteroids and numbing medications injected into the joint capsule. In a small percentage of cases, arthroscopic surgery may be indicated to loosen the joint capsule so that it can move more freely.
It's unusual for frozen shoulder to recur in the same shoulder, but some people can develop it in the opposite shoulder.
Frozen shoulder typically develops slowly, and in three stages. Each stage can last a number of months.
- Freezing stage. Any movement of your shoulder causes pain, and your shoulder's range of motion starts to become limited.
- Frozen stage. Pain may begin to diminish during this stage. However, your shoulder becomes stiffer, and using it becomes more difficult.
- Thawing stage. The range of motion in your shoulder begins to improve.
For some people, the pain worsens at night, sometimes disrupting sleep.
The bones, ligaments and tendons that make up your shoulder joint are encased in a capsule of connective tissue. Frozen shoulder occurs when this capsule thickens and tightens around the shoulder joint, restricting its movement.
Doctors aren't sure why this happens to some people, although it's more likely to occur in people who have diabetes or those who recently had to immobilize their shoulder for a long period, such as after surgery or an arm fracture.
Certain factors may increase your risk of developing frozen shoulder.
Age and sex
People 40 and older, particularly women, are more likely to have frozen shoulder.
Immobility or reduced mobility
People who've had prolonged immobility or reduced mobility of the shoulder are at higher risk of developing frozen shoulder. Immobility may be the result of many factors, including:
- Rotator cuff injury
- Broken arm
- Recovery from surgery
People who have certain diseases appear more likely to develop frozen shoulder. Diseases that might increase risk include:
- Overactive thyroid (hyperthyroidism)
- Underactive thyroid (hypothyroidism)
- Cardiovascular disease
- Parkinson's disease
One of the most common causes of frozen shoulder is the immobility that may result during recovery from a shoulder injury, broken arm or a stroke. If you've had an injury that makes it difficult to move your shoulder, talk to your doctor about exercises you can do to maintain the range of motion in your shoulder joint.