Frozen shoulder is characterized by pain and loss of motion or stiffness in the shoulder. It affects about two percent of the general population. Frozen shoulder most commonly affects patients between the ages of 40 and 60 years, with no clear predisposition based on sex, arm dominance, or occupation.
The causes of frozen shoulder are not fully understood. The process involves thickening and contracture of the capsule surrounding the shoulder joint.
Frozen shoulder occurs much more commonly in individuals with diabetes, affecting 10 percent to 20 percent of these individuals. Other medical problems associated with increased risk of frozen shoulder include: hypothyroidism, hyperthyroidism, Parkinson’s disease, and cardiac disease or surgery.
Frozen shoulder can develop after a shoulder is immobilized for a period of time. Attempts to prevent frozen shoulder include early motion of the shoulder after it has been injured.
Pain due to frozen shoulder is usually dull or aching. It can be worsened with attempted motion. The pain is usually located over the outer shoulder area and sometimes the upper arm.
The hallmark of the disorder is restricted motion or stiffness in the shoulder. The affected individual cannot move the shoulder normally. Motion is also limited when someone else attempts to move the shoulder for the patient.
Some physicians have described the normal course of a frozen shoulder as having three stages:
- Stage one: In the “freezing” stage, the patient develops a slow onset of pain. As the pain worsens, the shoulder loses motion. This stage may last from six weeks to nine months.
- Stage two: The “frozen” stage is marked by a slow improvement in pain, but the stiffness remains. This stage generally lasts four months to nine months.
- Stage three: The final stage is the “thawing,” during which shoulder motion slowly returns toward normal. This generally lasts five months to 26 months.
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