Frozen shoulder, also called adhesive capsulitis, is a condition that causes restriction of motion and pain in the shoulder joint. The cause of a frozen shoulder is often unknown, but there are certain people who seem to have a higher likelihood of developing this condition. Frozen shoulder causes the capsule surrounding the shoulder joint to contract and form scar tissue.
Causes of Frozen Shoulder
Most often, frozen shoulder occurs with no associated injury or discernible cause. However, there are some common themes in many patients who develop this condition.
Age & Gender
Frozen shoulder most commonly affects patients between the ages of 40 to 60 years old, and it is much more common in women than in men.
Patients with diabetes are at particular risk for developing a frozen shoulder. Other endocrine abnormalities, such as thyroid problems, can also lead to development of this condition.
Shoulder Trauma or Surgery
Patients who sustain a shoulder injury, or undergo surgery on the shoulder can develop a frozen shoulder joint. When injury or surgery is followed by prolonged joint immobilization, the risk of developing a frozen shoulder is highest.
Other Systemic Conditions
Several systemic conditions such as heart disease and Parkinson's disease have also been associated with an increased risk for developing a frozen shoulder.
No one really understands why some people develop a frozen shoulder. For some reason, the shoulder joint becomes stiff and the capsule that surrounds the shoulder becomes contracted. The shoulder joint is a ball and socket joint. The ball is the top of the arm bone (the humeral head), and the socket is part of the shoulder blade (the glenoid). Surrounding this ball-and-socket joint is a capsule of tissue that envelops the joint.
Normally, the shoulder joint allows more motion than any other joint in the body. When a patient develops a frozen shoulder, the capsule that surrounds the shoulder joint becomes contracted. The capsule forms bands of scar tissue called adhesions. The contraction of the capsule and the formation of the adhesions cause the frozen shoulder to become stiff and cause movement to become painful.
The most common complaint of people with a frozen shoulder is pain. While they may realize that there is restricted motion, the most common concern is the pain associated with this condition. Many shoulder conditions cause pain, including rotator cuff problems, and therefore frozen shoulder is one of the most commonly misdiagnosed problems in orthopedics. Many people who have signs of a rotator cuff tear actually have a frozen shoulder.