Frozen shoulder, also known as adhesive capsulitis, is a common condition in which the articular shoulder capsule (a sac of ligaments surrounding the joint) swells and stiffens, restricting its mobility. It typically affects only one shoulder, but one in five cases affect both.
The term "frozen shoulder" is often used incorrectly for arthritis, even though the two conditions are unrelated. Frozen shoulder refers specifically to the shoulder joint, while arthritis may refer to other/multiple joints.
The shoulder has a spheroidal joint (ball - and - socket joint), in which the round part of one bone fits into the concavity of another. The proximal humerus (round head of the upper arm bone) fits into socket of the scapula (shoulder blade). Frozen shoulder is thought to cause the formation of scar tissue in the shoulder, which makes the shoulder joint's capsule (not to be confused with the rotator cuff) thicken and tighten, leaving less room for movement. Therefore, movement may be stiff and even painful.
The modern English words "adhesive capsulitis" are derived from the Latin words adhaerens meaning "sticking to" and capsula meaning "little container" and the Greek word itis meaning "inflammation".
Frozen shoulder is a condition that commonly occurs in people between 40 and 60 years of age. Women tend to suffer with frozen shoulder more than men.
Causes of frozen shoulder
The cause of frozen shoulder is not fully understood and in some cases is unidentifiable. However, most people with frozen shoulder have suffered from immobility as a result of a recent injury or fracture. The condition is common in people with diabetes.
Risk factors for frozen shoulder
Common risk factors for frozen shoulder are:
You're more likely to suffer from frozen shoulder if you're female and over 40 years of age.
- Age - being over 40 years of age.
- Gender - 70% of people with frozen shoulder are women.
- Recent surgery or arm fracture - immobility of recovery may cause the shoulder capsule to stiffen.
- Diabetes - two to four times more likely to develop frozen shoulder for unknown reasons; symptoms may be more severe.
- Having suffered a stroke.
- Hyperthyroidism (overactive thyroid).
- Hypothyroidism (underactive thyroid).
- Cardiovascular disease (heart disease).
- Parkinson's disease.
Symptoms of frozen shoulder
A symptom is something the patient feels and/or reports, while a sign is something others, including the doctor observe. For example, pain is usually a symptom, while a rash could be a sign.
The most pervasive sign or symptom of frozen shoulder is a persistently painful and stiff shoulder joint. Signs and symptoms of frozen shoulder develop gradually; usually in three stages in which signs and symptoms worsen gradually and resolve within a two - year period.
There are three stages of frozen shoulder:
- Painful stage - the shoulder becomes stiff and then very painful with movement. Movement becomes limited. Pain typically worsens at night.
- Frozen/adhesive stage - the shoulder becomes increasingly stiff, severely limiting range of motion. Pain may not diminish, but it does not usually worsen.
- Thawing stage - movement in the shoulder begins to improve. Pain may fade, but occasionally recur.
On the next page we look at how frozen shoulder is diagnosed, the available treatment options for the condition and the ways in which frozen shoulder can be prevented.