Frozen shoulder, also called adhesive capsulitis, is a condition in which the capsule lining the shoulder joint becomes inflamed, thickened and contracted. It typically affects people between the ages of 40 and 60, and occurs in roughly 2% of the population.
It is more common in people with certain other medical conditions, including diabetes, thyroid disease and cardiac problems. The association with diabetes is the strongest: in that group, somewhere in the order of 10 to 20% experience frozen shoulder at some stage.
Frozen shoulder appears to be a unique condition, in that it does not seem to affect joints other than the shoulder, and it seems to resolve in time.
What causes it
The cause of frozen shoulder, and the way in which it develops, is not known. Inflammation appears to play a significant role.
In many people it occurs without any discernible cause, arising spontaneously. In others there are precipitating factors, including shoulder trauma that may be mild or severe. It can follow an operation, either on the shoulder or on another part of the body such as cardiac surgery, and it can follow a period of prolonged immobilisation.
Symptoms
There are two main symptoms: pain and stiffness.
Pain tends to be a dull ache felt in the outer aspect of the shoulder and the upper part of the arm. It is often worse at night and frequently disturbs sleep. The pain is due to inflammation in the capsule lining the joint.
Stiffness typically develops some months after the pain begins. The restriction in range of motion can be severe and genuinely incapacitating. Reaching behind the back, fastening a seatbelt or washing hair can all become difficult.
The three stages
Frozen shoulder is classically described as developing in three stages.
1. The painful, or freezing, phase
Characterised by the gradual onset of pain. As the pain worsens, the shoulder starts to lose range of motion. The capsule is highly inflamed during this phase, and gradually becomes thickened and fibrous in response. Viewed arthroscopically at this stage, the capsule appears red and inflamed.
2. The stiffening, or frozen, phase
Pain gradually subsides, but the shoulder remains stiff and restricted. The capsule is no longer a thin, flexible membrane; it has become thickened, fibrous and non-pliable, often 5 or 6 mm thick compared with a more normal thickness of a millimetre or so. The inflammation has largely settled by this point.
3. The thawing phase
Range of motion gradually increases and discomfort continues to subside, as the capsule remodels and returns from its thickened fibrous state towards a more normal, soft, pliable membrane.
Frozen shoulder often takes 18 to 24 months to resolve, and can take considerably longer in some people. It typically takes longer to resolve in people with diabetes.
Diagnosis
There is no single investigation that reliably diagnoses frozen shoulder. It is normally diagnosed on the basis of history and examination, in particular the characteristic loss of both active and passive external rotation.
An x-ray of the shoulder is usually performed to rule out arthritis as a cause of the stiffness. An ultrasound or MRI scan is often undertaken to confirm that the rotator cuff tendons are intact. An MRI may demonstrate thickening of the joint capsule, which can help support the diagnosis.
Treatment
Frozen shoulder normally resolves of its own accord. Because the underlying cause is unknown, there is no treatment directed at the cause itself; treatment is aimed at the symptoms of pain and stiffness.
Non-surgical treatment
A steroid injection placed into the shoulder joint is often helpful in relieving the aching pain, by decreasing inflammation in the joint capsule. A single injection can have a long-lasting effect, although pain may return if the shoulder is injured or aggravated again. The injection does not normally make any difference to the stiffness.
Physiotherapy has a role in maintaining what movement is available and in guiding activity, though it is important to understand that stretching cannot force the capsule to release during the inflamed phase.
Surgical treatment
When considering treatment for the stiffness, it must be kept in mind that frozen shoulder resolves of its own accord even without treatment. For people whose symptoms are severe or prolonged, surgery may be discussed as an option to address the stiffness.
Surgery normally involves an arthroscopic release of the joint capsule. A manipulation of the shoulder is usually performed first, to assess the range of motion prior to release. In severe cases the capsule is thickened and contracted to such a degree that the humeral head is held tightly in the glenoid, unable to move. In an arthroscopic release, an incision is made in the capsule to release one side of the joint from the other. Dr Cutbush performs a complete 360° release of the capsule, rather than the partial release that was taught 10 to 15 years ago.
A substantial part of the range of motion is often regained immediately after surgery, with further range returning over time as the condition settles. Surgery is usually performed on a Monday morning, with physiotherapists seeing the patient that afternoon and the following morning.
Post-operative physiotherapy is used to maintain the range of motion achieved, and is normally fairly intensive. While range of motion is usually improved, it is not always completely restored following surgery.
As with any operation there are risks, including those of the general anaesthetic, infection, nerve injury, fracture, and recurrence of stiffness. These are discussed individually in consultation before any decision is made.
What to do next
If your shoulder is painful at night and you are losing the ability to rotate your arm outwards, see your general practitioner. A referral is needed to claim the Medicare rebate for a specialist consultation.
This page is general information and is not a diagnosis. Individual circumstances vary, and the right treatment for you can only be determined after assessment. Any procedure carries risk; these are discussed in consultation.
