Frozen shoulder is a relatively common condition involving the shoulder joint, which causes pain and loss of motion of the joint often for a substantial period of time. The shoulder joint, (the joint between the humerus and the glenoid – the socket of the scapula or shoulder blade) like all joints is surrounded by a capsule which is a thin but relatively strong sack of tissue which holds the normal joint fluid within the joint. In addition to that function however this capsule is responsible for holding the joint together so that it does not dislocate and secondly for restricting the amount of motion in the joint. If this capsule is somewhat lax there is a large range of motion available, but the joint in turn may dislocate. On the other hand if the capsule is tight the range of motion will be restricted, but the joint is held together tightly and cannot dislocate.
The exact underlying cause of frozen shoulder is often unknown (primary frozen shoulder) but what actually happens is that the capsule of the shoulder joint becomes inflamed and eventually scarred and thickened resulting in a stiff shoulder. It is thought to be precipitated as a result of minor shoulder trauma causing a tear in the capsule at the front of the shoulder. Other conditions such as arthritis of the shoulder, subacromial impingement, rotator cuff disease, shoulder fractures and gout can cause a frozen shoulder to develop (secondary frozen shoulder).
Frozen shoulder occurs in 2-3% of the population, this condition is more common in diabetics with 10 – 20% developing frozen shoulders; it is also more difficult to treat in this patient group. The second shoulder may be involved in 10-20% of patients, usually within 5 years of onset of symptoms at the first shoulder.
The Clinical Picture
Initially when the inflammation begins the shoulder becomes sore. This may be noticed as a gradual onset of soreness but often it is noticed as a distinct pain when the shoulder is stretched or pushed, such as during a game of tennis or when reaching out suddenly. After that the pain becomes gradually worse. It is relatively constant in nature, it is always worse at night time and the shoulder is often very difficult to lie on. Unguarded movements, ie. reaching suddenly to catch a falling object are classically very painful. With time the condition passes through three distinct stages.
First (Painful or Freezing) Stage
Initially, the capsule, which is becoming increasingly inflamed, starts to become swollen and thickened, and as a result it begins to tighten up. As it tightens up, the range of motion in the shoulder becomes gradually restricted and often within 1-2 months of the commencement of the disorder this restriction of motion has become apparent. The movement most sensitive to this restriction, and therefore most easily noted, is that of putting the arm behind the back. During this stage the shoulder becomes progressively more painful. The shorter this period lasts for the better the prognosis for your frozen shoulder.
Second (Frozen) Stage
Once the condition becomes established the shoulder pain becomes constant and the inflammatory process diminishes and the capsule becomes increasingly scarred. As the capsule becomes tighter due to scarring not only is the humeral head jammed into its socket but it is also pushed upwards towards the acromion. Between the top of the humeral head and the acromion lie the rotator cuff tendons and these become increasingly squashed (particularly so when the arm is taken into an outstretched or elevated position). Pain in the rotator cuff is thus induced and this frequently gives the typical pain down the side of the arm which may well go down the arm even into the hand. It is this pain that frequently leads people to the diagnosis of impingement (of the rotator cuff tendons) as a primary problem. In this case, however, the impingement occurs as a secondary problem, the main problem being within the glenohumeral joint itself. For this reason, a standard injection into the subacromial space and around the rotator cuff tendons, does not fully settle down the problem because it does not deal with the scarring in the shoulder joint capsule itself.
If the inflammatory condition within the shoulder joint is left alone it will continue unabated, often for some months or even years, until gradually the inflammatory cycle settles down and the pain starts to go. By that time however, the swelling in the capsule around the joint has turned into scarring, and thus, despite the fact that the pain gradually eases off the restriction in motion may remain.
Third (Thawing) Stage
With the subsequent passage of time this scarring gradually stretches up and in approximately 90% of cases the pain diminishes and the full range of motion eventually returns. In most cases the time course for this condition to go through all three stages is somewhere between eighteen months and three years depending on the severity of the capsulitis. Recent research suggests that in a significant percentage of people who have this condition that it can persist for five years and that at the end of this time a full range of shoulder movement may not return.
Treatment of First (Painful or Freezing) Stage
One treatment that does seem to offer benefit in this condition is injection of cortico-steroid (cortisone) into the shoulder joint itself. It is thought that the inflammatory cycle within the shoulder joint somehow becomes self perpetuated, probably long after the instigating cause has gone. The aim then is to break this cycle and to try to get the inflammation to resolve. At the time when the shoulder joint is injected, the subacromial space can also be injected to decrease the element of rotator cuff impingement pain. This often dramatically reduces the inflammation in these tendons and the arm pain that it causes.
Cortico-steroids are very strong anti-inflammatory agents and they attack the inflammatory cycle at several points simultaneously. Because of this they are much more powerful and much more effective than anti-inflammatory tablets which generally have very little effect in this condition. If the cortico-steroid can be placed into the shoulder joint itself, then in over 90% of cases, the inflammatory cycle can be broken and the inflammatory process will gradually resolve. This happens over a few days following injection and generally, by 1-2 weeks, the constant ache of the inflammation is gone and the only remaining ache occurs at the extremes of motion when the capsule is tight. Once the inflammation starts to subside, the swelling in the capsule gradually decreases. As a result of this, the range of motion starts to improve, and in general one would expect a return of around 10-15% of the range within two weeks of injection. To some degree however, this does depends on just how long the problem has gone on, and by how much the range of motion has been restricted.
Once the inflammatory cycle has been broken, the body itself mops up the remaining inflammation. The capsule then starts to gradually stretch up, allowing motion to return again, in exactly the same manner as described above. In this case however, because the inflammation has been treated, the condition passes through the stages towards resolution much more quickly.
Despite the fact that the restriction of motion will not have resolved within 2 weeks of the injection, the relief by removing the constant ache is often extremely gratifying, particularly if it allows unbroken sleep. Following injection complete rest is required and nothing must be done that makes your shoulder painful. Hot showers before going to bed followed by ice packs on the shoulder often help to produce a better night’s sleep, along with sitting propped up at 45 degrees in bed.
Once the inflammatory cycle has been broken it still takes a couple of months for everything to settle down and during that couple of months it is very important not to stretch the shoulder or push it too hard. This also means that activities such as sport should not be undertaken in that time frame. Subsequently, once the inflammatory cycle has definitely resolved, a gradual stretching program can be embarked on and at this stage physiotherapy can be very helpful. If during the recovery phase there is a flare up of the inflammation, then this should be treated immediately by injection to try and stop the inflammatory cycle reforming. It is usual to inject an affected shoulder on two separate occasions six weeks apart but relatively unusual to have to inject it on three occasions.
Treatment of Second (Frozen) Stage
If you present during this stage of the process where there is a restriction of shoulder motion and the pain is not getting any worse then the tight, scarred capsule has to be either stretched up or released. Sometimes it can be stretched up by distending the capsule with high pressure fluid (hydrodilatation), and this is usually performed under ultrasound guidance and using a local anaesthetic. This tends to work in shoulders with relatively mild restriction of motion but it is not so effective in those with more major degrees of restriction.
Where the capsule is very tight, some form of rupture or release may be required. This can be achieved either by manipulation under anaesthesia or by surgical release of the capsule. There are risks and problems with all of these procedures, firstly that the capsule may not stretch, secondly that the top of the humerus may be broken during the manipulation, although this is rare. Following manipulation and steroid injection 80% of patients are back to a reasonably normal situation with regard to their shoulder within six weeks, 15% of patients feel that they are not any different and 5% feel that they are worse off following manipulation.
Recently research has suggested that gently manipulating a shoulder under anaesthetic and then introducing an arthroscope into the shoulder and surgically releasing the capsule may produce better results over a shorter time scale and cause less post-operative pain than simple manipulation.
In the case of the patient who has protracted impingement (possibly with subacromial spurs) which is made worse by the concomitant onset of frozen shoulder, there may be a case to be made for subacromial decompression (removal of the spurs to stop impingement). Because of the risk of stirring up the inflammation in the shoulder joint and making the restriction of motion worse however, it is generally recommended that the decompression be delayed as long as possible, preferably until the range of motion has either returned or been static for a period of longer than 3-6 months.
Frozen shoulder as a complication of subacromial decompression is now thought to occur in up to 3% of cases. In general this is mild and can be resolved with steroid injections into the shoulder and subacromial space as described.
Frozen shoulder, or gleno-humeral capsulitis, is an inflammatory condition in its initial stages and the treatment of the condition is directed towards the resolution of that inflammation in the first stage. This is achieved by rest and local corticosteroid injection into the shoulder joint itself. In the second and third stages manipulation or arthrscopic surgery to release the scarred capsule may be necessary to regain the range of motion which may take years to return to normal if the condition is allowed to take its own course.
There is a strong association between developing a frozen shoulder and having diabetes (or a diabetic tendency), thyroid disease and high cholesterol levels. You should therefore arrange to undergo a blood sugar, thyroid function tests and a cholesterol test with your General Practitioner.