by Keith Borowksy, Consultant Orthopaedic Surgeon with Upper Limb interest.
Amongst all the conditions that afflict the shoulder frozen shoulder or capsulitis is unique. It can and often does produce devastating pain and restriction in range , and miraculously it has the ability to spontaneously resolve to a pain free, largely functional range of motion.
The term frozen shoulder is perhaps loosely used, and as many conditions that produce pain will invariably be accompanied by reduction in range of motion, the term may be incorrectly applied. However key diagnostic features are a shoulder that is normal on plain x-ray but shows stiffness that is both global (affecting all planes of motion) and not only related to pain i.e. the stiffness would be present even with examination under anaesthetic. A true contracture is present.
In its initial stage pain can be severe, even with minor movements , and certainly with manoeuvres that stretch the tight capsule. The pain can radiate almost anywhere in the upper limb, and at times up into the neck and across the upper chest. Although the victim might ascribe the onset to a particular (usually minor) incident, most cases are in fact of no known cause – idiopathic. However diabetics tend to have a more refractory version of capsulitis, and other conditions e.g. thyrotoxicosis also have an association. It can also follow trauma, not necessarily to the shoulder itself; especially if pain and immobilisation have been associated- e.g. a patient with an elbow fracture that has had the limb immobilised.
Possibly the most trying aspect is the so called first phase, where both pain and progressive stiffness occur.
On arthroscopy the internal lining of the shoulder is significantly reddened.
Besides usual pain relief medication, Cortisone injections into the joint may be helpful to ease the pain and thereby allow earlier stretching of the tight capsule. Hydrodistension is a technique whereby under anaesthetic the joint is distended with fluid under pressure in order to rupture the tight capsule.
The greatest difficulty patients have perhaps at this stage is seeing “light at the end of the tunnel.” It can be a miserable experience, not easily amenable to pain relief, often made worse by attempted mobilisation and perhaps the most trying – the fact that this stage can last up to 9 months!
The 2nd stage is somewhat more forgiving, the pain miraculously tends to settle, but stiffness remains. For a person involved in mechanical work this can be
problematic, and the fairer sex have a singularly common complaint – they can not manage their hair. Generally self care and function is also restricted, but
often the relief from pain is gratefully accepted, and compensatory mechanisms to cope with the restricted range develop. Again this stage can be prolonged – about 6-9 months.
In the last stage, one of resolution, the range slowly returns to an almost full functional range, although this is not invariable and some restriction may remain. Overall the condition is said to take 18 months to 2 years to spontaneously resolve.
A variety of treatments have evolved. The simplest is supervised neglect. Attempts at external physiotherapeutic mobilisation in the early painful stages are probably unrealistic and better avoided Lastly arthroscopic release is the latest of treatments whereby the tight capsule is cut under direct vision via small incisions:
All of these treatment modalities have their pros and cons and indications. E.g. if the bone is more frail and the risk of fracture is high, arthroscopy might be
preferred to manipulation. The aim of all these treatments is to speed up the process of resolution.
The diagnosis is often clear. The joint is painful, has a restricted range in almost all planes (particularly external rotation) and on plain x-ray the joint is normal with no arthritis – a condition that also causes pain and stiffness.
Perhaps more difficult to characterise is when aspects of capsulitis follow trauma to the shoulder – such as the stiffness and pain that may follow a fracture. Stiffness may also follow previous shoulder surgery for whatever cause- rotator cuff surgery, instability, joint replacement e.t.c. In these cases, if the stiffness is not due to mal-union of bone elements or irregularity of the joint surfaces, then it is often more in the extra-articular or extra-capsular soft tissues, and generally more difficult to treat.
These cases are less common. All in all idiopathic frozen shoulder is a very common shoulder condition in the middle aged population. Despite this the exact cause of its ostensibly spontaneous presentation remains elusive, although a variety of mechanisms including subtle forms of low grade infection have been proposed.
Although frozen shoulder is a common condition and usually readily diagnosed, earlier more subtle forms can be confusing, especially when there is other shoulder pathology e.g. tendonitis and impingement. Often a period of conservative treatment makes this very clear as definitive stiffness develops, particularly
in external rotation. Similarly, difficult situations arise whereby capsulitis coexists with a rotator cuff tear. It is often unclear whether the tear is a new or old
feature. Repairing a cuff tear in the presence of significant stiffness is generally not advised, and very often capsulitis takes precedence as a cause for the symptoms and as the condition to be treated before anything else is addressed.
Medico-legally, the condition and its treatment may result in various claims. Both manipulation and arthroscopic release have potentially significant complications (fracture, dislocation, brachial plexus lesions .etc.) – fortunately significant complications are not common. There can be errors in diagnosis. One of the commonest of these is mistaking frozen shoulder for osteoarthritis. Both cause pain and restriction in range. Usually a plain x-ray can distinguish the two, although subtle and early osteoarthritis may be missed. Subjecting a patient to manipulation under anaesthetic in this setting often results in significant exacerbation of pain for some months and no improvement in the overall condition.