Clinical: Shoulder disorders - part one

THE ESSENTIALS

- Pain can occur in the shoulder or be referred from or to it.

- The classical chronology of frozen shoulder involves three phases.

- Patients find it hard to cope with the limitations of a frozen shoulder.

- Rotator cuff disease is a spectrum of problems.

- Tears in the rotator cuff have a destabilising effect on the humeral head.

1. THE ORIGINS OF SHOULDER PAIN

The most common presenting complaint in shoulder patients is pain.

It can originate from a variety of sources, including true shoulder pain, acromioclavicular pain and referred pain.

True shoulder pain is felt around the shoulder, usually radiating down the arm to the level of the deltoid insertion. It can also radiate along the radial border of the forearm.

Radiation to the hand is unusual, but when this occurs it is to the thenar eminence. Pain reaching as far as the fingers is more likely to be nerve root pain, commonly from the sixth, seventh and eighth cervical nerves.

Thoracic outlet pain radiates to the chest, axilla and the ulna side of the forearm. The pain of cervical spondylosis has a variable radiation depending on the level involved, but often goes up to the occiput and down to the supraclavicular fossae and upper arms.

Pain may also be referred to the shoulder. Pain from the diaphragm and gall bladder can be referred to the shoulder and cardiac pain can be felt in either shoulder.

Relevance of the history History may point to a diagnosis. A sudden violent force suggests dislocation or fracture. Moderate injury may cause a rotator cuff tear or subluxation.

If the pain is of slow onset, impingement, frozen shoulder or arthritis are likely.

Shoulder disorders cause night pain because patients may be unable to lie on the affected side.

Certain activities can provoke shoulder pain. Window cleaners suffer rotator cuff pain, tennis players often have rotator cuff impingement.

Some systemic conditions predispose to shoulder pathology. For example, patients with diabetes are at increased risk of frozen shoulder and Ehlers-Danlos syndrome predisposes to subluxation.

Begin an examination with the normal side, then compare both sides. If the pain is worse in adduction, it may arise from the acromioclavicular joint. Pain that worsens on reaching upwards suggests rotator cuff disorders.

If the pain radiates into the hand, arrange a neurological examination.

There is no single investigation that can make a certain diagnosis. X-rays are useful as an initial investigation, but they do not reveal information about the soft tissues.

Arthrography can be useful in adhesive capsulitis (frozen shoulder), but it is expensive and uncomfortable for the patient. In many centres it is regarded as an investigation of historical interest only, except when it is combined with a CT scan for looking at the bones.

MRI investigations in shoulder injury An MRI scan is the investigation of choice for many specialists. It can detect full thickness cuff tears. Contrast MRI arthrography can give even more information. But it does not show a specific appearance in frozen shoulder. Ultrasound is useful for looking at rotator cuff tears. It is cheap and is an operator-dependent investigation and the patient must have a mobile shoulder.

KEY POINTS

- Radiation to the hand is unusual.

- Slow onset of pain suggests impingement.

- Occupations can give a clue to the type of shoulder disorder likely to be present.

- No single investigation can confirm the cause of shoulder pain.

2. FROZEN SHOULDER

Frozen shoulder, or adhesive capsulitis, accounts for about 5 per cent of all referrals made to shoulder specialists.

Patients who suffer from frozen shoulders are typically aged 50-60 years old. The condition is equally common in both men and women, and has no apparent preference for the left or right side of patients.

Nature of the pain The nature of the pain is the crucial feature in diagnosis. A gradual onset of true shoulder pain, often related to a specific event of minor trauma, is a specific sign of a frozen shoulder.

The pain builds up to a maximum level over a relatively short period of time. The pain is much worse near the deltoid insertion, and can often keep patients awake at night.

Underlying the problem is a contraction of the joint capsule, which becomes too tight. The humeral head is held so tightly that movement becomes reduced and painful.

External rotation of the shoulder can be particularly reduced, and any limitation of internal rotation can also usually be demonstrated. Simple X-rays can often help to eliminate other pathology.

They are usually normal, although a disuse osteopenia may be present.

Abnormalities in X-rays However, because of the age group of most patients, their shoulder X-rays will often display some abnormalities that are incidental to the frozen shoulder. MRI is usually also normal and shoulder arthrography is usually diagnostic and should reveal the classical reduction in joint volume that led to the name adhesive capsulitis.

However, the term adhesive capsulitis is a misnomer, because we now know that there is no inflammatory component to frozen shoulder and no adhesions.

The three phases A frozen shoulder has three phases: pain, stiffening and resolution.

However, because of the tendency of frozen shoulder to present late, many patients cannot remember whether the pain preceded the stiffness.

Only osteoarthritis of the shoulder and a locked posterior dislocation can cause the classic finding of marked reduction in passive external rotation.

KEY POINTS

- Frozen shoulder accounts for about 5 per cent of specialist referrals in orthopaedics.

- Patients with frozen shoulders are typically 50-60 years old.

- Shoulder arthrography is usually diagnostic, showing reduction in joint volume.

- Most cases will resolve without treatment over a period of six-18 months, but some patients have reported suffering from the condition for many years.

3. ASSOCIATIONS, FIBROMATOSIS AND TREATMENT

Frozen shoulder can be associated with diabetes mellitus, Dupuytren's contracture, cardiac disease, hyperlipidaemia, hyperthyroidism and minor trauma.

Up to a quarter of patients with frozen shoulder have Dupuytren's contracture, and there is a close histological similarity between Dupuytren's and frozen shoulder.

Both are forms of fibromatosis. Once a patient has been affected by one form of fibromatosis they are more likely to be affected by another. Besides Dupuytren's, other forms of fibromatosis are lederhosen disease in the leg and Peyronie's disease in the penis.

Of these, only frozen shoulder is associated with severe pain. The other conditions are almost pain free, so many surgeons suggest that there is more to frozen shoulder than fibromatosis.

Management

Up to 10 per cent of patients suffer ongoing disability, and up to a half may have mild pain and stiffness in the long term. Many patients find it difficult to cope with the pain and limitation of activities.

Manipulation under anaesthesia, and in selected cases surgical division of the coraco-humeral ligament, can increase the range of movement and reduce pain.

Intervention is not recommended in the early stages, because as in Dupuytren's disease, the condition may be exacerbated. A recommended strategy is to control pain with analgesia until pain at rest has resolved. Pain should only be present at the ends of the range of movement before manipulation is attempted which is usually three to four months after onset.

With the patient under anaesthetic or local anaesthetic nerve block, subacromial infiltration can be performed to provide sufficient post-operative analgesia to allow early mobilisation.

Supervised physiotherapy

Supervised physiotherapy is essential after any manipulation, and 75 per cent of these patients return to work within nine weeks. Diabetic patients are more likely to need surgical release.

It has not been clearly demonstrated that intra-articular steroid injection is of benefit in a primary frozen shoulder.

KEY POINTS

- Frozen shoulder can be associated with a number of other conditions.

- Up to a quarter of patients with frozen shoulder also have Dupuytren's contracture.

- Supervised physiotherapy is essential after manipulation of frozen shoulder.

- The benefits of intra-articular steroid injection have not been clearly demonstrated.

4. ROTATOR CUFF DISEASE

Rotator cuff disease is a spectrum of problems ranging from impingement syndrome to rotator cuff arthropathy. Most patients are aged over 40, and 78 per cent of them have problems on their dominant side. MRI scans on healthy volunteers reveal complete rotator cuff tears in 14 per cent of people, and incomplete tears in 20 per cent. So it is possible to have normal shoulder function despite rotator cuff damage.

Over the age of 60, 54 per cent of people have a rotator cuff tear on MRI, so operative decisions should not be based only on MRI evidence.

The reasons for these findings are unknown, but it may be that the location of the tear is more important than its size. The rotator cuff would also appear to have considerable reserve function.

Impingement is the first stage of the continuum of cuff disease, characterised by pain around the shoulder and down the muscles of the arm. There is usually a painful arc of movement. The arm can be abducted to 90deg before pain begins, and can be pain-free past 120deg.

There is not usually any muscle weakness or wasting, but there may be pain on resisted movements. An injection of a small amount of 2 per cent lignocaine into the subacromial space may obliterate the patient's pain and clinical signs after five minutes. This confirms the diagnosis. Any lesion within the subacromial space can lead to impingement. This may be a bursitis, calcific deposits, the swollen edges of a cuff tear or the presence of bony spurs.

Treatment

Steroid injection into the subacromial space is effective in the short term. The injection is aimed at the leading edge of the coraco-acromial ligament through an anterolateral or posterolateral approach. There may be a temporary exacerbation of symptoms.

Surgery involves resection of the anterior part of the acromion and division of the coraco-acromial ligament. It is indicated for symptoms not responding to conservative measures. Recovery is slow and supervised physiotherapy is usually necessary.

The rate of recovery often depends on the motivation of the patient.

KEY POINTS

- About 14 per cent of healthy volunteers have complete rotator cuff tears on MRI scanning.

- It is possible to have normal shoulder function despite substantial rotator cuff damage.

- There is often a painful arc of movement.

- Steroid injection into the subacromial space is effective in relieving pain and improving movement in the short term.

5. ROTATOR CUFF TEARS

Rotator cuff tears are the next stage of the disease. The rotator cuff is made up of the tendons of supraspinatus, infraspinatus, subscapularis and teres minor, the joint capsule and ligamentous reinforcements.

When the cuff tears, the stabilising effect of these elements on the humeral head is lost and this allows anterosuperior subluxation. Cuff tears are common, and partial cuff tears often occur in young athletic patients.

The incidence of tears increases with age. Patients may work with their arms above shoulder height or in a fixed position.

Cause and classification

Whether the cause is impingement or tendon failure has not been established.

Cuff tears are classified as being partial or full thickness and are measured in centimetres. Most tears are thought to begin in the supraspinatus tendon, just behind the leading edge. There may be acute, chronic or acute-on-chronic pain, and loss of power. In severe cases, complete loss of active arm abduction occurs, and the patient has to lift the arm up using the opposite hand and is unable to hold it there unaided. Passive movements are usually maintained, and this distinguishes the condition from a frozen shoulder.

Treatment

Treatment of rotator cuff tears is usually surgical. Small tears can be repaired via an open or arthroscopic route, usually combined with a subacromial decompression. Larger tears and more chronic tears, especially those in the elderly, are more difficult to repair. However, subacromial decompression will usually help control pain.

The final stage

Rotator cuff arthropathy is the last stage in the continuum of rotator cuff disease. Following a massive tear, the head of the humerus gradually erodes the undersurface of the acromial arch. This is diagnosed on plain X-rays, but treatment is difficult. Shoulder arthroplasty has a place, but results are much poorer than those for glenohumeral arthritis. Special types of prosthesis have been designed to address this problem.

KEY POINTS

- Cuff tears are common and partial cuff tears often occur in young athletic patients.

- There is often a history of working with the arms above shoulder height.

- In severe cases, complete loss of active arm abduction can be demonstrated.

- Passive movements are maintained.

 

Further reading

- Apley's System of Orthopaedics and Fractures by A Graham Apley and L Solomon, published by Hodder Arnold (2001).

- Primary care orthopaedics by S Cutts, A Edwards and R Prince, RCGP publications, (2004).

 

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