Shoulder pain

Shoulder pain is a common cause of presentation to primary care and can be due to a number of causes. These include:

Pain arising from the shoulder: rotator cuff disorders, frozen shoulder, instability disorders, acromioclavicular disorders, glenohumeral joint osteoarthritis, inflammatory arthritis, Paget’s disease, avascular necrosis of the humeral head, septic arthritis.

Pain arising from elsewhere: referred from the neck (for example degenerative disc disease), diaphragm (for example in intraabdominal sepsis), heart (for example ischaemic heart disease) or lungs (for example apical lung cancer). Polymyalgia rheumatica. Malignancy, for example, metastases to the humeral head. Early herpes zoster (C5-T1 dermatomes).

The four most common causes of shoulder pain in primary care are rotator cuff disorders, glenohumeral disorders (frozen shoulder or glenohumeral osteoarthritis), acromioclavicular joint disease, referred neck pain.

Assessment of someone with a painful shoulder

Assessment of a person with shoulder pain involves taking a history and performing an examination to help identify the underlying cause, and any red flags for a serious underlying condition. 

Take a history including the following features:

• Characteristics of the pain: onset; duration; site of maximal pain; whether the pain is felt at rest, on movement, or both; night pain and whether pain affects sleeping position; radiation; aggravating and relieving factors. 
• Neck pain or other upper limb pain.
• Stiffness. 
• Instability: any past history of dislocations or concerns that the shoulder might come out of joint during certain movements. If there is a past history of dislocation, ask if the first dislocation was caused by an injury; how old the person was when the shoulder was first dislocated; number of dislocations and the direction in which the shoulder dislocated. 
• Trauma: any preceding injury, or strenuous activity. Interval between this and the onset of pain. 
• Mechanism of injury: site injured, arm position at the time of injury and any subjective experiences, such as feeling something ‘pop out’.
• Functional impairment: whether the dominant or non-dominant arm is affected; any restriction of activities or effects on work or sports.
• Pain in other joints.
• Systemic features such as fever, night sweats, weight loss, rash, respiratory symptoms.
• Neurological symptoms.
• Occupation and sporting activities, for example, involving repetitive arm movements and long periods of elevation.
• Past history of shoulder or musculoskeletal problems.
• Past medical history, in particular significant comorbidities such as diabetes, stroke, ischaemic heart disease, malignancy (such as lung or breast cancer), gastrointestinal or renal disease.
• Current medications. Consider potential adverse drug reactions, such as statin myopathy.
• Family history.

Examination should include a comparison of both shoulders: 

• As an initial screening test, ask the person to place the palms of their hands at the base of the neck with elbows pointing laterally and then to put their arms down and try to put the back of the hands between the shoulder blades. However, be aware that this also involves joints other than the shoulder (such as elbow and wrist). 
• Inspect the shoulder from the front, side, and behind for muscle wasting, swelling, deformity or bruising.
• Palpate the shoulder bones (clavicle, proximal humerus, and scapula) and joints (sternoclavicular, acromioclavicular, glenohumeral), looking for tenderness, warmth, swelling and crepitus.
• Assess active, passive, and resisted movement of the shoulder joint. Assess flexion, extension, abduction, adduction and internal and external rotation.
• Look for the painful arc of abduction, if this is possible within the limits of discomfort (pain between 70–120 degrees of active abduction), and if present, check if there is pain on abduction with the thumb down, worse against resistance. 
• Perform the cross-arm test. This is positive if there is pain over the acromioclavicular joint when the person raises the affected arm to 90 degrees, then actively adducts it.
• Examine the neck, arms, axillae and chest wall for possible sources of referred pain. Assess the range of movement of the cervical spine. 
• Perform a neurological examination if indicated. 
• If neck movement reproduces the pain, and the shoulder pain is thought to be referred from the neck. 

Investigations. Investigations should be guided by the suspected cause. (Blood tests and radiography are not usually indicated as part of a primary care assessment of shoulder pain). Perform blood tests if malignancy, polymyalgia rheumatica or inflammatory arthritis is suspected. Consider testing for diabetes if this is suspected in a person with shoulder pain (frozen shoulder is more common in people with diabetes than those without diabetes).

• Consider anteroposterior and lateral shoulders X-rays if:
• There is a history of trauma.
• The person is not improving with conservative treatment or symptoms are lasting more than four weeks. 
• Movement is significantly restricted.
• There is severe pain.
• Any red flags are present.Arthritis is suspected.
• Ultrasound or MRI should not usually be requested by primary care.

Management. Refer a person urgently to secondary care if any red flags are identified in the history or examination. These include:

• Trauma, pain and weakness, or sudden loss of ability to actively raise the arm (with or without trauma): suspect acute rotator cuff tear.
• Any shoulder mass or swelling: suspect malignancy.
• Red skin, painful joint, fever or the person is systemically unwell: suspect septic arthritis.Trauma leading to loss of rotation and abnormal shape: possible shoulder dislocation.New symptoms of inflammation in several joints: suspect inflammatory arthritis. 

If there is pain and tenderness over the AC joint, high arc pain or a positive cross-arm test acromioclavicular joint disease is likely.

Rotator Cuff Disorders

The term ‘rotator cuff’ refers to the group of muscles and tendons that surround and stabilise the shoulder joint. Rotator cuff disorders cause subacromial shoulder pain, which is felt in the top and lateral side of the shoulder. These include rotator cuff tendinopathy and partial rotator cuff tears. Rotator cuff tendinopathy is also known as shoulder impingement. Impingement occurs between the acromion and the rotator cuff tendons (which can be intact or torn). As the diagnosis of other causes of subacromial pain, such as supraspinatus tendinopathy, tendinitis and subacromial bursitis, is essentially the same as rotator cuff tendinopathy, these are referred to as rotator cuff tendinopathy in this article.

Subacromial shoulder pain from rotator cuff disorders is the most common cause of shoulder pain presenting to primary care. It typically affects people between the ages of 35 and 75. There may be a history of repetitive movements at or above shoulder height, or of heavy lifting. It can occur in athletes, workers who perform overhead activities and the elderly.

Diagnosis is based on the history and examination. There is pain in the top and lateral side of the shoulder which is made worse by lifting the arm (for example when lifting a full kettle) or with overhead activities. There can be night pain. On examination, active movements are painful and may be restricted, whereas passive movements tend to be full but painful. 

Clinical signs can include: 

Painful arc of movement between 70-120 degrees of abduction (however research has not shown this to be sensitive or specific as a clinical sign).

Pain on abduction with the thumb down, which is worse against resistance.

It is important to distinguish traumatic rotator cuff tear from other causes of subacromial shoulder pain. Success of surgical repair is adversely affected by delayed diagnosis. People with traumatic tears are usually active young-middle aged adults and have usually sustained a dislocation or traction type injury (where the shoulder is forcibly stretched). On examination there is usually severe pain and significant weakness. There may be a positive ‘drop arm test’, where the person cannot support the weight of the affected arm when it is abducted to 90 degrees. Urgent referral to orthopaedics is required. 

Management. This includes: rest (in the acute phase), exercise/ physiotherapy, corticosteroid injection, referral to intermediate or secondary care. Advise modification of activities that exacerbate symptoms (such as reaching overhead). Usual activities, within the limits of pain, should be restarted as soon as possible. Offer analgesia including paracetamol and NSAIDS (but stop if there is not early benefit from this).  Refer to secondary care if the person has not benefited from at least 6 weeks of a non-surgical treatment (for example has persistent pain and reduced function) or the diagnosis is uncertain.

Frozen Shoulder

Frozen shoulder is a painful condition which leads to stiffness and disability. It is characterised by a progressive restriction of both active and passive shoulder movement and typically affects people aged between 40-60 years. Frozen shoulder can be primary (idiopathic) or secondary. Secondary frozen shoulder is associated with trauma, rotator cuff disease, cardiovascular disease, hemiparesis, diabetes and thyroid dysfunction. It has been estimated that the prevalence of frozen shoulder in people with diabetes is around 13 percent. Symptoms are often more severe and resistant to treatment compared to people without diabetes. Frozen shoulder is more common in women and in people who have previously had frozen shoulder in the opposite arm. 

Frozen shoulder progresses through three overlapping phases:

Painful phase (lasts 2-9 months). There is progressive pain on movement. The pain can become severe and disturb sleep.

Stiffness phase (lasts 4-12 months).The pain becomes less severe but is present at the end of the range of movement. Stiffness remains and there is reduction in the range of shoulder movements. Function can be substantially limited. 

Resolution phase (lasts 12-42 months). Gradual improvement in range of movement with less stiffness.

As there is overlap between phases, frozen shoulder has been more recently classified into ‘pain predominant’ and ‘stiffness predominant’ phases. Although symptoms usually settle in 18-24 months, there are reports of residual pain and stiffness persisting for several years in some people.

The diagnosis of frozen shoulder is clinical and includes:

Gradual onset of pain in the deltoid region, with worsening shoulder stiffness. This may make activities of daily living, such as putting on a jacket, difficult.

Restricted active and passive external rotation, and pain at the end of external rotation. There is a global (in all directions) limitation of active and passive range of shoulder movements with a capsular pattern, that is, a disproportionately severe reduction in passive external rotation. 

No obvious crepitus on movement.

X-rays are not necessary routinely. If these are performed, the glenohumeral joint should appear normal.

It is important to note that restricted passive external rotation is seen in other disorders, such as glenohumeral osteoarthritis, avascular necrosis and dislocation.

Management.  Explain the diagnosis and what the person should expect that pain is the main problem initially. It can be worse in bed and disturb sleep. The pain gradually improves, but stiffness slowly worsens and becomes the main problem. The stiffness then gradually resolves. Frozen shoulder is usually self-limiting, but it can take months to years to resolve. 

Advise on activity modification and pain control. When the shoulder is painful, continue to use the arm to maintain movement and ease spasm. Avoid movements which worsen the pain. This may require time off work or away from leisure activities. Take analgesia as advised and hot packs may be helpful. In bed, support the arm with pillows (to prevent rolling onto the affected shoulder).

Consider analgesia, supervised physiotherapy/domestic exercise programme, intra-articular corticosteroid injection and referral to secondary care. Follow a step-up approach, starting with noninvasive treatments, and moving on to invasive ones, if required.

Instability Disorders

Shoulder instability is the abnormal movement of the head of the humerus. It can cause pain, subluxation (partial loss of contact between joint surfaces) or dislocation (the complete loss of contact between joint surfaces which needs a reduction manoeuvre). Dislocation can happen once

(acute), more than once (recurrent), or be persistent (locked). Shoulder joint laxity is the asymptomatic movement of the humeral head on the glenoid cavity at the upper end of the normal range of movement. Laxity can occur without instability, and vice versa, or the two may co-exist.

Shoulder instability has been classified as:

Traumatic structural instability. This is when the shoulder is dislocated by an external force. As the shoulder does not heal in the correct anatomical position, or structures do not heal properly, the person is more susceptible to recurrent dislocations and further damage. 96% of shoulder dislocations are due to trauma. 

Atraumatic structural instability. This is common in adolescent females with hypermobile joints. If the shoulder is lax, it becomes unstable spontaneously or following a minor injury. 

Muscle patterning. This is due to unbalanced muscle recruitment around the shoulder and there is no structural abnormality. The person may have poor posture. 

These patterns can co-exist, or develop one after another with time. 

Instability disorders usually occur in people aged less than 35 years of age. The person may give a history of the shoulder feeling that it moves partly or completely ‘out of joint’ and may be concerned their shoulder may dislocate during certain activities or sports. There may be other non-specific symptoms such as shoulder ache or intermittent clicking. If the instability is longstanding, there may be hand or arm weakness, tingling or numbness from proximal nerve traction. Few tests of shoulder instability have been shown to be useful in practice. Often, there are no abnormalities on examination. The Beighton’s score can be used if hypermobility is suspected.

Anterior dislocation is the most common traumatic dislocation and is most often seen in people aged 15-30. There is another peak in women aged over 80. Typically the person presents with significant pain following a fall onto an outstretched hand. On examination, there is loss of the normal contour of the shoulder. The younger the person is when they first dislocate their shoulder, the more likely it is they will have a future dislocation. A person aged less than 20 has a 90% chance of having a further dislocation. Men are more likely than women to have a recurrence, and people with hyperlaxity are more likely than those without hyperlaxity.

Management. Refer immediately to an Emergency Department if acute dislocation is suspected. The person, or any bystanders, should not try to reduce the dislocation. There may be associated injuries, and so clinical assessment and radiological investigations should be performed, and the reduction done in a controlled environment. 

Following initial assessment and reduction of an acute traumatic shoulder dislocation: 

• Encourage early mobilisation (as soon as the pain allows). 
• Refer to physiotherapy. The course of physiotherapy is usually 4-12 weeks. 

Note that most people with an acute dislocation will have follow up through the fracture clinic in secondary care. It has been proposed that people aged under 25 should be seen by a shoulder surgeon by 6 weeks to consider whether surgical repair is appropriate. People aged 25-40 should be assessed for symptoms of shoulder instability at 3-6 months, and further imaging and surgery considered if there are still symptoms.  People aged over forty should have early imaging following a dislocation to check the integrity of the rotator cuff. If a rotator cuff tear is found, the person should be reviewed by a shoulder surgeon regarding the need for surgery.

Refer urgently to orthopaedics if a rotator cuff tear is suspected in a person who has recently sustained an acute shoulder dislocation. Suspect a rotator cuff tear if there is still pain and weakness 2-3 weeks following dislocation.

Refer to a shoulder surgeon. Following first-time dislocation. 

• If the person has had recurrent painful dislocations.
• If symptoms are impacting on the person’s job or leisure activities. 
• If the person has had a shoulder dislocation associated with an epileptic seizure.
• If symptoms following shoulder dislocation are not improving with physiotherapy.
• If there are associated injuries, such as fracture.

Refer to physiotherapy if:

• Atraumatic shoulder instability is suspected. Refer to orthopaedics if physiotherapy is not beneficial. 
• Muscle patterning instability is suspected. Refer to orthopaedics if the shoulder is still unstable despite physiotherapy.

Acromioclavicular Joint Disorders

Acromioclavicular osteoarthritis is more common than osteoarthritis of the glenohumeral joint, but is often asymptomatic. It usually presents in people over 60. The person may have previously sustained an acromioclavicular joint sprain. Weightlifting (putting the joint under repetitive strain) is a risk factor. Symptoms include tenderness over the acromioclavicular joint, which is made worse by raising the arm up high or when the arm is brought across the body. It may also be associated with rotator cuff disorders.

Acromioclavicular joint injuries can involve stretching or tearing of the acromioclavicular or coracoclavicular ligaments and subluxation or dislocation of the acromioclavicular joint. They most commonly occur in men aged 20-50 years, and ten result from a fall onto the point of the shoulder during sporting activity (for example rugby and skiing).

Acromioclavicular joint injuries are classified as:

• Grade I: Intact joint with minor tear of the acromioclavicular ligaments.
• Grade II: Up to 50% vertical subluxation of the clavicle with rupture of the acromioclavicular ligament and stretching of the coracoclavicular ligaments. 
• Grade III: more than 50% vertical subluxation of the clavicle with complete rupture of both acromioclavicular and coracoclavicular ligaments. 

On examination there, may be tenderness localised to the AC joint, limited range of movement due to pain, high arc pain or a positive cross arm test (see www.ouh.nhs.uk). There may be asymmetry of the shoulder contours following AC joint injury, however this may only become apparent weeks after the injury occurred.

Management. For osteoarthritis of the acromioclavicular joint advise the person on activity modification, in particular, to avoid cross body shoulder adduction (for example in a golf swing), and to avoid heavy lifting. Offer analgesia, consider referral to physiotherapy, consider corticosteroid injection if pain is severe. Arrange an X-ray (if this has not already been done) and refer to orthopaedics if there is no, or only temporary, improvement following the above measures. For acromioclavicular joint injuries refer for an X-ray or to accident and emergency, depending on clinical judgement.

If the acromioclavicular joint pain is caused by a mild sprain following an acute injury. Initially, advise rest, consider providing a sling for 5–7 days, and offer analgesia (see analgesia section above). Start gentle mobilisation and strengthening when the person is more comfortable. Consider referral to physiotherapy. Advise the person to resume normal activities as tolerated, but avoid heavy lifting and contact sports for 8–12 weeks. Refer to orthopaedics if symptoms are not settling following conservative management. Consider earlier referral for certain groups for whom shoulder pain is particularly disabling (for example, athletes involved in overhead sports, or people involved in heavy manual labour).

Reference

https://cks.nice.org.uk/shoulder-pain