Introduction

The shoulder joint provides a large range of movement, but consequentially, it is relatively open, and unstable. As a result it is prone to dislocation and subluxation (incomplete or partial dislocation – often most ligaments are still in the right place, but in one plane, the joint may be ‘subluxed’). The role of the joint is to help move and place the arm. Stability of the joint is provided mainly by the rotator cuff muscles, and to a less extent by the ligaments and joint capsule.

Shoulder pain is a very common presentation. The first important differential is to work out where the pain is arising from:

  • The shoulder itself
  • The cervical spine
    • Pain arising from the C5 nerve root can cause pain that appears to originate form the shoulder – almost all shoulder structure are innervated by this nerve root
  • The AC joint
    • Typically the result of trauma when landing on the tip of the shoulder – .e.g in contact sports
  • Heart / lungs / intra-thoracic structures
    • g. cardiac, pancreatic or peptic ulcer pain, diaphragmatic irritation radiating to the shoulder tip

In this article we will be discussing primary shoulder injuries.

For the majority of presentations, imaging is not often necessary and blood tests are usually not required.

Treatment of choice is typically physiotherapy +/- corticosteroid injections for most non-traumatic or minor trauma induced injuries.

For inflammatory shoulder conditions in particular, corticosteroid injections are usually effective and may be considered earlier in the disease process.

Anatomy

The shoulder may be considered as a group of three separate parts, two of which may be considered as joints in their own right:

  • The glenohumeral joint
  • The AC joint
  • The subacromial complex – housing the subacromial bursa and supraspinatus tendon

The glenohumeral joint is a shallow ball and socket joint, and as a result is inherently unstable.

  • Like a golf ball on a tee

Therefore, much of the stability of the joint is provided by the rotator cuff and to a lesser extent, the ligaments and joint capsule.

The rotator cuff

Shoulder Joint Posterior View

Shoulder Joint Posterior View

 

Shoulder Joint Anterior View

Shoulder Joint Anterior View

Rotator cuff injuries are a very common presenting complain in individuals over the age of 50. By the age of 50, about 25% of people will have some chronic damage to the muscles of the rotate cuff – which may or may not be symptomatic.

There may be a history of trauma but this is often not the case. Overuse injuries are also common.

Rotate cuff injuries are best diagnosed with resisted movement tests on shoulder examination.

The most common injury to the rotator cuff is supraspinatus tendinopathy.

There are four main muscles in the rotator cuff, detailed below. You can use the mnemonic ‘SITS’ to remember the muscles.
Muscle
Origin (on scapula)
Attachment
Function
Innervation
Supraspinatus
Supraspinatus fossa on posterior surface , above the spine
Greater tubercle of humerus
Abducts the arm (first 15’, deltoid does the rest)
Suprascapular nerve (C5)
Infraspinatus
Infraspinatus fossa, on posterior surface, below the spine
Greater tubercle of humerus
Externally rotates the arm
Suprascapular nerve (C5, C6)
Teres Minor
Lateral border of posterior surface
Greater tubercle of humerus
Externally rotates the arm
 
Subscapularis
Subscapular fossa, anterior surface
Lesser tubercle of humerus
Internally rotates the arm
 

 

Ligaments of the shoulder

Sometimes referred to as “static stabilisers” of the shoulder joint.

Shoulder Ligaments

Shoulder Ligaments

 

Investigations for shoulder pain

The cause of shoulder pain is often a clinical diagnosis and investigations are not commonly required. But in certain cases, clinical suspicion may indicate the need for further investigation. Tests may include:

  • ESR – if polymyalgia rheumatic or RA are considered
  • ECGif cardiac cause suspected
  • X-ray
    • Of shoulder – if suspected AC joint injury, or of the glenohumeral joint if OA is suspected
    • Of c-spine
  • Bone scan – if tumour suspected
  • USS – useful to see rotator cuff injuries and capsulitis. However, interpretation can be difficult – especially in the over 50s (of whom 25% have a rotator cuff injury anyway, which is often asymptomatic). Should really only be reserved for those in whom surgery is being contemplated, and a good clinical diagnosis is often all that is needed in the majority of cases.
  • CT and MRI – only really useful in the pre-op planning stage and after an acute injury (e.g. in the emergency department)
  • Arthroscopy

 

Differential Diagnoses of shoulder pain

  • Common
    • Cervical referred pain
    • Rotator cuff tendonopathy
      • Typically age 30-60, pain worse at night, pain on lifting hands overhead
    • Adhesive capsulitis
      • Typically age 40-60, pain at night, reduce rotation – particularly external, later globally reduced ROM
    • Glenohumeral capsule injuries and tears
      • Typically after multiple dislocations, often younger patients – e.g. teenagers and young adults
    • Others
      • AC joint injury
      • Arthritis
        • Typically age >70, crepitus, globally reduced movement
      • Angina / MI
      • Tumour – e.g. lung ca, humeral ca (primary or metastasis)
      • Septic arthritis
      • Rheumatoid arthritis
      • Polymyalgia rheumatica
        • Typically bilateral, patient over 60, worse in the morning
      • Intra-abdominal pathology
        • Causing diaphragm irritation and referred shoulder pain

 

Shoulder Impingement

Shoulder impingement, also commonly referred to as impingement syndrome or most properly referred to as rotator cuff tendonopathy. A common shoulder disorder – results from ‘impingement’ of the tendons of the rotator cuff muscles in the subacromial space, usually a result of inflammation of the supraspinatus tendon. In more severe cases, there may be calcification of the tendon, and associated subacromial bursitis – whereby the subacromial bursa also becomes inflamed. This can then exaggerate the problem, as the now inflamed tendons rub against the achromium, and clavicoaromial joint and ligament.

  • In these cases, subacromial tenderness is a useful sign to help confirm the diagnosis.

The area 1cm medial to the supraspinatus tendon attachment, in the subacromial space, is a critical area. This area is prone to ischaemia, when the arm is abducted (hands above the head position).

It is thought that this ischaemia plays a role in the cause of impingement syndrome and hence why impingement is associated with prolonged periods of the hands being raised above the head.

It is believed that similar mechanical factors play a role in many shoulder “overuse” injuries – particularly in Swimmer’s shoulder (See below).

Presentation

  • Constant pain – including at night – patients often not able to lie on the affected shoulder
  • Pain felt at shoulder and down outside of arm
  • May radiate to elbow
  • May be gradual onset, or sudden after mechanical injury – e.g. dog pulling hard on leash, lifting an object
  • Aggravated by specific movements – e.g. putting on a shirt. Particularly restricted are overhead activities.
  • May be tender over supraspinatus tendon

 

Diagnosis

Diagnosis is usually clinical, and relies heavily on shoulder examination. Of particular importance is the empty can test.

 

Management

Management is not universally agreed, and there is a lack of good quality evidence.

NSAIDs can be useful for analgesia, but probably don’t have much effect on long-term outcome. Corticosteroid injections are often useful, particularly if there is associated subacromial bursitis.

  • Corticosteroid injections should be avoided if a tear is noted on ultrasound

In reality, many patients heal with rest, analgesia and physiotherapy, and those who don’t usually undergo USS +/- corticosteroid injections. If symptoms still do not resolve then patients should be referred as an outpatient for an orthopaedic assessment.

Injections may still often be performed without USS guidance, although this is likely to become less and less common in the coming years due to the increased accuracy (and thus likely increased efficacy) of USS guided injections.

Physiotherapy programs usually involve strengthening of the rotate cuff, and stabilising of the scapula.

Referral to orthopaedics should be considered in long term pain. Surgery may involve:

  • Widening of the subacromial space by dividing the coracoacromial ligament (often this is thickened and contributing to the problem)
  • Repair of rotator cuff tear – can useful even in elderly patients with a long history

 

Calcific tendonitis is a term used to describe calcification of the supraspinatus tendon, which typically causes an acute onset, severe impingement syndrome. It may respond well to early corticosteroid injection, but often causing a more severe and longer term pain than non-calcified cases. Usually settled with other non-surgical interventions.

Swimmer’s Shoulder

Common in adults, and also seen in children. One study in the USA of college level swimmers showed about 50% of them had suffered at some point.

It is a variation of impingement syndrome, whereby, through thousands of repeated shoulder abductions, the supraspinatus tendon is repeatedly compressed.

Swimmer’s shoulder can be divided into three stages:

  • Stage I – pain after activity only
  • Stage II – pain at the beginning of activity, and then after activity
  • Stage III – pain throughout activity, restricting performance

 

Management

  • Early recognition is important
  • Ice after each swim
  • NSAIDs
  • Avoid corticosteroid injections
  • Modified swimming technique – often needs to be done in conjunction with swimming coach
  • Physiotherapy – techniques to stabilise the scapula re particularly effective

 

Rotator cuff tears

  • Usually also mainly affect the supraspinatus muscle (like rotator cuff tendonopathy)
  • Often asymptomatic
  • 4% of individuals <40 years
  • 50% of individuals >60 years
  • Explain that it is a normal part of ageing, try to use words like “worn” not “torn”
  • 98% chance of rotator cuff tear if:
    • Supraspinatus weakness
    • Weak external rotation
    • Impingement symptoms

Adhesive capsulitis

  • Known colloquially as “frozen shoulder”.
  • Typically occurs as the result of an injury
  • Patients usually aged 40-70
  • Caused by acute inflammation of the glenohumeral joint, and then later there is fibrosis and contraction of the joint soft tissues.
  • Affects 2% of the population
  • Associated with diabetes
    • Occurs in 10-20% of diabetics
  • It lasts a long time!Often 1-2 years
  • Diagnosis
    • Pain at shoulder and outer arm
    • Radiates to elbow
    • Constant pain, including at night
    • Usually spontaneous onset – often at night and awakes patient from sleep
    • Aggravated by movement – particularly dressing and doing hair
    • May have stiffnes and globally reduced ROM
  • It typically has three stages (freezing, frozen, thawing)
    • Inflammatory painful phase – 2-9 months
    • Fibrotic contracted phase – 4-12 months
    • Improvement phase – 6-24 months
      • May not be a full recovery
    • Differentials
      • Septic arthritis
      • Rheumatoid arthritis (single joint)
      • Gout

 

Avascular humeral head

This is usually a complication of proximal humeral fracture.

The fracture may be occult, or in other cases, there may be no fracture, with an insidious onset of pain.

X-rays can be useful but MRI is the imaging modality of choice.

  • Crescent sign on x-ray indicates subchondral collapse
  • MRI will show subchondral oedema and has almost 100% sensitivity and specificity

 

Treated with prosthetic replacement of the humeral head.

Delayed treatment leads to worse outcomes.

 

Biceps Tendonopathy

  • Usually refer to a tear of the long head of the biceps tendon
  • Causes anterior shoulder pain
  • Signs
    • Pain on flexion of elbow against resistance
    • Pain on supination of the hand, when elbow flexed to 90 degrees (Yergason’s test)
    • May be tenderness to palpation along the biceps tendon in the bicipital groove
  • If the intracapsular pat of the tendon is affected it can mimic shoulder impingement
  • Can be diagnosed with USS
  • Treated similarly as for shoulder impingement – physio and rest first, consider steroid injection if not resolving, and orthopaedic referral if still not improving

 

Posterior Shoulder dislocation

  • Rare, but often misdiagnosed
  • Typically shoulder dislocation occurs anteriorly and is clinically quite obvious
  • Posterior shoulder dislocation may not present with any significant deformity, and with relatively little trauma
  • Associated with seizures
  • External rotation is often completely blocked
  • Requires prompt identification and management to prevent a poor long-term outcome
  • Can be seen on x-ray

References

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