The Shoulder

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The Shoulder

Fracture prevalence Projections Normal paediatric anatomy Proximal humerus Clavicle Scapula Glenoid
Anterior dislocation Posterior dislocation Acromioclavicular joint subluxation Pseudo-subluxation Rotator cuff arthropathy Bone metastases Simple bone cyst

(hover over images to zoom, click to enlarge)

Learning outcomes

Assess skeletal radiographs using a systematic approach
Understand the different radiographic projections and how the anatomy changes with position
Understand what injuries will be demonstrated on different projections
Describe shoulder girdle anatomy
Understand mechanisms of injury and the likely fractures/dislocations which may result
Recognise less common fractures to the individual bones of the shoulder girdle
Accurately describe glenohumeral dislocations and associated fractures
Understand common eponyms
Recognise potential ligament injuries
Identify normal paediatric anatomy and the development of secondary ossification centres
Recognise common pathological conditions seen around the shoulder girdle

Fracture prevalence

A fall onto the shoulder tends to result in specific injuries depending on the general age of the patient:

Under 10 years	Fractured clavicle
15-40 years	Acromioclavicular joint subluxation
15-40 years	Glenohumeral joint dislocation
Under 20 years and over 60 years	Fractured proximal humerus

Projections

AP - then view image.

The second image may be:
Supero-inferior axial or infero-superior axial if the AP is normal, and the patient can easily abduct their arm.
Modified axial, or lateral scapula "Y" view. The patient does not need to abduct their arm for these views and these projections can be easily obtained with the patient on a trolley.

Normal paediatric anatomy

In the unfused skeleton, the epiphyseal growth plate for the proximal humerus appears as two lucent lines. Commonly mistaken for fractures.
Also, secondary ossification centres are often seen at the acromion and the coracoid processes (images from same patient):

12 years

14 years

15 years

17 years

On the axial view, the ossification centre for the coracoid process may develop from the base or the tip. Both may simulate fractures:

Proximal humeral fractures

Humeral neck (anatomical and surgical), and greater tuberosity should be assessed carefully for evidence of:
Break to the cortex
Disruption to the trabecular pattern
Sclerosis, suggesting impaction

$Greater tuberosity, surgical neck fractures$

In the paediatric skeleton, the proximal humeral metaphysis should be examined carefully for cortical disruption:

$Metaphyseal fracture$ $Metaphyseal fracture$

Assess the whole radiograph (inc. ribs and lung), particularly injury due to high velocity, eg, RTA:

$Clavicle, ribs, scapular fractures$ $Clavicle, ribs, scapular fractures$

Clavicle fractures

Are usually easy to spot. If the fracture is minimally displaced and overlies the scapula/ribs, an angled up projection is helpful.
Fractures of the middle third of the clavicle are most common (especially in <20 year olds). Fractures of the lateral third are more likely to be seen in an older age group. Fractures of the medial third are uncommon.

Fractured clavicle, normal ossification centres

Scapula fractures

Will occur due to high velocity, eg, RTA.
Can be subtle due to overlying ribs/clavicle. If the mechanism of injury fits, then the scapula must be scrutinised, particularly the blade and spine of the scapula, and also the corocoid and acromion processes:

Glenoid fractures

Fractures to the anterior lip of the glenoid are usually very subtle and are therefore easily missed. They may occur due to direct trauma or following anterior dislocation.

$Glenoid fracture$

Anterior glenohumeral dislocation

Often occur due to sporting injuries.
Humeral head lies under the coracoid on the AP. On the axial it is displaced towards the coracoid. On the modified axial and lateral scapula "Y" view, humeral head is displaced towards the ribs/coracoid.

Important to identify associated fractures. Common fractures involve:
- the postero-lateral aspect of the humeral head (Hill-Sachs defect):

- the anterior lip of the glenoid (Bankart lesion):

- the greater tuberosity:

$Anterior dislocation, fracture greater tuberosity$ $Anterior dislocation, fracture greater tuberosity$

Posterior glenohumeral dislocation

Tend to occur due to muscle spasm during epileptic fits, or electric shock.
The humerus is usually internally rotated, therefore the humeral head has a "light bulb" appearance on the AP. This is not always the case, however. There is widening of the joint (>6mm) as the humeral head is displaced laterally; this is called the rim sign. On the axial, the humeral head will be displaced towards the acromion/away from the ribs:

Associated with avulsion fractures of the lesser tuberosity. Also, a medial and anterior humeral head compression fracture may be evident (trough line).

Acromioclavicular joint subluxation

Width of the normal joint is less than 7mm in adults. Widening indicates moderate sprain with rupture of the acromioclavicular ligament.
The inferior surfaces of the lateral clavicle and the acromion should be level. Subluxation is identified when the clavicle is elevated due to rupture of the coracoclavicular ligaments:

Pseudo-subluxation

Blood within the joint causes inferior subluxation of the humeral head, however, this is not a true dislocation. Look for a possible underlying fracture:

$Pseudosubluxation, fracture surgical neck$

Rotator cuff arthropathy

Causes superior elevation of the humeral head, with reduction in the subacromial space, often with erosions developing on the inferior surface of the acromion. Causes impingement of the supraspinatus tendon. May occur in association with RA.

Bone metastases

Primary tumours often metastasise to the proximal humerus, and it is important to search for any moth-eaten, lytic lesions, or areas of sclerosis.
Potential lesions may be an incidental finding on a non-fractured humerus, or the fracture may be pathological in origin:

Simple/Solitary/Unicameral bone cyst

A benign lytic lesion that is often seen at the diametaphyseal region of the proximal humerus. Again, may be an incidental finding, however, will sometimes fracture.
"Falling fragment sign" is sometimes seen, which refers to cortical fragments from the fracture, which fall through the fluid-filled lesion:

TAKE THE SHOULDER SELF-TEST

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Norwich Image Interpretation Course

Heidi Nunn (Advanced Practice Reporting Radiographer)

The Shoulder