PJ Whooley and James Foley. Shoulder x-ray interpretation, Don't Forget the Bubbles, 2020. Available at:
https://doi.org/10.31440/DFTB.29653
Don’t be bamboozled by a paediatric shoulder x-ray. Use an ABCD approach and pick up some tips and tricks in our step-by-step guide.
A – An adequate x-ray
Is it the right patient and do you have the 2 views you want to see? The typical views are AP (external rotation) and the scapular Y view. (Not sure why then thisx meme may help). Occasionally an axillary view is added to assess for dislocations and glenohumeral instability.
B – Bones
Go through the bones one at a time. Follow the cortex of every bone in each view. Look for a disruption or a buckle in the cortex or any fracture fragments. They should all be smooth.
- The clavicle is a good bone to start with – it is by far the most common paediatric shoulder injury. Midshaft fractures account for 80% of clavicle fractures. Make sure there are no distal or medial fractures as they can often be subtle.
- Move onto the proximal humerus – check the epiphysis and metaphysis. A normal humeral head looks like a walking stick on the AP view. The most common fracture of the humerus is a metaphyseal fracture. Metaphyseal fractures occur in ages 5-12 and Salter-Harris fractures outside of this range.
- Don’t forget the scapula, seen best on the Y view. Management is conservative but a fracture here indicates a significant trauma.
Like the paediatric elbow, the paediatric shoulder has ossification centres, so x-ray appearances differ depending on the age of the child.
At birth, the humeral diaphysis, mid position of clavicle and the body of the scapula are ossified – the rest are essentially cartilage.
The proximal humerus has three ossification centres:
- Head – 1 year of age
- Greater tubercle – 3 years
- Lesser tubercle – 5 years
- The scapula has 7 secondary ossification centres.
Look carefully for the following two – if they appear early they may be the only sign of an avulsion fracture:
- The sub-coracoid ossificiation centre appears between 8 to 10 years and completely fuses between 16 and 17 years of age, forming the upper third of the glenoid articular surface . If it appears before the age of 8, this may indicate an avulsion (pulled by the long head of biceps at its attachment to the superior glenoid).
- The inferior glenoid ossification centre, appears at the lower two-thirds of the glenoid articular surface. It grows and fuses to form a horseshoe shaped epiphysis that combines with glenoid rim and sub-coracoid ossification centre. This appears between 14 and 15 years (although sometimes as young as 11 years), with complete fusion by 17 to 18 years. It can be difficult to view on standard radiographs but sometimes it can be seen on the Grashey (AP oblique) view
A top tip: If you are unsure whether what you are seeing is an avulsion fracture or a simple ossification centre, then press directly on the patient where the fragment is. If this isn’t painful then it is highly likely to be an ossification centre and not an avulsion. Range of movement is another great give-away – it is quite hard to have an avulsion fracture and intact range of movement! If in doubt, speak to a friendly radiologist (in hours) or be conservative and place in an arm sling and bring back to clinic (out of hours) for re-assessment (when the x-ray will have been reported).
Don’t forget the other bones that don’t make up the shoulder. Have a look for rib fractures, and if you see old healing rib fractures then consider non accidental injury.
C – Connections & Connective Tissue
Are all the bits connected to where they should be? Ask yourself a few questions when you’re looking at the different joints.
Glenohumeral joint:
- Do the articular surfaces of the humerus and glenoid have 2 parallel lines with an even joint space?
- Does the humeral head sit evenly on the glenoid in all views?
- Does the humeral head sit adjacent to the glenoid on the AP view? Does it sit over the glenoid on the Y view? If the answers to these questions are no, and instead the humeral head is lying under the coracoid process, this indicates an anterior shoulder dislocation
Anterior Shoulder Dislocation (AP and Y views).The humeral head is located beneath the coracoid on the AP view and no longer located centrally on the Y view. In addition there is flattening of the humeral head suggesting a Hill Sachs lesion (more on this in the upcoming shoulder dislocation post)
- Has the humeral head lost its characteristic walking stick appearance on the AP view? Does it instead look rounder, like a light bulb? If the answer to these questions is yes, this suggests a posterior shoulder dislocation.
- Is there a joint effusion or lipohaemarthorsis present? This could indicate an intra-articular fracture of the glenoid or the humeral head.
Acromioclavicular (AC) joint:
- Does the bottom of the acromion lines up with the bottom of the distal clavicle? If there’s a step, think clavicle fracture or physeal injury
- Is there widening of the acromioclavicular joint (normal is 5-8mm) or coracoclavicular distance (normal is 10-13mm)? A widened AC joint > 8mm suggests an AC ligament rupture. If the coracoclavicular (CC) distance is >13 mm consider CC ligament rupture. If you’re unsure, get weighted views of both AC or CC joints to compare each side (literally with the child holding weights in each hand to stress the joints).
D – Don’t forget the other tissues
Always look around the area to look for foreign bodies or subcutaneous emphysema indicating a pneumothorax or pneumomediastinum. If there are, then a dedicated chest x-ray should be performed.
And finally, although the above may seem complicated, realistically common things are common.
- Clavicle Fractures. By far the most common. 80% are mid-shaft and occur following a fall onto the outstretched hand or shoulder or direct trauma from a seatbelt or during sport.
- Proximal humeral fractures. These occur in older children.
- Anterior shoulder dislocation. Usually in older children playing sports. Falls result in forced ABDuction, external rotation, and extension. Account for 95% of shoulder dislocations.
Don’t miss
- Acromioclavicular Joint injuries – widening or step at acromioclavicular joint and/or increased coraco-clavicular distance.
- Rib fractures – healing rib fracture? Consider NAI.
References
- JS. Zember, ZS Rosenberg, S. Kwong, SP. Kothary, MA. Bedoya. Normal Skeletal Maturation and Imaging Pitfalls in the Pediatric Shoulder. Radiographics. 2015 Jul-Aug;35(4):1108-22
- https://radiopaedia.org/articles/paediatric-shoulder-radiograph-an-approach
Wrist x-rays
Sian Edwards. Wrist x-rays, Don't Forget the Bubbles, 2020. Available at:
https://doi.org/10.31440/DFTB.29082
The wrist is one of the most commonly requested X-Rays in the children’s emergency department. Wrist views are requested when injury to the distal radius/ulna or carpal bones are suspected. Below is a systematic approach to interpretation.
The wrist series examines the carpal bones (scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate and hamate), the radiocarpal joint and the distal radius and ulna.
There are eight carpal bones present and each one is named according to its shape:
How to best remember the carpal bones
There are many mnemonics around – some too rude for mention here! You will need to find the one that works for you… here’s one that’s super suited for clinicians working with kids:
Sam Likes To Push The Toy Car Hard
Failing that, save an image to your phone for quick reference!
Ossification
The carpal bones are formed entirely from cartilage at birth – this is important from a radiological viewpoint as it means they are not visible on x-ray initially. They begin to ossify from about 1-2 months of age and are fully developed by the age of 8-12 years. Although there is variability in the timing, the order is always the same.
Generally, on x-ray, one carpal bone is visible every year until full development – this acts as a handy (pun intended) ageing tool!
On requesting wrist X-Rays, most commonly you will receive posteroanterior and lateral projections, with oblique views forming part of the series usually when carpal injury is suspected.
1. Check the soft tissues
Look for signs of swelling or any incidental findings.
2. Trace the bony cortices
Trace each bone in turn to look for breaks or irregularities in the cortex.
Look closely at the distal radius, proximal carpal row (especially the scaphoid) and the proximal metacarpals. Disruptions in the cortex may be very subtle as in the case of this torus fracture (aka a buckle fracture)
3. Check bony alignment
On the AP view:
The distal radial articular surface should curve round the carpals with the articular surface getting more distal towards the ulnar styloid. The articular surfaces of the proximal and distal carpal rows should form three smooth arcs – these can be traced on the AP film.
The spacing between all carpal bones should be 1-2mm.
If the arc is broken or there is widening or lack of uniformity between the spaces, think about carpal dislocation.
The articular cortex at the base of each metacarpal parallels the articular surface of the adjacent carpal bone.
The carpo-metacarpo (CMC) joint spaces should be clearly seen and of uniform width (1-2mm).
The 2nd to 5th CMC joints are visualised as a zigzag tram line – on a normal view, there will always be the “light of day” seen between the bases of the 4th and 5th metacarpals and the hamate bone. If this is narrowed, think dislocation of the 4th or 5th metacarpal.
On the lateral view:
The distal radius, lunate and capitate should articulate with each other in a straight line on the lateral x-ray – the apple, cup, saucer analogy – the cup of the lunate should never be empty.
If the cup is empty, this suggests a perilunate dislocation.
References
https://radiopaedia.org/articles/wrist-radiograph-an-approach?lang=gb