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CRITOE Quick Quiz


This quick quiz is to test your CRITOE knowledge. See this post for how to interpret an elbow x-ray.

Click on the image to see them in full size…


Q1: What age is this child?


View Q1 answer

This child is 6 years old.

Ossification centres develop in the order CRITOE (1, 3, 5, 7, 9, 11)


Capitellum (1 year)

Radial head (3 years)

Internal (medial) epicondyle (5 years)

Trochlear (7 years)

Olecranon (9 years)

External (lateral) epicondyle (11 years)


On these XRs you can see C, R and I (I not usually visible on the lateral) so the child is roughly 6 years old.


Understanding ossification centres order of development is crucial to recognising paediatric elbow fractures.

Q2: What is the abnormality in the XR of this child who sustained a fall onto the lateral aspect of her elbow?

lateral condyle avulsion

View Q2 answer

Lateral condyle avulsion.

The capitellum, radial head and the start of internal epicondyle are there (approx. 5 years old).  There is no trochlear or olecranon and therefore there should be no lateral epicondyle.  The small area shown in red (below) is an avulsed lateral condyle.

lateral condyle avulsion annot

Lateral condyle fractures account for 20% of all elbow fractures in children and are most common in 5-7 year olds after falling onto an outstretched arm.  All should be discussed with ortho as there is a high risk of complications if not treated properly.

The displacement (gap between the distal humerus and the fractured condyle) needs to be measured.

Undisplaced fractures can be put in a long-arm backslab (with 90 degree elbow flexion). Displaced fractures with a <2 mm gap sometimes require closed reduction.  Displaced fractures with a >2 mm gap or angulation of the lateral condyle will require surgical intervention.

Q3: What is the abnormality in this X-ray of a 12 year old boy who fell onto his outstretched hand (with the elbow extended)?

medial epicondy latmedial epicondyle ap

View Q3 answer

Medial epicondyle avulsion.

This child is 12 so should have all CRITOE ossification centres.  Checking through one by one, the medial epicondyle is missing. In fact it has been displaced.

Medial epicondyle ap annotmedial epicondyle annot lat

The yellow lines show where it should be, the red lines show where it is.

On the lateral you can actually see the medial epicondyle which you should not be able to do in a good lateral view.

Medial epicondyle fractures occur between 7-15 years (they account for 10% of elbow fractures in children). They are often associated with elbow dislocation (50%). The degree of displacement of the medial epicondyle needs to be assessed.

Undisplaced or minimally displaced (<5 mm) fractures will not need surgical repair and can be managed in a long arm backslab (with 90 degrees elbow flexion). Displacement of 5-15 mm requires ortho input – surgical intervention usually depends on multiple factors (e.g. age, dominant hand, sports involvement).  Displacement of >15 mm or neurovascular compromise (ulnar nerve palsy) will require ORIF.

Q4: What is the abnormality in this child who fell directly onto her elbow?


View Q4 answer

Olecranon fracture.

The ossification centres in the lateral view show a capitellum but no radial head (see below).

olecranon annot

The fragment on the end of the ulnar must be an olecranon fracture as there is no ossification centre yet developed.

These fractures account for 5% of elbow fractures in children.  They are often associated with other injuries so thoroughly check the rest of XR.

Undisplaced, or minimally displaced fractures can be put into a long arm backslab (90 degree elbow flexion).  Displaced fractures should be referred to ortho as will likely need surgical intervention.


  • Tessa Davis is a Consultant in Paediatric Emergency Medicine at the Royal London Hospital and a Senior Lecturer at Queen Mary University of London.


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