Hi welcome to another radiology channel tutorial on the pediatric elbow radiograph i’m dr jeremy jones from radiopaedia and today we’re going to be looking at supracondylar fractures. take a look at these three radiographs and see if you can identify those that have a supracondylar fracture. if you’re not already viewing this in high definition i suggest you do so. you can always pause the tutorial if you need more time the elbow joint is made up of the humerus, the ulnar and the radius. the radial head sits in the radial notch of the ulnar.
And is surrounded by the annular ligaments. It sits adjacent to the capitellum which is central in the elbow. when the elbow is extended the olecranon sits within the olecranon fossa. this is the narrowest point of the distal humerus and therefore the weakest point of the pediatric elbow. if we apply force to the capitellum the supracondylar portion of the distal humerus is the weakest area and therefore the area most like to fracture. as such supracondylar fractures are the commonest of the pediatric elbow fractures. they typically occur following a fall onto a hyperextended elbow.
As with any fracture complications include damage to local vessels such as the brachial artery, and damage to local nerves such as the ulnar nerve which can be damaged in severe displacement. a line drawn down the anterior surface of the humus should intersect the middle third of the capitellum. since the capitellum is displaced posteriorly in the vast majority of supracondylar fractures this is an extremely helpful tool for demonstrating correct alignment at the elbow joint. let’s look back at our cases. in case A, if we draw a line down the anterior surface of the humerus.
Supracondylar fracture radiology tutorial tutorial xray
And then draw in the expected location of the capitellum, we can see that a force applied down the radius has displaced the capitellum posteriorly. in addition there is an anterior fat pad indicative of an elbow effusion. there is also irregularity of the dorsal cortex which represents the fracture. if we move on to case B, we can draw in our anterior humeral line and the expected location of the capitellum. there is no capitellar displacement however there’s a large anterior fat pad suggesting an elbow effusion, which has been caused by this longitudinal fracture to the radial neck.
Let’s move on to case C. again we can draw in the anterior humeral line, and we can draw in the expected location of the capitellum. again, force down the radius has caused posterior displacement of the capitellum. on this occasion there is no evidence of an elbow effusion, but if you look carefully in the olecranon fossa there’s irregularity of the cortex caused by the supracondylar fracture. So we have seen two cases of supracondylar fracture, learnt that they are the commonest pediatric elbow fracture, and subtle and easy to miss in certain circumstances,.