Presentation
Fall onto the outstretched hand while playing on a trampoline.
Patient Data
Radiographs revealed an undisplaced supracondylar fracture of the humerus, in keeping with a Gartland type I supracondylar fracture.
The fracture itself is quite subtle. In the frontal view, a thin fracture line can be seen going from the medial epicondyle to the coronoid fossa.
Moderate elbow joint effusion is noted by the sail sign and the posterior fat pad sign.
Case Discussion
Supracondylar fractures are the most common elbow fractures in children. Falling onto the outstretched hand with the elbow in full extension is the main mechanism of injury.
Gartland type I fractures are undisplaced or minimally displaced (<2 mm) supracondylar fractures. Sometimes, fracture lines are difficult to be seen on Gartland type I fractures. In these cases, it is important to look for indirect signs of a supracondylar fracture, such as:
- presence of elbow joint effusion;
- the anterior humeral line does not intersect the middle third of the capitellum.
In the present case, the fracture was initially missed, but the moderate elbow joint effusion showed by the sail sign, and the posterior fat pad sign raised suspicion of a hidden fracture. Reviewing the radiographs, a subtle supracondylar fracture was then noticed.
The anterior humeral line was passing through the middle third of the capitellum, further suggesting that the fracture is undisplaced.
Finally, it's important to be familiar with the elbow ossification centers when assessing a pediatric elbow. In this case, the patient is completing the ossification, with most centers fused already and the radial head and olecranon finishing the fusion, which is normal for the patient's age and gender.
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