Elbow x-ray

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Four Questions

Anterior and posterior fat pad signs (in a case of an undisplaced fracture of the radius head which is not visible directly).
A normal anterior fat pad in a non-fractured arm.
Anterior "Sail sign"
Normal pediatric elbow alignment
  1. Are the fat pads normal?
    • A visible ant. fat pad is normal but if displaced anteriorly (Sail sign) it is abnormal
    • A visible post. fat pad is always abnormal
    • What if have fat pad displacement but no fracture or displacement is identified?
      • Adults: Treat as radial head fracture
      • Peds: Be certain that neither an undisplaced supracondylar fracture nor a displaced internal epicondyle fracture is overlooked!
  2. Is the radiocapitellar line normal?
    • A line drawn along the longitudinal axis of the radial head and neck should pass through the capitellum
    • Whenever there is a fracture of the ulnar shaft must evaluate the radiocapitellar line for possible radial head dislocation (Monteggia fracture-dislocation)
    • This rule is always valid on a true lateral film
      • In pediatric cases the AP view may be misleading
  3. Is the anterior humeral line normal?
    • A line drawn along the ant cortex of the humerus will have at least 1/3 of the capitellum anterior to it
  4. Are the ossification centers normal (pediatric patients only)?
    • CRITOE (Capitellum, Radial head, Internal epicondyle, Trochlea, Olecranon, Lateral Epicondyle)
      • Dislocated elbow may result in avulsion of internal epicondyle
        • Because the trochlea ossifies after the internal epicondyle if you see the trochlea you must find the epicondyle!

Elbow Ossification by Age (CRITOE)

Ossification Center Age of Appearance (add 1yr for boys)
Capitellum 1yr
Radial head 3yr
Internal epicondyle 5yr
Trochlea 7yr
Olecranon 9yr
External epicondyle 11yr


See Also


  • Accident and Emergency Radiology