Elbow x-ray

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.

• 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 fx or displacement is identified?
    • Adults: Treat as radial head fx
    • Peds: Be certain that neither an undisplaced supracondylar fx nor a displaced internal epicondyle fx is overlooked!
• Is the radiocapitellar line normal?
  • A line drawn along the longitudinal axis of the radial head and neck should pass through the capitellum
    • If line does not pass through capitellum then dislocation of radial head is probable
  • Whenver there is a fx of the ulnar shaft must evaluate the radiocapitellar line for poss radial head dislocation (Monteggia fx dislocation)
  • This rule is always valid on a true lateral film
    • In peds cases the AP view may be misleading
• Is the anterior humeral line normal?
  • A line drawn along the ant cortex of the humerus will have at leats 1/3 of the capitellum anterior to it
    • If less than 1/3 then strong probability of supracondylar fx w/ distal fragment displaced posteriorly
• Are the ossification centers normal?
  • 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!

See Also

• Elbow Diagnoses
• Elbow X-ray (Peds)

References

• Accident and Emergency Radiology