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.

1. Are the fat pads normal?
   1. A visible ant. fat pad is normal but if displaced anteriorly (Sail sign) it is abnormal
   2. A visible post. fat pad is always abnormal
   3. What if have fat pad displacement but no fx or displacement is identified?
      1. Adults: Treat as radial head fx
      2. Peds: Be certain that neither an undisplaced supracondylar fx nor a displaced internal epicondyle fx is overlooked!
2. Is the radiocapitellar line normal?
   1. A line drawn along the longitudinal axis of the radial head and neck should pass through the capitellum
      1. If line does not pass through capitellum then dislocation of radial head is probable
   2. Whenver there is a fx of the ulnar shaft must evaluate the radiocapitellar line for poss radial head dislocation (Monteggia fx dislocation)
   3. This rule is always valid on a true lateral film
      1. In peds cases the AP view may be misleading
3. Is the anterior humeral line normal?
   1. A line drawn along the ant cortex of the humerus will have at leats 1/3 of the capitellum anterior to it
      1. If less than 1/3 then strong probability of supracondylar fx w/ distal fragment displaced posteriorly
4. Are the ossification centers normal?
   1. CRITOE (Capitellum, Radial head, Internal epicondyle, Trochlea, Olecranon, Lateral Epicondyle)
      1. Dislocated elbow may result in avulsion of internal epicondyle
         1. 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)

Source

• Accident and Emergency Radiology