Elbow XRay

Standard Views
1. Anteroposterior
  1. Epicondyles (medial and lateral)
  2. Humeral capitellum and trochlea
  3. Radial head
  4. Ulna's coronoid process
2. Lateral
  1. True lateral view
    1. Lateral and medial condyles should overlap
    2. Figure of 8 (hour glass, or snowman)
      1. Bottom of the figure 8 represents overlapping distal humeral capitellum and trochlea
  2. Landmarks include radial head and olecranon
  3. Posterior olecranon fossa (posterior fat pad)
  4. Anterior coronoid fossa (anterior fat pad and Sail Sign)
Special views
1. Radial Head-Capitellum View (oblique view)
  1. Isolates radial head without overlapping shadows

Anterior humeral line
1. Line drawn along the anterior edge of the Humerus
2. Passes through middle third of the capitellum
Radiocapitellar Line
2. Line drawn longitudinally through center of proximal radius
3. Line should bisect the capitellum (or through the middle third of the capitellum)

Background
1. Anterior and posterior fat pads fill the normal elbow recesses
  1. Anterior: Coronoid fossa
  2. Posterior: Olecranon fossa
2. When injury or inflammation results in a hemarthrosis or joint effusion, the fat pads are displaced outwards
  1. XRay with dark fat overlying lighter appearing soft tissue results in fat pad related signs
  2. Anterior fossa is more shallow, displacing its fat pad with less fluid than the posterior fossa
  3. Posterior fat pad is always abnormal
Sail Sign
1. Effusion displaces the anterior fat pad forming a dark triangle in the anterior fossa
2. Consider Radial Head Fracture
3. May also represent synovitis or spontaneous hemarthrosis without Fracture
4. Small anterior fat pads that hug the bone (no "sail") are typically normal and physiologic
Posterior fat pad sign (always pathologic)
1. Child: Supracondylar Fracture
2. Adult: Radial Head Fracture