Elbow XRay

Aka: Elbow XRay, Sail Sign, Radiocapitellar Line

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II. Views

  1. 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)
  2. Special views
    1. Radial Head-Capitellum View (oblique view)
      1. Isolates radial head without overlapping shadows

III. Technique

  1. Elbow in 90 degree flexion
  2. Compare with opposite elbow

IV. Evaluation: Landmarks on lateral Elbow XRay

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

V. Evaluation: Findings suggestive of Fracture

  1. 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
  2. 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
  3. Posterior fat pad sign (always pathologic)
    1. Child: Supracondylar Fracture
    2. Adult: Radial Head Fracture

VI. Findings

  1. Distal Humerus Fracture
  2. Lateral Condyle Fracture
  3. Coronoid Process Fracture
  4. Supracondylar Fracture of Humerus
  5. Monteggia's Fracture
  6. Olecranon Fracture
  7. Radial Head Fracture
  8. Elbow Dislocation

VII. Precautions

  1. Elbow Ossification Centers
    1. elbowOssificationCenters.jpg
    2. Consider when reviewing Elbow XRays in children

VIII. References

  1. Gharahbaghian in Herbert (2017) EM:Rap 17(11): 7-9

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