1

Radiographic examination

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  AP

  
  
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  External oblique

  
  
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  Lateral

The three views ( Figure 3-1 ) selected have been proven to disclose the majority of fractures and dislocations. Certain injuries can be inapparent on standard PA ( Figure 3-1 A ) and lateral ( Figure 3-1 B ) projections and may be seen only on the external oblique view ( Figure 3-1 C ). This is particularly true of fractures of the radial head, accounting for over one-half of all fractures (60%) of the elbow in adults.

Certain injuries can be unapparent on standard posteroanterior ( A ) and lateral ( B ) projections and may be seen only on the external oblique view ( C ).

Normal elbow in children

The presence and sequential appearance of multiple ossification centers in the child’s elbow ( Figures 3-2 A and B ), particularly in the distal humerus, makes for complex and potentially confusing anatomy. The capitellum is the first to appear at 3 to 5 months of age, followed by the medial epicondyle center at 4 to 6 years of age. The trochlear center appears at age 9 to 10 years. Note that the trochlear center never appears before the medial epicondylar center. The last center to appear is the lateral epicondyle at 9.4 to 11.5 years. Note the normal ossification center of the apophysis of the olecranon ( Figures 3-2 C ). This center is multipartite, a normal variant.

The presence and sequential appearance of multiple ossification centers in the child’s elbow ( A and B ), particularly in the distal humerus, makes for complex and potentially confusing anatomy. Normal ossification center of the apophysis of the olecranon ( C ). This center is multipartite, a normal variant.

2

Elbow joint effusions and the fat pad sign

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  Visible posterior fat pad

  
  
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  Elevation of the anterior fat pad, the sail sign

In the setting of trauma it is very likely that an intraarticular fracture is present if a joint effusion is identified. The presence of a joint effusion is an important clue to an otherwise obscure underlying fracture of the elbow in adults as well as children and adolescents.

Elbow joint effusions are detected on the lateral view ( Figure 3-3 ). The anterior and posterior fat pads reside in the joint capsule. On the lateral view of the normal elbow ( Figures 3-3 A and C ) without a joint effusion, the posterior fat pad is not apparent, while the anterior fat pad is visible but not elevated. In the presence of a joint effusion (hemarthrosis), the fat pads are displaced, and both the anterior and posterior fat pads become visible ( Figures 3-3 B and D ). This is known as the “fat pad sign.” The posterior fat pad is displaced posteriorly, and the anterior fat pad is elevated, often referred to as the “sail sign.” Note the subtle fracture of the radial head ( Figure 3-3 D ).

Elbow joint effusions. On the lateral view of the normal elbow without a joint effusion ( A and C ), the posterior fat pad is not apparent, whereas the anterior fat pad is visible but not elevated. In the presence of a joint effusion (hemarthrosis), the fat pads are displaced, and both the anterior and posterior fat pads become visible ( B and D ). Note the subtle fracture of the radial head in panel D .

3

Common sites of injury in adults

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  Radial head and neck

  
  
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  Olecranon

  
  
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  Coronoid process of ulna

  
  
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  Distal humerus

Pattern of search

Diagrams of the elbow ( Figures 3-4 A and B ) pinpoint the common sites of fracture in adults. The most common sites of fracture are identified by broad red lines. Less common sites are designated by fine red lines. Your pattern of search should include all sites.

Fractures of the radial head.

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