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A 24-year-old man was hit with a nightstick during an altercation. He held up both his arms to protect himself and received blows to the forearms. He had pain on the ulnar aspect of his left forearm and the extensor surface of his right elbow.

  • Are any fractures seen on these radiographs (Figures 1 and 2)?
  • What are the radiographic signs of a fracture?

Fracture diagnosis is based on both clinical and radiographic findings. Three clinical predictors of a fracture are: 1) the mechanism of injury, 2) the findings on physical examination, and 3) age-related common injuries (Table 1). Likewise, there are three radiographic findings of a fracture: 1) visualization of the fracture line; 2) alterations in skeletal contour or alignment (most useful in children); and 3) soft tissue changes. Supplementary views are occasionally needed to visualize the fracture. These principles are illustrated for the elbow in this and the following chapter.

Table 1 Common Elbow Injuries

The elbow is a prime example of the usefulness of soft tissue signs in fracture diagnosis. Soft tissue changes can sometimes be easier to see than the fracture itself (see Principles of Skeletal Radiology, Table 3, in Section III: Skeletal Radiology—Upper Extremity). Soft tissue changes include swelling, joint effusions, and distortion or obliteration of the fats planes between muscle layers.

Post-traumatic joint effusions can serve as a clue to an intra-articular fracture. An effusion usually appears as an area of fluid density adjacent to the joint. Examples include ankle and knee effusions (although knee effusions are more reliably detected by physical examination).

The elbow anatomy is unusual because there are two collections of fatty tissue contained within the joint capsule (anterior and posterior fat pads) (Figure 3A). When the elbow is flexed to 90°, these fat pads lie nearly entirely within the coronoid and olecranon fossae of the distal humerus. On a properly performed lateral radiograph, the anterior fat pad may appear as a small lucent area just anterior to the distal humerus. The posterior fat pad is not normally visible (Figure 4A). ...

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