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 ||Download (.pdf)
Table 1 Common Elbow Injuries
|Radial head or neck fracture||50%||Supracondylar fracture||60%|
|Olecranon fracture||20%||Lateral condyle fracture||15%|
|Elbow dislocation||15%||Medial epicondyle fracture||10%|
|Radial neck or head fracture||6-12%|
|Distal humerus fracture||Elbow dislocation|
|Capitellum fracture||Olecranon fracture|
|Coronoid fracture||Monteggia injury|
|Monteggia injury||Complete epiphyseal separation (rare)|
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
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). ...