Soft Tissue Evaluation on Wrist Radiography

Two images demonstrate five fat planes on the PA wrist radiograph, and four fat planes on the lateral wrist radiograph that should be scrutinized on any wrist radiography interpretation.

Facts:

• Soft tissue swelling is almost always seen in one or more compartments in cases of acute fracture or dislocation
• When swelling is observed on a trauma wrist radiograph, all soft tissue areas should be examined thoroughly and the assumption is that they may be a fracture or dislocation associated with swelling
• Abnormal fat planes = fat plane is convex out of the underlying bone, or loss of its distinct plane

What Do They Suggest?

• Dorsal hand swelling -> 2nd through 5th metacarpal injury
• Dorsal wrist swelling -> carpal fractures or wrist dislocation
• Dorsal radial swelling -> forearm fractures
• Pronator fat pad swelling -> forearm fractures
• Thenar swelling -> thumb fractures
• Hypothenar swelling -> 2nd through 5th metacarpal injury
• Scaphoid swelling -> carpal fractures
• Pararadial swelling -> forearm injury
• Paraulnar swelling -> forearm fracture

Reference:

Curtis DJ, Downey, Jr., EF, Brower AC, et al. Importance of soft-tissue evaluation in hand and wrist trauma: statistical evaluation. AJR 1984; 142:781-788.