Which type of fracture results from a fall on an outstretched hand with dorsal displacement?

• A. Smith fracture
• B. Bennett fracture
• C. Colles fracture
• D. Boxer fracture

Answer: (C)

A Colles fracture specifically occurs when there is a fall on an outstretched hand, resulting in a fracture of the distal radius. This type of fracture is characterized by the dorsal (posterior) angulation and often dorsal displacement of the distal fragment of the radius. Patients typically present with a notable "dinner fork" or "garden spade" deformity of the wrist due to this displacement.

In contrast, a Smith fracture involves a fracture of the distal radius with palmar displacement and does not occur from an outstretched hand. Bennett fractures are intra-articular fractures of the base of the first metacarpal, primarily due to axial loading or impact injuries, which are not related to the mechanism of falling on an outstretched hand. Lastly, Boxer fractures generally occur in the fifth metacarpal as a result of a punch or impact, and again, do not originate from the described fall mechanism. Thus, the characteristics specific to a Colles fracture align directly with the injury pattern described in the question.