What type of fracture is classified as a boxer's fracture?

A boxer's fracture specifically refers to a fracture of the 5th metacarpal, which is located in the hand and corresponds to the little finger. This type of fracture commonly occurs from a direct impact, such as when someone punches an object (often during a fistfight), which causes a fracture in the body of the fifth metacarpal.

The mechanism of injury typically involves a forceful impact that predominantly affects the fifth metacarpal as it is the farthest from the forearm and often bears the brunt of such forces. Clinically, this fracture is characterized by pain, swelling, and often a deformity at the base of the little finger, while functional loss can lead to difficulty in hand functions and gripping.

In contrast, other fractures mentioned in the options do not correspond to the typical scenario that defines a boxer's fracture. For example, a fracture of the 4th metacarpal is associated with different types of injuries, while fractures of the proximal phalanx of the thumb or the distal radius involve different treatment considerations and mechanisms of injury. Understanding the specific bones involved in common fractures helps in proper diagnosis and management.