A 22-year-old male medical student was seen in the emergency department with a complaint of pain in his hand. He confessed that he had hit a vending machine in the hospital when he did not receive his soft drink after inserting money twice. The medial side of the dorsum of the hand was quite swollen, and one of his knuckles could not be seen when he “made a fist.” The physician made a diagnosis of a “boxer’s fracture.” What was the nature of the impatient student’s injury?

## **Core Concept**
A boxer's fracture refers to a specific type of fracture that occurs at the neck of the fifth metacarpal bone in the hand. This injury is commonly seen in individuals who engage in boxing or other activities that involve punching, but it can also occur in non-athletic contexts, such as the one described. The fifth metacarpal bone is located on the medial (ulnar) side of the hand.

## **Why the Correct Answer is Right**
The correct answer, , describes a fracture of the neck of the fifth metacarpal bone. This type of fracture is characterized by a break in the bone just distal to the metacarpophalangeal joint, which is the joint that connects the metacarpal bone to the proximal phalanx of the finger. The description provided in the scenario, including swelling on the medial side of the dorsum of the hand and the inability to see one of the knuckles when making a fist, is consistent with a boxer's fracture. The mechanism of injury, involving a punch, is also typical for this type of fracture.

## **Why Each Wrong Option is Incorrect**
- **Option A:** A fracture of the distal phalanx would involve the tip of the finger, which does not match the description provided.
- **Option B:** A fracture of the proximal phalanx would involve the base of the finger but not specifically at the metacarpal level, which does not align with the clinical presentation.
- **Option D:** A fracture of the scaphoid bone would involve the wrist, not the metacarpal region, and would present with different symptoms.

## **Clinical Pearl / High-Yield Fact**
A key clinical feature of a boxer's fracture is the "dinner fork" deformity, which describes the typical angulation and displacement of the fracture. This type of fracture is often treated with closed reduction and immobilization in a splint or cast, and the patient is advised to avoid activities that could exacerbate the injury.

## **Correct Answer:** . Fracture of the neck of the fifth metacarpal bone.

✓ Correct Answer: B. Fracture of the neck of the fifth metacarpal