**Question:** Motor cycle fracture is otherwise called

A. Salter-Harris type IV fracture
B. Displaced physeal fracture
C. Greenstick fracture
D. Supination-external rotation fracture

**Correct Answer:** D. Supination-external rotation fracture

**Core Concept:** Motor cycle fractures are a specific type of pediatric distal radius fracture that occurs due to a specific mechanism of injury. These fractures are commonly seen in children who are riding bicycles or motorcycles, hence the term "motor cycle fracture."

**Why the Correct Answer is Right:** The correct answer, D. Supination-external rotation fracture, refers to a fracture that occurs when the child's forearm is in a position of supination (palmar tilt) and external rotation at the time of injury. This type of fracture is associated with high-energy trauma, often resulting from a motorcycle accident, which is why it is called a motor cycle fracture.

**Why Each Wrong Option is Incorrect:**

A. Salter-Harris type IV fracture: Salter-Harris classification is used to describe physeal fractures in pediatric patients. Salter-Harris type IV fracture is a specific type of physeal fracture involving a fracture line that crosses the physis, extending into the adjacent epiphysis. It is not related to the mechanism of injury described in a motor cycle fracture.

B. Displaced physeal fracture: This refers to a fracture that involves the growth plate (physeal fracture) but does not specify the mechanism of injury or the type of fracture (e.g., Salter-Harris type IV).

C. Greenstick fracture: A greenstick fracture refers to a fracture in which the bone bends but does not completely break. It is not specific to the mechanism of injury associated with motor cycle fractures.

**Clinical Pearl:** Motor cycle fractures and their associated injuries should be suspected in pediatric patients who present with a wrist injury after falling from a motorcycle or bicycle, especially if the injury occurs in a supinated position and with external rotation. These injuries are often associated with multiple injuries due to the high-energy trauma experienced during a motorcycle accident. A thorough clinical examination, including range of motion, swelling, deformity, and tenderness of the wrist, is essential in making the correct diagnosis.