## **Core Concept**
The "gun stock" deformity, also known as a cubitus varus deformity, is a common complication following a supracondylar fracture of the humerus. This type of fracture occurs just above the elbow in children. The deformity results from improper healing of the fracture, leading to a characteristic inward angulation of the distal fragment of the humerus.

## **Why the Correct Answer is Right**
The gun stock deformity is specifically associated with **supracondylar fractures of the humerus**. This type of fracture is common in pediatric patients and can result in a cubitus varus deformity if not properly aligned during healing. The deformity gets its name from its resemblance to the angle of an old-fashioned gun stock. This condition is a classic complication of this fracture type due to the anatomy of the distal humerus and the mechanism of injury.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because while fractures of the humerus can occur at various sites, the gun stock deformity is specifically related to the supracondylar region, not the shaft.
- **Option B:** This option is incorrect as there is no commonly recognized association of a "gun stock" deformity with fractures at the proximal end of the humerus.
- **Option D:** This option is incorrect because the term does not accurately describe a common fracture location associated with the gun stock deformity.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the gun stock deformity, or cubitus varus, is a common complication of supracondylar fractures of the humerus in children. It's essential to recognize that this deformity usually results from inadequate reduction or loss of reduction during the healing process. Clinically, while it can be cosmetically concerning, it often does not significantly impact elbow function.

## **Correct Answer:** C. Supracondylar fracture of humerus.