## **Core Concept**
A Colles fracture is a type of fracture that occurs at the distal end of the radius bone in the forearm, typically resulting from a fall onto an outstretched hand. This type of fracture is common in adults, especially the elderly. Complications can arise during or after the healing process.

## **Why the Correct Answer is Right**
The correct answer, **stiffness of wrist**, is a well-recognized complication of Colles fractures. This stiffness often results from prolonged immobilization of the wrist, leading to reduced range of motion and functional impairment. The immobilization period necessary for fracture healing can cause surrounding joints and soft tissues to become stiff.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Malunion is indeed a potential complication of Colles fractures but is not typically considered the most common complication. Malunion occurs when the fracture heals in an incorrect position.
- **Option B:** Reflex sympathetic dystrophy (RSD), also known as complex regional pain syndrome, can occur but is less common compared to stiffness of the wrist. RSD is characterized by chronic pain, swelling, and changes in skin color and temperature.
- **Option C:** Median nerve injury could potentially occur with wrist fractures but is not the most common complication of Colles fractures. Such injuries can lead to symptoms like numbness, tingling, and weakness in the hand.

## **Clinical Pearl / High-Yield Fact**
Early mobilization and physical therapy are crucial in preventing stiffness and promoting optimal recovery after a Colles fracture. Clinicians often emphasize the importance of moving the wrist and fingers as much as possible during the healing process to minimize the risk of stiffness.

## **Correct Answer:** D. stiffness of wrist