## **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. The fracture is characterized by a displacement of the distal fragment of the radius bone dorsally.

## **Why the Correct Answer is Right**
The correct answer, , implies that ulnar fracture is uncommon in Colles' fracture. A Colles' fracture primarily involves the radius bone. Ulnar fractures can occur but are less common in the context of a Colles' fracture. The ulna can be involved in other types of fractures or injuries, such as a fracture of the ulnar styloid process, but an ulnar fracture is not typical in the classic presentation of a Colles' fracture.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because a Colles' fracture often involves dorsal displacement of the distal radius.
- **Option B:** This option might seem plausible since nerve injury can occur, but it's not specifically uncommon in Colles' fracture; in fact, median nerve injury can sometimes be associated.
- **Option C:** This option might relate to the fracture itself but doesn't directly address what is uncommon in Colles' fracture as directly as the correct answer.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that while a Colles' fracture is a fracture of the distal radius, it is often associated with other injuries such as a fracture of the ulnar styloid process. However, an isolated ulnar shaft fracture (without the radius fracture) is less common in the context of a typical Colles' fracture mechanism.

## **Correct Answer:** . Ulnar fracture