**Core Concept**
In a Colles' fracture, there is a displacement of the distal radius due to a fall onto an outstretched hand. This type of fracture is characterized by a dorsal angulation of the distal fragment, leading to a characteristic "dinner fork" deformity. The displacement involves a combination of dorsal tilt, radial shortening, and ulnar variance.

**Why the Correct Answer is Right**
The correct answer is the one that does not describe a typical displacement seen in a Colles' fracture. In a classic Colles' fracture, there is a dorsal angulation of the distal fragment, which is a result of the force of the fall causing the distal radius to be displaced dorsally. This is due to the pull of the extensor muscles, particularly the extensor carpi radialis brevis, which acts to flex the wrist and extend the fingers.

* **Option A:** Dorsal angulation is a characteristic displacement seen in Colles' fractures, making it an incorrect answer.
* **Option B:** Radial shortening is a common finding in Colles' fractures, as the distal fragment is displaced proximally, leading to a shortening of the radius. This makes it an incorrect answer.
* **Option C:** Ulnar variance, specifically negative ulnar variance, is often seen in Colles' fractures due to the displacement of the distal radius. This makes it an incorrect answer.

**Clinical Pearl / High-Yield Fact**
In Colles' fractures, the "dinner fork" deformity is a classic sign, characterized by a dorsal angulation of the distal fragment. This deformity is a result of the combination of dorsal tilt, radial shortening, and ulnar variance.

**Correct Answer: A. Dorsal angulation is not seen in Colles' fractures.**