Common sites of fracture non union are the following except –
**Core Concept**
Nonunion of a fracture occurs when the bone fails to heal properly, resulting in a persistent fracture gap. This can be due to various factors such as inadequate blood supply, infection, or mechanical instability. The sites of nonunion are often related to the anatomy and blood supply of the bone.
**Why the Correct Answer is Right**
Nonunion is more common in areas with poor bone quality, inadequate blood supply, or high mechanical stresses. The distal radius, proximal humerus, and femoral neck are common sites of nonunion due to their anatomical characteristics and blood supply. For example, the distal radius has a poor blood supply, making it prone to nonunion. Similarly, the proximal humerus has a thin corticocancellous junction, which can lead to nonunion.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the distal radius is a common site of nonunion due to its poor blood supply and high mechanical stresses.
**Option B:** This option is incorrect because the proximal humerus is a common site of nonunion due to its anatomical characteristics and poor blood supply.
**Option C:** This option is incorrect because the femoral neck is a common site of nonunion due to its high mechanical stresses and poor blood supply.
**Clinical Pearl / High-Yield Fact**
Remember the "DASH" acronym to recall common sites of nonunion: Distal radius, Ankle, Shoulder, and Hip. These areas are prone to nonunion due to their anatomy and blood supply.
**Correct Answer:** D.