A spiral fracture is defined as:

A spiral fracture is characterized by a fracture line that encircles or coils around the long axis of the bone, resembling a staircase or corkscrew pattern. This type of fracture usually occurs due to rotational or twisting forces applied to the bone, resulting in a break that spirals around the bone rather than just across it.

In this context, the definition aligns accurately with the choice that describes a fracture that coils around the bone. Such a mechanism of injury is common in sports, falls, or accidents where the limb is subjected to a torsional force, leading to this specific type of fracture pattern. Understanding the unique characteristics of spiral fractures can assist in their identification and appropriate management in clinical practice.

The other definitions do not adequately capture the nature of a spiral fracture. For instance, defining it as a break that coalesces around the bone or one that occurs due to compressive forces does not align with the anatomy and injury mechanism typical of spiral fractures. Similarly, describing it as a simple break with no fragmentation does not consider the more intricate pattern of bone disruption seen with a spiral fracture.