Britannica Sources used in this answer

Why does a broken bone hurt when it moves?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Internal structure of a human long bone — bone A long bone of the human body, showing a magnified cross section of the interior.

A broken bone causes pain during movement primarily because of the damage sustained by the periosteum. This dense, fibrous membrane covers the surface of bones and contains numerous nerve fibers that are highly sensitive to damage.1

When a fracture occurs, the periosteum is traumatized, and the resulting injury triggers pain signals. Any movement of the fractured bone causes the broken ends to shift or grind against one another, which further irritates these damaged nerve fibers and the surrounding tissues. Additionally, the healing process involves the formation of a clot and the proliferation of cells to create new bone; until this tissue stabilizes the area, the bone remains vulnerable, and any weight-bearing or movement between the fracture ends can exacerbate pain and interfere with proper recovery.12