Fracture means a broken bone. A fracture may be displaced: in which case the fracture fragments are shifted apart, or it may be undisplaced: the fractured pieces of bone are lined up with each other.
Most fractured are treated in casts and braces. If the fracture is undisplaced or if the pieces of the broken bone can be pushed back into place (called "a Reduction") then a cast is applied to hold the fragments in place while the body forms new bone to heal the fracture.
Surgery does not cause fractures to heal. The purpose of surgery on broken bones is to put the pieces back together. The body then heals the fracture fragments in place.