How does a broken bone repair itself on its own in the body of a human adult?

A human adult body has the ability to repair a bone on its
own. Even the medical treatment that is provided to a patient usually is only to ensure
that the process is faster and the new bone is not deformed in any
way.

When a bone breaks, the blood vessels constrict to
stop the flow of blood and a blood clot is formed. New tissues grow from each end of the
fractured bone and unites with those from the other end. This tissue is then replaced by
a form of tissue that can create the same structure as the original bone. It is a
substitute for the original bone that was broken. Once the process is complete, the new
bone created is as good as the original bone.