Fractures occurring as a result of disease of a bone or from some undiscoverable cause, and not due to trauma. (dorland, 27th ed)

A pathologic fracture is a bone fracture caused by weakness of the bone structure that leads to decrease mechanical resistance to normal mechanical loads. This process is most commonly due to osteoporosis, but may also be due to other pathologies such as cancer, infection (such as osteomyelitis), inherited bone disorders, or a bone cyst...