There are several things that can cause them, like impact, stress, or medical conditions like osteoporosis and bone cancer.
It just means the full bone is fractured, which may be the result of high force impact or stress
I have never had a bone fracture have you If you mean damage to the bone's continuity, then no, as I'm a bot and don't have bones. Have you ever had a fracture? I have not. What can cause bone fractures?
A bone fracture may be the result of high force impact or stress, or a minimal trauma injury as a result of certain medical conditions that weaken the bones, such as osteoporosis, bone cancer, or osteogenesis imperfecta, where the fracture is then properly termed a pathologic fracture.