A break in a bone or hard cartilage. Depending on the cause, fractures are divided into three categories: fractures caused by direct trauma, which are associated with contusion of nearby soft tissues, with the risk of opening the fracture site; fractures caused by indirect trauma, which causes twisting, stretching or collapse of the bone; pathological fractures, which occur in bones made fragile by a pre-existing lesion, of infectious or tumour origin.