Bones break under varying degrees of pressure according to age, health and other circumstances. They are made of hard, strong, connective tissue and normally resist considerable force before breaking or fracturing. But when a bone has been softened by disease or grown fragile with age, fractures may follow very minor accidents or even occur spontaneously (pathological fractures).
The bones of children are not fully mature and are still relatively flexible. In childhood a severe blow or fall often results in a "greenstick" fracture, in which the bone does not completely break into tow separate pieces.
An impacted fracture occurs when the broken ends of the bone appear to be jammed together by the force of the injury. A com-minuted fracture is on one in which the ends are shattered into many pieces. A fracture is called simple (closed) when the overlying skin is not broken, or compound (open) when the bone is exposed.
All fractures attempt to heal themselves by producing new tissue to join the broken pieces together. At first this tissue is like putty and easily injured. So, generally a fractured limb should be straightened, immobilized and protected by a plaster cast while the healing takes place. In time, the new tissue or fracture callus, changes into mature bone.