When a broken bone
displaces, the blood vessels are interrupted.
Like bone, vessels will heal over time. Until they do the area of bone supplied by a vessel is without blood. If that is the only vessel to that part of the bone, the bone can die and collapse. This is called avascular, or aseptic, necrosis. Its most common with fractures of the scaphoid in the wrist or head of the femur in the hip.