Types of fracture, artwork. Fractures can be open (compound, top left), where the bone pierces the skin, or closed (simple, top right), where the skin remains intact. If the bone breaks into more than two pieces it is a comminuted fracture (bottom left). If the bone remains aligned it is an undisplaced fracture (bottom centre). If the bone is not completely broken, it is known as a greenstick fracture (bottom right). Greenstick fractures are more common in children as their bones are softer.