An intramedullary nail for a fractured elongated bone, comprising a cannulated rod having proximal and distal ends; an outside tubular sleeve for coaxially hosting and guiding the rod; and shape memory elements hosted in corresponding seats of the rod. Each shape memory element can be retractably housed in its respective seat in a first configuration, allowing insertion of the nail into the bone, and can project from a sleeve opening in another configuration. Proximal and distal pairs of the elements are provided at the proximal and distal rod ends. The proximal element pair lie on a same plane and are kept in their seats by a proximal cover. The distal element pair lie on an offset plane to the plane of the proximal element pair and are kept in their seats by a distal cover. This removes the need for bone screws to stabilize the nail inside the medullary canal.