An intramedullary nail comprising an outer tubular sheath, a flexible rod and a driver element mobile within the sheath longitudinally with an engagement element formed out of the wall of the tubular sheath. After the nail has been inserted, distal end first, into the intramedullary cavity, the flexible rod is pulled, thereby engendering the driver element to advance the engagement element into the cortical bone, thus keeping the intramedullary nail in position within the intramedullary cavity.