Apparatus for treating a fracture of a bone of a subject including an intramedullary (IM) nail insertable into a medullary canal of the bone of the subject. The IM nail has a proximal head that defines at least one hole therethrough. A sleeve, which includes a locking mechanism, is engaged with the hole when the sleeve is inserted in the hole. This engagement prevents rotational movement between the sleeve and the nail and inward and outward longitudinal movement of the sleeve relative to the nail.
