Apparatus and methods for preparing the interior of a bone for therapy. The therapy may include therapy for a bone fracture. The apparatus and methods may involve orienting a surgical instrument for proper deployment in the interior of the bone. An instrument guide may be positioned and retained against translation along, and rotation about one or more of three substantially orthogonal axes. Apparatus placed exterior to the bone may register the guide to a region inside the bone that is designated for preparation or treatment. One or more broaching members may be used to prepare the region for treatment. A broaching member may be expandable inside the bone. A broaching member may be flexible such that it broaches bone having a relatively lower density and it leaves bone having a relatively higher density substantially intact.