Abstract: A locking cap for anchoring an implanted medical device within a bone (such as an intramedullary fixation rod) has a cylindrical, helically threaded body, a socket concentrically disposed in one end, and an interface for cooperating with a driving tool, such as a wrench or screwdriver. Once a device such as an intramedullary fixation rod has been implanted within a bone, the locking cap is implanted by being threaded into the bone with a driving tool, its socket engaging the near end of the device. The socket of the locking cap can be smooth, or it can be threaded so as to thread onto the near end of the device as the cap is threaded into the bone. If threaded, the pitch of the cap's outer threads can exceed the pitch of the inner threads so that the cap advances into the bone more quickly than it advances onto the end of the device.

Abstract: A flexible inramedullary fixation rod for fractured bones is provided having a length sufficient to extend a substantial distance on either side of a diaphyseal fracture site and a substantially circular core with radially disposed fins extending substantially along the full length thereof. The radii of the core and fins are such that the rod can pass through the bone's medullary canal and engage the inner, or endosteal, surface of the bone along line contacts, thereby allowing normal endosteal healing and intramedullary revascularization. The rod is constructed of a flexible, bio-compatible material, such as titanium, stainless steel, resorbable polymers (e.g., polylactic acid) or carbon fiber-polysulfone. The radii of the fins are selected to be substantially equal to the minimum radius of the medullary canal.