Nail for fixing a fracture of the femur

DETAILED DESCRIPTION It is an object of the invention to provide a design for the distal end of a bone nail which does not incorporate such a danger but which nevertheless permits the absorption of all forces to be transmitted during manipulation of the nail so that, particularly for osteoporotic bones, a breaking into the bone by the nail in the region of its cortical part is prevented.
These and other objects and advantages are accomplished in accordance with the invention wherein an elastic nail for fixing a bone fracture of the femur is provided including an elongated cylindrical nail jacket having a distal end, a proximal end and an outer surface.
The nail jacket is curved along its length between the distal and proximal ends and has a circular cross section between its ends with a region adjacent its distal end having a cross section which differs from the circular.
The elasticity and curvature of the nail are such that when the nail is driven into the marrow cavity of the femur its distal end is supported by the cortical part of the bone.
The region deviating from the circular cross section has a concave face and a convex face which are curved predominantly about axes extending parallel to the lengthwise direction of the nail jacket.
The concave face forms a recess in the nail jacket, which recess is disposed at the inside of the curvature which relates to the entire length of the nail jacket.
The convex face extends only slightly beyond the circular cross section transverse to the logitudinal direction of the nail jacket to form edge regions.
Each edge region has a continuously curved surface joining the convex face to the concave face.
The invention is based on the realization that a chisel-like effect on the surrounding bone or tissue regions can be prevented only if sharp-edged angular portions and high contact pressures are avoided.
The solution achieved by the invention deviates from the principle that it is generally the custom in the art to select sharp-edged profiles (three, four or multi-edged designs) in order to transmit a torque by means of wrench-like tools