Helical osteosynthetic implant

A nail for setting a broken bone, the nail comprising first and second blades which are helically twisted along first and second coaxial helixes respectively and configured for implantation in a bone fragment, the first and second coaxial helixes being less than 180.degree. out of phase, wherein the second blade is tapered along the second coaxial helix and has a different shape than the first blade.

A nail for setting a broken bone, the nail comprising first and second blades which are helically twisted along first and second coaxial helixes respectively and configured for implantation in a bone fragment, the first and second coaxial helixes being less than 180.degree. out of phase, wherein the second blade is tapered and has a proximal portion and a distal portion that is wider than the proximal portion.

A method of setting a broken femur having a head on a proximal side and a shaft on a distal side, the method comprising:

• providing a nail with a helical axis, a uniform pair of blades, and a tapered pair of blades disposed such that each tapered blade is positioned between the uniform pair of blades, the tapered blades having a greatest width at a distal portion and a smallest width at a proximal portion, wherein the uniform and tapered blades have a total helical twist of at least about 30.degree. around the helical axis;
• and
• implanting the nail in the femur with the proximal portion of the tapered blades inside the head of the femur and substantially parallel to the shaft of the femur, and with the distal portion of the tapered blades disposed towards the distal side of the femur and substantially perpendicular to the shaft of the femur.