Endosteal nail
View Patent ↗The system includes an elongate intramedullary nail which is rigidly fixed under compression to the endosteal surface of a bone with unicortical locking machine screws inserted through the bone and into a plurality of longitudinally displaced threaded holes in the nail. A jig is provided for drilling holes through the bone in alignment with the screw holes in the nail. The nail and jig each include anti-rotation structure at which the nail and jig can be coupled together in a fixed alignment. A method is also provided for implanting an intramedullary nail on two sides of a bone fracture, and clamping the bone with sufficient force to immobolize the fracture by forcing the implant against an endosteal surface of the bone and applying a compressive force against the outer surface of the bone.
1. An intramedullary nail system for use with a jig, comprising:
an elongate nail including at least four threaded parallel screw holes in linear arrangement, said screw holes oriented normal to an endosteal surface of said nail, and a non-circular recess located at the upper portion of one of said threaded parallel screw holes of said linear arrangement, said recess for mating with a portion of the jig to lock the jig in a rotational orientation relative to said nail,
said nail having a longitudinal axis defining the length of said nail and a center along said longitudinal axis which divides said nail into first and second portions each having a length equal to one-half the length of said nail, said first and second portions extending in opposite directions from each other relative to said center, wherein said first portion has lateral reflection symmetry about said longitudinal axis, said second portion has lateral reflection symmetry about said longitudinal axis, and said first and second portions have longitudinal reflection symmetry with each other about said center.
2. A nail system according to claim 1 , wherein:
said non-circular recess is square or rectangular.
3. A nail system according to claim 1 , wherein:
an equal number of said threaded parallel screw holes are provided along each of said first and second portions.
4. A nail system according to claim 1 , wherein:
said nail includes first and second ends which are tapered.
5. A nail system according to claim 1 , further comprising:
a plurality of unicortical machine screws each having a head and a shaft configured to threadably engage in one of said threaded parallel screw holes,
wherein when said screws are insertable through bone and into said screw holes the bone is clamped between said head of said screws and said endosteal surface of said nail.
6. A nail system according to claim 5 , wherein:
said head of each of said screws have an undersurface for contacting bone which define a surface area, and said shaft of each of said screws having a cross-sectional area defined by a cross-section through said shaft, wherein the ratio of said surface area of said undersurface said cross-sectional area is at least 1.5.
7. An orthopedic nail system according to claim 6 , wherein:
the ratio of said surface area to said cross-sectional area is approximately √{square root over (3)}.
8. An orthopedic nail system according to claim 6 , wherein:
the ratio of said surface area to said cross-sectional area is at least approximately √{square root over (3)}.
9. An orthopedic nail system according to claim 6 , wherein:
said undersurface is substantially flat.
10. A nail system according to claim 1 , wherein:
said endosteal surface includes at most one non-circular recess.
11. A nail system according to claim 1 , wherein:
said endosteal surface includes at most two non-circular recesses.
12. A nail system according to claim 1 , wherein:
said recess has a polygonal shape.
13. A nail system according to claim 1 , wherein:
a plurality of said threaded screw holes of said linear arrangement each include a recess at an upper portion thereof.
14. An orthopedic nail system for use with a jig, comprising:
a) an elongate nail including at least four threaded screw holes in linear arrangement oriented normal to an endosteal surface of said nail, and a non-circular recess located at the upper portion of one of said threaded parallel screw holes of said linear arrangement, said recess for mating with a portion of the jig to lock the jig in a rotational orientation relative to said nail,
said nail having a longitudinal axis defining the length of said nail and a center along said longitudinal axis which divides said nail into first and second portions each having a length equal to one-half the length of said nail, said first and second portions extending in opposite directions from each other relative to said center, wherein said first portion has lateral reflection symmetry about said longitudinal axis, said second portion has lateral reflection symmetry about said longitudinal axis, and said first and second portions have longitudinal reflection symmetry with each other about said center; and
b) a plurality of unicortical machine screws each having a head and a shaft configured to threadably engage in one of said screw holes, said head having an undersurface for contacting bone, said undersurface defining a surface area, and cross-sectional area being defined by a cross-section through said shaft, wherein the ratio of said surface area of said undersurface of said head to said cross-sectional area through said shaft is at least 1.5.
15. An orthopedic nail system according to claim 14 , wherein:
the ratio of said surface area of said undersurface of said head to said cross-sectional area through said shaft is approximately √{square root over (3)}.
16. An orthopedic nail system according to claim 15 , wherein:
the ratio of said surface area of said undersurface of said head to said cross-sectional area through said shaft is at least approximately √{square root over (3)}.
17. An orthopedic nail system according to claim 15 , wherein:
said undersurface is substantially flat.
18. An orthopedic nail system according to claim 15 , wherein:
said recess has a polygonal shape.
19. An orthopedic nail system according to claim 15 , wherein:
a plurality of said threaded screw holes of said linear arrangement each include a recess at an upper portion thereof.