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US 8,617,225 B2Granted
Spline drive for threaded post-type bone anchors
AssigneeDePuy Synthes Products, Inc.
InventorsEdward McShane, Josef Gabelberger, Joseph Capozzoli
Life of this patent
Estimating the term…
Abstract
A threaded bone anchor includes a plurality of recesses formed lengthwise along an exterior cylindrical surface for engagement with a driver instrument through which a user applies clockwise or counterclockwise torque for the insertion or removal of the bone anchor into and from bone. The bone anchor includes a cross-sectional geometry that minimizes the anchor's outer diameter, survives high insertion/removal torque without compromising the anchor's bending/shear strength, and allows a mating clamp to be attached to the entire non-threaded surface, including the recessed portion.
Claims37
A bone anchor comprising:
- a shaft that defines a distal end and a proximal end, the shaft extending along a longitudinal direction from the distal end to the proximal end, the shaft includes external threads that extend radially outward from the shaft at a location between the distal end and the proximal end such that the external threads define a first outer diameter;
- and
- a head connected to the proximal end of the shaft, the head including a body that defines an outer surface and a second outer diameter measured between opposed locations of the outer surface in a direction substantially perpendicular to the longitudinal direction, the head further including a spline drive mechanism that has a plurality of equidistantly spaced, longitudinally elongate recesses that extend into the body along a direction substantially perpendicular to the longitudinal direction such that each recess defines a pair of spaced side walls and a base extending between the pair of spaced side walls, such that the base and the side walls define a region configured to engage a mating driver instrument, at least one of the plurality of recesses defining a height measured from the base of the respective recess to a location of the body that is spaced from the base along a radial direction that is perpendicular to the longitudinal direction, and the height of the at least one of the plurality of recesses is different at a first location of the respective recess than a second location of the respective recess that is spaced from the first location along the longitudinal direction;
- wherein the first outer diameter is greater than the second outer diameter.
1 more element
A bone anchor assembly comprising:
- a bone anchor including:
- a shaft that includes a distal end and a proximal end, the shaft extending from the distal end to the proximal end along a longitudinal direction, the shaft further including a threaded portion and an unthreaded portion, the threaded portion including external threads that extend radially outward from the shaft at a location between the distal end and the proximal end such that the external threads define a first outer diameter;
- and
- a head connected to the shaft, the head including a body that defines an outer surface, the head defining a spline drive mechanism including a plurality of equidistantly spaced, longitudinally elongate recesses extending into the body such that each recess defines a pair of spaced side walls;
- wherein neither the unthreaded portion of the shaft nor the outer surface of the head defines a diameter or other cross-sectional dimension that is greater than the first outer diameter and
- a driver instrument including a plurality of protrusions configured to extend into at least one of the recesses, each protrusion including a pair of side walls, wherein one of the side walls is configured to engage a complementary side wall of one of the recesses so as to impart a torque/force onto the bone anchor head.
3 more elements
A bone anchor comprising:
- a shaft that defines a distal end and a proximal end, the shaft extending along a longitudinal direction from the distal end to the proximal end, the shaft includes external threads that extend radially outward from the shaft at a location between the distal end and the proximal end such that the external threads define a first outer diameter;
- and
- a head connected to the proximal end of the shaft, the head including a body that defines an outer surface and a second outer diameter measured between opposed locations of the outer surface in a direction substantially perpendicular to the longitudinal direction, the head further including a spline drive mechanism that has a plurality of equidistantly spaced, longitudinally elongate recesses that extend into the body along a direction substantially perpendicular to the longitudinal direction such that each recess defines a pair of spaced side walls, the head further defining a threaded bore that extends in the longitudinal direction;
- wherein the first outer diameter is greater than the second outer diameter.
1 more element
Dependencies are inferred from the claim text.