Spline drive for threaded post-type bone anchors

摘要

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.