Screw, system comprising a screw and a plate, and method for producing a screw
The invention relates to a screw ( 1 ), preferably a bone screw, comprising a shaft ( 2 ) with a tip ( 3 ), a head ( 4 ) and a thread ( 5 ). The shaft further comprises a longitudinal axis (A). An array of radial cross-sectional surfaces (Q) of the head ( 4 ) extend through the longitudinal axis (A) of the screw ( 1 ), the location of each radial cross-sectional surface (Q) being defined by an azimuth angle ( 6 ) in a plane (E) perpendicular to the longitudinal axis (A). Each radial cross-sectional area (Q) has an area defined by the longitudinal axis (A) and the outer surface of the screw ( 8 ). The thread ( 5 ) extends into the head ( 4 ) in such a way that the surface areas of the radial cross-sectional surfaces (Q′) in a first azimuth angle range ( 9 ) are constant and the surface areas of the radial cross-sectional surfaces (Q″) in a second azimuth angle range ( 10 ), which is different from the first, have a different, preferably smaller, value than the surface areas in the first azimuth angle range ( 9 ). The first azimuth angle range ( 9 ) is at most 350°, preferably at most 345°.
1 . A screw, comprising:
a shaft with a tip, a head and a thread, as well as a longitudinal axis of the shaft, and a set of radial cross-sectional surfaces of the head passing through the longitudinal axis of the shaft, wherein a position of each of the set of radial cross-sectional surfaces is defined by an azimuth angle in a plane (E) perpendicular to the longitudinal axis, and wherein each of the set of radial cross-sectional surfaces comprises an area defined by the longitudinal axis and an outer surface of the screw, wherein the thread continuously extends from the tip of the shaft to at least the head of the screw,
wherein
the thread extends into the head in such a way that a surface area of each of the set of radial cross-sectional surfaces in a first azimuth angle range is constant and
the surface areas of each of the set of radial cross-sectional surfaces in a second azimuth angle range, which is different from the first azimuth angle range, has a different and smaller value than the surface area of each of the set of radial cross-sectional surfaces in the first azimuth angle range, the first azimuth angle range being at most 350°.
2 . The screw according to claim 1 , wherein the first and second azimuth angle ranges are each divided into at least two sections distributed at equal azimuth angle intervals.
3 . The screw according to claim 2 , wherein the first azimuth angle range is at most 330°.
4 . The screw according to claim 2 , wherein the head has, in the second azimuth angle range, at least one indentation formed by a continuation of the thread.
5 . The screw according to claim 4 , wherein the head has a number of indentations formed by the continuation of the thread corresponding to the number of sections of the azimuth angle range.
6 . The screw according to claim 5 , wherein each portion of the azimuth angle range comprises an indentation formed by the continuation of the thread.
7 . The screw according to claim 1 , wherein the thread is multi-threaded.
8 . The screw according to claim 1 , wherein the head has, in the second azimuth angle range, at least one indentation formed by a continuation of the thread.
9 . The screw according to claim 8 , wherein the at least one indentation, which is formed by the continuation of the thread, is arranged on an underside of the head in the region of a thread end.
10 . The screw according to claim 1 , further comprising geometric centers of each of the set of radial cross-sectional surfaces, wherein a distance between each of the geometric centers of the set of radial cross-sectional surfaces and the longitudinal axis is constant in the first azimuth angle range.
11 . The screw according to claim 1 , wherein the screw is formed, such that each of the set of radial cross-sectional surfaces is connected.
12 . The screw according to claim 1 , wherein a first normal cross-section in a plane perpendicular to the longitudinal axis in a head region is at least partially non-circular.
13 . The screw according to claim 12 , wherein a second normal cross-section is circular and is parallel to the first normal cross-section, and the first normal cross-section is arranged along the longitudinal axis of the screw between the tip of the screw and the second normal cross-section.