Bone screw
Bone graft comprising cortical bone material having a screw shank with an external thread and a screw head. Screw head has an outer jacket surface which is rotationally symmetrical about a screw head axis and has an external thread. At least two recesses, which are distributed about the screw head axis, extend axially in the direction of the screw head axis and open into an end face of a free end of the screw head, for receiving an insertion tool. The recesses are each formed by side faces, which extend from the outer jacket surface in the direction of the screw head axis and merge into one another in a surface section close to the axis. By this design, introduction of an insertion torque is optimized and new surgical areas of application such as in intramedullary splinting, arthroscopic insertion and deep insertion of the graft into an bearing bone are possible.
1. A bone graft comprising:
a screw shank provided with an external thread;
a screw head configured for introducing a torque;
the screw shank and the screw head comprising a cortical bone material;
the screw head having an outer jacket surface rotationally symmetrical about a screw head axis;
the screw head comprising an external thread and at least two recesses distributed about the screw head axis;
the screw head having a free end with an end face;
the at least two recesses of the screw head extending axially in a direction of the screw head axis and open into the end face of the free end of the screw head to thereby be configured to receive an insertion tool for endoscopic or arthroscopic insertion of the screw;
each of the recesses being formed by side surfaces that extend from the outer jacket surface in a direction toward the screw head axis and merge into one another in a surface section close to the screw head axis, with each of the recesses as seen in the direction of the screw head axis having an inner radial section being formed by the side surfaces that extend in a radial direction below the thread and an outer radial section being formed by the side surfaces that extend in a radial direction into the thread region, and the radial depth of the inner radial section being larger than the radial height of the outer radial section.
2. The bone graft according to claim 1 , wherein:
the side surfaces of the recesses extending from the outer surface in the direction of the screw head axis are of convex design, and the surface section merging close to the axis is of concave design.
3. The bone graft according to claim 1 , wherein:
the at least two recesses comprise four recesses that are distributed symmetrically about the screw head axis.
4. The bone graft according to claim 1 , wherein:
each of the recesses have, at a respective axial end remote from the end face, a region in which a depth of the recesses measured in the radial direction is continuously reduced.
5. The bone graft according to claim 1 , wherein:
the external thread extending over the screw shank and screw head has two sections of different thread pitch.
6. The bone graft according to claim 1 , wherein:
the external thread running via the screw shank and screw head-has two sections with different external thread diameters.
7. The bone graft according to claim 1 , wherein:
the screw shank is of cylindrical design.
8. The bone graft according to claim 1 , wherein:
the screw shank is of frustoconical design.
9. The bone graft according to claim 1 , wherein:
the screw shank has on a free end remote from the screw head an end face perpendicular to the screw head axis.
10. The bone graft according to claim 9 , herein:
the end face of the screw shank perpendicular to the screw head axis is provided with a groove that crosses the end face and that opens respectively on opposite sides into the outer jacket surface of the screw shank.