Implantable screw for stabilization of a joint or a bone fracture
A bone screw has a flexible shaft which prevents relative movements in the direction of tension, but permits smaller movements in all other directions. The bone screw is configured as a screw insertable into medullary cavities having a curved surface, where the screw adapts to the given contour.
1. A screw implant for stabilization of a joint or a bone fracture, comprising;
a screw including a head portion on one end;
a threaded portion on another end; and
a shaft portion extending between the head portion and the threaded portion and defining an axis, wherein the shaft portion is constructed in the form of a wire cable comprised of several wire strands and constructed sufficiently flexible to maintain a natural movement of bone participants in an area of the joint or bone fracture but rigid enough to prevent an elongation in a direction of the axis away from one another;
wherein the threaded portion includes a bone thread and a nut connected in one piece with the bone thread for attachment of an external wrench to screw the threaded portion into one of the bone participants, and
wherein the head portion includes a bolt connected to the shaft portion and a nut screwed onto the bolt and provided for attachment of an external wrench for securement of the head portion in the other one of the bone participants.
2. The screw implant of claim 1 , wherein the wire strands are arranged in spaced-apart relationship along a major portion of the axis.
3. The screw implant of claim 1 , wherein the nut is a hexagon nut.
4. The screw implant of claim 1 , wherein the head portion is a bolt having a socket for attachment of an external wrench for securement of the head portion in the other one of the bone participants.
5. The screw implant of claim 4 , wherein the socket is a hexagon socket.
6. The screw implant of claim 1 , and further comprising a reinforcement placed from outside over the shaft portion.
7. The screw implant of claim 6 , wherein the reinforcement is at least one sleeve or a spiral.