Damping element
A damping element for the dynamic stabilization of two bones, particularly of two adjacent bodies of the vertebra, has a central axis, a first end intersecting the central axis, a second end intersecting the central axis, and a spring element between the two ends and coaxial with the central axis. The damping element also has a ball-joint connection at at least one end that is concentric with the central axis. The ball-joint connection operative to receive and releasably lock a rod-shaped longitudinal support therein.
1 . A damping element for the dynamic stabilization of two bones, the damping element comprising:
a spring element having a first and second ends and a central axis intersecting the two ends; and
a ball joint concentric with the central axis and located at the first end, the ball joint having tightening means to releasably lock therein a rod-shaped longitudinal support.
2 . The damping element of claim 1 wherein the ball joint comprises a spherically convex clamping body having a diametral central bore, the central bore having a bore axis.
3 . The damping element of claim 2 wherein the ball joint allows rotation of the clamping body by an angle a ranging from 0° to ±25°, angle α measured between the bore axis and the central axis.
4 . The damping element of claim 2 wherein the ball joint comprises two axially separated bearing shells that accommodate at least partially the clamping body.
5 . The damping element of claim 4 , wherein the bearing shells can be pressed axially against the clamping body by the tightening means.
6 . The damping element of claim 4 wherein the spring element has at the first end a coaxial spigot with a thread, and wherein an end of the first bearing shell is integrated axially in the spigot such that the bearing shell converges towards the second end.
7 . The damping element of claim 6 wherein the tightening means comprises a nut that can be screwed onto the thread of the spigot and that the second bearing shell is concentrically joined to the nut.
8 . The damping element of claim 7 wherein the nut comprises a coaxial bore with at least first and second axially adjacent longitudinal sections, the first longitudinal section being closest to the spring element and having an inside thread complementary to the spigot thread, and the second longitudinal section having the second bearing shell integrated therewith such that the second bearing shell expands towards the first longitudinal section.
9 . The damping element of claim 1 wherein the tightening means is bored through coaxially.
10 . The damping element of claim 2 wherein the clamping body has an external wall and a slot parallel to the bore axis that penetrates the clamping body from the external wall.
11 . The damping element of claim 1 further comprising a rod-shaped connecting part coaxially joined at the second end.
12 . The damping element of claim 1 further comprising a rod-shaped longitudinal support inserted into the central bore and releasably fixed in the ball joint.