ZA200602371B

ZA200602371B - Damping element

Info

Publication number: ZA200602371B
Application number: ZA200602371A
Authority: ZA
Inventors: Hartmnan Stephan
Original assignee: Synthes Gmbh
Priority date: 2006-03-23
Filing date: 2006-03-23
Publication date: 2007-04-25

Description

2072/PCT ' > 29.9.2003 . .

English translation of the specification of the International Patent Application No.

PCT/CH03/00648 “Damping element” in_the name of Mathys Medizinaltechnik

AG

Damping element

The invention concems a damping element according to the preamble of patent claim 1.

A damping element of the generic type for the dynamic stabilisation of two adjacent bodies of the vertebra is known from EP-A 0 516 56 Navas. This known damping element comprises a coaxial damping body with a spherically convex axially protruding connecting part each, by means of which the damping element can be secured on two pedicle screws. By virtue of the spherical joint between the two connecting parts and the heads of the pedicle screws the damping element can be connected with the pedicle screws with varying angles between the longitudinal axes of the pedicle screws and the central axis of the damping element. A disadvantage of this known damping element is that due to the geometry of the damping element the distance between the pedicle screws is predetermined.

This is where the invention wants to provide remedy. The object of the invention is to produce a damping element, that can polyaxially pivot about at least one of its ends and is axially telescoping connected with a longitudinal support.

This objective is achieved by the invention by a damping element having the features of claim 1.

The advantages achieved by the invention are essentially that by virtue of the damping element by means of a ball joint connection at least at one end of the damping element: * in the unlocked state of the ball joint the damping element can be polyaxially pivotably connected with a rod-shaped longitudinal support of a device to stabilise bodies of the vertebra. For this reason during the implanting of a

. . : X longitudinal support no longitudinal support needs to be bent within a vertebra- stabilising device, and * the damping element can be axially telescoping connected with a longitudinal support of a vertebra-stabilising device.

Further advantageous developments of the invention are characterised in the dependent claims.

In a preferred embodiment the ball joint comprises a spherically convex, radially compressible clamping body with a diametral central bore having a bore axis, so that when the clamping body is compressed a rod-shaped longitudinal support, introduced into the central bore, is locked in the central bore relative to the clamping body.

The ball joint allows preferably a rotation of the clamping body by an angle a, in the range from 0° to + 25°, measured between the bore axis of the central bore in the clamping body and the central axis of the spring element. This will bring about the advantage that a rod-shaped longitudinal support, introduced into the central bore of the clamping body, can pivot relative to the spring element and consequently the rod-shaped longitudinal support does not have to be bent.

The ball joint preferably comprises two axially separated bearing shells, accommodating at least partially the clamping body, so that when the bearing shells are compressed the clamping body is equally compressed and thus the ball joint can be rigidly locked.

In another embodiment the bearing shells can be pressed against the clamping body by means of tightening means, whereby preferably the spring element has at its first end a coaxial spigot with a thread and the first bearing shell is integrated axially at the end in the spigot in such a manner, that the bearing shell converges towards the second end of the spring element. The tightening means is preferably constructed as a nut, that can be screwed onto the thread of the spigot. The second bearing shell is preferably concentrically integrated in the bore of the nut.

0) . M } . 3

In a further embodiment the nut comprises a coaxial bore with at least two axially adjacent longitudinal sections, wherein the outer longitudinal section facing the spring element has an inside thread that is complementary to the thread of the spigot and in the adjacent longitudinal section the second bearing shell is integrated in such a manner, that it expands towards the outer longitudinal section.

The tightening means is bored through to enable to pass through a rod-shaped longitudinal support.

In yet another further embodiment the clamping body has a slot that is parallel to the bore axis, said slot penetrating the wall of the clamping body from its external wall up to the central bore.

In another embodiment the damping element comprises a rod-shaped connecting part that is coaxial at its ends, which connecting part can be joined with a further part within an osteosynthetic stabilising device.

In yet another embodiment the damping element additionally comprises a rod- shaped longitudinal support that can be introduced into the central bore of the clamping body and can be releasably fixed in the clamping body.

The invention and developments of the invention are explained in detail in the following based on the partly schematic illustrations of several embodiments.

They show in:

Fig.1 - a longitudinal section through an embodiment of the damping element according to the invention, and

Fig.2 - an enlargement of the segment marked by circle A in Fig.1.

Figs.1 and 2 illustrate an embodiment that comprises a hollow-cylindrical damping element 1 with a central axis 11 and a releasably lockable ball joint 20 for a polyaxial connection of the damping element 1 with a rod-shaped longitudinal support 3 having a longitudinal axis 4. In addition to the ball joint 20 the damping element 1 comprises a spring element 10, that in the embodiment illustrated here is made up from a metal helical spring and a plastic part 31 which penetrates into the gap 30 between the coils of the spring and reduces the diameter of the hollow space 15. The ball joint 20 is provided on the first end 12 of the spring element 10, whereas on the second, axially opposed end 13 of the spring element 10 a coaxial rod-shaped connecting part 16 is provided, that is suitable to be connected to a further part (not illustrated) of a vertebra-stabilising device. The ball joint 20 comprises in this case a spherically convex clamping body 21 with a central bore 22 having a bore axis 27 and two concave bearing shells 23, 24, which are complementary to the clamping body 21. The first bearing shell 23 is integrated in the threaded spigot 39 concentrically with the central axis 11 on the first end 12 of the spring element 10 in such a manner, that it converges towards the hollow space 15 in the damping element 1. The threaded spigot 39 is passed through by a bore 14 coaxially with the central axis 11 and terminating in the hollow space 15, so that the bore 14 is suitable to accommodate a rod-shaped longitudinal support 3 that is guided through the central bore 22 in the clamping body 21. The second bearing shell 24 is integrated in a nut 25, that can be screwed on the threaded spigot 39 via the thread 26. The hollow space 15 is closed at the second end 13 of the spring element 10. To join the second end 13 of the spring element 10 with a further part, for example the head of a pedicle screw or of a pedicle hook (not illustrated), a rod-shaped connecting part 16 that is coaxial with the central axis 11 is provided on the second end 13 of the spring element 10.

As it is shown in Fig.2, the clamping body 21 is provided with slots 28 which are parallel to the bore axis 27, said slots penetrating the clamping body 21 from the external wall 29 of the clamping body 21 up to the central bore 22. When the nut 25 is tightened, the clamping body 21, provided between the bearing shells 23, 24, is clamped between the bearing shells 23, 24 and simultaneously radially compressed towards the bore axis 27 of the central bore 22, so that the longitudinal support 3, introduced into the central bore 22, will be locked.

i :

The nut 25 is passed through by a bore 32 that is coaxial with the central axis 11, said bore having a plurality of axially adjacent longitudinal sections 34, 35, 36 with various geometries. The longitudinal section 34, adjacent to the first end 12 of the damping element 1, is provided with an inside thread 33 that is complementary to the thread 26 on the first end 12 of the spring element 10, while the middle longitudinal section 35 comprises the second bearing shell 24 that is also bored through, and the externally situated longitudinal section 36 has a tapered construction. At the same time the second bearing shell 24 is so arranged, that it converges towards the externally situated longitudinal section 36.

The taper 38 in the externally situated longitudinal section 36 expands towards the external face 37 of the nut 25, so that a rod-shaped longitudinal support 3 can be pivotally accommodated in the ball joint 20.

Claims

cpl 2 WO 2005/030067 6 PCT/CH2003/000648 Patent claims

1. A damping element for the dynamic stabilisation of two bones, with a central axis and with A) a first end intersecting the central axis, a second end intersecting the central axis, and with a spring element that is coaxial with the central axis provided between them, characterised in that B) a ball joint is integrated at least at one end of the spring element, that is concentric with the central axis and releasably lockable by means of tightening means.

2. A damping element according to claim 1, characterised in that the ball joint comprises a spherically convex clamping body with a diametral central bore having a bore axis.

3. A damping element according to claim 1 or 2, characterised in that the ball joint allows a rotation of the clamping body by an angle a, in the range from 0° to + 25°, measured between the bore axis and the central axis.

4. A damping element according to claim 2 or 3, characterised in that the ball joint comprises two axially separated bearing shells, accommodating at least partially the clamping body.

5. A damping element according to claim 4, characterised in that the bearing shells can be pressed axially against the clamping body by means of the tightening means.

6. A damping element according to claim 4 or 5, characterised in that the spring element has at its first end a coaxial spigot with a thread and that the first bearing shell is integrated axially at the end in the spigot in such a manner, that the bearing shell converges towards the second end of the spring element.

7. A damping element according to claim 6, characterised in that the tightening means is a nut, that can be screwed onto the thread of the spigot and that the second bearing shell is concentrically joined with the nut. AMENDED SHEET

8. A damping element according to claim 7, characterised in that the nut comprises a coaxial bore with at least two axially adjacent longitudinal sections, wherein the outer longitudinal section facing the spring element has an inside thread that is complementary to the thread and in the adjacent longitudinal section the second bearing shell is integrated in such a manner, that it expands towards the outer longitudinal section.

9. A damping element according to claim 1 to 8, characterised in that the tightening means is bored through coaxially.

10. A damping element according to any one of claims 2 to 9, characterised in that the clamping wall has an external wall and that a slot parallel to the bore axis penetrates the wall of the clamping body from this external wall.

11. A damping element according to any one of claims 1 to 10, characterised in that at its second end it comprises at the end coaxially an adjacent rod-shaped connecting part, which connecting part can be joined with a further part within an osteosynthetic stabilising device.

12. A damping element according to any one of claims 2 to 11 characterised in that it additionally comprises a rod-shaped longitudinal support that can be introduced into the central bore and can be releasably fixed in the clamping body.

13. A damping element for the dynamic stabilisation of two bones substantially as herein described and as illustrated in Figures 1 and 2.

14. A damping element according to any one of the preceding claims, characterised in that the two bones are tow adjacent bodies of the vertebra. AMENDED SHEET