US20060254784A1

US20060254784A1 - Longitudinal support

Info

Publication number: US20060254784A1
Application number: US11/371,772
Authority: US
Inventors: Stephan Hartmann; Armin Studer
Original assignee: Synthes USA LLC
Current assignee: DePuy Spine LLC; DePuy Synthes Products Inc
Priority date: 2003-09-08
Filing date: 2006-03-08
Publication date: 2006-11-16
Also published as: ATE407634T1; AU2003258438B2; WO2005023125A1; BR0318482A; NZ545758A; CA2538105A1; CN1893883A; DE50310488D1; AR045611A1; JP2007506453A; EP1663031B1; CN100435745C; AU2003258438A1; EP1663031A1; ES2315576T3

Abstract

A longitudinal support having a first and second longitudinal support element. The first longitudinal support element having a longitudinal axis, includes first and second coaxial connecting segments provided with a first end and a second end, and an deformable articulated socket on the second connecting segment first longitudinal support element. The deformable articulated socket is axially open and can be deformed transversely to the longitudinal axis. The articulated socket includes a hollow spherical segment-like cavity with a diameter of D with an opening on the second end that is concentric with the longitudinal axis and has a diameter of d, while d<D. Further, the first connecting segment of the first longitudinal support element has a thread extending parallel to the longitudinal axis. The second longitudinal support element having a longitudinal axis, includes first and second coaxial connecting segments with a first end and a second end. The first connecting segment is able to be connected with the first connecting segment of the longitudinal support element, and the second connecting segment includes an articulated head that is complementary to the articulated socket.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of International Patent Application No. PCT/CH2003/000605, filed Sep. 8, 2003, the entire contents of which is expressly incorporated herein by reference.

TECHNICAL FIELD

The present invention relates generally to longitudinal support elements to stabilize bones, particularly bodies of the vertebra.

BACKGROUND OF THE INVENTION

The current treatment for damaged or tumorous bodies of the vertebra usually comprises implanting a rigid longitudinal support, anchored on the bodies of the vertebra by bone anchoring means or a rigid bone plate. The purpose of these devices is to prevent, by means of the rigid implants, the movement of the bodies of the vertebra stabilized in this manner relative to one another and to promote the fusion of adjacent bodies of the vertebra.
A device to stabilize the bodies of the vertebra using a multi-segmented longitudinal support that can be fixed in a desirable form, is known from document FR 2 796 828 to Jammet. By using the Jammet device, a longitudinal support, comprising a plurality of axial segments that can be joined with the head segments of pedicle screws or pedicle hooks, which for the purpose of stabilization are screwed into the pedicle of the corresponding body of the vertebra, and can be adapted without using great force to suit the form specified by the positions of the pedicle screws. A disadvantage of the Jammet device is that the longitudinal support elements can be fastened individually on the head segments of the pedicle screws or pedicle hooks but cannot be joined with one another. As a result, each longitudinal support element has to be individually inserted and placed into the body of the patient, representing to the surgeon a tedious and time-consuming step of the operation.

SUMMARY OF THE INVENTION

The present invention is to provide a remedy for the above-discussed disadvantage. It is an object of the invention to produce a longitudinal support element with an articulated socket, in the cavity of which a complementary articulated head of a further longitudinal support element can be elastically snapped in, so that a longitudinal support, comprising a plurality of longitudinal support elements, can be pre-assembled outside of the patient's body.
The present invention accomplishes the objective set out above with a longitudinal support having a first and second longitudinal support element. The first longitudinal support element having a longitudinal axis, includes first and second coaxial connecting segments provided with a first end and a second end, and an deformable articulated socket on the second connecting segment first longitudinal support element. The deformable articulated socket is axially open and can be deformed transversely to the longitudinal axis. The articulated socket includes a hollow spherical segment-like cavity with a diameter of D with an opening on the second end that is concentric with the longitudinal axis and has a diameter of d, while d<D. Further, the first connecting segment of the first longitudinal support element has a thread extending parallel to the longitudinal axis. The second longitudinal support element having a longitudinal axis, includes first and second coaxial connecting segments with a first end and a second end. The first connecting segment is able to be connected with the first connecting segment of the longitudinal support element, and the second connecting segment includes an articulated head that is complementary to the articulated socket.
The advantages achieved by the longitudinal support are that the longitudinal support may comprise a plurality of longitudinal support elements which can be joined to one another, in a pre-assembled manner; the longitudinal support can be adapted in-situ to suit the desired geometry without using any force; and implanting of the longitudinal support can be considerably simplified. Also, because a first longitudinal support element has an articulated socket, the first longitudinal support element can be polyaxially pivotably joined with a second longitudinal support element having a complementary articulated head.
In a preferred embodiment, the articulated socket can be made from a nickel-titanium alloy (Nitinol), wherein 45%<Ni<55%, 45%<Ti<55% and the composition of Ni and Ti equals 100%. Such a material is biocompatible and highly elastic.
In another embodiment, the articulated socket has an external spherical convex construction, thus achieving the advantage of a polyaxially pivotable accorumodation of the articulated socket in, for example, a bone anchoring means constructed as a tulip screw.
In yet another embodiment, the first connecting segment of the longitudinal support element comprises an outside thread.
In a preferred embodiment, the connection between a first connecting segment of a first longitudinal support element and a first connecting segment of a second longitudinal support element can be axially lengthened or shortened, so that a first longitudinal support element can be coaxially joined with a second longitudinal support element and the length of the longitudinal support segment formed by the two longitudinal support elements can be adjusted. This longitudinally adjustable connection between the two longitudinal support elements can telescope or be realized as a screw joint. For this purpose, the first connecting segment may be constructed as a coaxial shaft on the first longitudinal support element and the thread may be constructed as an outside thread and that the first connecting segment is constructed as a sleeve on the second longitudinal support element. The sleeve comprises a central bore with an inside thread that complements the outside thread.
In a further embodiment, the articulated head has a spherical convex design and the cavity of the articulated socket is complementary to it.
In another embodiment, the articulated head and the articulated socket can be elastically snapped into one another. This has the advantage that a simple pre-assembly of a longitudinal support, comprising a plurality of longitudinal support segments, is possible.
In yet another embodiment, the longitudinal support comprises an end-piece with an articulated head that can be snapped into an articulated socket. This has the advantage that an articulated socket, provided at the end of the longitudinal support, will not be compressed when mounted in the receptacle on the head of a pedicle screw. The longitudinal support preferably comprises a second end-piece with an articulated socket.
In a further embodiment, a device to stabilize bodies of the vertebra essentially comprises a longitudinal support according to one of the above illustrated embodiment and at least two bone anchoring means each with a central axis. The anchoring means have an anchoring segment to fix the bone anchoring means onto a bone, in particular on a body of the vertebra. The anchoring means also have a head segment with means to accommodate the articulated socket, and fixing means to fix the articulated sockets in the means to accommodate the articulated socket.
In a preferred embodiment, the means to accommodate the articulated socket are constructed as a concave spherical recess that complements the articulated socket.
In another embodiment, the fixing means comprise a tightening screw that can be screwed into an inside thread in the head of the bone anchoring means so that an articulated socket can be secured in the bone anchoring means.
In yet another embodiment, the fixing means may comprise an elastically expandable clamp that can be placed over the articulated socket and snapped onto the head segment of the bone fixing means. After the assembly of the clamp, the articulated socket is compressed by the clamp. This has the advantage, that due to the compressing of the second articulated part, the articulated socket is locked between the two longitudinal support segments, and the longitudinal support is fixed on the bone anchoring means. The clamp has preferably a lug on each of its free end, that can be snapped onto the head segment of the bone anchoring means. For a better acceptance of the lugs, notches complementing the lugs may be provided on the head segment.

BRIEF DESCRIPTION OF THE DRAWINGS

The longitudinal support is explained in even greater detail in the following exemplary drawings. The longitudinal support may be better understood by reference to the following drawings, wherein like references numerals represent like elements. The drawings are merely exemplary to illustrate the structure, operation and method of use of the longitudinal support and certain features that may be used singularly or in combination with other features and the invention should not be limited to the embodiments shown.
FIG. 1 shows a side view of an embodiment of the longitudinal support according to the invention, with type A and type B longitudinal support elements provided alternating behind one another,
FIG. 2 a shows a longitudinal section through an embodiment of the device according to the invention,
FIG. 2 b shows a cross-section through the embodiment of the device according to the invention and illustrated in FIG. 2 a, and
FIG. 3 a cross-section through another embodiment of the device according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates an embodiment of the longitudinal support 20. The longitudinal support 20 has type A longitudinal support elements 7, type B longitudinal support elements 8, and end- pieces 18 and 21.
Type A longitudinal support element 7 includes first connecting segment 9 and second connecting segment 10 which are coaxial with a first longitudinal axis 23 of the longitudinal support element 7. The longitudinal support element 7 has a first end 14 and a second end 15. The second end 15 is located next to the second connecting segment 10. The first connecting element 9 of the longitudinal support element 7 (type A) is constructed as a cylindrical shaft 31 with a thread 11. The second connecting segment 10 of longitudinal support element 7 (type A) comprises an articulated socket 28 with a hollow spherical segment-like, coaxial cavity 30. The socket 28 can be elastically deformed transversely to the first longitudinal axis 23, while the cavity 30 at the second end 15 of the longitudinal support element 7 has an opening 16 that is concentric with the first longitudinal axis 23. An articulated head 29 of longitudinal support element 8 (type B) (discussed later), which has a construction complementing the cavity 30, can be introduced into the cavity 30 through the opening 16, so that the articulated head 29 and the articulated socket 28 form a ball and socket joint.
The longitudinal support element 8 (type B) comprises a first connecting segment 12 and a second connecting segment 13. The first connecting segment 12 and the second connecting segment 13 are coaxially with a second longitudinal axis 24 of the longitudinal support element 8 (type B). The longitudinal support element 8 (type B) has a first end 25 and a second end 26. The second connecting end 26 is located next to the second connecting segment 13. The first connecting segment 12 of longitudinal support element 8 (type B) is constructed as a sleeve 32 that is coaxial with the second longitudinal axis 24 and has a central bore 33. The central bore 33 is provided with an inside thread 34, that is complementary to the thread 11. The second connecting segment 13 of longitudinal support element 8 (type B) is constructed as a spherical articulated head 29, that is complementary to the articulated socket 28 of longitudinal support element 7 (type A).
The longitudinal support elements 7 and 8 are connected in an alternating manner with end-piece 18 at one end connected to a type A longitudinal support element 7, and end-piece 21 at the other end connected to a type B longitudinal support element 8. First connecting segment 9 of the first longitudinal support element 7 (type A) forms a coaxial connection with the first connecting segment 12 of a second longitudinal support element 8 (type B) that can be adjusted only axially longitudinally. A second connecting element 10 of a first longitudinal support element 7 (type A) may connect with a second connecting element 13 of a second longitudinal support element 8 (type B) and allows a polyaxially pivotable connection of the two longitudinal support elements 7, 8. In this case, the first connecting segment 9 of longitudinal support element 7 (type A) and first connecting segment 12 of longitudinal support element 8 (type B) may be particularly joined by a thread connection 42 in such a manner that the first longitudinal axis 23 of the longitudinal support element 7 (type A) and the second longitudinal axis 24 of the longitudinal support element 8 (type B) are arranged coaxially. The thread connection 42 is constructed so that the first connecting segment 9 of the longitudinal support element 7 (type A) comprises a shaft 31 with an outside thread 11 and the first connecting segment 12 of the longitudinal support element 8 (type B) comprises a sleeve 32 with a central bore 33 having an inside thread 34 that complements the outside thread 11. The construction of the threaded bore 33 may be constructed by interchanging the connecting segments 9, 12.
The two longitudinal support elements 7, 8 (types A and B), connected in the manner discussed above, are then displaceable relative one another in such a manner, that the first and the second longitudinal axis 23, 24 can pivot relative one another about the centre of the articulate joint. Furthermore, cavity 30 has a diameter D, that is greater than the diameter d of opening 16, so that an articulated head 29, introduced into the cavity 30, is axially enclosed by more than 180°. In addition, the articulated socket 28 may be provided with four slots 22 which are parallel to the first longitudinal axis 23 and pass through from the outside to the cavity 30 allowing radial elastic deformation of the articulated socket 28.
The first end-piece 18 has an analogous construction with the articulated head 29, while the second end-piece 21 has an analogous construction with the articulated socket 28. The two end- pieces 18, 21 allow to accommodate the articulated socket 28 and the articulated head 29, respectively, in, for example, a commercially available pedicle screw or pedicle hook with a spherical concave recess 36 (FIGS. 2 a and 2 b).
FIGS. 2 a and 2 b depict a longitudinal support 20 according to FIG. 1 used to stabilize bodies of the vertebra with two bone anchoring means 3, connected by a longitudinal support 20. The bone anchoring means 3 are constructed, for example, as pedicle screws, having a head segment 6 and a shank (anchoring) segment 5. The longitudinal support 20 may comprise several longitudinal support elements 7, 8 (type A and type B), alternating with one another. As illustrated, two longitudinal support elements 7 (type A) are articulately connected via their first connecting segments 9 with the first connecting segments 12 of two longitudinal support elements 8 (type B) and the longitudinal support element 7 (type A) is connected with the longitudinal support element 8 (type B) via its second connecting segment 10 in such a manner that it can be only axially displaceable. The articulated heads 29 of the second longitudinal support elements 8 (type B) may be snapped into the articulated sockets 28 of the adjacent first longitudinal support elements 7 (type A). To connect head segments 6, having a fixed end 51, of the bone anchoring means 3 with the articulated sockets 29, channels 50 are provided on the head segments 6, with channel axes 53 extending transversely to the central axis 4 of the bone anchoring means 3. The channels 50 pass through the head segments 6 of the bone anchoring means 3, transverse to the central axis 4, and are open to the free end 52 of the head segment 6. For a polyaxially pivotable mounting of the articulated sockets 28 in the channels 50, spherical recesses 36 at the bottom of the channels 50 complement the articulated sockets 28. The head segments 6 further comprise bores 55, penetrating from the free end 52, with inside threads 54. Fixing means 27 which secure the articulated sockets 28 are constructed in this case as tightening screws 37 and may be screwed into the inside thread 54 from the free end 52 of the head segment 6, so that the articulated sockets 28, placed into the channels 50, together with the snapped-in articulated heads 29, can be fixed in the channels 50 by tightening the tightening screws 37. When fixing the articulated sockets 28, the articulated sockets 28 are compressed transversely to the longitudinal axes 23 of the first longitudinal support elements 7 (type A), due to which the snapped-in articulated heads 29 of the second longitudinal support elements 8 (type B) are blocked in the articulated sockets 28.
The embodiment illustrated in FIG. 3 differs from that illustrated in FIGS. 2 a and 2 b only by that the fixing means 27 is constructed as a clamp 38, the legs 43 of which can be elastically expanded so that he clamp 38 can be guided over the articulated socket 28 and may be snapped onto the head segment 6 of the bone fixing means 3 by its elastic spring-back in such a manner, that after being assembled the articulated socket 28 is compressed by the clamp 38. Thus, the articulated socket 28 is secured in the head segment 6 of the bone anchoring means 3 first by virtue of the clamp 38 and, in addition, by compressing the articulated socket 28 the articulated head 29 snapped in the articulated socket 28 is locked in the head segment 6 of the bone anchoring means 3. To fasten the clamp 38 on the head segment 6, the clamp 38 has at the free ends 39 of both legs 43 an inward directed lug 40 that may snap into the complementary notches 41, arranged at the fixed end 51 of the head segment.
In a preferred embodiment, the articulated socket 28 can be made from a nickel-titanium alloy (Nitinol), wherein 45%<Ni<55%, 45%<Ti<55% and the composition of Ni and Ti equals 100%. Such a material is biocompatible and highly elastic.
In another embodiment, the articulated socket 28 has an external spherical convex construction, achieving the advantage of a polyaxially pivotable accommodation of the articulated socket in, for example, a bone anchoring means constructed as a tulip screw.
In another embodiment, the connection between a first connecting segment 9 of a longitudinal support element 7 (type A) and a first connecting segment 12 of a longitudinal support element 8 (type B) can be axially lengthened or shortened, so that the longitudinal support element 7 (type A) can be coaxially joined with a longitudinal support element 8 (type B) and the length of the longitudinal support segment formed by the two longitudinal support elements 7 and 8 can be adjusted. This longitudinally adjustable connection between the two longitudinal support elements 7 and 8 can telescope or be realized as a screw joint. For this purpose the first connecting segment 9 can be constructed as a coaxial (cylindrical) shaft 31 on the longitudinal support element 7 (type A) and the thread 11 be constructed as an outside thread and the first connecting segment 12 constructed as a sleeve 32 on the longitudinal support element 8 (type B), the sleeve 32 comprising a central bore 33 with an inside thread 34 that complements the outside thread 11.
In a further embodiment, the articulated head 29 has a spherical convex design and the cavity 30 of the articulated socket 28 is complementary to it.
In another embodiment, the articulated head 29 and the articulated socket 28 may be elastically snapped into one another. This has the advantage that simple pre-assembly of a longitudinal support 20, comprising a plurality of longitudinal support segments, is possible.
In yet another embodiment, the longitudinal support 20 comprises an end-piece 18 with an articulated head that can be snapped into an articulated socket 28. This has the advantage that an articulated socket 28, provided at the end of the longitudinal support, will not be compressed when mounted in the receptacle on the head of a pedicle screw. The longitudinal support preferably comprises a second end-piece with an articulated socket.
In another embodiment, the means to accommodate the articulated socket 28 are constructed as a concave spherical recess, that complements the articulated socket 28.
A method of inserting the longitudinal support 20 into a patient will now be described. First, all bone anchoring means 3, in particular the pedicle screws or pedicle hooks, are placed by the surgeon onto the pedicles of the bodies of the vertebra to be fixed.
The longitudinal support elements 7, 8 (type A and type B) are then joined alternating together outside of the patient's body until the longitudinal support 20 has the desired length and contains the desired number of joints. The assembled longitudinal support 20 is then introduced into the patient's body by a minimally invasive incision and placed below the soft tissue surrounding the body of the vertebra to be fixed and is bent at the articulated joints until the assembled longitudinal support 20 has the desired shape and the articulated heads 29 are introduced into the means 35 to accommodate the articulated heads 29 on the bone anchoring means 3. Following this, the fixing means 27 are pre-assembled on the head segments 6 of the bone anchoring means 3, i.e., not yet locked, so that the longitudinal support 20 can still be adjusted. At this stage the shape of the longitudinal support 20, as well as the distances of the individual longitudinal support elements 7, 8 are still flexibly adjustable. When the desired shape of the longitudinal support 20 is set, the fixing means 27 are locked and consequently the entire fixing device is fixed.
Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims

1. A longitudinal support comprising:

a first longitudinal support element with a longitudinal axis, comprising:

first and second connecting segments provided with a first end and a second end;

deformable articulated socket on the second connecting segment of the first longitudinal support element, the deformable articulated socket is axially open and can be deformed transversely to the longitudinal axis,

wherein the articulated socket comprises a hollow spherical segment-like cavity, being larger than a semi-sphere, with a diameter of D with an opening on the second end that is concentric with the longitudinal axis and has a diameter of d, where d<D, and

wherein the first connecting segment of the first longitudinal support element has a thread extending parallel to the longitudinal axis, and;

a second longitudinal support element with a longitudinal axis, having first and second connecting segments each provided with a first end and a second end,

wherein the first connecting segment of the second longitudinal support element is connectable with the first connecting segment of the longitudinal support element, and

wherein the second connecting segment includes an articulated head that is complementary shaped to the articulated socket.

2. A longitudinal support according to claim 1, wherein the articulated socket is made from Nitinol.

3. A longitudinal support according to claim 1, wherein the articulated socket has an external spherical convex construction.

4. A longitudinal support according to claim 1, wherein the first connecting element of the first longitudinal support element comprises an outside thread that is coaxial with the longitudinal axis of the first longitudinal support element.

5. A longitudinal support according to claim 1, wherein a length of the connected first connecting segment of the first longitudinal support element with the first connecting segment of the second longitudinal support element is able to be axially lengthened or shortened.

6. A longitudinal support according to claim 1, wherein the first connecting segment of the first longitudinal support element and the first connecting element of the second longitudinal support element are able to telescope with respect to one another.

7. A longitudinal support according to claim 1, wherein the connection between the first connecting segment of the first longitudinal support element and the first connecting element of the second longitudinal support element is a screw connection.

8. A longitudinal support according to claim 1, wherein the articulated head has a spherical convex construction that is complementary shaped with the cavity.

9. A longitudinal support according to claim 1, wherein the articulated head and the articulated socket can be elastically snapped together.

10. A longitudinal support according to claim 7, wherein:

the first connecting segment of the first longitudinal support element is constructed as a shaft having an external thread; and

the first connecting segment of the second longitudinal support element is constructed as a sleeve having a central bore with an internal thread that complements the external thread of the first connecting segment of the first longitudinal support element.

11. A longitudinal support according to claim 1, further comprising at least one end-piece with an articulated head.

12. A longitudinal support according to claim 1, further comprising at least a second end-piece with an articulated socket.

13. A device to stabilize bodies of the vertebra comprising:

a longitudinal support according to claim 1;

at least two bone anchors, each bone anchor having a central axis, an anchoring segment to fix the bone anchor to a vertebra, and a head segment configured to accommodate the articulated socket; and

fixing means to fix the articulated sockets to the anchoring means.

14. A device according to claim 13, wherein the head segment comprises a concave spherical recess that complements the articulated socket.

15. A device according to claim 13, wherein the fixing means comprise a screw, the screw configured to engage an inside thread in the head segment of the bone anchor.

16. A device according to claim 14, wherein the fixing means comprise an elastically expandable clamp having at least on free end, the clamp is capable of being placed over the articulated socket and snapped onto the head segment of the bone anchor so that the articulated socket is compressed by the clamp.

17. A device according to claim 16, wherein the clamp has a lug on at least one of the free ends that can be snapped onto the head segment of the bone anchor.

18. A device according to claim 17, wherein the head segment comprises notches matching the lugs.

19. A method of inserting a longitudinal support into a patient comprising the steps of:

attaching a bone anchor onto pedicles of two adjacent vertebra, the bone anchor comprising head segments and anchoring segments;

assembling the longitudinal support by alternatingly joining at least one first longitudinal support element to at least one second longitudinal support element to form at least one articulated joint until the longitudinal support has a desired length, wherein each first longitudinal support element has an articulated socket and each second longitudinal support element has an articulated head such that each first longitudinal support element is joined to each second longitudinal support element by inserting each articulated head into each articulated socket;

introducing the assembled longitudinal support into the body of the patient through a minimally invasive incision, placing the assembled longitudinal support below the soft tissue surrounding the vertebra bodies to be securely fixed;

positioning the articulated joint so that the assembled longitudinal support has a desired shape;

positioning each articulated joint onto the head segment of the bone anchor;

adjusting the length of the each longitudinal support, as desired; and

securing each articulated joint to the bone anchor.