US20060254784A1 - Longitudinal support - Google Patents

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. 2ashows a longitudinal section through an embodiment of the device according to the invention,
• FIG. 2bshows a cross-section through the embodiment of the device according to the invention and illustrated inFIG. 2a,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 thelongitudinal support20. Thelongitudinal support20 has type Alongitudinal support elements7, type Blongitudinal support elements8, and end-pieces18 and21.
• Type Alongitudinal support element7 includes first connectingsegment9 and second connectingsegment10 which are coaxial with a firstlongitudinal axis23 of thelongitudinal support element7. Thelongitudinal support element7 has afirst end14 and asecond end15. Thesecond end15 is located next to the second connectingsegment10. The first connectingelement9 of the longitudinal support element7 (type A) is constructed as acylindrical shaft31 with athread11. The second connectingsegment10 of longitudinal support element7 (type A) comprises an articulatedsocket28 with a hollow spherical segment-like,coaxial cavity30. Thesocket28 can be elastically deformed transversely to the firstlongitudinal axis23, while thecavity30 at thesecond end15 of thelongitudinal support element7 has anopening16 that is concentric with the firstlongitudinal axis23. An articulatedhead29 of longitudinal support element8 (type B) (discussed later), which has a construction complementing thecavity30, can be introduced into thecavity30 through theopening16, so that the articulatedhead29 and the articulatedsocket28 form a ball and socket joint.
• The longitudinal support element8 (type B) comprises a first connectingsegment12 and a second connectingsegment13. The first connectingsegment12 and the second connectingsegment13 are coaxially with a second longitudinal axis24 of the longitudinal support element8 (type B). The longitudinal support element8 (type B) has afirst end25 and asecond end26. The second connectingend26 is located next to the second connectingsegment13. The first connectingsegment12 of longitudinal support element8 (type B) is constructed as asleeve32 that is coaxial with the second longitudinal axis24 and has acentral bore33. Thecentral bore33 is provided with aninside thread34, that is complementary to thethread11. The second connectingsegment13 of longitudinal support element8 (type B) is constructed as a spherical articulatedhead29, that is complementary to the articulatedsocket28 of longitudinal support element7 (type A).
• Thelongitudinal support elements7 and8 are connected in an alternating manner with end-piece18 at one end connected to a type Alongitudinal support element7, and end-piece21 at the other end connected to a type Blongitudinal support element8. First connectingsegment9 of the first longitudinal support element7 (type A) forms a coaxial connection with the first connectingsegment12 of a second longitudinal support element8 (type B) that can be adjusted only axially longitudinally. A second connectingelement10 of a first longitudinal support element7 (type A) may connect with a second connectingelement13 of a second longitudinal support element8 (type B) and allows a polyaxially pivotable connection of the twolongitudinal support elements7,8. In this case, the first connectingsegment9 of longitudinal support element7 (type A) and first connectingsegment12 of longitudinal support element8 (type B) may be particularly joined by athread connection42 in such a manner that the firstlongitudinal axis23 of the longitudinal support element7 (type A) and the second longitudinal axis24 of the longitudinal support element8 (type B) are arranged coaxially. Thethread connection42 is constructed so that the first connectingsegment9 of the longitudinal support element7 (type A) comprises ashaft31 with anoutside thread11 and the first connectingsegment12 of the longitudinal support element8 (type B) comprises asleeve32 with acentral bore33 having aninside thread34 that complements theoutside thread11. The construction of the threaded bore33 may be constructed by interchanging the connectingsegments9,12.
• The twolongitudinal support elements7,8 (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 secondlongitudinal axis23,24 can pivot relative one another about the centre of the articulate joint. Furthermore,cavity30 has a diameter D, that is greater than the diameter d of opening16, so that an articulatedhead29, introduced into thecavity30, is axially enclosed by more than 180°. In addition, the articulatedsocket28 may be provided with fourslots22 which are parallel to the firstlongitudinal axis23 and pass through from the outside to thecavity30 allowing radial elastic deformation of the articulatedsocket28.
• The first end-piece18 has an analogous construction with the articulatedhead29, while the second end-piece21 has an analogous construction with the articulatedsocket28. The two end-pieces18,21 allow to accommodate the articulatedsocket28 and the articulatedhead29, respectively, in, for example, a commercially available pedicle screw or pedicle hook with a spherical concave recess36 (FIGS. 2aand2b).
• FIGS. 2aand2bdepict alongitudinal support20 according toFIG. 1 used to stabilize bodies of the vertebra with two bone anchoring means3, connected by alongitudinal support20. The bone anchoring means3 are constructed, for example, as pedicle screws, having ahead segment6 and a shank (anchoring)segment5. Thelongitudinal support20 may comprise severallongitudinal support elements7,8 (type A and type B), alternating with one another. As illustrated, two longitudinal support elements7 (type A) are articulately connected via their first connectingsegments9 with the first connectingsegments12 of two longitudinal support elements8 (type B) and the longitudinal support element7 (type A) is connected with the longitudinal support element8 (type B) via its second connectingsegment10 in such a manner that it can be only axially displaceable. The articulated heads29 of the second longitudinal support elements8 (type B) may be snapped into the articulatedsockets28 of the adjacent first longitudinal support elements7 (type A). To connecthead segments6, having afixed end51, of the bone anchoring means3 with the articulatedsockets29,channels50 are provided on thehead segments6, withchannel axes53 extending transversely to the central axis4 of the bone anchoring means3. Thechannels50 pass through thehead segments6 of the bone anchoring means3, transverse to the central axis4, and are open to thefree end52 of thehead segment6. For a polyaxially pivotable mounting of the articulatedsockets28 in thechannels50,spherical recesses36 at the bottom of thechannels50 complement the articulatedsockets28. Thehead segments6 further comprise bores55, penetrating from thefree end52, withinside threads54. Fixing means27 which secure the articulatedsockets28 are constructed in this case as tighteningscrews37 and may be screwed into theinside thread54 from thefree end52 of thehead segment6, so that the articulatedsockets28, placed into thechannels50, together with the snapped-in articulatedheads29, can be fixed in thechannels50 by tightening the tightening screws37. When fixing the articulatedsockets28, the articulatedsockets28 are compressed transversely to thelongitudinal axes23 of the first longitudinal support elements7 (type A), due to which the snapped-in articulatedheads29 of the second longitudinal support elements8 (type B) are blocked in the articulatedsockets28.
• The embodiment illustrated inFIG. 3 differs from that illustrated inFIGS. 2aand2bonly by that the fixing means27 is constructed as aclamp38, thelegs43 of which can be elastically expanded so that he clamp38 can be guided over the articulatedsocket28 and may be snapped onto thehead segment6 of the bone fixing means3 by its elastic spring-back in such a manner, that after being assembled the articulatedsocket28 is compressed by theclamp38. Thus, the articulatedsocket28 is secured in thehead segment6 of the bone anchoring means3 first by virtue of theclamp38 and, in addition, by compressing the articulatedsocket28 the articulatedhead29 snapped in the articulatedsocket28 is locked in thehead segment6 of the bone anchoring means3. To fasten theclamp38 on thehead segment6, theclamp38 has at the free ends39 of bothlegs43 an inward directedlug40 that may snap into thecomplementary notches41, arranged at thefixed end51 of the head segment.
• In a preferred embodiment, the articulatedsocket28 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 articulatedsocket28 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 connectingsegment9 of a longitudinal support element7 (type A) and a first connectingsegment12 of a longitudinal support element8 (type B) can be axially lengthened or shortened, so that the longitudinal support element7 (type A) can be coaxially joined with a longitudinal support element8 (type B) and the length of the longitudinal support segment formed by the twolongitudinal support elements7 and8 can be adjusted. This longitudinally adjustable connection between the twolongitudinal support elements7 and8 can telescope or be realized as a screw joint. For this purpose the first connectingsegment9 can be constructed as a coaxial (cylindrical)shaft31 on the longitudinal support element7 (type A) and thethread11 be constructed as an outside thread and the first connectingsegment12 constructed as asleeve32 on the longitudinal support element8 (type B), thesleeve32 comprising acentral bore33 with aninside thread34 that complements theoutside thread11.
• In a further embodiment, the articulatedhead29 has a spherical convex design and thecavity30 of the articulatedsocket28 is complementary to it.
• In another embodiment, the articulatedhead29 and the articulatedsocket28 may be elastically snapped into one another. This has the advantage that simple pre-assembly of alongitudinal support20, comprising a plurality of longitudinal support segments, is possible.
• In yet another embodiment, thelongitudinal support20 comprises an end-piece18 with an articulated head that can be snapped into an articulatedsocket28. This has the advantage that an articulatedsocket28, 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 articulatedsocket28 are constructed as a concave spherical recess, that complements the articulatedsocket28.
• A method of inserting thelongitudinal support20 into a patient will now be described. First, all bone anchoring means3, 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.
• Thelongitudinal support elements7,8 (type A and type B) are then joined alternating together outside of the patient's body until thelongitudinal support20 has the desired length and contains the desired number of joints. The assembledlongitudinal support20 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 assembledlongitudinal support20 has the desired shape and the articulated heads29 are introduced into themeans35 to accommodate the articulated heads29 on the bone anchoring means3. Following this, the fixing means27 are pre-assembled on thehead segments6 of the bone anchoring means3, i.e., not yet locked, so that thelongitudinal support20 can still be adjusted. At this stage the shape of thelongitudinal support20, as well as the distances of the individuallongitudinal support elements7,8 are still flexibly adjustable. When the desired shape of thelongitudinal support20 is set, the fixing means27 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 (19)

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 toclaim 1, wherein the articulated socket is made from Nitinol.

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

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

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

10. A longitudinal support according toclaim 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 toclaim 1, further comprising at least one end-piece with an articulated head.

12. A longitudinal support according toclaim 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 toclaim 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 toclaim 13, wherein the head segment comprises a concave spherical recess that complements the articulated socket.

15. A device according toclaim 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 toclaim 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 toclaim 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 toclaim 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.

Images