U.S. patent application number 12/606857 was filed with the patent office on 2010-02-25 for height-adjustable intervertebrae implant.
This patent application is currently assigned to BIEDERMANN MOTECH GMBH. Invention is credited to Lutz Biedermann, Wilfried Matthis.
Application Number | 20100049325 12/606857 |
Document ID | / |
Family ID | 34524068 |
Filed Date | 2010-02-25 |
United States Patent
Application |
20100049325 |
Kind Code |
A1 |
Biedermann; Lutz ; et
al. |
February 25, 2010 |
HEIGHT-ADJUSTABLE INTERVERTEBRAE IMPLANT
Abstract
An intervertebral implant for insertion between two vertebrae is
disclosed. A first part has a first contact surface extending
between its two ends a first guide surface extending out from the
first contact surface. A second part has a second contact surface
extending between its ends, and a second guide surface recessed
into the second contact surface. The first guide surface and the
second guide surface cooperate so that the first contact surface of
the first part can slide relative to the second contact surface of
the second part with a translation motion guided by the cooperating
structures of the first and second guide surfaces. The height of
the intervertebral implant can be altered by shifting the first
part and the second part relative to each other by moving the
contact surfaces relative to each other by using the cooperating
guide surfaces.
Inventors: |
Biedermann; Lutz;
(VS-Villingen, DE) ; Matthis; Wilfried; (Weisweil,
DE) |
Correspondence
Address: |
CHRISTIE, PARKER & HALE, LLP
PO BOX 7068
PASADENA
CA
91109-7068
US
|
Assignee: |
BIEDERMANN MOTECH GMBH
|
Family ID: |
34524068 |
Appl. No.: |
12/606857 |
Filed: |
October 27, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11009224 |
Dec 9, 2004 |
7618458 |
|
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12606857 |
|
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|
60528412 |
Dec 9, 2003 |
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Current U.S.
Class: |
623/17.16 ;
606/279 |
Current CPC
Class: |
A61F 2002/30387
20130101; A61F 2002/30904 20130101; A61F 2/442 20130101; A61F
2002/30879 20130101; A61F 2002/30892 20130101; A61F 2220/0025
20130101; A61F 2002/304 20130101; A61F 2/30965 20130101; A61F
2002/30785 20130101; A61F 2002/30556 20130101; A61F 2002/30604
20130101; A61F 2002/30131 20130101; A61F 2002/3055 20130101; A61F
2230/0063 20130101; A61F 2250/0009 20130101; A61F 2002/30308
20130101; A61F 2/4465 20130101; A61F 2230/0013 20130101; A61F
2310/00023 20130101 |
Class at
Publication: |
623/17.16 ;
606/279 |
International
Class: |
A61F 2/44 20060101
A61F002/44; A61B 17/88 20060101 A61B017/88 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 9, 2003 |
DE |
103 57 960.5 |
Claims
1. An intervertebral implant comprising: a first part having a
first end, a second end, a first contact surface provided between
the first and second ends and a first guide surface extending out
from the first contact surface; and a second part having a third
end, a fourth end, a second contact surface provided between the
third and fourth ends, and a second guide surface recessed into the
second contact surface; the first guide surface and the second
guide surface comprising cooperating structures so that the first
contact surface of the first part can slide relative to the second
contact surface of the second part with a translation motion guided
by the cooperating structures of the first and second guide
surfaces.
2. The intervertebral implant according to claim 1, wherein the
first part further comprises a first base surface opposite to said
first contact surface and a first plane parallel to said first
contact surface intersects a second plane parallel to said first
base surface forming an inclination angle of contact .alpha.; and
wherein the second part further comprises a second base surface
opposite to said second contact surface and a third plane parallel
to said second contact surface intersects a fourth plane parallel
to said second base surface forming an inclination angle of contact
.alpha..
3. The intervertebral implant according to claim 1, wherein the
first and second contact surfaces and the first and second guide
surfaces comprise an arcuate shape.
4. The intervertebral implant according to claim 1, wherein said
first and second parts are straight.
5. The intervertebral implant according to claim 1, further
comprising a terminal stop.
6. The intervertebral implant according to claim 2, wherein said
implant comprises a material and said angle .alpha. is determined
based on the material and the surface properties of the first and
second contact surfaces such that a self-locking mechanism between
the first part and the second part is effected.
7. The intervertebral implant according to claim 1, wherein one of
the first guide surface and the second guide surface comprises a
ridge and the other of the first guide surface and the second guide
surface comprises a groove.
8. The intervertebral implant according to claim 7, wherein the
first and second contact surfaces, the ridge and the groove each
comprise an arcuate shape.
9. The intervertebral implant according to claim 7, wherein the
groove is located in the second contact surface and extends from
the third end to a pre-set distance from the fourth end of the
second contact surface, thereby providing a terminal stop.
10. The intervertebral implant according to claim 6, wherein the
ridge comprises a first cross-section and the groove comprises a
second cross-section, the first cross-section comprising a shape
selected from the group comprising a dovetail-shape, a T-shape, a
rectangle, a square or a semicircle, and the second cross-section
comprises a complementary shape to the first cross-section shape
such that the ridge and groove cooperate.
11. The intervertebral implant according to claim 1, said implant
further comprising an orifice or a recess.
12. The intervertebral implant according to claim 1, wherein the
first contact surface and/or the second contact surface comprise a
roughened surface or a step-like surface.
13. The intervertebral implant according to claim 1, wherein the
first part comprises a first base surface and the second part
comprises a second base surface, wherein at least one of first and
second base surfaces comprise groove-shaped recesses.
14. The intervertebral implant according to claim 1, wherein said
first part and said second part are formed from a polymer.
15. The intervertebral implant according to claim 14, wherein said
polymer is polyetheretherketone.
16. The intervertebral implant according to claim 14, wherein said
polymer is polytetrafluoroethylene.
17. The intervertebral implant according to claim 1, wherein said
first and second part are formed from a body compatible metal or
metal alloy.
18. A method of stabilizing two spaced vertebrae, the method
comprising: providing an intervertebral implant comprising: a first
part having a first end, a second end, a first contact surface
extending between the first and second ends and a first guide
surface extending out from the first contact surface; and a second
part having a third end, a fourth end, a second contact surface
extending between the third and fourth ends, and a second guide
surface recessed into the second contact surface; the first guide
surface and the second guide surface comprising cooperating
structures so that the first contact surface of the first part can
slide relative to the second contact surface of the second part
with a translation motion guided by the cooperating structures of
the first and second guide surfaces; adjusting the height of the
implant by connecting the second end of the first part with the
third end of the second part and moving the first contact surface
relative to the second contact surface to bring the first end of
the first part closer to the fourth end of the second part using
the cooperating guide surfaces; and inserting the adjusted height
implant between the vertebrae in need of stabilization.
19. The method according to claim 18, the method further comprising
fixing the two spaced vertebrae relative to each other.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from U.S. Provisional
Application Ser. No. 60/528,412 filed Dec. 9, 2003.
FIELD OF THE INVENTION
[0002] The present invention relates to intervertebral implants,
particularly, to height-adjustable intervertebral implants.
BACKGROUND OF THE INVENTION
[0003] Intervertebral implants are employed generally after the
removal of an intervertebral disc in order to stabilize the space
between the vertebrae.
[0004] An intervertebral implant is described in EP 0 977 529 B1.
The implant is shaped essentially like a rectangular parallelepiped
and comprises two side walls, one front wall, and one back wall.
The bottom surface and the top surface are open. The hollow space
of the intervertebral implant enclosed by the four walls contains
at least one movable element with a surface facing towards the top
surface or bottom surface, and one adjustment element that is
supported in the front wall and back wall, allowing the movable
element to be moved back and forth between a first position, in
which its surface does not protrude beyond the top surface or
bottom surface, and a second position, in which its surface
protrudes beyond the top surface or bottom surface. This movement
between the first and second positions allows for the final height
of the intervertebral implant to be adjustable.
[0005] Moreover, a curved intervertebral implant resembling the
shape of a banana and made as one part also is known. However, this
known intervertebral implant is not height-adjustable.
[0006] Thus, a height-adjustable intervertebral implant remains
desirable. The implant should also be particularly well-suited for
the use in minimally-invasive applications.
SUMMARY OF THE INVENTION
[0007] The present invention provides an intervertebral implant
comprising two parts. A first part has a first end, a second end, a
first contact surface provided between the ends and a first guide
surface extending out from the first contact surface. A second part
also has two ends (more specifically referred to as the third and
fourth ends), a second contact surface provided therebetween, and a
second guide surface recessed into the second contact surface. The
first guide surface and the second guide surface have cooperating
or mating structures so that the first contact surface of the first
part can slide relative to the second contact surface of the second
part with a translation motion guided by the cooperating structures
of the first and second guide surfaces.
[0008] Certain preferred embodiments of an intervertebral implant
in accordance with the present invention can have one or more of
the following features:
[0009] the distance between the first contact surface of the first
part and a first base surface that is opposite to the first contact
surface is smaller at the first end of the first part than at the
second end, and the distance between the second contact surface of
the second part and a second base surface that is opposite to the
second contact surface is smaller at one end (i.e., the third end)
of the second part than the other end (i.e., the fourth end);
[0010] the first part comprises a first base surface opposite to
said first contact surface, and a first plane parallel to said
first contact surface intersects a second plane parallel to said
first base surface forming an inclination angle of contact .alpha.;
and the second part comprises a second base surface opposite to
said second contact surface, and a third plane parallel to said
second contact surface intersects a fourth plane parallel to said
second base surface forming an inclination angle of contact
.alpha.;
[0011] the contact surfaces and the guiding surfaces can be
arcuate, curved or shaped like a segment of a helix;
[0012] at least one of the contact surfaces includes a terminal
stop to prevent further translation of the surfaces;
[0013] an inclination angle (.alpha.) of the contact surfaces with
their respective base surfaces is formed which depends on the
material used to form the parts and the surface properties of the
two contact surfaces such that a self-locking mechanism results
between the first part and the second part;
[0014] the guide surfaces are provided with cooperating
ridge-and-groove structures;
[0015] the first contact surface, the second contact surface, the
ridge, and the groove are each arcuate, curved or shaped like a
segment of a helix;
[0016] the groove terminates at a distance from the distal end of
the second contact surface such that a terminal stop is effected
for the gliding of the contact surfaces on each other;
[0017] the cross-section of the ridge protruding from the first
contact surface comprises a shape having a cross section selected
from the group comprising a dovetail-shape, a T-shape, a
rectangular or a square shape or a semicircular shape, and the
groove in the second contact surface comprises a complementary
shape for receiving the ridge;
[0018] the first part and/or the second part can comprise an
orifice or a recess;
[0019] the first contact surface and/or the second contact surface
comprise a roughened portion or a step-like portion; and
[0020] the first base surface and/or the second base surface
comprise groove-shaped recesses.
[0021] The invention also provides a method for stabilizing the
space between vertebrae by providing an intervertebral implant as
described herein, adjusting the height of the implant by
connecting, for example, the second end of the first part with the
third end of the second part and moving the first contact surface
relative to the second contact surface to bring the first end of
the first part closer to the fourth end of the second part using
the cooperating guide surfaces, and inserting the adjusted height
implant between the vertebrae needing to be stabilized.
[0022] Use of an intervertebral implant in accordance with the
present invention can enable one to alter the height (or thickness)
of the implant in its assembled state by shifting the first part
and the second part relative to each other by means of the contact
surfaces moving relative to each other. The motion of the first
part and the second part relative to each other, preferably
proceeding in an arcuate path such as a screw or helical motion, is
particularly well-suited for the use of the intervertebral implant
in minimally-invasive applications.
[0023] In certain preferred embodiments, a terminal stop is
provided, which prevents the gliding motion of the first part and
the second part relative to each other from proceeding beyond a
terminal position.
[0024] In other preferred embodiments, a self-locking mechanism
such as, for example, roughened or stepped contact surfaces, are
provided, which prevents the inadvertent shifting of the first part
and the second part relative to each other.
[0025] Additional features and expediencies of the present
invention are evident from the description of embodiments and the
attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 shows a perspective view of an intervertebral implant
according to one embodiment of the present invention in a state in
which the two parts are minimally engaged;
[0027] FIG. 2 shows a perspective view of the intervertebral
implant depicted in FIG. 1 in a state in the two parts are fully
engaged;
[0028] FIG. 3 shows a perspective view of a first part of the
intervertebral implant of FIG. 1;
[0029] FIG. 4 shows a perspective view of a second part of the
intervertebral implant of FIG. 1;
[0030] FIG. 5 shows a front elevational view of the intervertebral
implant in the state illustrated in FIG. 1;
[0031] FIG. 6 shows a front elevational view of the intervertebral
implant in the state illustrated in FIG. 2;
[0032] FIG. 7 shows a schematic representation of a self-locking
mechanism effected by the acting force F;
[0033] FIG. 8 shows a perspective view of another embodiment of an
intervertebral implant in accordance with the present
invention;
[0034] FIG. 9a) to 9e) show different shapes of the mating
groove/ridge structure provided at the contact surfaces;
[0035] FIG. 10 shows a further modification of the intervertebral
implant; and
[0036] FIG. 11a to 11b show a still further modification of the
intervertebral implant.
DETAILED DESCRIPTION OF THE INVENTION
[0037] An intervertebral implant according to one embodiment of the
present invention is illustrated with reference to FIGS. 1 to 6. As
is evident from FIG. 1 and FIG. 2, intervertebral implant 1
consists of two curved parts 10, 20, which are provided to be in
the shape of an arc, curve or segment of a helix in this particular
embodiment.
[0038] As is best seen in FIG. 6, the two parts 10, 20 are provided
as wedge-like sections with opposite tapers, each of which has a
thick end 14, 24 that forms a base end of the wedge and a tapered
end 13, 23 opposite to the thick end. In this arrangement, the two
parts 10, 20 can be connected together by contacting each other at
their wedge surfaces 12, 22 using the guide surfaces provided by
ridge 15 and groove 25. Thus, reference generally will be made to
these wedge surfaces as "contact surfaces" 12, 22, hereinafter.
Thus, seen from an elevational view (such as FIG. 6), when the two
parts are fully engaged, intervertebral implant 1 is approximately
rectangular in shape. By shifting the two parts 10, 20 relative to
each other along their contact surfaces 12, 22, the total height of
intervertebral implant 1 can be adjusted.
[0039] As is best seen in FIG. 3, first part 10 comprises a first
contact surface 12 and a first base surface 11 opposite to contact
surface 12. First contact surface 12 is provided preferably in the
form of a section of an arc, curve or shaped like a segment of a
helix. In this embodiment, a ridge 15 with a dovetail-shaped
cross-section is provided on first contact surface 12 such that it
protrudes at a right angle from the surface (i.e. in a direction
perpendicular to the plane of the surface). Ridge 15 can be in the
form of an arc, curve or shaped like a segment of a helix. Ridge 15
extends from the second end 14 of first part 10, which forms the
base of the wedge, preferably to a distance from the tapered first
end 13.
[0040] As is best seen in FIG. 4, second part 20 includes a second
contact surface 22 and a second base surface 21 opposite to second
contact surface 22. Second contact surface 22 also is in the form
of an arc, curve or a segment of a helix, provided that it is
complementary to that of the first contact surface 12 and matingly
cooperates with the first contact surface. A groove 25 with a
dovetailed cross-section that corresponds to the cross-section of
ridge 15 is provided in second contact surface 22. Groove 25 also
is shaped like an arc, curve or segment of a helix. Groove 25
extends from the tapered first end 23 of second part 20 preferably
to a distance from the second end 24, which forms the base end of
the wedge.
[0041] Alternatively to the ridge and groove shown any type of a
positive structure protruding from the first contact surface which
cooperates with a corresponding negative structure or recess in the
second contact surface and which can slide relative to the second
contact surface can be used. Positive and negative structures can
be interchanged, so that the positive structure is provided on the
second contact surface and the negative structure is provided in
the first contact surface.
[0042] The first base surface 11 and the second base surface 21 may
also be provided with groove-shaped recesses, which also are
circular arc-shaped in this embodiment when viewed in a top view.
Any type or shape of grooved recess may be used in the
alternative.
[0043] In order to adjust the height of intervertebral implant 1 as
desired, first part 10 and second part 20 are shifted relative to
each other in a sliding motion along their contact surfaces 12, 22
contacting between a first position A (see FIGS. 1 and 5) and a
second position B (see FIGS. 2 and 6), whereby ridge 15 is guided
within groove 25. The second position B is reached once ridge end
16 pushes against groove end 26 forming a terminal stop. In this
embodiment, groove end 26 prevents the parts from being pushed
beyond the terminal stop position.
[0044] As is best seen in FIGS. 5 and 6, the inclination of contact
surfaces 12, 22 with respect to base surfaces 11, 21 causes
intervertebral implant 1, after being pushed together into the
second position B to be of a height Y that exceeds the height X in
the first position A before the parts are pushed together.
Therefore, it is possible to adjust the height of intervertebral
implant 1 between the two limits X and Y by means of a gliding
motion of first part 10 and second part 20 relative to each
other.
[0045] In application, for the insertion of intervertebral implant
1 between two vertebrae, the desired height is obtained by moving
the first part 10 and second part 20 relative to each other with
the contact surfaces and guide surfaces in contact. Once the
desired height is obtained the intervertebral implant 1 is inserted
between the vertebrae. The vertebrae are then fixed with the
implant positioned between them.
[0046] FIG. 7 shows a force F acting upon the intervertebral
implant 1 after its insertion between the vertebrae. In order to
prevent force F from moving the first part 10 inadvertently with
respect to the second part 20, the inclination angle .alpha. of
contact surfaces 12, 22, defining the angle of the contact surface
12, 22 of each part relative to the base surface 11, 21 preferably
is determined to result in a self-locking mechanism. The angle is
dependent on the material used to form the actual implant and the
frictional surface properties of contact surfaces 12, 22 to result
in a self-locking mechanism so that the following condition
.alpha.<.rho..sub.o (whereby .rho..sub.o=arc tan .mu..sub.o)
is essentially satisfied. In the above equation .rho..sub.o is the
friction angle and .mu..sub.o is the static friction coefficient of
the material.
[0047] Preferably the intervertebral implant is formed from
titanium. However, alternatively, other body-compatible metals or
alloys or polymer materials including those well known to those
skilled in the art can be used. Examples of suitable polymer
materials are polyetheretherketone("PEEK") or
polytetrafluoroethylene ("PTFE") or. The polymeric material can be
reinforced with fibers, including carbon fibers.
[0048] In the embodiment shown in FIG. 8, the external surfaces of
first part 10 and/or second part 20 can include recesses 31 formed
as boreholes or orifices. The recesses allow for the in-growth of
bone material into intervertebral implant 1.
[0049] In yet another embodiment, ridge 15 and groove 25 are
provided such that they each extend from first end 13, 23 of the
corresponding part 10, 20 to the corresponding second end 14, 24.
This arrangement allows the two parts to be shifted relative to
each other beyond second position B and, thus, provides for the
height in the assembled state to have a larger adjustable
range.
[0050] Other modifications within the spirit and scope of the
invention also can be made. For example, the cross section of ridge
and groove can be T-shaped, rectangular or square in shape, or can
be any alternative geometric shape to provide a substantially
mating connection for the guide surfaces. FIG. 9a) to e) show
examples of cross sections, like dove-tail shape (FIG. 9a), T-shape
(FIG. 9b), rectangular shape (FIG. 9c) and square shape (FIG. 9d)
or semicircular shape (FIG. 9e). Further, the cross sectional shape
of the groove does not have to be exactly the same as that of the
ridge, as long as the grove cross section receives the ridge cross
section in a manner that provides a mating connection to enable the
two parts to slide relative to each other. In a further
modification, the connection between ridge and groove is not
provided as a section of a screw or helical line, but is provided
to be straight.
[0051] In yet a further modification, at least one of the two parts
is hollow in the interior and comprises orifices in the base
surface or the side wall to allow filling with bone material and/or
ingrowth of bone material.
[0052] In a further modification, the contact surfaces of the first
and/or second part are roughened and/or milled to be step-like as
shown in FIG. 10.
[0053] In a yet another modification, the outer shape (top view) of
the first and/or second part are each straight and not shaped as an
arc, curve or segment of a helix. It is possible to make the first
and second part exactly the same, wherein the part has both a ridge
and a groove. Alternatively the first and second contact surfaces
can be shaped like an arc, curve or segment of a helix. Thus, the
implant can be made from two like parts.
[0054] FIG. 11a shows an intervertebral implant 100 comprising two
straight, wedge-shaped parts 110, 120 in a first state (A) in which
the two parts are minimally engaged. Like in the first embodiment,
the parts have corresponding ridge 115 and groove 125 and guide
surfaces 112, 122. FIG. 11b shows the implant in a state (B) where
the two parts are fully engaged.
[0055] In yet a further modification, the base surfaces of the
first part and/or second part are provided without grooves.
[0056] The embodiments described above and shown herein are
illustrative and not restrictive. The scope of the invention is
indicated by the claims rather than by the foregoing description
and attached drawings. The invention may be embodied in other
specific forms without departing from the spirit of the invention.
Accordingly, these and other changes which come within the scope of
the claims are intended to be embraced therein.
* * * * *