U.S. patent application number 12/775386 was filed with the patent office on 2010-08-26 for intervertebral disc prosthesis.
This patent application is currently assigned to CERVITECH, INC.. Invention is credited to Arnold Keller.
Application Number | 20100217398 12/775386 |
Document ID | / |
Family ID | 34079864 |
Filed Date | 2010-08-26 |
United States Patent
Application |
20100217398 |
Kind Code |
A1 |
Keller; Arnold |
August 26, 2010 |
Intervertebral Disc Prosthesis
Abstract
An intervertebral disc prosthesis has two cover plates and a
prosthesis core which is connected to one of the cover plates by
connection profiles on one of the cover plates which are undercut
in a complementary manner and include at least one pair of profile
sections which are symmetrical with respect to the AP
(anteroposterior) direction of the prosthesis in its implanted
position and are arranged at an angle to one another.
Inventors: |
Keller; Arnold; (Kayhude,
DE) |
Correspondence
Address: |
Cervitech, Inc.
c/o NuVasive, Inc., 7475 Lusk Blvd.
San Diego
CA
92121
US
|
Assignee: |
CERVITECH, INC.
San Diego
CA
|
Family ID: |
34079864 |
Appl. No.: |
12/775386 |
Filed: |
May 6, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10623803 |
Jul 22, 2003 |
7722673 |
|
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12775386 |
|
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Current U.S.
Class: |
623/17.16 ;
29/428 |
Current CPC
Class: |
A61F 2002/30879
20130101; Y10T 29/49826 20150115; A61F 2/4425 20130101; A61F
2002/30604 20130101; A61F 2002/30578 20130101; A61F 2002/30892
20130101; A61F 2002/30383 20130101; A61F 2220/0025 20130101 |
Class at
Publication: |
623/17.16 ;
29/428 |
International
Class: |
A61F 2/44 20060101
A61F002/44; B23P 11/00 20060101 B23P011/00 |
Claims
1. An intervertebral disc prosthesis comprising: a first cover
plate and a second cover plate; a prosthesis core defined by a
generally hexagonal perimeter profile that connects to the first
cover plate by a connection profile and an engagement groove;
wherein the generally hexagonal perimeter profile is configured
with five substantially straight profile sections: two posterior
profile sections that are arranged at an angle to one another, two
lateral sections, and an anterior profile section; and wherein the
connection profile formed by the two angled posterior profile
sections and the two lateral profile sections is configured with an
undercut connection profile that corresponds to a complementary
undercut connection profile on the first cover plate.
2. The intervertebral disc prosthesis of claim 1, wherein the
connection profile formed by the anterior edge is a groove for
receiving an engaging structure.
3. The intervertebral disc prosthesis of claim 2, wherein the
engaging structure is a plate.
4. The intervertebral disc prosthesis of claim 1, wherein the angle
enclosed by the posterior profile sections is not greater than
150.degree..
5. The intervertebral disc prosthesis of claim 1, wherein the angle
enclosed by the posterior profile sections is approximately
140.degree..
6. The intervertebral disc prosthesis of claim 1, wherein the
prosthesis core has a top surface configured as a slide surface
that cooperates with the second cover plate to form a hinge.
7. The intervertebral disc prosthesis of claim 5, wherein the top
surface of the prosthesis core has a circumferential contour that
is identical to a circumferential contour of the first cover
plate.
8. An intervertebral disc prosthesis comprising: a first cover
plate and a second cover plate; a prosthesis core being connected
to the first cover plate by at least one pair of connection
profiles which are substantially straight and symmetrical with
respect to an anterior to posterior direction of implantation and
are arranged at an angle to one another, and by a connection
profile formed by the anterior edge; wherein the connection profile
formed by the at least one pair of connection profiles is
configured with an undercut connection profile that corresponds to
a complementary undercut connection profile on the first cover
plate; and wherein the connection profile formed by the anterior
edge is a groove for receiving an engaging structure.
9. The intervertebral disc prosthesis of claim 8, wherein the
engaging structure is a plate.
10. The intervertebral disc prosthesis of claim 8 further
comprising two lateral sections which are configured with an
undercut connection profile, wherein the two lateral sections are
substantially straight and arranged substantially parallel to one
another.
11. The intervertebral disc prosthesis of claim 8, wherein the
angle enclosed by the posterior profile sections is not greater
than 150.degree..
12. The intervertebral disc prosthesis of claim 8, wherein the
angle enclosed by the posterior profile sections is approximately
140.degree..
13. The intervertebral disc prosthesis of claim 8, wherein the
prosthesis core has a top surface configured as a slide surface
that cooperates with the second cover plate to form a hinge.
14. The intervertebral disc prosthesis of claim 8, wherein the top
surface of the prosthesis core has a circumferential contour that
is identical to a circumferential contour of the first cover
plate.
15. A method for assembly of an intervertebral disc prosthesis
comprising a first cover plate and a second cover plate, a
prosthesis core defined by a generally hexagonal perimeter profile
that connects to the first cover plate by a connection profile and
an engagement groove, wherein the generally hexagonal perimeter
profile is configured with five substantially straight profile
sections: two posterior profile sections that are arranged at an
angle to one another, two lateral sections, and an anterior profile
section; and, wherein the connection profile formed by the two
angled posterior profile sections and the two lateral profile
sections is configured with an undercut connection profile that
corresponds to a complementary undercut connection profile on the
first cover plate, the method comprising: inserting the prosthesis
core from an open anterior side of the first cover plate; sliding
the prosthesis core from an anterior to posterior direction to
fully engage the undercut connection profile with the complementary
undercut connection profile of the first cover plate; inserting an
engaging structure into the anterior profile section to secure the
prosthesis core to the first cover plate; and wherein the
arrangement of the posterior profile sections at an angle to one
another increases rotational stability of the prosthesis core
relative to the first cover plate.
16. The intervertebral disc prosthesis of claim 15 wherein the
engaging structure is a plate.
17. The intervertebral disc prosthesis of claim 15, wherein the
angle enclosed by the posterior profile sections is not greater
than 150.degree..
18. The intervertebral disc prosthesis of claim 15, wherein the
angle enclosed by the posterior profile sections is approximately
140.degree..
19. The intervertebral disc prosthesis of claim 15, wherein the
prosthesis core has a top surface configured as a slide surface
that cooperates with the second cover plate to form a hinge.
20. The intervertebral disc prosthesis of claim 19, wherein the top
surface of the prosthesis core has a circumferential contour that
is identical to a circumferential contour of the first cover plate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 10/623,803 filed Jul. 23, 2003, the entire contents of which
are hereby expressly incorporated by reference into this disclosure
as if set forth fully therein.
FIELD AND BACKGROUND OF THE INVENTION
[0002] A known type of intervertebral disc prosthesis (WO 01/01893)
has two metal cover plates and a polyethylene prosthesis core which
forms a pair of slide surfaces with one of the two cover plates and
is fixed on the other cover plate. For this fixing, the cover plate
is provided with edge ridges whose undercut connection profile
cooperates with a complementary connection profile on the underside
of the prosthesis core. On the right and left lateral edges of the
cover plate and of the prosthesis core, such connection profiles
are provided parallel to one another. In addition, there is one
such profile running in a straight line on the dorsal edge of the
cover plate and of the prosthesis core. There is no such profile on
the ventral edge, with the result that the prosthesis core can be
pushed into the connection profiles of the cover plate from the
ventral direction. The prosthesis core is secured in the assembled
position by a pair of locking elements provided on the ventral
edge. Although the connection profiles are produced almost free of
play, an important concern in prosthesis production is to ensure
that, even in the case of production tolerances, it is possible to
rule out any movement of the prosthesis core relative to the cover
plate holding it. In particular, rotation movements of the
prosthesis core relative to the cover plate holding it must be
ruled out. The invention has recognized that this can be improved
not only by precision production by also by a special arrangement
of the connection profiles.
SUMMARY OF THE INVENTION
[0003] According to the invention, provision is made that the
connection profiles include at least one pair of connection profile
sections which are symmetrical with respect to the AP direction and
are arranged at an angle to one another. AP direction signifies the
anteroposterior direction. The profile sections arranged at an
angle to one another according to the invention create a triangular
configuration which counteracts twisting of the prosthesis core
relative to the cover plate if play exists between the connection
profiles of the cover plate and of the prosthesis core. The
connection profiles can basically be made up exclusively of such
profile sections arranged at an angle to one another. However,
these can also be provided additionally to connection profiles
arranged in parallel on the lateral edge of the cover plate and of
the prosthesis core. They are intended to run in a substantially
straight line and are preferably arranged at least on the dorsal
side. The angle between the profile sections arranged at an angle
to one another should not be greater than 150.degree.. The limit
preferably lies for example at 140.degree..
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] The invention is explained in more detail below with
reference to the drawing which depicts an advantageous illustrative
embodiment and in which:
[0005] FIG. 1 shows a perspective view of the end plate with the
prosthesis core secured on it,
[0006] FIGS. 2 to 4 show different views of the same end plate
without the prosthesis core, and
[0007] FIGS. 5 and 6 show perspective views of the prosthesis
core.
DETAILED DESCRIPTION OF THE INVENTION
[0008] The end plate 1, which is normally used as the lower end
plate, has an approximately oval contour and comprises a toothed
fastening surface 2 for bearing on the vertebral body and a flange
3 which comes to lie on the ventral side of the vertebral body and
can be screwed to the latter via screw holes 4. On that side
opposite the fastening surface 2, the one normally lying to the
top, the cover plate 1 forms a support for the prosthesis core 5.
This support consists of a plane surface 6, and surrounding the
latter, an edge 7 which is composed of two parallel sections 7' on
the lateral sides of the plate and of a dorsal edge 7''. The outer
contour of the edge 7 corresponds to the oval contour of the cover
plate. On its side facing toward the surface 6, the edge is
provided with a profile ridge 8 and, below the latter, with an
undercut 8'. The connection profile thereby formed on the inner
side of the edge 7 runs in a straight line in the lateral section 7
and 7' and parallel on both sides. In the dorsal section 7'', the
connection profile is composed of two sections 9. In each of these
sections, the connection profile runs in a straight line. The
profiles of both sections are arranged symmetrically with respect
to the AP axis 10 of the implant and enclosed an angle .alpha.
which, in the example shown, is 140.degree..
[0009] The top of the edge 7 forms a plane surface 6' which runs
parallel to the support surface 6 and likewise forms a support
surface for the prosthesis core.
[0010] The flange 3 of the cover plate has a slit 11 which runs
perpendicular to the connection profile 6 and whose function is
explained later.
[0011] On its top 12, the prosthesis core 5 forms a slide surface
which cooperates with the second cover plate (not shown) to form a
hinge. The contour of the prosthesis core is identical to that of
the cover plate 1. On its underside, it has a plane surface 13
which is intended to bear on the support surface 6 of the end plate
1 and has substantially the same contour shape. It is limited by a
connection profile which is formed by a profile ridge 14 and an
undercut 14'. This connection profile corresponds in a
complementary manner to the connection profile 8, 9 of the edge
ridge 7 of the cover plate 1. In particular, the connection profile
is composed of two lateral sections 15 and two dorsal sections 16
which correspond respectively to the lateral and dorsal sections of
the edge 7 of the cover plate 1 and can cooperate with these in a
form-fitting manner.
[0012] Outside the connection profile 14, 14', on the underside of
the prosthesis core 5 there is a plane surface 17 which corresponds
to the support surface 6' on the top of the edge 7 of the cover
plate 1 and cooperates with this when the prosthesis core is
mounted on the cover plate 1.
[0013] The prosthesis is assembled by means of the prosthesis core
being pushed with its connection profile 14, 14' into the
corresponding connection profiles 8, 8' from the direction of the
open ventral side. When the prosthesis core has been pushed in
fully, its profile ridge 14 fits, not only in the area of the
lateral sections 7' but also in the area of the dorsal section 7'',
into the undercut 8' of the edge 7 of the cover plate, the
connection profiles lying on one another with substantially
full-surface contact.
[0014] At the location where the slit 11 is situated in the gap 3,
the prosthesis core has a groove 18 which is flush with the gap 11
when the prosthesis core has reached its end position in which the
dorsal connection profiles abut one another. A plate (not shown) is
pushed into the gap 11 and the groove 18 and secures the prosthesis
core in this position relative to the cover plate 1. The plate is
in turn secured by means of also having a bore at the location of
the screw hole shown on the left in FIG. 3, through which bore a
fastening screw extends.
[0015] By virtue of the fact that the connection profiles of the
prosthesis core and of the cover plate are equipped, respectively,
with the sections 9 and 16 which each form a triangle, it is
possible, in comparison with known prostheses, to obtain increased
stability of the position of the prosthesis core relative to the
cover plate 1. In particular, its stability with respect to
relative movements in the sense of rotation is thereby
increased.
* * * * *