U.S. patent application number 11/194786 was filed with the patent office on 2005-12-01 for spacerless artificial disc replacements.
This patent application is currently assigned to SpineCore, Inc.. Invention is credited to Ferree, Bret A., Tompkins, David.
Application Number | 20050267582 11/194786 |
Document ID | / |
Family ID | 38997908 |
Filed Date | 2005-12-01 |
United States Patent
Application |
20050267582 |
Kind Code |
A1 |
Ferree, Bret A. ; et
al. |
December 1, 2005 |
Spacerless artificial disc replacements
Abstract
Spacerless artificial disc replacements (ADR) are disclosed. One
preferred embodiment includes two saddle-shaped components to
facilitate more normal spinal flexion, extension, and lateral
bending while limit axial rotation, thereby protecting the facet
joints and the annulus fibrosus (AF). Either or both of the
superior and inferior components are made of a hard material such
as chrome cobalt, titanium, or a ceramic including alumina,
zirconia, or calcium phosphate. The articulating surfaces of the
ADR are also preferably highly polished to reduce friction between
the components. Metals, alloys or other materials with shape-memory
characteristics may also prove beneficial.
Inventors: |
Ferree, Bret A.;
(Cincinnati, OH) ; Tompkins, David; (Milford,
OH) |
Correspondence
Address: |
LERNER, DAVID, LITTENBERG,
KRUMHOLZ & MENTLIK
600 SOUTH AVENUE WEST
WESTFIELD
NJ
07090
US
|
Assignee: |
SpineCore, Inc.
Summit
NJ
|
Family ID: |
38997908 |
Appl. No.: |
11/194786 |
Filed: |
August 1, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11194786 |
Aug 1, 2005 |
|
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|
10413028 |
Apr 14, 2003 |
|
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60372520 |
Apr 12, 2002 |
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Current U.S.
Class: |
623/17.15 |
Current CPC
Class: |
A61F 2/4425 20130101;
A61F 2002/30884 20130101; A61F 2/30767 20130101; A61F 2002/302
20130101; A61F 2002/30878 20130101; A61F 2210/0014 20130101; A61F
2310/00239 20130101; A61L 27/10 20130101; A61F 2002/30528 20130101;
A61F 2310/00011 20130101; A61F 2220/0025 20130101; A61F 2310/00203
20130101; A61F 2/442 20130101; A61F 2002/30301 20130101; A61F
2002/30092 20130101; A61F 2002/4631 20130101; A61F 2310/00023
20130101; A61F 2230/0095 20130101; A61L 2430/38 20130101; A61F
2002/30934 20130101; A61F 2310/00029 20130101; A61L 27/04 20130101;
A61F 2310/00293 20130101 |
Class at
Publication: |
623/017.15 |
International
Class: |
A61F 002/44 |
Claims
1. An artificial disc replacement comprising: a first component
having a first articulating surface, said first articulating
surface being a single saddle-shaped surface; and a second
component having a second articulating surface in contact with said
first articulating surface, said second articulating surface being
a single saddle-shaped surface, wherein said first and second
components are operable to articulate relative to one another about
at least one of (i) a first center of rotation located above said
first and second articulating surfaces for one of flexion/extension
or lateral bending, and (ii) a second center of rotation located
below said first and second articulating surfaces for the other of
flexion/extension or lateral bending.
2. The artificial disc replacement of claim 1, wherein said first
and second articulating surfaces engage one another.
3. The artificial disc replacement of claim 1, wherein said first
and second articulating surfaces include substantially congruent
surfaces.
4. The artificial disc replacement of claim 1, wherein said first
articulating surface includes a single substantially continuous
concave surface and a single substantially continuous convex
surface, and said second articulating surface includes a single
substantially continuous concave surface and a single substantially
continuous convex surface.
5. The artificial disc replacement of claim 4, wherein the concave
surface of said first articulating surface engages the convex
surface of said second articulating surface, and the convex surface
of said first articulating surface engages the concave surface of
said second articulating surface.
6. The artificial disc replacement of claim 4, wherein the single
concave and convex surfaces of said first articulating surface
extend between outer edges of said first articulating surface, and
the single concave and convex surfaces of said second articulating
surface extend between outer edges of said second articulating
surface.
7. The artificial disc replacement of claim 1, wherein said first
articulating surface is defined by a concave arc having a
substantially constant radius of curvature A about a first axis,
and a convex arc having a substantially constant radius of
curvature B about a second axis perpendicular to the first axis,
and said second articulating surface is defined by a convex arc
having a substantially constant radius of curvature C about a third
axis, and a concave arc having a substantially constant radius of
curvature D about a fourth axis perpendicular to the third
axis.
8. The artificial disc replacement of claim 7, wherein said radius
of curvature A is substantially equal to said radius of curvature C
and said radius of curvature B is substantially equal to said
radius of curvature D.
9. The artificial disc replacement of claim 7, wherein at least one
of: (i) said first and third axes are coaxial; and (ii) said second
and fourth axes are coaxial.
10. The artificial disc replacement of claim 7, wherein at least
one of: (i) said first and third axes are coplanar; and (ii) said
second and fourth axes are coplanar.
11. The artificial disc replacement of claim 1, wherein said first
and second member further include projections for engaging a
vertebral body.
12. The artificial disc replacement of claim 11, wherein said
projections are keels.
13. The artificial disc replacement of claim 11, wherein said
projections are selected from the group consisting of flanges,
keels and spikes.
14. The artificial disc replacement of claim 1, wherein said first
and second components are constructed of hard materials.
15. The artificial disc replacement of claim 14, wherein said hard
materials are selected from the group consisting of chrome cobalt,
titanium, alumina, zirconia, and calcium phosphate.
16. The artificial disc replacement of claim 1, wherein said first
and second components each further include vertebral surfaces for
contacting vertebral bodies.
17. The artificial disc replacement of claim 16, wherein said
vertebral surfaces have plasma spray or beads thereon.
18. The artificial disc replacement of claim 1, wherein said first
component is cemented to a first vertebral body and said second
component is cemented to a second vertebral body.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of the filing date of
U.S. Provisional Patent Application No. 60/372,520, filed Apr. 12,
2002 and this application is a continuation of U.S. application
Ser. No. 10/413,028, filed on Apr. 14, 2003, the disclosures of
which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates generally to artificial disc
replacements (ADRs) and, more particularly, to devices that operate
without softer spacer materials such as polyethylene.
BACKGROUND OF THE INVENTION
[0003] Polyethylene spacers are common in some artificial joint
situations, including total knee replacements (TKRs). Polyethylene
spacers are also used between metal plates in many artificial disc
replacement (ADR) designs.
[0004] Complications arising from poly debris are well documented,
however, including fracture of the spacer once it becomes too thin,
absorptions and migration of poly particles throughout the body,
and loosening of the bone metal junction as a reaction of the poly
debris.
[0005] Metal-on-metal and ceramic-on-metal surfaces have much lower
wear characteristics. In fact, metal-on-metal surfaces demonstrate
400 times less wear than polyethylene on metal surfaces.
[0006] While there have been attempts to limit the use of the poly
in ADR designs, all existing approaches constitute call-and-socket
configurations which do not inherently limit axial rotation.
Instead, axial rotation is limited through the use of multiple
ball-and-socket joints or an elongated ball-and-socket joint, which
complicates the design.
SUMMARY OF THE INVENTION
[0007] The present invention replaces polyethylene artificial disc
replacement (ADR) spacers with harder, more wear resistant
materials. In the preferred embodiments, an ADR according to the
invention includes opposing saddle-shaped components to facilitate
more normal spinal flexion, extension, and lateral bending.
Preferably, the ADR allows at least 10 degrees of movement on the
flexion to extension direction and at least 5 degrees of movement
in the lateral bending direction. The saddle-shaped articulating
surfaces also limit axial rotation, thereby protecting the facet
joints and the annulus fibrosis (AF).
[0008] According to the invention, either or both the superior and
inferior components are made of a hard material such as chrome
cobalt, titanium, or a ceramic including alumina, zirconia, or
calcium phosphate. The articulating surfaces of the ADR are also
preferably highly polished to reduce friction between the
components. Metals, alloys or other materials with shape-memory
characteristics may also prove beneficial.
[0009] The vertebral surfaces of the components may be treated to
promote bone ingrowth. For example, the vertebral surfaces of the
components may have plasma spray or beads. Alternatively, one or
both components may be cemented to the vertebrae. The
vertebra-facing surfaces may also include projections such as keels
that fit into the vertebrae. In embodiments adapted for
cementation, one of the components could be made of polyethylene or
other softer material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1A is an anterior view of an ADR according to the
invention;
[0011] FIG. 1B is a lateral view of the ADR of FIG. 1;
[0012] FIG. 1C is an oblique view of the ADR of FIG. 1;
[0013] FIG. 2A is a view of the anterior aspect of an alternative
embodiment of the ADR;
[0014] FIG. 2B is a view of the lateral aspect of an alternative
embodiment of the ADR shown in FIG. 2B;
[0015] FIG. 3A is a view of the anterior aspect of an alternative,
less constrained, embodiment of the saddle-shaped ADR shown in a
fully flexed position;
[0016] FIG. 3B is a view of the lateral aspect of the embodiment of
the ADR shown in FIG. 3A;
[0017] FIG. 4A is a view of the lateral aspect of another
embodiment of a saddle-shaped ADR;
[0018] FIG. 4B is a view of the anterior aspect of the embodiment
of the ADR shown in FIG. 4A in a fully flexed position;
[0019] FIG. 4C is a view of the anterior aspect of an alternative
embodiment;
[0020] FIG. 4D is a view of the anterior aspect of the ADR shown in
FIG. 4A; and
[0021] FIG. 4E is a view of the anterior aspect of the ADR shown in
FIG. 4A.
DETAILED DESCRIPTION OF THE INVENTION
[0022] FIG. 1A is an anterior view of an ADR according to the
invention. FIG. 1B is a lateral view of the ADR of FIG. 1. FIG. 1C
is an oblique view of the ADR of FIG. 1.
[0023] FIG. 2A is a view of the anterior aspect of an alternative
embodiment of the ADR, wherein the articulating surfaces of both
components have a flat area centrally from the front to the back of
the ADR. FIG. 2B is a view of the lateral aspect of an alternative
embodiment of the ADR drawn in FIG. 2B. The flat area of the
articulating surfaces courses centrally from side of the DR to the
other side. The flat area allows one component to translate
slightly on the other component. Alternatively, a curved area with
a large radius could replace the flat area.
[0024] FIG. 3A is a view of the anterior aspect of an alternative,
less constrained, embodiment of the saddle-shaped ADR drawn in a
fully flexed position. The less constrained embodiment facilitates
spinal flexion, extension, and lateral bending. FIG. 3B is a view
of the lateral aspect of the embodiment of the ADR drawn in FIG.
3A.
[0025] FIG. 4A is a view of the lateral aspect of another
embodiment of a saddle-shaped ADR. The center of rotation for
flexion and extension is not necessarily located in the center of
the ADR. For example, the center of rotation is preferably located
in the posterior half of the ADR. FIG. 4B is a view of the anterior
aspect of the embodiment of the ADR drawn in FIG. 4A, drawn in a
fully flexed position.
[0026] FIG. 4C is a view of the anterior aspect of an alternative
embodiment, showing how the radius of curvature of the articulation
for lateral bending may be different than the radius of curvature
for articulation for flexion and extension. For example, the radius
of curvature for the articulation for flexion and extension, as
seen in FIG. 4A, may be smaller than the radius of curvature for
the articulation for lateral bending, as seen in FIG. 4C.
Articulating surfaces with smaller radii, facilitate movement.
Thus, the embodiment of the ADR drawn in FIG. 4A flexes and extends
more easily than the embodiment of the ADR drawn in FIG. 3A. The
ADR is drawn in a fully flexed position.
[0027] FIG. 4D is a view of the anterior aspect of the ADR drawn in
FIG. 4A. The ADR is drawn in a neutral position. The area of the
drawing with diagonal lines represents the articulating surface of
the lower ADR component. FIG. 4E is a view of the anterior aspect
of the ADR drawn in FIG. 4A, also drawn in a fully extend
position.
* * * * *