U.S. patent application number 11/067214 was filed with the patent office on 2005-09-01 for method of preparing for an artificial intervertebral implant using tool.
This patent application is currently assigned to St. Francis Medical Technologies, Inc.. Invention is credited to Flynn, John, Hsu, Ken Y., Mitchell, Steve, Winslow, Charles J., Yerby, Scott A., Zucherman, James F..
Application Number | 20050192586 11/067214 |
Document ID | / |
Family ID | 32233470 |
Filed Date | 2005-09-01 |
United States Patent
Application |
20050192586 |
Kind Code |
A1 |
Zucherman, James F. ; et
al. |
September 1, 2005 |
Method of preparing for an artificial intervertebral implant using
tool
Abstract
This invention relates to tools for preparing vertebral bodies
in the spine for the implantation of an artificial vertebral disk
replacement and related method. A first tool is disclosed that
prepares the vertebral bodies for implantation by cutting offset
channels in the vertebral bodies. The second tool holds two plates
of the implant during the implantation process. This invention also
relates to an artificial vertebral disk replacement, a method of
operation, and a method of implanting.
Inventors: |
Zucherman, James F.; (San
Francisco, CA) ; Hsu, Ken Y.; (San Francisco, CA)
; Winslow, Charles J.; (Walnut Creek, CA) ; Yerby,
Scott A.; (Montara, CA) ; Mitchell, Steve;
(Pleasant Hill, CA) ; Flynn, John; (Concord,
CA) |
Correspondence
Address: |
FLIESLER MEYER, LLP
FOUR EMBARCADERO CENTER
SUITE 400
SAN FRANCISCO
CA
94111
US
|
Assignee: |
St. Francis Medical Technologies,
Inc.
Alameda
CA
|
Family ID: |
32233470 |
Appl. No.: |
11/067214 |
Filed: |
February 25, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11067214 |
Feb 25, 2005 |
|
|
|
10685134 |
Oct 14, 2003 |
|
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60422011 |
Oct 29, 2002 |
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Current U.S.
Class: |
606/82 ;
623/17.15 |
Current CPC
Class: |
A61F 2002/3065 20130101;
A61F 2002/30892 20130101; A61F 2002/30654 20130101; A61F 2002/30224
20130101; A61F 2/4425 20130101; A61F 2002/443 20130101; A61B
17/1671 20130101; A61F 2002/30662 20130101; A61F 2002/4627
20130101; A61F 2002/30904 20130101; A61F 2002/448 20130101; A61F
2002/30665 20130101; A61F 2/4611 20130101; A61F 2002/30808
20130101; A61F 2230/0069 20130101 |
Class at
Publication: |
606/082 ;
623/017.15 |
International
Class: |
A61B 017/88; A61F
002/44 |
Claims
What is claimed is:
1. A method of implanting an implant between adjacent vertebral
bodies comprising the steps of: a. simultaneously preparing a first
slot in an upper vertebral body and a second slot in a lower
vertebral body; and b. implanting keels of an implant in the first
slot and the second slot.
2. The method of claim 1 wherein the step of preparing further
comprises inserting a cutting tool having an upper blade protruding
therefrom to form the first slot and a lower blade protruding
therefrom to form the second slot.
3. The method of claim 1 wherein the step of preparing further
comprises inserting a cutting tool having a pair of tines between
the upper and lower vertebral bodies, each tine having a first
blade protruding from an inner surface and a second blade
protruding from an outer surface.
4. The method of claim 1 wherein the step of preparing further
comprises inserting a cutting tool having an upper blade protruding
therefrom to form the first slot and a lower blade protruding
therefrom to form the second slot, the cutting tool having a
beveled leading edge.
5. The method of claim 1 wherein the step of preparing further
comprises inserting a cutting tool having an upper blade protruding
therefrom to form the first slot and a lower blade protruding
therefrom to form the second slot, wherein the cutting tool
includes a retractable blade protector configured to expose at
least one of the upper and lower blade when inserted between the
vertebral bodies.
6. The method of claim 1 wherein the step of preparing further
comprises removing the cutting tool from between the upper and
lower vertebral bodies to allow the implant to be inserted
therebetween.
7. The method of claim 1 wherein the step of implanting further
comprises inserting an implantation tool between the vertebral
bodies, wherein the implantation tool is adapted to hold the
implant, the implantation tool including a curved surface to at
least partially contour an outer edge of the implant.
8. A method of implanting an artificial disk between adjacent
vertebral bodies comprising the steps of: a. distracting an upper
vertebral body and a lower vertebral body and simultaneously
cutting a first slot in the upper vertebral body and a second slot
in the second vertebral body; and b. inserting an implant between
the upper and lower vertebral bodies, wherein a first keel of the
implant is inserted into the first slot and a second keel of the
implant is inserted into the second slot.
9. The method of claim 8 wherein the step of distracting further
comprises inserting a cutting tool between the upper and lower
vertebral bodies, the cutting tool having an upper blade protruding
therefrom to form the first slot and a lower blade protruding
therefrom to form the second slot.
10. The method of claim 8 wherein the step of distracting further
comprises inserting a cutting tool having a pair of tines between
the upper and lower vertebral bodies, each tine having an upper
blade protruding from an inner surface and a lower blade protruding
from an outer surface.
11. The method of claim 8 wherein the step of distracting further
comprises inserting a cutting tool having an upper blade protruding
therefrom to form the first slot and a lower blade protruding
therefrom to form the second slot, the cutting tool having a
beveled leading edge.
12. The method of claim 8 wherein the step of distracting further
comprises inserting a cutting tool having an upper blade protruding
therefrom to form the first slot and a lower blade protruding
therefrom to form the second slot, wherein the cutting tool
includes a retractable blade protector configured to expose the
upper and lower blade when inserted between the vertebral
bodies.
13. The method of claim 8 wherein the step of distracting further
comprises removing the cutting tool from between the vertebral
bodies to allow the implant to be inserted therebetween.
14. The method of claim 8 wherein the step of inserting further
comprises inserting an implantation tool between the vertebral
bodies, wherein the implantation tool is adapted to hold the
implant, the implantation tool including a curved surface to at
least partially contour an outer edge of the implant.
15. A method of implanting an artificial disk between adjacent
vertebral bodies comprising the steps of: a. selecting a cutting
tool having an upper blade protruding therefrom and a lower blade
protruding therefrom; b. inserting the cutting tool between an
upper vertebral body and a lower vertebral body, wherein the upper
blade forms a first slot in the upper vertebral body and the lower
blade forms a second slot in the lower vertebral body; and c.
inserting an implant between the upper and lower vertebral bodies,
wherein a first keel of the implant is inserted into the first slot
and a second keel of the implant is inserted into the second
slot.
16. The method of claim 15 wherein the cutting tool further
comprises a pair of tines, wherein each tine includes the upper
blade protruding from an inner surface and the lower blade
protruding from an outer surface.
17. The method of claim 15 wherein the cutting tool further
comprises a beveled leading edge.
18. The method of claim 15 wherein the cutting tool further
comprises a retractable blade protector configured to expose the
upper and lower blade when inserted between the upper and lower
vertebral bodies.
19. The method of claim 15 further comprising the step of removing
the cutting tool from between the vertebral bodies to allow the
implant to be inserted therebetween.
20. The method of claim 15 wherein the implant is inserted between
the vertebral bodies using an implantation tool, the implantation
tool adapted to hold the implant along a curved surface, wherein
the curved surface at least partially contours an outer edge of the
implant.
Description
CLAIM OF PRIORITY
[0001] This application is a divisional of U.S. application Ser.
No. 10/685,134, filed Oct. 14, 2003 (Attorney Docket No.
KLYCD-05009US1), which claims priority to U.S. Provisional
Application No. 60/422,011, filed Oct. 29, 2002, entitled "TOOLS
FOR IMPLANTING AN ARTIFICIAL VERTEBRAL DISK AND METHOD" (Attorney
Docket No. KLYC-01065US2).
CROSS-REFERENCE TO RELATED APPLICATIONS
[0002] This application is related to U.S. Provisional Patent
Application No. 60/422,039, filed Oct. 29, 2002, entitled
"ARTIFICIAL VERTEBRAL DISK REPLACEMENT IMPLANT WITH TRANSLATING
PIVOT POINT AND METHOD" (Attorney Docket No. KLYCD-05007US0), U.S.
patent application Ser. No. 10/684,669, filed Oct. 14, 2003,
entitled "ARTIFICIAL VERTEBRAL DISK REPLACEMENT IMPLANT WITH
TRANSLATING PIVOT POINT AND METHOD (Attorney Docket No.:
KLYCD-05007US1), U.S. Provisional Patent Application No.
60/422,021, filed Oct. 29, 2002, entitled "ARTIFICIAL VERTEBRAL
DISK REPLACEMENT IMPLANT WITH CROSSBAR SPACER AND METHOD" (Attorney
Docket No. KLYCD-05008US0), U.S. patent application Ser. No.
10/684,668, filed Oct. 14, 2003, entitled "ARTIFICIAL VERTEBRAL
DISK REPLACEMENT IMPLANT WITH CROSSBAR SPACER AND METHOD" (Attorney
Docket No. KLYCD-05008US1), U.S. Provisional Patent Application No.
60/422,022, filed Oct. 29, 2002, entitled "ARTIFICIAL VERTEBRAL
DISK REPLACEMENT IMPLANT WITH A SPACER AND METHOD" (Attorney Docket
No. KLYCD-05010US0), and U.S. patent application Ser. No.
10/685,011, filed Oct. 14, 2003, entitled "ARTIFICIAL VERTEBRAL
DISK REPLACEMENT IMPLANT WITH A SPACER AND METHOD" (Attorney Docket
No. KLYCD-05010US1), all of which are incorporated herein by
reference.
FIELD OF THE INVENTION
[0003] This invention relates to tools for preparing vertebral
bodies in the spine for the implantation of an artificial vertebral
disk replacement and related method. This invention also relates to
an artificial vertebral disk replacement, a method of operation,
and a method of implanting.
BACKGROUND OF THE INVENTION
[0004] As the present society ages, it is anticipated that there
will be an increase in degenerative and dysfunctional spinal disk
conditions. Pain associated with such disk conditions can be
relieved by medication and/or surgery.
[0005] Over the years, a variety of intervertebral implants have
been developed in an effort to relieve the pain associated with
such degenerative and dysfunctional disk conditions. For example,
U.S. Pat. No. 4,349,921 to Kuntz discloses an intervertebral disk
prosthesis. The Kuntz prosthesis is designed to restore the space
between the disks.
[0006] U.S. Pat. No. 4,714,469 to Kenna discloses a spinal implant
that fuses vertebrae to the implant. The implant has a rigid body
that fits between the vertebrae with a protuberance extending from
a vertebral contacting surface and into the vertebral body.
[0007] U.S. Pat. No. 5,258,031 to Salib et al. discloses another
prosthetic disk with a ball that fits into a socket.
[0008] U.S. Pat. Nos. 5,425,773 and 5,562,738 are related patents
to Boyd et al. that disclose a disk arthroplasty device for
replacement of the spinal disk. A ball-and-socket are provided to
enable rotation.
[0009] U.S. Pat. No. 5,534,029 to Shima discloses an articulated
vertebral body spacer with a pair of upper and lower joint pieces
inserted between the vertebrae. An intermediate layer is provided
to allow for movement between the upper joint piece and the lower
joint piece.
[0010] U.S. Pat. No. 5,782,832 to Larsen et al. discloses a
two-piece ball-and-socket spinal implant with upper and lower
plates for insertion within the intervertebral space.
[0011] U.S. Pat. No. 6,156,067 to Bryan et al. discloses a
prosthesis having two plates with a nucleus therebetween.
[0012] None of these solutions provide an implant that restores a
wide range of natural movement.
[0013] Accordingly, what is needed is an implant for alleviating
such conditions and that restores natural movement.
SUMMARY OF THE INVENTION
[0014] The present invention includes embodiments that are directed
to a set of tools used to implant an intervertebral disk
replacement, and a method of placing the implant between vertebral
bodies of the spine. A first tool is provided for use in preparing
the vertebral bodies for the implant. A second tool is provided for
installing the implant between the vertebral bodies.
[0015] Other aspects, objects, features, and elements of the other
embodiments of the invention are described or are evident from the
accompanying specification, claims and figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1A is a posterior view of an embodiment of the
assembled implant of the invention. FIG. 1B is a cross-section of
the device shown in FIG. 1A. FIG. 1C is a posterior view of two
bottom plates of the implant of the embodiment of the invention.
FIGS. 1D and 1E are posterior views of the embodiment of the
implant of the invention shown in FIG. 1A illustrating the
operation of the device in bending to the left and bending to the
right, respectively.
[0017] FIG. 2A is a side view of the implant of FIG. 1A showing the
implant in flexion. FIG. 2B is a side view of the implant showing
the implant in extension. FIG. 2C is a partial cross-sectional view
of a side view of the implant of an embodiment of the invention.
FIG. 2D is a partial cross-sectional view of an alternative
embodiment of the implant of the invention having a protuberance
adjacent the socket.
[0018] FIG. 3A is a top view of a portion of an embodiment of the
assembled implant of the invention. FIG. 3B is a top view of an
embodiment of the implant of the invention showing a rotation to
the right. FIG. 3C is a top view of an embodiment of the implant of
the invention showing a rotation to the left.
[0019] FIG. 4A is a perspective view of a ball portion of the
embodiment of the implant of the invention. FIG. 4B is a
perspective view of a socket portion of the embodiment of the
implant of the invention.
[0020] FIG. 5A is a posterior view of the embodiment of the implant
of the invention after being implanted between two vertebral
bodies. FIG. 5B is a side view of the embodiment of the implant of
the invention after being implanted between two vertebral
bodies.
[0021] FIG. 6 is a rear view of an alternate embodiment of the
invention having two plates.
[0022] FIG. 7A is a top view of an embodiment of a cutting tool of
the invention used to prepare the vertebral bodies for the implant.
FIG. 7B is a side view of the embodiment of the cutting tool of the
invention. FIG. 7C is a distal end view of an embodiment of the
cutting tool of the invention. FIG. 7D is a top view of the cutting
portion of an alternative embodiment of the cutting tool of the
invention showing blade protectors. FIG. 7E is a side view of the
cutting portion of an alternative embodiment of the cutting tool of
the invention showing the blade protectors.
[0023] FIG. 8A is a side view of an embodiment of the implant
insertion tool of the invention. FIG. 8B is a top view of the
embodiment of the implant insertion tool of the invention. FIG. 8C
is a distal end view of the embodiment of the implant insertion
tool of the invention. FIG. 8D is a top view of an embodiment of
the implant insertion tool holding an embodiment of the
implant.
[0024] FIG. 9 is a block diagram illustrating the steps of a method
for inserting the implant between vertebral bodies.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE
INVENTION
[0025] The following description is presented to enable any person
skilled in the art to make and use the invention. Various
modifications to the embodiments described will be readily apparent
to those skilled in the art, and the principles defined herein can
be applied to other embodiments and applications without departing
from the spirit and scope of the present invention as defined by
the appended claims. Thus, the present invention is not intended to
be limited to the embodiments shown, but is to be accorded the
widest scope consistent with the principles and features disclosed
herein. To the extent necessary to achieve a complete understanding
of the invention disclosed, the specification and drawings of all
patents, patent publications, and patent applications cited in this
application are incorporated herein by reference.
[0026] Turning now to FIG. 1A, a posterior view of an
intervertebral implant 100 is depicted having a four-piece
configuration. Although, as will be appreciated by those of skill
in the art, other configurations, such as a two-piece configuration
or a three-piece configuration, are possible without departing from
the scope of the invention. As depicted, the intervertebral implant
100 has a pair 130 of first plates 110. Each first plate 110 has a
first surface 112 and a second surface 114. The first surface 112
is configured to abut an end plate surface of a vertebral body. A
keel 116 can be provided on the first surface 112 to anchor the
first surface 112 into the vertebral body upon implantation. One or
more additional protrusions 118 can also be provided that act as a
detent or catch, thus providing a further mechanism to prevent the
first plate 110 from moving relative to the vertebral body once
implanted.
[0027] The intervertebral implant 100 also has a pair 132 of second
plates 120. The second plates 120 have a first surface 122 and a
second surface 124. The first surface 122 is configured to abut an
end plate surface of a vertebral body. As with the first plate 110,
a keel 126 can be provided on the first surface 122 to anchor the
first surface 122 into the vertebral body upon implantation. One or
more additional protrusions 128 can also be provided that act as a
detent or catch, again providing a further mechanism to prevent the
second plate 120 from moving relative to the vertebral body once
implanted.
[0028] FIG. 1B depicts the pair 130 of upper plates 110 and the
pair 132 of lower plates 120 in cross-section. Each upper plate 110
has a socket 136 that has a first elongated sidewall 150, a
corresponding second elongated sidewall 152 (shown in FIG. 3B), an
end wall 154, and an open end 156. The open ends 156 of each of the
first plates 110 are oriented so that the open ends 156 face each
other. The lower plates 120 each have a ball 134. As illustrated in
FIG. 1B, the ball 134 is an elongated ball. Each of the plates 110,
120 has a first end 138, 141 and a second end 139, 143,
respectively. The ends 139 of the first plate 110 face each other
and the ends 143 of the second plate 120 also face each other. The
ends 138, 141 are curved and convex, as shown in FIG. 3A, so that
the implant 100 has a configuration that correlates to the curved
shape of a vertebra.
[0029] As shown in FIG. 1C, the ball 134 has four sides: a first
elongated sidewall 140, a second elongated sidewall 142, a third
end wall 144, and a fourth end wall 146. The third end wall 144 is
flush with the end 143 of the plate 120 of the implant. The third
end wall 144 has a profile height 160 and the fourth end wall 146
has a profile height 162. Comparing the profile heights 160, 162 to
each other at the same point on the second surface 124 of the
second plate 120, the overall profile height of the third end wall
144 is greater than the fourth end wall 146 (i.e., 160>162).
Thus, it is evident that the upper surface 135 of socket 136 slopes
downwardly from the end wall 144 to the end wall 146. Together
balls 134 comprise a ball structure that has a high surface where
the third end walls 144 abut each other and slope to a lower
surface adjacent to fourth end walls 146. Also, preferably, the
upper surfaces 135 are barrel shaped and have a "U" shaped profile
along a cross-section that is perpendicular to the page of FIG. 1C
(parallel the sagittal plane on implantation). The sloping upper
surface 135, as will be explained later, allows the pair 130 of
upper plates 110 to easily slide, or rock, side-to-side on the ball
structure and slide, or ride, forward and backward with enough
looseness of fit to allow for some twisting in order to emulate the
motion of the vertebral bone and intervertebral disk tissue. This
arrangement, thus, has a sliding or translating pivot point.
Further, as indicated in FIG. 1C, the edges are eased or rounded to
allow for further range of motion of the pair 130 of plates 110
relative to the pair 132 of plates 120. As will be appreciated by
those of skill in the art, the overall height of the third end wall
144 and the fourth end wall 146 can be equivalent while still
having an effective third end wall height 160 that is greater than
the effective fourth end wall height 162 due to the overall slope
of the second surface 124. Alternatively, the overall height of the
third end wall 144 and the fourth end wall 146, can be different
with the third end wall 144 having a height greater than the fourth
end wall 146, thus eliminating the need for the second surface 124
to have a slope or further increasing the net difference between
the height of the third end wall and the fourth end wall.
[0030] Further, although the ball 134 is depicted such that the
third end wall 144 is flush with the second end 143, those of skill
in the art will appreciate that the ball 134 could also be
configured such that the third end wall 144 was recessed relative
to the end 143 of the second plate. In such a configuration, the
third end wall 144 and the end 143 would not be flush.
[0031] FIGS. 1D and 1E illustrate posterior views of the implant
100 showing the clearance for left and right lateral bending.
Typically, left and right lateral bending ranges from 3-5.degree..
As evident from these figures (and FIG. 1B), the length L1 of the
ball 134 can be less than the length L2 of the socket 136. Further,
as shown, the open ends 156 of the sockets facilitate movement of
the balls 134 within the socket 136 to accommodate side-bending
movement.
[0032] FIG. 2A is a side view of the intervertebral implant 100.
The first plate 110 with this socket 136 and the second plate 120
with the ball portion 134 are depicted. As is apparent from the
figure, the sloping of the second surface 114 of the first plate
110 facilitates rotation of the ball-and-socket joint in an
anterior "A" 280 direction and a posterior "P" 282 direction. As
depicted, the second surface 114 slopes from a high point at about
where the socket is located to low points at the ends 111 and 113
of the plate 110. As shown in FIG. 2A, the implant 100 is
positioned to achieve flexion 272 (i.e., forward bending) in a
range up to about 150, but more preferably 100.
[0033] As shown in FIG. 2A, the second plate 120 can also have
channels 264, 265 or a groove adjacent the ball 134. The channels
264, 265 can be configured such that it surrounds a portion of the
ball 134 or the entire ball 134. As will be explained below, the
channel allows the sides of the ball 134 to be made more
perpendicular so as to create a greater blocking wall thus
preventing the socket of the upper plate 100 from moving too much
anteriorly or posteriorly relative to the lower plate 120.
[0034] Either one or both of the keels on the first surface 116 and
the second surface 126 can have one or more posteriorly pointing
teeth 266 to enable it to more securely engage the vertebral body
into which it is implanted. As can be seen in FIG. 2A, the
protrusions 128, as well as the additional protrusions 118 (FIG.
1A) can also have posteriorly pointing teeth in order to lock the
implant 100 in position in the vertebrae.
[0035] FIG. 2B is an alternate side view of the intervertebral
implant 100 wherein the plates 110, 120 are shown and the
ball-and-socket joint is positioned to achieve extension 274 (i.e.,
backward bending) in a preferable range of up to about
5.degree..
[0036] FIG. 2C is a cross-section of the side view of the
intervertebral implant 100 showing the mating of the ball 134 to
the socket 136. FIG. 2D illustrates an alternate embodiment of the
first plate 110 wherein the socket 136 has ridges 268, 269 forming
a protuberance that extends into the channel 264, 265 respectively
on the second plate 120. As will be appreciated by those of skill
in the art, the protuberances 268, 269 can extend partially into
the channel, such as the configuration shown, or can have a channel
conforming shape such that when the ball-and-socket joint are moved
to achieve flexion 272 or extension 274 the protuberance or ridge
268, 269 extends into the channels 264, 265. This embodiment allows
the surfaces 114 and 115 of the first plate 110 and the second
plate 115 to be flat and non-sloping as shown while still allowing
for the implant to emulate forward and backward bending and allow
for the blocking of the motion of the socket relative to the
ball.
[0037] Turning now to FIG. 3A, a top view of one-half of the
intervertebral implant 100 is shown. Each of the top first plate
110 and the bottom second plate 120 have a bore 376 for receiving a
pin of an implant tool. The keel 116 on the first plate 110 is
positioned so that it is does not align in the same plane with the
keel 126 on the second plate 120. As will be explained in further
detail later, the non-alignment allows for the implant including
the keels to be properly positioned between the vertebrae in such a
way to accommodate the position of the nerves as the nerves extend
out from the between adjacent vertebrae. Additionally, the length
of ball 134 from the third end wall 144 to the fourth end wall 146
is shorter than the length of the socket 136 from the end wall 154
to the open end 156 as discussed before.
[0038] FIGS. 3B and 3c show the relative rotation of the upper
first plate 110 to the lower second plate 120 to achieve rotation
about a central axis 378. This rotation results in about a
3.degree.-6.degree. rotation about the axis (i.e., 3.degree. of
torso twisting in each direction).
[0039] FIG. 4A shows a perspective view of a second plate 120 of
the intervertebral implant 100. The second surface 124 of the
second plate 120 with the ball 134 and channels or grooves 264, 265
extending thereabout. As illustrated in FIG. 4A, the channels 264,
265 are formed on two sides of the ball 134. However, as will be
appreciated by those of skill in the art, the channels 264, 265 can
alternatively surround the ball 134.
[0040] FIG. 4B shows a perspective view of the first plate 110. The
first plate 110 has a second surface 114, as described above, and,
extending therefrom is the socket 136 therein. The socket 136 of
FIG. 4B is configured to mate with the ball 134 of FIG. 4A, as
described above.
[0041] FIG. 5A illustrates a posterior view of the implant shown in
FIG. 1A implanted between vertebral bodies in a spine. FIG. 5A
illustrates the spinal column 500 and the cauda equina 504 (a
collection of lumbar and sacral nerve roots that fill the caudal
end of the spinal cord) with individual nerves 506 exiting the cord
between lumbar vertebrae. The implant 100 is positioned between two
vertebral bodies 520, 521 such that the keels 116, 126 do not
interfere with the cauda equina 504 and the exiting nerve 506. As
can be seen in FIG. 5A, the keel 116 of the upper first plates 110
are close together and inboard of the keel 126 of the lower second
plate 120. This allows the lower keels 126 to be clear of the
nerves 506 as the nerves exit from between the adjacent
vertebrae.
[0042] FIG. 5B illustrates a side view of the implant 100, such as
that shown in FIG. 1A, implanted between vertebral bodies 520, 521.
The implant 100 is implanted so that the ball-and-socket joint
enables about a 5.degree. extension (backward bending) and about a
10.degree. flexion (forward bending). In this view the ball and
socket arrangement crosses the centerline 50 of the implant 100 and
extends in a posterior 282 direction. In this embodiment, the
ball-and-socket arrangement can be more centered on the centerline
50 or extend from a position when the implant 100 crosses the
centerline 50 and extends in an anterior 280 direction. Further, in
another preferred embodiment, the ball can be approximately
bisected by the centerline.
[0043] FIG. 6 illustrates a rear view of an alternate embodiment of
the implant shown in FIG. 1A. The implant 600 of FIG. 6 is in the
form of a two-piece implant 600 having a first plate 610 and a
second plate 620. The first plate 610 has a first surface 612 that
contacts the vertebral body and has one or more keels 616 and
detents 618 for anchoring the first plate 610 into the vertebral
body. The implant 600 also has a second plate 620 that has a first
surface 622 that contacts the vertebral body and has one or more
keels 626 and detents 628 for anchoring the second plate 620 into
the vertebral body. The second surface 614 of the first plate 610
has a socket 632 formed therein while the second surface 624 of the
second plate 620 has a ball 630. This implant 600 moves in much the
same way as implant 100 described above.
[0044] As will be appreciated by those of skill in the art, implant
100 is predominantly designed for a posterior implantation method.
However, implant 100 can also be implanted from an anterior
direction. Implant 600 is designed for predominantly an anterior
implantation approach.
[0045] Further, a combination of the two embodiments shown in FIG.
1A and FIG. 6 can be used to create a three-piece implant as will
also be appreciated by those of skill in the art. For example, the
first plate 610 of FIG. 6 with its socket 632 can be combined with
two-second plates 120 of FIG. 1A to form an implant. Similarly, the
second plate 620 of FIG. 6 and its ball 630 can be combined with
two first plates 110 from FIG. 1A to achieve an implant. Neither of
these configurations depart from the scope of the invention. It is
also to be understood that the implant 100, 600 can be comprised of
any suitable biocompatible material, such as titanium.
[0046] Turning now to FIGS. 7 and 8 and the tools for preparing the
vertebral bodies and implanting the implant 100 as described. FIG.
7A depicts a top view of a cutting tool 700 used to prepare the
vertebral bodies for the implant 100 and FIG. 7B depicts a side
view of tool 700. The cutting tool 700 has a handle 710 at its
proximal end for controlling the tool during operation. As will be
appreciated by those of skill in the art, the handle 710 can be
removable or affixed to the cutting end.
[0047] The distal end 702 of the tool 700 is forked to form two
prongs or tines 705, 706. The end of each tine 705, 706 has a
beveled edge 716 at its distal most end. Each tine 705, 706 also
has an inner blade 712 located on an inner upper side and an outer
blade 714 located on an outer lower side (shown in FIG. 7C).
Preferably the inner blades 712 are coplanar with the surface of
the inner side of the tine and the outer blades 714 are coplanar
with the outer side of the tine. The inner blades 712 are oriented
to cut a space in a first intervertebral body for the first surface
keel 116 of the implant and the outer blades 714 are oriented to
cut a space in the facing intervertebral body for the second
surface keel 126. The orientation of the blades is such that each
of the cuts made for the keels of the implant are offset and avoid
the nerves in the cauda equina or exiting the cauda equina.
[0048] FIG. 7C is a view of the distal end of the cutting tool 700
showing the beveled edges 716 of the tines 705, 706 and the inner
blades 712 and outer blades 714. The distance 722 between the inner
blades 712 is less than the distance 724 between the outer blades
and the height h of the tines approximates the distance between two
vertebral bodies or the height of the disk space. The blades 712,
714 extend above and below the tines or the height of the tines. As
can be seen in FIG. 7C, the beveled sides of the distal end 716
extend and form at least one of the beveled sides of the blades
712, 714.
[0049] FIG. 7D depicts an enlarged top view of the tines 705, 706
of the distal end of cutting tool 700 with the beveled distal edges
716. FIG. 7E is an enlarged side view of the distal end of cutting
tool 700. FIGS. 7D and 7E show the retractable blade protector 720
for the blade 712 positioned in a retracted position. As the
cutting tool is inserted between vertebral bodies, the retractable
blade protector 720 moves in a posterior direction 715 (i.e.,
toward the handle 710) to expose the inner blade 712 and the outer
blade 714 and to enable the blades to cut into the vertebral
bodies. These protectors 720 can be spring biased as desired in
order to cover the blade 712, 714 as the tool 700 is inserted past
the nerves. The protectors 720 are urged in a posterior direction
as the blades 712, 714 are urged into the vertebral bodies in order
to cut channels for the keels. Springs 721 provide the desired bias
to keep the protectors 720 in a forward position covering the
blades 712, 718.
[0050] As will be appreciated by those of skill in the art, the
tool shown in FIG. 7 can be modified such that instead of cutting
keel-receiving channels in the upper and lower vertebral bodies at
the same time, two tools are provided so that only one vertebral
body is cut for keel-receiving channels at a time. For example, a
first tool having two tines as described above could be provided
having a pair of inner blades located on an upper surface of the
tines. A second tool could be provided having tines as described
with a pair of outer blades located on the lower surface of the
tines. Optionally, the second tool can have a guide corresponding
to the location of the first blade on the first tool to ensure that
the second cut is optimally aligned with the first cut. In use, a
pair of channels can be cut into the upper vertebral body using the
first tool. Thereafter a second pair of channels can be cut into
the lower vertebral body. Alternate arrangements are also possible,
for example, where the first tool has a pair of outer blades and
the second tool has a pair of inner blades, or where the first tool
has upper and lower blades on a first tine (e.g., right tine) and
the second tool has upper and lower blades on a second tine (e.g.,
left tine).
[0051] FIG. 8A depicts the implanting tool used to insert the
implant 100 of FIG. 1A between vertebral bodies. FIG. 8A is a side
view of the implantation tool 800 that has a handle 810 and an
implant holder 820. The implant holder 820 has an implant
conforming surface 824 and two pins 822 for holding a first plate
110 and a second plate 120 of a first half of the implant 100. The
conforming surface 824 is curved to follow the convex outer edges
138, 139 of the plate 100, 120, respectively (shown in FIG. 3A).
The implant 100 nests within a conforming surface 824 and is held
by pins 822. FIG. 8c shows the distal view of the end of the tool
with two pins 822, 823 for securing the first and second plate of
the implant. The tool can be rotated by the user 180.degree. to
implant the other half of the implant.
[0052] Where an implant such as that shown in FIG. 6 is implanted,
the implant conforming surface 824 of the implant tool would have a
mirror image conforming surface provided to capture the implant
600. An additional series of pins, for a total of four, can be
provided for holding a first plate 610 and a second plate 620 of
the implant 600, if required. The implant 600 would nest within the
conforming surface of the "U" shaped cavity.
[0053] A variety of kits can be assembled that include an implant
100 (or 600) sized for a particular patient. The kit could also
include several cutting tools 700 and several implanting tools 800
or a single handle that cooperates with cutting ends 702 and
implantation ends 820.
[0054] FIG. 9 is a block diagram showing the steps for implanting
an implant. In order to implant the implant of FIG. 1A, the spine
is exposed posteriorly 910. The intervertebral disk to be replaced
is either partially or completely removed 920. The cutting tool 700
is inserted between the vertebral bodies to create channels in the
bodies to receive the keels of the implant. Nerves can be retracted
and then the implant holder 810 is used to insert the implant
between the vertebral bodies 930, lining the keels up with the
channels created by the cutting tool 700. Next, the nerves are
retracted in the other direction and the other plates 100, 120 are
attached to a tool and are implanted. The implant first and second
plates 110, 120 are now inserted between the vertebrae, and the
keel are placed in the channels prepared by the cutting tool 700.
Once the implant is inserted, the wound is closed 940.
[0055] In order to implant the implant of FIG. 6, the spine is
exposed anteriorly 910. The intervertebral disk to be replaced is
either partially or completely removed 920. The cutting tool 700 is
inserted between the vertebral bodies to create channels in the
bodies to receive the keels of the implant. The implant is then
inserted into an implant holder and the implant tool is used to
insert the implant between the vertebral bodies 930, lining the
keels up with the channels created by the cutting tool 700. Once
the implant is inserted, the wound is closed 940.
[0056] The foregoing description of embodiments of the present
invention has been provided for the purposes of illustration and
description. It is not intended to be exhaustive or to limit the
invention to the precise forms disclosed. Many modifications and
variations will be apparent to the practitioner skilled in the art.
The embodiments were chosen and described in order to best explain
the principles of the invention and its practical application,
thereby enabling others skilled in the art to understand the
invention and the various embodiments and with various
modifications that are suited to the particular use contemplated.
It is intended that the scope of the invention be defined by the
following claims and their equivalence.
* * * * *