U.S. patent application number 11/534946 was filed with the patent office on 2007-04-26 for modular articulating and fusion spinal disc implant system.
Invention is credited to T. Wade Fallin, Raymond Joseph Gardocki, Daniel F. Justin, Nathan Pierce, Lytton A. Williams.
Application Number | 20070093900 11/534946 |
Document ID | / |
Family ID | 37900424 |
Filed Date | 2007-04-26 |
United States Patent
Application |
20070093900 |
Kind Code |
A1 |
Williams; Lytton A. ; et
al. |
April 26, 2007 |
MODULAR ARTICULATING AND FUSION SPINAL DISC IMPLANT SYSTEM
Abstract
The present invention provides an intervertebral implant for
replacing intervertebral disc material and controlling relative
motion between adjacent vertebral bodies. The intervertebral
implant may have at least one end plate and an intermediate
component which slides into engagement with the end plate. The
intermediate component may be engageable with the end plate from an
anterior approach, or a right or left lateral approach. The
intermediate component can be a set of bearing surfaces which
articulate to provide relative motion between two vertebral bodies,
an elastic insert which deforms to provide motion between two
vertebral bodies, or a rigid insert which prevents relative motion
between two vertebral bodies. The intermediate component is
replaceable with a different intermediate component which provides
a different function. The present invention also provides one or
more retaining members which snap into engagement with the end
plate and secure the intermediate component to the end plate.
Inventors: |
Williams; Lytton A.; (Los
Angeles, CA) ; Justin; Daniel F.; (Logan, UT)
; Fallin; T. Wade; (Hyde Park, UT) ; Gardocki;
Raymond Joseph; (Germantown, TN) ; Pierce;
Nathan; (Millville, UT) |
Correspondence
Address: |
MEDICINELODGE INC.
180 SOUTH 600 WEST
LOGAN
UT
84321
US
|
Family ID: |
37900424 |
Appl. No.: |
11/534946 |
Filed: |
September 25, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60720513 |
Sep 26, 2005 |
|
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60720514 |
Sep 26, 2005 |
|
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60741513 |
Nov 30, 2005 |
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Current U.S.
Class: |
623/17.11 |
Current CPC
Class: |
A61B 17/025 20130101;
A61F 2002/30538 20130101; A61F 2/4611 20130101; A61F 2002/30772
20130101; A61F 2002/30517 20130101; A61F 2002/4622 20130101; A61F
2002/4628 20130101; A61F 2/4455 20130101; A61F 2/442 20130101; A61F
2/4425 20130101; A61F 2002/30607 20130101; A61F 2220/0025 20130101;
A61F 2002/30604 20130101; A61F 2250/0006 20130101; A61F 2002/30484
20130101; A61F 2002/30387 20130101; A61F 2220/0033 20130101; A61F
2250/0097 20130101; A61B 2017/0256 20130101; A61F 2002/2835
20130101; A61F 2002/4627 20130101; A61F 2002/2817 20130101; A61F
2002/30841 20130101; A61F 2002/30617 20130101; A61F 2002/305
20130101; A61F 2250/0062 20130101; A61F 2002/30901 20130101; A61F
2002/30614 20130101; A61F 2002/30331 20130101; A61F 2002/30495
20130101 |
Class at
Publication: |
623/017.11 |
International
Class: |
A61F 2/44 20060101
A61F002/44 |
Claims
1. An intervertebral implant comprising: a first end plate
configured to be secured to a first vertebral body; and a first
intermediate component that is slidable into engagement with the
first end plate along either of at least two selections from the
group consisting of a first lateral direction, a second lateral
direction different from the first lateral direction, and a
posterior direction.
2. The intervertebral implant of claim 1, wherein the first
intermediate component is selected from the group consisting of a
first bearing surface configured to articulate with a second
bearing surface to provide relative motion between the first
vertebral body and a second vertebral body, an elastic insert
configured to deform to provide motion between the first vertebral
body and a second vertebral body, and a rigid insert configured to
substantially prevent relative motion between the first vertebral
body and a second vertebral body.
3. The intervertebral implant of claim 1, wherein the first
intermediate component is detachable from the first end plate to
permit replacement of the first intermediate component with a
second intermediate component.
4. The intervertebral implant of claim 3, wherein the second
intermediate component causes the intervertebral implant to perform
a function which is different from a function performed with the
first intermediate component.
5. The intervertebral implant of claim 1, further comprising a
first retention member configured to be secured to the first end
plate independently of the first intermediate component to secure
the first intermediate component to the first end plate.
6. The intervertebral implant of claim 5, wherein the first
retention member is configured to be inserted into engagement with
the first intermediate component.
7. The intervertebral implant of claim 5, wherein the first
retention member snaps into securement with the first end
plate.
8. The intervertebral implant of claim 5, further comprising a
second retention member configured to be secured to the first end
plate independently of the first intermediate component and the
first retention member to further secure the first intermediate
component to the first end plate.
9. The intervertebral implant of claim 8, wherein the first
retention member is securable to the first end plate prior to
insertion of the first intermediate component along a first
direction of the two selections, and the second retention member is
securable to the first end plate after the insertion of the first
intermediate component, and wherein the second retention member is
securable to the first end plate prior to the insertion of the
first intermediate component along a second direction of the two
selections, and the first retention member is securable to the
first end plate after the insertion of the intermediate
component.
10. The intervertebral implant of claim 1, further comprising a
second end plate configured to be secured to a second vertebral
body, wherein the first intermediate component is slidable into
engagement with the second end plate along either of at least two
selections from the group consisting of the first lateral
direction, the second lateral direction, and the posterior
direction.
11. An intervertebral implant comprising: a first end plate
configured to be secured to a first vertebral body; a first
intermediate component configured to engage the first end plate to
control or prevent motion of the first vertebral body relative to a
second vertebral body; and a first retention member configured to
be engageable to the first end plate, wherein the first retention
member is slidable into engagement with the first end plate to
secure the first intermediate component to the first end plate.
12. The intervertebral implant of claim 11, wherein the first
intermediate component is selected from the group consisting of a
first bearing surface configured to articulate with a second
bearing surface to provide relative motion between the first
vertebral body and a second vertebral body, an elastic insert
configured to deform to provide motion between the first vertebral
body and a second vertebral body, and a rigid insert configured to
substantially prevent relative motion between the first vertebral
body and a second vertebral body.
13. The intervertebral implant of claim 11, wherein the first
intermediate component is detachable from the first end plate to
permit replacement of the first intermediate component with a
second intermediate component.
14. The intervertebral implant of claim 13, wherein the second
intermediate component causes the intervertebral implant to perform
a function which is different from a function performed with the
first intermediate component.
15. The intervertebral implant of claim 11, further comprising a
second retention member configured to be secured to the first end
plate independently of the first intermediate component and the
first retention member to further secure the first intermediate
component to the first end plate.
16. The intervertebral implant of claim 15, wherein the first and
second retention members are independently slidable into engagement
with the first end plate along either of at least two selections
from the group consisting of a first lateral direction, a second
lateral direction different from the first lateral direction, and a
posterior direction.
17. The intervertebral implant of claim 16, wherein the first
retention member is securable to the first end plate prior to
insertion of the first intermediate component along a first
direction of the two selections, and the second retention member is
securable to the first end plate after the insertion of the first
intermediate component, and wherein the second retention member is
securable to the first end plate prior to the insertion of the
first intermediate component along a second direction of the two
selections, and the first retention member is securable to the
first end plate after the insertion of the intermediate
component.
18. The intervertebral implant of claim 11, wherein the first
retention member is configured to be inserted into engagement with
the first intermediate component.
19. The intervertebral implant of claim 11, wherein the first
retention member snaps into securement with the first end
plate.
20. The intervertebral implant of claim 11, further comprising a
second end plate configured to be secured to a second vertebral
body, wherein the first intermediate component is slidable into
engagement with the second end plate along either of at least two
selections from the group consisting of a first lateral direction,
a second lateral direction different from the first lateral
direction, and a posterior direction.
21. An intervertebral implant comprising: a first end plate
configured to be secured to a first vertebral body; a first
intermediate component configured to engage the first end plate to
control or prevent motion of the first vertebral body relative to a
second vertebral body; and at least two retention members that are
activatable independently of each other to secure the first
intermediate component to the first end plate.
22. The intervertebral implant of claim 21, wherein the first
intermediate component is selected from the group consisting of a
first bearing surface configured to articulate with a second
bearing surface to provide relative motion between the first
vertebral body and a second vertebral body, an elastic insert
configured to deform to provide motion between the first vertebral
body and a second vertebral body, and a rigid insert configured to
substantially prevent relative motion between the first vertebral
body and a second vertebral body.
23. The intervertebral implant of claim 21, wherein the first
intermediate component is detachable from the first end plate to
permit replacement of the first intermediate component with a
second intermediate component.
24. The intervertebral implant of claim 23, wherein the second
intermediate component causes the intervertebral implant to perform
a function which is different from a function performed with the
first intermediate component.
25. The intervertebral implant of claim 21, wherein the first
intermediate component is slidable into engagement with the first
end plate.
26. The intervertebral implant of claim 21, wherein each of the
retention members is slidable into engagement with the first end
plate along either of at least two selections from the group
consisting of a first lateral direction, a second lateral direction
different from the first lateral direction, and a posterior
direction.
27. The intervertebral implant of claim 21, further comprising a
third retention member that is independently activatable to secure
the first intermediate component to the first end plate.
28. The intervertebral implant of claim 21, wherein each retention
member has an engaged position and a free position relative to the
first end plate, and wherein each retention member snaps into
engagement in response to motion from the free position to the
engaged position.
29. A method for implanting an intervertebral implant, the method
comprising: securing a first end plate to a first vertebral body;
and sliding a first intermediate component into engagement with the
first end plate along either of at least two selections from the
group consisting of a first lateral direction, a second lateral
direction different from the first lateral direction, and a
posterior direction.
30. The method of claim 29, further comprising selecting the first
intermediate component from the group consisting of a first bearing
surface configured to articulate with a second bearing surface to
provide relative motion between the first vertebral body and a
second vertebral body, an elastic insert configured to deform to
provide motion between the first vertebral body and a second
vertebral body, and a rigid insert configured to substantially
prevent relative motion between the first vertebral body and a
second vertebral body.
31. The method of claim 30, wherein the first intermediate
component is replaceable, wherein replacing the first intermediate
component comprises detaching the first intermediate component from
the first end plate and engaging a second intermediate component
with the first end plate.
32. The method of claim 31, wherein engaging the second
intermediate component causes the intervertebral implant to perform
a function which is different than the function performed with the
first intermediate component.
33. The method of claim 29, further comprising securing at least
one retention member to the first end plate independently of the
first intermediate component, wherein securing the retention member
secures the first intermediate component to the first end
plate.
34. The method of claim 33, further comprising inserting the first
retention member with the first intermediate component.
35. The method of claim 33, further comprising snapping the first
retention member to the first end plate to secure the first
retention member to the first end plate.
36. The method of claim 33, further comprising securing a second
retention member to the first end plate independently of the first
intermediate component, wherein securing the second retention
member further secures the first intermediate component to the
first end plate.
37. The method of claim 36, further comprising selecting from a
group including securing the first retention member to the first
end plate prior to inserting the first intermediate component along
a first direction of the two selections, then securing the second
retention member to the first end plate after inserting the first
intermediate component, and securing the second retention member to
the first end plate prior to inserting the first intermediate
component along a second direction of the two selections, then
securing the first retention member to the first end plate after
the insertion of the first intermediate component.
38. The method of claim 29, further comprising securing a second
end plate to a second vertebral body, and sliding the first
intermediate component into engagement with the second end plate
along either of at least two selections from the group consisting
of the first lateral direction, the second lateral direction, and
the posterior direction.
39. A method for implanting an intervertebral implant, the method
comprising: securing a first end plate to a first vertebral body;
engaging a first intermediate component with the first end plate to
control or prevent motion of the first vertebral body relative to a
second vertebral body; and sliding a first retention member into
engagement with the first end plate to secure the first
intermediate component to the first end plate.
40. The method of claim 39, further comprising selecting the first
intermediate component from the group consisting of a first bearing
surface configured to articulate with a second bearing surface to
provide relative motion between the first vertebral body and the
second vertebral body, an elastic insert configured to deform to
provide motion between the first vertebral body and the second
vertebral body, and a rigid insert configured to substantially
prevent relative motion between the first vertebral body and the
second vertebral body.
41. The method of claim 39, wherein the first intermediate
component is replaceable, wherein replacing the first intermediate
component comprises detaching the first intermediate component from
the first end plate and engaging a second intermediate component
with the first end plate.
42. The method of claim 41, wherein engaging the second
intermediate component causes the intervertebral implant to perform
a function which is different than the function performed with the
first intermediate component.
43. The method of claim 39, further comprising securing a second
retention member to the first end plate independently of the first
intermediate component and the first retention member, to further
secure the first intermediate component to the first end plate.
44. The method of claim 43, further comprising sliding the first
and second retention members independently into engagement with the
first end plate along either of at least two selections from the
group consisting of a first lateral direction, a second lateral
direction different from the first lateral direction, and a
posterior direction.
45. The method of claim 44, further comprising selecting from a
group including securing the first retention member to the first
end plate prior to inserting the first intermediate component along
a first direction of the two selections, then securing the second
retention member to the first end plate after inserting the first
intermediate component, and securing the second retention member to
the first end plate prior to inserting the first intermediate
component along a second direction of the two selections, then
securing the first retention member to the first end plate after
the insertion of the first intermediate component.
46. The method of claim 39, further comprising inserting the first
retention member with the first intermediate component.
47. The method of claim 39, further comprising snapping the first
retention member to the first end plate to secure the first
retention member to the first end plate.
48. The method of claim 39, further comprising securing a second
end plate to the second vertebral body, and sliding the first
intermediate component into engagement with the second end plate
along either of at least two selections from the group consisting
of a first lateral direction, a second lateral direction different
from the first lateral direction, and a posterior direction.
49. A method for implanting a device within an intervertebral
space, the method comprising: securing a first end plate to a first
vertebral body; engaging a first intermediate component with the
first end plate to control or prevent motion of the first vertebral
body relative to a second vertebral body; and activating at least
two retention members independently of each other to secure the
first intermediate component to the first end plate.
50. The method of claim 49, further comprising selecting the first
intermediate component from the group consisting of a first bearing
surface configured to articulate with a second bearing surface to
provide relative motion between the first vertebral body and the
second vertebral body, an elastic insert configured to deform to
provide motion between the first vertebral body and the second
vertebral body, and a rigid insert configured to substantially
prevent relative motion between the first vertebral body and the
second vertebral body.
51. The method of claim 49, wherein the first intermediate
component is replaceable, wherein replacing the first intermediate
component comprises detaching the first intermediate component from
the first end plate and engaging a second intermediate component
with the first end plate.
52. The method of claim 51, wherein engaging the second
intermediate component causes the intervertebral implant to perform
a function which is different than the function performed with the
first intermediate component.
53. The method of claim 49, further comprising sliding the first
intermediate component into engagement with the first end
plate.
54. The method of claim 49, further comprising sliding each of the
retention members into engagement with the first end plate along
either of at least two selections from the group consisting of a
first lateral direction, a second lateral direction different from
the first lateral direction, and a posterior direction.
55. The method of claim 49, further comprising independently
activating a third retention member to further secure the first
intermediate component to the first end plate.
56. The method of claim 49, further comprising snapping each
retention member in response to motion from a free position to an
engaged position relative to the first end plate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of the following:
[0002] U.S. Provisional Application No. 60,720,513, filed Sep. 26,
2005, which carries Applicants' Docket No. MLI-45 PROV and is
entitled MODULAR ARTICULATING AND FUSION SPINAL DISC IMPLANT
SYSTEM;
[0003] U.S. Provisional Application No. 60/720,514, filed Sep. 26,
2005, which carries Applicants' Docket No. MLI-46 PROV and is
entitled UNIVERSAL SPINAL DISC IMPLANT SYSTEM FOR PROVIDING
INTERVERTEBRAL ARTICULATION AND FUSION; and
[0004] U.S. Provisional Application No. 60/741,513, filed Nov. 30,
2005, which carries Applicants' Docket No. MLI-50 PROV and is
entitled SYSTEM AND METHOD FOR INTERVERTEBRAL IMPLANT DELIVERY AND
REMOVAL.
[0005] All of the foregoing are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0006] 1. The Field of the Invention
[0007] The present invention relates generally to spinal
orthopedics, and more precisely, to intervertebral implants.
[0008] 2. The Relevant Technology
[0009] Severe back pain can be caused by a number of different
ailments, including spinal stenosis, degenerative disc disease,
spondylolisthesis, and the like. Many such ailments can be
corrected by controlling or limiting relative motion between the
affected vertebrae. Accordingly, a variety of devices including
artificial discs and fusion devices have been proposed.
[0010] Such devices are limited in that they typically provide only
one mode of correction. Many such devices cannot be replaced or
corrected. This is particularly true with intervertebral implants,
in which bone-growth is often stimulated to integrate the implants
with the surrounding bone tissue. Thus, if the device fails to
solve the problem, there may be no other recourse for the
patient.
[0011] Further, many known devices are expensive or difficult to
manufacture, or are difficult to implant. Some known intervertebral
devices require the adjacent vertebrae to be distracted
excessively, thereby endangering the surrounding ligaments and
other connective tissues. Accordingly, there is a need in the art
for a device that remedies these problems. Such a device would
considerably enhance outcomes for patients with spinal
disorders.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Various embodiments of the present invention will now be
discussed with reference to the appended drawings. It is
appreciated that these drawings depict only typical embodiments of
the invention and are therefore not to be considered limiting of
its scope.
[0013] FIG. 1 is a perspective view illustrating a portion of a
spine.
[0014] FIG. 2 is a perspective lateral view of one embodiment of a
total disc implant implanted in the spine, comprising inferior and
superior end plates, inferior and superior bearings, and a
plurality of clips.
[0015] FIG. 3 is a perspective anterior view of the total disc
implant of FIG. 2 in an disassembled state.
[0016] FIG. 4 is a bottom elevation view of the clip shown in FIG.
3.
[0017] FIG. 5 is a top elevation view of the clip shown in FIG.
3.
[0018] FIG. 6 is a perspective side view of the clip shown in FIG.
3.
[0019] FIG. 7 is a perspective posterior view of the bone engaging
side of the inferior end plate shown in FIG. 3.
[0020] FIG. 8 is a lateral end view of the inferior end plate shown
in FIG. 3.
[0021] FIG. 9 is a perspective anterior view of the bearing
engaging side of the inferior end plate shown in FIG. 3, and one
clip.
[0022] FIG. 10 is a perspective posterior view of the bearing
engaging side of the superior end plate shown in FIG. 3, and one
clip.
[0023] FIG. 11 is a perspective posterior view of the caudal side
of the inferior bearing and one clip shown in FIG. 3.
[0024] FIG. 12 is an anterior side view of the inferior bearing
shown in FIG. 3.
[0025] FIG. 13 is a perspective anterior view of the cephalad side
of the inferior bearing shown in FIG. 3.
[0026] FIG. 14 is a perspective anterior view of the cephalad side
of the superior bearing and one clip shown in FIG. 3.
[0027] FIG. 15 is an anterior side view of the superior bearing
shown in FIG. 3.
[0028] FIG. 16 is a perspective posterior view of the caudal side
of the superior bearing shown in FIG. 3.
[0029] FIG. 17 is an anterior side view of the total disc implant
of FIG. 3, in a partially assembled state.
[0030] FIG. 18 is a perspective lateral view of one embodiment of a
fusion block implant, shown in a portion of the spine.
[0031] FIG. 19 is a perspective anterior view of the cephalad side
of the fusion block shown in FIG. 16.
[0032] FIG. 20 is an anterior side view of the fusion block shown
in FIG. 16.
[0033] FIG. 21 is a perspective anterior-cephalad view of the
fusion block shown in FIG. 16, and two clips.
[0034] FIG. 22 is a perspective lateral side view of the fusion
block implant of FIG. 18, in a partially assembled state.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0035] The present invention relates to human spinal disc
replacement systems. Those of skill in the art will recognize that
the systems and methods described herein may be readily adapted for
other modular implant systems for anatomic replication of
orthopedic joints by man made implant systems.
[0036] Referring to FIG. 1, a perspective view illustrates a
portion of a spine 10. FIG. 1 illustrates only the bony structures;
accordingly, ligaments, cartilage, and other soft tissues are
omitted for clarity. The spine 10 has a cephalad direction 12, a
caudal direction 14, an anterior direction 16, a posterior
direction 18, and a medial/lateral axis 20, all of which are
oriented as shown by the arrows bearing the same reference
numerals. In this application, "left" and "right" are used with
reference to a posterior view, i.e., a view from behind the spine
10. "Medial" refers to a position or orientation toward a sagittal
plane (i.e., plane of symmetry that separates left and right sides
from each other) of the spine 10, and "lateral" refers to a
position or orientation relatively further from the sagittal
plane.
[0037] As shown, the portion of the spine 10 illustrated in FIG. 1
includes a first vertebra 24, which may be the L5 (Fifth Lumbar)
vertebra of a patient, and a second vertebra 26, which may be the
L4 (Fourth Lumbar) vertebra of the patient. The systems and methods
may be applicable to any vertebra or vertebrae of the spine 10
and/or the sacrum (not shown). In this application, the term
"vertebra" may be broadly interpreted to include the sacrum.
[0038] As shown, the first vertebra 24 has a body 28 with a
generally disc-like shape and two pedicles 30 that extend
posteriorly from the body 28. A posterior arch, or lamina 32,
extends between the posterior ends of the pedicles 30 to couple the
pedicles 30 together. The first vertebra 24 also has a pair of
transverse processes 34 that extend laterally from the pedicles 30
generally along the medial/lateral axis 20, and a spinous process
36 that extends from the lamina 32 along the posterior direction
18.
[0039] Similarly, the second vertebra 26 has a body 48 from which
two pedicles 50 extend posteriorly. A posterior arch, or lamina 52,
extends between the posterior ends of the pedicles 50 to couple the
pedicles 50 together. The second vertebra 26 also has a pair of
transverse processes 54, each of which extends from the
corresponding pedicle 50 generally along the medial/lateral axis
20, and a spinous process 56 that extends from the lamina 52 along
the posterior direction 18. The vertebrae 24, 26 are separated from
each other by an intervertebral disc 66.
[0040] Referring to FIG. 2, a perspective view illustrates one
embodiment of an implant 70, which may be referred to as a total
disk implant. The implant 70 is designed for placement between
spinal vertebrae to replace degenerated intervertebral disc
material. More specifically, the implant 70 is designed to be
inserted between the vertebral bodies 28, 48 of the first and
second vertebrae 24, 26, respectively, after removal of the
intervertebral disc 66. The implant 70 has end plates which secure
the implant to the vertebral bodies, and an intermediate component
which engages with the end plates, to control or prevent relative
motion between the vertebral bodies. The intermediate component may
be a first bearing surface configured to articulate with a second
bearing surface, to provide relative motion between the vertebral
bodies. The intermediate component may also be a deformable elastic
insert which provides motion between the vertebral bodies, or a
rigid insert to promote fusion, thus preventing relative motion
between the vertebral bodies. Retention members, which in this
embodiment of the invention take the form of clips, secure the
intermediate component to the end plates.
[0041] In the embodiment depicted in FIG. 2, the assembled implant
70 is of a generally rectangular box-like shape with rounded edges,
with top and bottom surfaces which form a slight wedge. In
alternative embodiments, it is appreciated that implant 70 need not
have a rectangular box shaped configuration but can be square,
circular, or have any other polygonal or irregular configuration.
Furthermore, it is appreciated that the implant 70 can be
configured at any desired wedge angle or can have substantially
parallel top and bottom surfaces. The implant 70 comprises an
inferior end plate 100, an inferior bearing 300, a superior bearing
400, and a superior end plate 200. When fully assembled, the
inferior bearing 300 is releasably attached to the inferior end
plate 100 by a plurality of clips 500. The superior bearing 400 is
releasably attached to the superior end plate 200 by a plurality of
clips 500.
[0042] FIG. 3 depicts the implant 70 in a disassembled state, to
illustrate the individual components of the implant. The inferior
bearing 300 has a rounded dome, surrounded by a trough, which fits
into a cup, surrounded by a ridge, on the superior bearing 400. The
inclusion of the ridge and trough in the bearing design allows the
patient less impeded flexion/extension and lateral bending.
[0043] During the implantation procedure, initially the inferior
100 and superior 200 end plates are placed in the intervertebral
space, adjacent to the vertebral bodies 28, 48. In the embodiment
depicted the end plates 100, 200 are identical, but are inserted in
an opposite orientation from one another. Thus, as depicted in
FIGS. 2 and 3, the inferior end plate 100 is inserted adjacent to
vertebral body 28 with a bone engaging side 102 in a caudal
direction 14 and a bearing engaging side 104 in a cephalad
direction 12. Conversely, the superior end plate 200 is inserted
adjacent to vertebral body 48 with a bone engaging side 202 in a
cephalad direction 12 and a bearing engaging side 204 in a caudal
direction 14. Because the features of the end plates 100, 200 in
this embodiment are identical except in orientation, only the
inferior end plate 100 will be described in detail below. All
description of the structure of the inferior end plate 100 also
applies to the superior end plate 200. However, it is appreciated
that in alternative embodiments of the invention, end plates of
varying configurations may be used in combination.
[0044] FIG. 4 depicts a bottom side view of the clip 500. In this
embodiment of the invention the clip 500 is roughly quadrilateral
in shape, with substantially parallel top and bottom sides, and is
bilaterally symmetrical. However, it is appreciated that in
alternative embodiments, the clip 500 may vary in configuration
and/or use. It has a top side 510, a bottom side 512, an interior
edge 514 and an exterior edge 516. The interior edge 514 is
chamfered on the bottom side 512. The exterior edge 516 has a tab
502 which extends perpendicularly from the edge. The tab 502 is
configured to fit a gap in each end plate 100 or 200, and moving
the tab into the gap snaps the clip 500 to the end plate 100 or
200. A body 506 extends from the tab 502 and the exterior edge 516
toward the interior edge 514. One arm 504 extends perpendicularly
from each lateral side of the body 506, on either side of the tab
502. A T-shape is formed by the arms 504 and the body 506. At the
interior end of the body 506, two prongs 508 extend initially
perpendicularly from the body 506, then, turning right angles,
extend back toward the arms 504.
[0045] Referring to FIG. 5, a top side view of the clip 500 is
shown. The outside edges of the prongs 508 are chamfered on the top
side 510, forming chamfered edges 518. The chamfered edges 518 of
the prongs 508 are slightly angled in their lengthwise orientation;
that is, the width of the clip 500 at the interior edge 514 is
slightly narrower than its width at the arms 508 and exterior edge
516. A protrusion 520 projects from the body 506 on the top side
510. The protrusion 520 appears as a square projecting upward from
the top side 510, and is centered between the arms 508. The
protrusion 520 is wedge-shaped in profile, the higher end adjacent
to the tab 502, and the opposite end slanting down until it is
flush with the body 506 at the midpoint of the body 506.
[0046] FIG. 6 depicts a side profile view of the clip 500. The clip
500 has a spring bias 522, such that when the clip 500 is not
secured to another component, the body 506, the arms 504 and the
tab 502 are held at a slight downward angle relative to the prongs
508; that is, the body 506, the arms 504 and the tab 502 angle in
the direction of the bottom side 512.
[0047] Referring to FIG. 7, a bone-engaging side view of the
inferior end plate 100 is shown. In this embodiment the inferior
end plate 100 is of a quadrilateral shape with rounded corners, and
is bilaterally symmetrical. It has an anterior end 120, a posterior
end 122, a right end 124 and a left end 126. The inferior end plate
100 has a bone engaging face 106 and a bearing engaging face 108
which are connected by a support member 1 10. Projecting from the
bone engaging face 106 is a plurality of bone engaging spikes 112.
Each bone engaging spike 112 is columnar in form and projects
perpendicularly in the caudal direction 14 from the bone engaging
face 106. The protruding end of each bone engaging spike 112 tapers
and terminates in an acute angle. This angled tapering creates a
point which facilitates seating the inferior end plate 100 in the
adjacent vertebral body 28 during the implantation process; the
point will more easily penetrate the vertebral body 28 than would a
blunt end.
[0048] A hollow grafting channel 114 runs through the center of
each bone engaging spike 112. Each grafting channel 114 originates
on the bearing engaging face 108, runs through the support member
110, and ends at the pointed termination of the bone engaging spike
1 12. This hollowed point configuration may be compared to the
hollow point of a hypodermic needle, and further facilitates the
penetration of the vertebral body 28 by the bone engaging spikes
112. The grafting channels 114 also allow for the growth of bony
columns from the vertebral body 28 through the channels, thereby
fusing the inferior end plate 100 to the vertebral body 28.
[0049] A plurality of grafting ports 116 is present in the inferior
end plate 100. Each grafting port is an opening from the bearing
engaging face 108 through the support member 110 to the bone
engaging face 106. The grafting ports 116 allow for the growth of
bony material from the vertebral body 28 through the ports, thereby
fusing the inferior end plate 100 to the vertebral body 28.
[0050] A groove 118 is present on each outer corner of the inferior
end plate 100. Each groove 118 is an indentation into the support
member 1 10. Each groove 118 is designed to fit closely around the
end of an insertion tool such that the insertion tool (not shown)
may securely grip the inferior end plate 100 during insertion or
removal of the end plate.
[0051] Referring to FIG. 8, a lateral end view of the inferior end
plate 100 is shown. It is slightly wedge shaped when viewed from
either lateral end. That is, the height of the inferior end plate
100 at the posterior end 122 is shorter than its height at the
anterior end 120. This is because this embodiment of the invention
is designed for the lumbar portion of the spine, which is curved
such that the intervertebral space is wider at the anterior end
than at the posterior end. However, it is appreciated that the
inferior end plate 100 can be configured at any desired wedge angle
or can have substantially parallel top and bottom surfaces.
[0052] FIG. 9 illustrates the bearing engaging side 104 of the
inferior end plate 100, with one clip 500 snapped on the left side.
The end plate 100 has symmetrically placed lateral gaps 128 in the
right end 124 and the left end 126. The anterior end 120 has an
anterior gap 130 which is identically shaped as the lateral gaps
128 but is located perpendicular to them. The lateral 128 and
anterior 130 gaps are shaped to accommodate the insertion of clips
500, which releasably hold the inferior bearing 300 to the inferior
end plate 100. The caudal or lower portions of the gaps 128, 130,
which are cut out of the bone engaging side 102 of the inferior end
plate 100, are shaped to fit the tab 502 of the clip 500. The
cephalad or upper portions of the gaps 128, 130 are wider to
accommodate passage of arms 504 of the clip 500. The walls 132 of
the gaps 128, 130 are formed from the support member 110, and are
perpendicular to the bearing engaging side 104 of the inferior end
plate 100.
[0053] Moving toward the center of the inferior end plate 100, each
lateral 128 and anterior 130 gap is adjacent to a pocket 134, which
is recessed into the bearing engaging face 108. The sides of the
pocket 134 are part of the support member 1 10. The pocket 134 is
T-shaped to fit the arms 504 and the body 506 of the clip 500 when
it is snapped to the inferior end plate 100. The floor of the
pocket 134 is sloped such that the pocket arms 136 are deeper than
the pocket body 138. The floor of the pocket body 138 slopes upward
until it is flush with a slot 140.
[0054] Continuing toward the center of the inferior end plate 100,
the slot 140 extends from the pocket 134 to the central grafting
port 116. The slot 140 is also recessed into the bearing engaging
face 108 but to a lesser extent than the pocket 134. Each slot 140
has two side walls which are chamfered, forming two opposing
chamfered edges 142 into which prongs 508 of the clip 500 fit
closely. The opposing chamfered edges 142 of each slot 140 are
slightly angled toward one another as the edges approach the center
of the inferior end plate 100. A chamfered wall 144 is formed by
the continuation of the posterior chamfered edges 142 of the two
lateral slots 140; the two posterior chamfered edges 142 continue
past their respective slots 140 and meet, forming the chamfered
wall 144. The gaps 128, 130, the pocket 134 and the slot 140 are
shaped to hold the clip 500 in place once it has been inserted.
Once the clip 500 has been inserted, the chamfered edges 142 retain
the prongs 508 of the clip 500, while the tab 502 of the clip fits
into the lateral 128 or anterior 130 gap. The spring bias 522 of
the clip 500 causes the body 506, arms 504 and tab 502 to be held
in the pocket 134 against the bearing engaging side 104 of the
inferior end plate 100 once the clip 500 has been inserted and the
tab 502 snapped into the gap 128 or 130.
[0055] In the embodiment depicted, the inferior end plate 100 is
intended to be implanted using one of three approaches into the
intervertebral area with two clips 500 snapped to it. Implantation
may be from an anterior approach, a right lateral approach, or a
left lateral approach. If implantation is from the anterior
approach, the anterior gap 130 is left empty with no clip secured,
and with clips 500 snapped in the right and left lateral gaps 128.
When the inferior bearing 300 is later inserted, an anterior clip
500 will inserted with it, and once inserted, the anterior clip 500
is snapped to the inferior end plate 100, into the empty anterior
gap 130.
[0056] If implantation is from the right lateral approach, the
right lateral gap 128 is left empty with no clip secured, and clips
500 are snapped in the anterior gap 130 and left gap 128 prior to
implantation. When the inferior bearing 300 is later inserted, a
right lateral clip 500 will be inserted with it, and once inserted,
the right lateral clip 500 is snapped to the inferior end plate
100, into the empty right lateral gap 128.
[0057] If implantation is from the left lateral approach, the left
lateral gap 128 is left empty with no clip secured and clips 500
are snapped in the anterior gap 130 and right gap 128 prior to
insertion. When the inferior bearing 300 is later inserted, a left
lateral clip 500 will be inserted with it, and once inserted, the
left lateral clip 500 is snapped to the inferior end plate 100,
into the empty left lateral gap 128. It is appreciated that in
alternative embodiments of the invention, the number and location
of gaps and associated clips may vary.
[0058] Referring to FIG. 10, a bearing facing side of the superior
end plate 200 is shown, with one clip 500 snapped on the right
side. The superior end plate 200 has a bone facing side 206 and a
bearing facing side 208. It has a plurality of grafting channels
214 and grafting ports 216. An anterior end 220 has an anterior gap
230, shaped to receive a clip 500. The end plate 200 has a right
lateral end 224 with a gap 228, and a left lateral end with a gap
228. Each gap 228, 230 leads into a pocket 234. Each pocket 234
extends into a slot 240, with chamfered edges 242. The posterior
chamfered edges 242 of the two lateral slots 240 meet, forming a
chamfered wall 244.
[0059] Returning to FIGS. 2 and 3, following the surgical placement
of the inferior end plate 100 with two clips 500 snapped to it, the
superior end plate 200 is similarly placed, but in a superior
orientation on the superior vertebral body 48. The superior end
plate 200 will also have two clips 500 snapped to it, in the same
positions of the clips 500 snapped to the inferior end plate
100.
[0060] Referring to FIG. 11, a caudal side of the inferior bearing
300 is shown, with one clip 500. The bearing 300 is quadrilateral
in form with rounded edges, and is bilaterally symmetrical. It has
a caudal side 302, a cephalad side 304, a posterior end 306, an
anterior end 308, a right end 310 and a left end 312. The caudal
side 302 has an end plate engaging surface 314. Adjacent to the
anterior end 308 is an anterior pocket 316, which is recessed into
the end plate engaging surface 314. Similarly, adjacent to the
right end 310 is a right pocket 318 and adjacent to the left end
312 is a left pocket 320. Each pocket 316, 318, 320 is recessed
into the end plate engaging surface 314, and is shaped to fit
around the protrusion 520 of the clip 500.
[0061] Referring to FIG. 12, a side profile view of the inferior
bearing 300 is shown. A square detent 322 is located on the end
plate engaging surface 314, laterally centered but slightly
displaced toward posterior end 306. The detent 322 is elevated from
the end plate engaging surface 314 and has chamfered edges 324. The
cephalad side 304 has an inferior articulation surface 330 from
which arises a round dome 332.
[0062] FIG. 13 illustrates the cephalad side 304 of the inferior
bearing 300. The dome 332 is encircled by a trough 334, which is a
recessed ring surrounding the dome 332. The dome 332 and its
encircling trough 334 are centered laterally on the cephalad side
304 of the inferior bearing 300, but are slightly displaced toward
the posterior end 306. Recessed into the interior articulation
surface 330 on the anterior end 308 is a notch 336. The notch is
recessed partway into the interior articulation surface 330 and
extends perpendicularly from the edge of the anterior end 308 to
the trough 334. Similar notches 336 are present on the right 310
and left 312 ends of the inferior bearing 300. The notches 336 are
designed to fit closely around the end of an insertion tool such
that the insertion tool may securely grip the inferior bearing 300
during insertion or removal of the bearing. It is appreciated that
the design and placement of notches may vary in other embodiments
of the invention.
[0063] Referring to FIG. 14, the superior bearing 400 with one clip
500 in the right lateral position is shown. The superior bearing
400 is quadrilateral in form with rounded edges. It has a cephalad
side 402, a caudal side 404, a posterior end 406, an anterior end
408, a right end 410 and a left end 412. The cephalad side 402 has
an end plate engaging surface 414. Adjacent to the anterior end is
an anterior pocket 416, which is recessed into the end plate
engaging surface 414. Similarly, adjacent to the right end 410 is a
right pocket 418 and adjacent to the left end 412 is a left pocket
420. Each pocket 416, 418, 420 recessed into the end plate engaging
surface 414, and is configured to fit around the protrusion 520 on
the clip 500.
[0064] Referring to FIG. 15 a side profile view of the superior
bearing 400 is shown. A square detent 422 is located on the end
plate engaging surface 414, laterally centered but slightly
displaced toward posterior end 406. The detent 422 is elevated from
the end plate engaging surface 414 and has chamfered edges 424. The
caudal side 404 has a superior articulation surface 430 into which
is depressed a circular cup 432. The cup 432 is encircled by a
ridge 434, which appears as a raised ring or donut surrounding the
cup 432.
[0065] Referring to FIG. 16, a caudal side view of the superior
bearing 400 is shown. The cup 432 and its encircling ridge 434 are
centered laterally on the caudal side 404 of the superior bearing
400, but are slightly displaced toward the posterior end 406.
Recessed into the superior articulation surface 430 on the anterior
end 408 is a notch 436. The notch is recessed partway into the
superior articulation surface 430 and extends perpendicularly from
the edge of the anterior end 408 to the ridge 434. Similar notches
436 are present on the right 410 and left 412 ends of the superior
bearing 400. The notches 436 are designed to fit closely around the
end of an insertion tool such that the insertion tool may securely
grip the superior bearing 400 during insertion or removal of the
bearing. It is appreciated that the design and placement of notches
may vary in other embodiments of the invention.
[0066] The inferior bearing 300 and the superior bearing 400 are
inserted together into the space between the end plates 100, 200.
Inserting the bearings 300, 400 together requires less distraction
of the vertebral bodies 28, 48 than if they were inserted
separately. If inserted separately, additional distraction would be
required to allow the dome 332 on the inferior bearing 300 to pass
by the ridge 434 on the superior bearing 400. When inserted
together, the dome 332 is fit into the cup 432, allowing the two
bearings 300, 400 to fit into the smallest space possible. The
bearings 300, 400 can be inserted from an anterior approach, a
right lateral approach, or a left lateral approach; they will be
inserted using whichever approach was chosen for the placement of
the end plates 100, 200 during the same surgical procedure.
However, it is appreciated that should there be any subsequent
procedure for replacement or adjustment of the bearings 300, 400
such procedure may be carried out from any one of the three
approaches.
[0067] Returning to FIG. 11, one clip 500 is held in place next to
the inferior bearing 300 as it is being inserted. The clip may be
placed in an anterior position, a right lateral position, or a left
lateral position, depending upon which surgical approach is
implemented. If an anterior approach is implemented, the chamfered
interior edge 514 of the clip is placed under the anterior
chamfered edge 324 of the detent 322 of the inferior bearing 300.
Thus, the top side 510 of the clip 500 is held against the caudal
side 302 of the inferior bearing 300. The protrusion 520 of the
clip 500 fits into the anterior pocket 316 of the inferior bearing
300, when the inferior bearing 300 and the clip 500 are held
together.
[0068] If a right lateral approach is implemented, the chamfered
interior edge 514 of the clip is placed under the right chamfered
edge 324 of the detent 322 of the inferior bearing 300. The
protrusion 520 of the clip 500 fits into right pocket 318 of the
inferior bearing 300, when the inferior bearing 300 and the clip
500 are held together. If a left lateral approach is implemented,
the chamfered interior edge 514 of the clip is placed under the
left chamfered edge 324 of the detent 322 of the inferior bearing
300. The protrusion 520 of the clip 500 fits into left pocket 320
of the inferior bearing 300, when the inferior bearing 300 and the
clip 500 are held together.
[0069] Returning to FIG. 14, one clip 500 is held in place next to
the superior bearing 400 as it is being inserted. The clip may be
placed in an anterior position, a right lateral position, or a left
lateral position, depending upon which surgical approach is
implemented. If an anterior approach is implemented, the chamfered
interior edge 514 of the clip is placed under the anterior
chamfered edge 424 of the detent 422 of the superior bearing 400.
Thus, the top side 510 of the clip 500 is held against the cephalad
side 402 of the superior bearing 400. The protrusion 520 of the
clip 500 fits into the anterior pocket 416 of the superior bearing
400, when the superior bearing 400 and the clip 500 are held
together.
[0070] If a right lateral approach is implemented, the chamfered
interior edge 514 of the clip is placed under the right chamfered
edge 424 of the detent 422 of the superior bearing 400. The
protrusion 520 of the clip 500 fits into right pocket 418 of the
superior bearing 400, when the superior bearing 400 and the clip
500 are held together. If a left lateral approach is implemented,
the chamfered interior edge 514 of the clip is placed under the
left chamfered edge 424 of the detent 422 of the superior bearing
400. The protrusion 520 of the clip 500 fits into left pocket 420
of the superior bearing 400, when the superior bearing 400 and the
clip 500 are held together.
[0071] Referring to FIG. 17, the bearings 300, 400 are shown
immediately prior to being inserted in between the end plates 100,
200 from a left lateral direction. As the inferior bearing 300 and
the superior bearing 400 and their associated clips 500 are
inserted, they are held together and slid along the medial-lateral
axis 20 into the space between the end plates 100, 200. The
bearings 300, 400 and clips 500 are slid between the end plates
100, 200 and into the open left lateral gaps 128, 228 until the
leading chamfered edge 324 of the detent 322 engages under the
interior edge 514 of the opposite lateral clip 500 already in
place. Simultaneously, on the superior bearing 400, the leading
chamfered edge 424 of the detent 422 engages under the interior
edge 514 of the opposite lateral clip 500 already in place. Thus
engaged, the bearings cannot slide in any further. As the clips 500
are slid in with the bearings 300, 400 the chamfered edges 518 on
the prongs 508 also slide under the chamfered edges 142, 242 of the
pockets.
[0072] If an anterior approach is used, the bearings 300, 400 and
clips 500 are slid in a posterior direction parallel to the end
plates 100, 200 so that the detents 322, 422 slide into the empty
anterior gaps 130, 230. They are slid until the leading chamfered
edge 324 of the detent 322 engages under the chamfered wall 144 at
the end of the slot 140. Simultaneously, on the superior bearing
400, the leading chamfered edge 424 of the detent 422 engages under
the chamfered wall 244 at the end of the slot 240.
[0073] After the bearings 300, 400 and clips 500 are fully slid in
with all chamfered edges engaged, the tabs 502 are pinched downward
or caudally following the spring bias 522 so that the tabs 502 snap
into the anterior gaps 130 or lateral gap 128 of the inferior end
plate 100, and the arms 504 are seated in the pockets 134.
Similarly, the tabs 502 on the clips 500 adjacent to the superior
end plate 200 are pinched upward in the cephalic direction, so that
the tabs 502 snap into the anterior gaps 230 or lateral gaps 228 of
the superior end plate 200, and the arms 504 are seated in the
pockets 234. Once the tabs 502 are thus pinched, the spring bias
522 holds the clips 500 against end plates 100, 200, and bearings
300, 400 are prevented from slipping in a lateral, anterior,
posterior, caudal or cephalad direction.
[0074] Should revision of the initial implantation be necessary, it
can be accomplished by any of the three approaches: anterior, right
lateral, or left lateral. For example, if the bearings 300, 400
need to be replaced by those of a different size or configuration
(or by an elastic insert or the fusion block that will be described
below), the surgery may be approached from a different direction
than the initial implantation, thus avoiding disturbance of scar
tissue. To remove the bearings 300, 400, the tabs 502 of the two
clips 500 on one approach (anterior, right or left) are pinched
together. For example, if the anterior approach is used, the tab
502 of the anterior clip 500 on the inferior end plate 100 is
pinched toward the tab 502 of the anterior clip 500 on the superior
end plate 200. The pinching action will free the tab arms 504 from
the pockets 134, 234 of the inferior 100 and superior 200 end
plates. Simultaneously, the protrusions 520 on the clips 500 will
fit into the pockets 316, 416 in the inferior 300 and superior 400
bearings. The clips are then pulled perpendicularly away from the
end plates 100, 200, with the bearings 300, 400 held between them.
The replacement bearings 300, 400 can then be inserted with clips
500 in place, as described in the original insertion procedure.
[0075] FIG. 18 illustrates a fusion block 600, shown assembled with
the inferior end plate 100 and the superior end plate 200, within a
portion of the spine. A plurality of clips 500 are used to position
the fusion block 600 and attach it to the end plates 100, 200. The
fusion block 600 may be inserted in place of the inferior bearing
300 and the superior bearing 400, if fusion of the involved
vertebrae is desired. Insertion of the fusion block 600 may occur
during the initial procedure, following the placement of the
inferior and superior end plates 100, 200. Alternatively, it can be
used to replace the inferior and superior bearings 300, 400 after
they have been implanted in the patient for some period of time. As
with the end plates 100, 200 and the bearings 300, 400, the fusion
block 600 may be inserted from the anterior, right lateral, or left
lateral approach.
[0076] As viewed in FIG. 19, fusion block 600 is of a quadrilateral
shape with rounded corners. It has a cephalad side 602 and a caudal
side 604, which are substantially parallel. It has an anterior end
606, a posterior end 608, a right end 610 and a left end 612. The
cephalad side has a first end plate engaging surface 640, and the
caudal side has a second end plate engaging surface 642. In this
embodiment of the invention the cephalad and caudal sides 602, 604
are identical, and the fusion block 600 is bilaterally symmetrical,
with identical right and left ends 610, 612. However, it is
appreciated that in alternative embodiments, sides and ends may
vary from one another and symmetry may or may not occur.
[0077] A plurality of grafting ports 614, passing through a support
member 620, is present on the fusion block 600. In this embodiment
of the invention, these grafting ports 614 are configured to line
up with the grafting ports 116, 216 on the inferior and superior
end plates 100, 200. These adjacent openings extend through the
entire implant to allow growth of bone material through the fusion
block 600 and the end plates 100, 200, thus fusing the fusion block
600, end plates 100, 200, and vertebral bodies 28, 48 together.
Before, during or after positioning of the end plates 100, 200
between the vertebral bodies, the fusion block 600 is at least
partially packed with an osteogenic substance. In this application,
"osteogenic substance" is broadly intended to include natural bone,
such as autogenous bone graft or bone allograft, synthetic bone,
growth factors and cytokines (including bone morphogenic proteins),
and/or combinations thereof.
[0078] Referring to FIG. 20, an anterior side view of the fusion
block 600 is shown. A plurality of grafting holes 616 is present on
each side of the block, passing through the support member 620. As
with the grafting ports 614 previously described, the grafting
holes 616 allow growth of bone material throughout the fusion block
600. Grooves 618 are recessed into the support member 620 on each
outer corner of the block. Each groove 618 is designed to fit
closely around the end of an insertion tool such that the insertion
tool (not shown) may securely grip the fusion block 600 during
insertion of the block.
[0079] A square first detent 622 is located on the cephalad side
602 while a similar, square second detent 624 is on the caudal side
604. The detents 622, 624 are laterally centered but slightly
displaced toward the posterior end 608. The detents 622, 624
project outward from the end plate engaging surfaces 640, 642 of
each side 602, 604. The first detent 622 has chamfered edges 626,
and the second detent 624 has chamfered edges 628.
[0080] As depicted in FIG. 21, adjacent to the anterior end 608 is
a pocket 630, which is recessed into the first end plate engaging
surface 640. Similar pockets 630 are adjacent to the right end 610
and the left end 612. Each pocket 630 is recessed into the first
end plate engaging surface 640, and is configured to fit around the
protrusion 520 on the clip 500. Three pockets 630 are similarly
located on the second end plate engaging surface 642.
[0081] Returning to FIG. 18, before insertion of the fusion block
600, the end plates 100, 200 are placed against the vertebral
bodies 28, 48 as previously described, each with two clips 500
snapped in place. The clips 500 are used to position the fusion
block 600 during the insertion process, and then hold the fusion
block in place once inserted. Prior to insertion of the block, the
interior edge 514 of a clip 500 is slid under a chamfered edge 626
of the first detent 622 on the cephalad side 602. Once the clip is
in place, its protrusion 520 fits into the facing pocket 630 on the
first end plate engaging surface 640. Similarly, the interior edge
514 of a clip 500 is slid under the matching chamfered edge 628 of
the second detent 624 on the caudal side 604, with that clip's
protrusion 520 in the facing pocket 630 of the second end plate
engaging surface 642. As a result, the fusion block 600 is
sandwiched between two clips 500, the clips being in matching
anterior, right lateral or left lateral positions.
[0082] Referring to FIG. 22, the fusion block 600 is shown as is it
being inserted from the anterior approach into the gap between the
end plates 100, 200. The fusion block 600 and its associated clips
500 are held together and slid into the empty anterior gaps 130,
230 on the end plates 100, 200. The fusion block 600 and clips 500
are held parallel to the end plates and slid posteriorly into place
such that the lateral chamfered edges 626 of the first detent 622
engage under the chamfered edges 242 of the open pocket 234 on the
superior end plate 200. Simultaneously, the lateral chamfered edges
628 of the second detent 624 engage under the chamfered edges 142
of the open pocket 134 on the inferior end plate 100.
[0083] If an anterior approach is used, the fusion block 600 and
clips 500 are slid until the leading chamfered edges 626, 628 of
the detents 622, 624 engage under the chamfered walls 244, 144 at
the end of the slots 240, 140. If a lateral approach is used, the
fusion block 600 and clips 500 are slid until the leading chamfered
edges 626, 628 of the detents 622, 624 engage under the interior
edges 514 of the opposite lateral clips 500 already in place. Thus
engaged, the fusion block cannot slide in any further. As the clips
500 are slid in with the fusion block 600, the chamfered edges 518
on the prongs 508 also slide under the chamfered edges 142, 242 of
the pockets 134, 234.
[0084] After the fusion block 600 and clips 500 are fully slid in
with all chamfered edges engaged, the tabs 502 are pinched
individually toward the end plates following the spring bias 522 so
that the tabs 502 snap into the anterior gaps 130, 230 or lateral
gaps 128, 228 of the end plates 100, 200 and the arms 504 are
seated in the pockets 134, 234. Once the tabs 502 are thus snapped
into place, the spring bias 522 holds the clips 500 against the end
plates 100, 200 and the fusion block 600 is prevented from slipping
in a lateral, anterior, posterior, caudal or cephalad
direction.
[0085] As with the bearings, if revision of the initial
implantation of the fusion block is necessary, it can be
accomplished by any of the three approaches: anterior, right
lateral, or left lateral. For example, if the fusion block 600
needs to be replaced by one of a different size or configuration,
the surgery may be approached from a different direction than the
initial implantation, thus avoiding disturbance of scar tissue. To
remove the fusion block 600, the tabs 502 of the two clips 500 on
one approach (anterior, right or left) are pinched together. For
example, if the anterior approach is used, the tab 502 of the
anterior clip 500 on the cephalad side 602 is pinched toward the
tab 502 of the anterior clip 500 on the caudal side 604. The
pinching action will free the tab arms 504 from the pockets 134,
234 of the inferior 100 and superior 200 end plates.
Simultaneously, the protrusions 520 on the clips 500 will fit into
the pockets 630 in the first and second end plate engaging surfaces
640, 642. The clips are then pulled perpendicularly away from the
end plates 100, 200, with the fusion block 600 held between them. A
replacement fusion block 600, elastic insert, or bearings 300, 400
can then be inserted with clips 500 snapped in place, as described
in the original insertion procedure.
[0086] The present invention may be embodied in other specific
forms without departing from its spirit or essential
characteristics. It is appreciated that various features of the
above-described examples can be mixed and matched to form a variety
of other alternatives. As such, the described embodiments are to be
considered in all respects only as illustrative and not
restrictive. The scope of the invention is, therefore, indicated by
the appended claims rather than by the foregoing description. All
changes which come within the meaning and range of equivalency of
the claims are to be embraced within their scope.
* * * * *