U.S. patent application number 12/587272 was filed with the patent office on 2010-02-04 for spinal implant construct and method for implantation.
Invention is credited to Fred J. Molz, IV.
Application Number | 20100030334 12/587272 |
Document ID | / |
Family ID | 34749420 |
Filed Date | 2010-02-04 |
United States Patent
Application |
20100030334 |
Kind Code |
A1 |
Molz, IV; Fred J. |
February 4, 2010 |
Spinal implant construct and method for implantation
Abstract
A spinal construct and method for implantation is provided which
utilizes a spinal implant adapted for insertion within an
intervertebral space between an adjacent pair of vertebral bodies,
and an elongate member adapted for anchoring to the adjacent
vertebral bodies. The spinal implant defines a first transverse
dimension and a different second transverse dimension, and is
initially inserted into the intervertebral space while in a first
operational configuration wherein the first transverse dimension
extends along the height of the intervertebral space. The elongate
member is anchored to the vertebral bodies to establish and
maintain a select height of the intervertebral space. The spinal
implant is then rotated to a second operational configuration
wherein the second transverse dimension extends along the height of
the intervertebral space. The elongate member serves to maintain
the select height of the intervertebral space to provide a
controlled amount of compression onto the spinal implant and/or a
bone growth promoting material contained therein. The elongate
member also serves to resist tensile loads during extensional
movement of the vertebral bodies to maintain the vertebral
endplates in intimate contact with the spinal implant.
Inventors: |
Molz, IV; Fred J.;
(Collierville, TN) |
Correspondence
Address: |
MEDTRONIC;Attn: Noreen Johnson - IP Legal Department
2600 Sofamor Danek Drive
MEMPHIS
TN
38132
US
|
Family ID: |
34749420 |
Appl. No.: |
12/587272 |
Filed: |
October 5, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10757819 |
Jan 15, 2004 |
7621938 |
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12587272 |
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Current U.S.
Class: |
623/17.11 |
Current CPC
Class: |
A61F 2002/30579
20130101; A61F 2002/30576 20130101; A61F 2002/30507 20130101; A61F
2002/30578 20130101; A61F 2002/2835 20130101; A61F 2002/30789
20130101; A61F 2310/00017 20130101; A61F 2002/30785 20130101; A61F
2/4611 20130101; A61F 2310/00023 20130101; A61F 2002/30593
20130101; A61B 17/7062 20130101; A61F 2/447 20130101; A61F
2002/2817 20130101; A61F 2220/0025 20130101 |
Class at
Publication: |
623/17.11 |
International
Class: |
A61F 2/44 20060101
A61F002/44 |
Claims
1. A spinal construct for engagement with adjacent vertebral
bodies, comprising: a spinal implant comprising an interbody
implant configured for implantation within an intervertebral space
between the adjacent vertebral bodies, said spinal implant
extending along a longitudinal axis and having a first transverse
dimension sized for insertion into the intervertebral space and a
second transverse dimension greater than said first transverse
dimension and corresponding to a select height of said
intervertebral space; and an elongate member sized to span the
intervertebral space and engaged between the adjacent vertebral
bodies to maintain said select height of the intervertebral space;
and wherein said spinal implant is rotatably coupled to said
elongate member by a connector member such that said spinal implant
is rotatable relative to said elongate member about the
longitudinal axis, wherein said connector member selectively
interlocks said spinal implant with said elongate member to
selectively prevent rotational and lateral movement of said spinal
implant relative to said elongate member subsequent to alignment of
said second transverse dimension along said select height of the
intervertebral space.
2. The spinal construct of claim 1, wherein said spinal implant
includes: a first pair of side surfaces spaced apart and arranged
generally opposite one another to define said first transverse
dimension; and a second pair of side surfaces spaced apart and
arranged generally opposite one another to define said second
transverse dimension.
3. The spinal construct of claim 2, wherein said second pair of
side surfaces are arranged substantially parallel to one
another.
4. The spinal construct of claim 2, wherein said second pair of
side surfaces are angled relative to one another to define a taper
extending along said longitudinal axis corresponding to the natural
lordotic angle between the adjacent vertebral bodies.
5. The spinal construct of claim 2, wherein said first pair of side
surfaces are angled relative to one another to define a taper
extending along said longitudinal axis to facilitate insertion of
said spinal implant within the intervertebral space between the
adjacent vertebral bodies.
6.-9. (canceled)
10. The spinal construct of claim 1, further comprising an
interlock between said spinal implant and said elongate member to
selectively prevent at least one of said rotational and lateral
movement of said spinal implant relative to said elongate member
subsequent to alignment of said second transverse dimension along
said select height of the intervertebral space.
11. (canceled)
12. The spinal construct of claim 10, wherein said interlock
comprises: at least one projection portion extending from one of
said spinal implant and said elongate member; and at least one
aperture defined by another of said spinal implant and said
elongate member; and wherein said connector member forces said at
least one projection into a respective one of said at least one
aperture; and wherein insertion of said at least one projection
portion into a said respective one of said at least one aperture
prevents said rotational and lateral movement of said spinal
implant relative to said elongate member.
13.-23. (canceled)
24. The spinal construct of claim 1, wherein said elongate member
comprises a plate having first and second end portions, said plate
defining at least one opening adjacent each of said first and
second end portions; and further comprising a bone screw extending
through each of said at least one opening for engaging said plate
to the adjacent vertebral bodies.
25. A spinal implant assembly, comprising: an interbody fusion
device adapted for insertion into an intervertebral space between
an adjacent pair of vertebral bodies, said interbody fusion device
extending along a longitudinal axis and defining a primary
transverse dimension and a secondary transverse dimension, said
secondary transverse dimension sized for insertion into the
intervertebral space, said primary transverse dimension sized
greater than said secondary transverse dimension and corresponding
to a select height of said intervertebral space; and an elongate
member sized to span the intervertebral space and engaged between
the adjacent vertebral bodies to maintain said select height of the
intervertebral space; and wherein said interbody fusion device is
rotatable coupled to said elongate member by a connector member
such that said interbody fusion device is rotatable relative to
said elongate member about the longitudinal axis, wherein said
connector member selectively interlocks said interbody fusion
device with said elongate member to selectively prevent rotational
and lateral movement of said interbody fusion device relative to
said elongate member subsequent to alignment of said primary
transverse dimension along said select height of the intervertebral
space.
26.-29. (canceled)
30. The spinal implant assembly of claim 25, further comprising an
interlock between said interbody fusion device and said elongate
member to selectively prevent said rotational and lateral movement
of said interbody fusion device relative to said elongate member
subsequent to alignment of said primary transverse dimension along
said select height of the intervertebral space.
31. The spinal implant assembly of claim 30, wherein said interlock
comprises: at least one projection portion extending from one of
said interbody fusion device and said elongate member; and at least
one aperture defined by another of said interbody fusion device and
said elongate member; and wherein said connector member forces said
at least one projection into a respective one of said at least one
aperture; and wherein insertion of said at least one projection
portion into said respective one of said at least one aperture
prevents said rotational and lateral movement of said interbody
fusion device relative to said elongate member.
32.-34. (canceled)
35. A spinal construct for engagement with adjacent vertebral
bodies, comprising: a spinal implant comprising an interbody
implant configured for implantation within an intervertebral space
between the adjacent vertebral bodies, said spinal implant
extending along a longitudinal axis and having a first transverse
dimension sized for insertion into the intervertebral space between
the adjacent vertebral bodies and a second transverse dimension
greater than said first transverse dimension and corresponding to a
select height of said intervertebral space; an elongate member
sized to span the intervertebral space and engaged between the
adjacent vertebral bodies to maintain said select height of the
intervertebral space; means for rotatably coupling said spinal
implant with said elongate member; and means for interlocking said
spinal implant with said elongate member to selectively prevent
rotational and lateral movement of said spinal implant relative to
said elongate member subsequent to alignment of said second
transverse dimension along said select height of the intervertebral
space.
36.-62. (canceled)
63. The spinal construct of claim 1, wherein said connector member
comprises a fastener extending through a passage in said elongate
member and engaged with said spinal implant; and wherein
displacement of said fastener interlocks said spinal implant with
said elongate member to selectively prevent said rotational and
lateral movement of said spinal implant relative to said elongate
member.
64. The spinal construct of claim 63, wherein said fastener
comprises a threaded fastener.
65. The spinal construct of claim 64, wherein said threaded
fastener extends through said passage in said elongate member and
is threadedly engaged within a threaded opening in said spinal
implant, wherein rotation of said threaded fastener threads said
threaded fastener into said threaded opening and interlocks said
spinal implant with said elongate member to selectively prevent
said rotational and lateral movement of said spinal implant
relative to said elongate member.
66. The spinal construct of claim 12, wherein said connector member
comprises a threaded fastener extending through a passage in said
elongate member and threadedly engaged within a threaded opening in
said spinal implant; and wherein rotation of said fastener threads
said fastener into said threaded opening and positions said at
least one projection portion within said respective one of said at
least one aperture to thereby selectively prevent said rotational
and lateral movement of said spinal implant relative to said
elongate member.
67. The spinal implant assembly of claim 25, wherein said connector
member comprises a fastener extending through a passage in said
elongate member and engaged with said interbody fusion device; and
wherein displacement of said fastener interlocks said interbody
fusion device with said elongate member to selectively prevent said
rotational and lateral movement of said interbody fusion device
relative to said elongate member.
68. The spinal implant assembly of claim 67, wherein said fastener
comprises a threaded fastener.
69. The spinal implant assembly of claim 68, wherein said threaded
fastener extends through said passage in said elongate member and
is threadedly engaged within a threaded opening in said interbody
fusion device, wherein rotation of said threaded fastener threads
said threaded fastener into said threaded opening and interlocks
said interbody fusion device with said elongate member to
selectively prevent said rotational and lateral movement of said
interbody fusion device relative to said elongate member.
70. The spinal implant assembly of claim 31, wherein said connector
member comprises a threaded fastener extending through a passage in
said elongate member and threadedly engaged within a threaded
opening in said interbody fusion device; and wherein rotation of
said fastener threads said fastener into said threaded opening and
positions said at least one projection portion within said
respective one of said at least one aperture to thereby selectively
prevent said rotational and lateral movement of said interbody
fusion device relative to said elongate member.
Description
[0001] The present invention relates generally to a spinal
interbody implant construct and method for implantation. While the
actual nature of the invention covered herein can only be
determined with reference to the claims appended hereto, one aspect
of the present invention involves insertion of a fusion device into
a space between adjacent vertebral bodies from which at least a
portion of an intervertebral disc has been removed via a discectomy
procedure. Another aspect of the present invention involves
rotation of the fusion device within the intervertebral space to
establish and maintain controlled compression between the opposing
endplates of the adjacent vertebral bodies and the device and/or
bone growth promoting material contained within the device. A
further aspect of the present invention involves the prevention of
an unintentional change of position or orientation of the fusion
device subsequent to implantation. There is a general need in the
industry to provide an improved spinal implant construct and method
of implantation. The present invention meets this need and provides
other benefits and advantages in a novel and unobvious manner.
BRIEF DESCRIPTION OF THE DRAWINGS
[0002] FIG. 1 is a front elevational view of a device according to
one form of the present invention, as inserted within a disc space
between adjacent vertebral bodies in a first operational
configuration.
[0003] FIG. 2 is a side view of the device illustrated in FIG. 1 in
the first operational configuration.
[0004] FIG. 3 is a front elevational view of the device illustrated
in FIG. 1, as transitioned to a second operational
configuration.
[0005] FIG. 4 is a side view of the device illustrated in FIG. 3 in
the second operational configuration.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
[0006] For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to the
embodiments illustrated in the drawings and specific language will
be used to describe the same. It will nevertheless be understood
that no limitation of the scope of the invention is hereby
intended, such alterations and further modifications in the
illustrated devices, and such further applications of the
principles of the invention as illustrated herein being
contemplated as would normally occur to one skilled in the art to
which the invention relates.
[0007] Referring to FIGS. 1-4, shown therein is a schematic
representation of a portion of the spinal column in which two
adjacent vertebral bodies 11 and 12 are held in distraction via a
distraction tool 13 to provide an intervertebral space 14 between
the vertebral bodies following the removal of at least a portion of
a natural intervertebral disc (not shown). However, it should be
understood that such distraction of the vertebral bodies via the
distraction tool 13 is not essential to practicing the present
invention, and in some instances can be avoided.
[0008] In a preferred embodiment of the invention, it is desirable
to establish fusion between the vertebral bodies 11 and 12. For
that purpose, a fusion construct or assembly 16 is provided
according to one form of the present invention. In the illustrated
embodiment, the fusion construct 16 is generally comprised of a
cage portion 17 and an elongate plate portion 26. However, it
should be understood that other configurations of the fusion
construct 16 are also contemplated as falling within the scope of
the present invention. For example, in other embodiments of the
invention, the cage portion 17 can be configured as a spacer-type
device or any other type of intervertebral implant. Additionally,
in other embodiments of the invention, the elongate plate portion
26 can be configured as a rod, a staple, a cable, a tether, or any
other type of elongate member. The components of the fusion
construct 16 may be formed from any bio-compatible material such
as, for example, titanium, stainless steel or any other suitable
material.
[0009] In one embodiment of the present invention, the cage portion
17 of the fusion construct 16 extends along a longitudinal axis 18
and has a generally rectangular, parallelepiped configuration
including front and rear portions 17F, 17R, left and right side
portions 17L, 17P (also referred to as primary portions), and top
and bottom portions 17T, 17B (also referred to as secondary
portions). However, it should be understood that other shapes and
configurations of the fusion cage 17 are also contemplated as
falling within the scope of the present invention. For example, the
fusion cage 17 can take on an elliptical or semi-elliptical
configuration, a cam-like configuration, a polygonal configuration,
or any other suitable configuration. The overall height of the cage
17 between the top and bottom portions 17T, 17B (transverse
dimension A illustrated FIG. 1) is less than the overall width of
the cage 17 between the left and right side portions 17L, 17P
(transverse dimension B illustrated in FIG. 1). This dimensional
configuration facilitates insertion of the cage 17 into the
intervertebral space 14 between the lower endplate 11P of upper
vertebral body 11 and the upper endplate 12P of lower vertebral
body 12 by simply pushing the cage 17 in the direction of arrow 21
(FIG. 2).
[0010] In the illustrated embodiment of the cage 17, the primary
side portions 17L, 17P are arranged substantially parallel to one
another. However, in an alternative embodiment, the primary side
portions 17L, 17P may be angularly offset relative to one another
so as to define a taper to accommodate for an offset angle between
the upper and lower vertebral endplates 11P, 12P (e.g., to
accommodate for a particular lordotic angle associated with portion
of the spinal column being treated). Additionally, in the
illustrated embodiment of the cage 17, the secondary side portions
17T, 17B are arranged substantially parallel to one another.
However, in an alternative embodiment, the secondary side portions
17T, 17B may be angularly offset relative to one another so as to
define a taper to facilitate axial insertion of the cage 17 into
the intervertebral space 14.
[0011] In the illustrated embodiment of the invention, the cage 17
includes features for engaging the plate 26. For example, the cage
17 defines a threaded opening 22 positioned generally along the
longitudinal axis 18 which opens onto a front surface of the front
end portion 17F. Additionally, the cage 17 includes a first pair of
posts 23, 24 projecting axially from the front end portion 17F and
radially offset from and located on diametrically opposite sides of
the longitudinal axis 18. However, it should be understood that
other positions and arrangements of the posts 23, 24 are also
contemplated as falling within the scope of the present invention.
In one embodiment of the invention, the elongate plate 26 is
selectively engaged with the cage 17 via a fastener 27. However, it
should be understood that in other embodiments of the invention,
the plate 26 need not necessarily be engaged with the cage 17. In a
specific embodiment, the elongate plate 26 is provided with a
central passage 32 through which extends a threaded shank 28 of the
fastener 27. The threaded shank 28 is in turn threadedly engaged
within the opening 22 in the cage 17, as shown in FIG. 2, to
securely engage the plate 26 with the cage 17. In a further
embodiment of the invention, the plate 26 extends along a
longitudinal axis 33 and defines a pair of openings 34, 36 disposed
adjacent opposite ends thereof which are configured to receive a
respective fastener therethrough, the details of which will be
discussed below.
[0012] The elongate plate 26 also defines a pair of passages 37, 38
that are radially offset from and located on diametrically opposite
sides of the longitudinal axis 18. The passages 37, 38 are sized
and positioned so as to receive the respective posts 23, 24
extending from the cage 17 therein. As should be appreciated, the
angular orientation of the posts 23, 24 extending from the cage 17
is initially offset 90.degree. from the angular orientation of the
passages 37, 38 in the plate 26 when the cage 17 is positioned in
the first operational configuration illustrated in FIGS. 1 and 2.
However, when the cage 17 is rotated to the second operational
configuration illustrated in FIGS. 3 and 4, the posts 23, 24 are
aligned with the passages 37, 38. Once rotated to the second
operational configuration, tightening of the fastener 27 into the
threaded opening 22 in the cage 17 results in displacement of the
cage 17 toward the plate 26 and positioning of the posts 23, 24
within the passages 37, 38. However, it should be understood that
in another embodiment, tightening of the fastener 27 into the
threaded opening 22 in the cage 17 may result in displacement of
the plate 26 toward the cage 17 to position the posts 23, 24 within
the passages 37, 38.
[0013] Positioning of the posts 23, 24 within the passages 37, 38
in turn prevents further rotation and/or lateral displacement of
the cage 17 relative to the plate 26. However, it should be
understood that the cage 17 and the plate 26 may define other
elements or features that interlock with one another to selectively
prevent rotational and/or lateral displacement therebetween. For
example, in another embodiment of the invention, the cage 17 and
the plate 26 may have a splined configuration wherein the cage 17
and the plate 26 define a number of splines that are positionable
within a corresponding number of grooves to selectively prevent
rotational and/or lateral displacement therebetween. Other
interlocking elements or features are also contemplated including,
for example, a tongue and groove configuration, or any other
interlocking configuration suitable for selectively preventing
rotational and/or lateral displacement between the cage 17 and the
plate 26.
[0014] The elongate plate 26 further defines a pair of curved or
arcuate slots 39, 41 extending from opposite edges 42, 43 of the
plate 26 and progressing inwardly toward the center of the plate 26
adjacent the longitudinal axis 33. In the illustrated embodiment,
the arcuate slots 39, 41 extend along a common radius; however,
other slot configurations and arrangements are also contemplated as
falling within the scope of the invention. As illustrated in FIG.
1, the front end portion 17F of the cage 17 defines a pair of
tool-receiving passages 44, 46. The passages 44, 46 are radially
offset from and located on diametrically opposite sides of the
longitudinal axis 18 and are positioned generally along the radius
of the arcuate slots 39, 41. The tool-receiving passages 44, 46 are
sized and positioned so as to receive respective portions 52, 53 of
a tool 51 therein (FIG. 4). As should be appreciated, the angular
orientation of the tool-receiving passages 44, 46 in the cage 17 is
initially offset 90.degree. from the longitudinal axis 33 of the
plate 26 when the cage 17 is positioned in the first operational
configuration illustrated in FIGS. 1 and 2. However, as the cage 17
is rotated to the second operational configuration illustrated in
FIGS. 3 and 4, the tool-receiving passages 44, 46 and the
respective portions 52, 53 of the tool 51 received therein are
displaced along the arcuate slots 39, 41 in the plate 26 to avoid
interference between the tool 51 and the plate 26. Once rotated to
the second operational configuration, the tool 51 may be disengaged
from the passages 44, 46 and removed from the surgical site.
[0015] In a preferred embodiment of the invention, a bone growth
promoting material may be packed within a hollow interior portion
of the cage 17 to promote fusion with the adjacent vertebral
endplates 11P, 12P. In one embodiment, the primary side portions
17L, 17P of the cage 17 define a number of relatively small
diameter fusion openings 47 extending therethrough in communication
with the hollow interior of the cage 17. However, it should be
understood that various types and sizes of openings may be provided
to expose the bone growth promoting material to the vertebral
endplates 11P, 12P including, for example, perforations or openings
of various sizes and shapes including relatively large slotted
openings or windows extending through the primary side portions
17L, 17P of the cage 17. In another embodiment of the invention, at
least the primary side portions 17L, 17P of the cage 17 may be
formed of a relatively porous material to promote bony on-growth.
Additionally, although not specifically shown in the illustrated
embodiment of the invention, the secondary side portions 17T, 17B
of the cage 17 may be provided with a number of fusion openings
and/or may be formed of a porous material to further promote fusion
between the adjacent vertebral endplates 11P, 12P and the secondary
side portions 17T, 17B of the cage 17.
[0016] In one embodiment of the invention, the bone growth
promoting material is comprised of a bone graft material, a bone
morphogenic protein (BMP), or any other suitable bone growth
promoting material or substance including but not limited to bone
chips or bone marrow, a demineralized bone matrix (DBM),
mesenchymal stem cells, and/or a LIM mineralization protein (LMP).
It should be understood that the bone growth promoting material can
be used with or without a suitable carrier. In a further embodiment
of the invention, the bone growth promoting material is positioned
within the hollow interior of the cage 17 prior to insertion within
the space 14 between the adjacent vertebral bodies 11, 12. However,
in another embodiment, the bone growth promoting material may be
positioned within the hollow interior of the cage 17 subsequent to
insertion within the intervertebral space 14.
[0017] Having illustrated and described various elements and
features associated with the fusion construct 16, reference will
now be made to a technique for engaging the fusion construct 16
with the adjacent vertebral bodies 11, 12 according to one
embodiment of the invention. However, it should be understood that
other techniques and procedures are also contemplated, and that the
following technique in no way limits the scope of the present
invention.
[0018] The vertebral level to be treated is initially identified
followed by the removal of at least a portion of the natural
intervertebral disc via a total or partial discectomy. The
endplates 11P, 12P of the upper and lower vertebral bodies 11, 12
are then prepared using known surgical instruments and techniques
(e.g., rotating cutters, curettes, chisels, etc.). In some
instances, it may be desirable to remove an amount of cortical bone
from the vertebral endplates 11P, 12P to facilitate passage of the
leading corners of the cage 17 as the cage is rotated about the
longitudinal axis 18. As discussed above, the upper and lower
vertebral bodies 11, 12 may be held in a distracted condition via
the distraction tool 13 to provide an open space 14 between the
vertebral bodies following the discectomy. Depending on the
preference of the surgeon, the distraction tool 13 may be removed
or left in place throughout the remainder of the surgical
procedure.
[0019] The cage 17 used for treatment of the spinal column is
selected such that the transverse dimension A between the secondary
side portions 17T, 17B is sized to allow for insertion of the cage
17 within the intervertebral space 14 between the vertebral
endplate 11P, 12P while in the first operational configuration
illustrated in FIGS. 1 and 2. Additionally, the transverse
dimension B between the primary side portions 17L, 17P is selected
to provide a select height of the intervertebral space 14 between
the vertebral endplate 11P, 12P and to impart a desired amount of
compression onto the cage 17 and/or the bone growth promoting
material contained therein following rotation of the cage 17 to the
second operational configuration illustrated in FIGS. 3 and 4.
[0020] After selection of the appropriately sized cage 17, the cage
17 is inserted into the intervertebral space 14, preferably via an
anterior surgical approach, with the secondary side portions 17T,
17B facing and arranged substantially parallel with the vertebral
endplates 11P, 12P. However, in other embodiments, the cage 17 may
be inserted into the intervertebral space 14 via other surgical
approaches, such as, for example, via a posterior surgical
approach. Following insertion of the cage 17 within the
intervertebral space 14, the elongate plate 26 is attached to the
upper and lower vertebral bodies 11, 12 via a pair of fasteners or
bone screws 48, 49 (FIGS. 3 and 4) that are received through the
openings 34, 36 extending through the end portions of the plate 26.
Attachment of the plate 26 to the vertebral bodies 11, 12
preferably occurs subsequent to engagement of the plate 26 with the
cage 17 via the threaded fastener 27 (FIG. 2). However, it should
be understood that in other embodiments, the elongate plate 26 may
be attached to the vertebral bodies 11, 12 prior to engagement with
the cage 17. As shown in FIGS. 3 and 4, the elongate plate 26
extends between the vertebral bodies 11, 12 and bridges the
intervertebral space 14.
[0021] With the elongate plate 26 secured to the vertebral bodies
11, 12 and with the cage 17 engaged with the plate 26 (but still
rotatable relative thereto), a tool 51 including axial prongs 52
and 53 (FIG. 4) is advanced in the direction of arrow 54 until the
tool prongs 52, 53 are inserted into the corresponding tool
receiving opening 44, 46 in the cage 17. The tool 51 is then
rotated in a clockwise direction (in the direction of arrow 56 in
FIG. 1) to correspondingly rotate the cage 17 90.degree. from the
first operational configuration/orientation illustrated in FIGS. 1
and 2 to the second operational configuration/orientation
illustrated in FIGS. 3 and 4. Once rotated to the second
operational configuration/orientation, the primary side portions
17L, 17P intimately engage the vertebral endplates 11P and 12P of
the upper and lower vertebral bodies 11, 12, with the secondary
side portions 17T, 17B arranged perpendicular to the vertebral
endplates 11P, 12P.
[0022] As discussed above, as the cage 17 is rotated from the first
operation configuration to the second operational configuration,
the tool prongs 52, 53 are displaced through the arcuate slots 39,
41 in the plate 26 to avoid interference between the tool 51 and
the edges 42, 43 of the plate 26. However, in an alternative
embodiment of the invention, it is possible to omit the arcuate
slots 39, 41 from the plate 26 via relocation of the tool receiving
openings 44, 46 to the alternative locations 44A and 46A shown in
dashed lines in FIG. 1. As should be appreciated, with the tool
receiving openings 44, 46 positioned at locations 44A and 46A,
rotation of the cage 17 to the second operational configuration
illustrated in FIG. 3 would avoid any interference between the tool
prongs 52, 53 and the lateral edges 42, 43 of the plate 26.
[0023] As discussed above, the transverse dimension B between the
primary side portions 17L, 17P is selected to impart a desired
amount of compression onto the cage 17 and/or the bone growth
promoting material contained therein following rotation of the cage
17 to the second operational configuration. The plate 26 extending
between the vertebral bodies 11, 12 serves to prevent the vertebral
bodies 11, 12 from distracting or separating apart during rotation
of the cage 17 to the second operational configuration, thereby
controlling the amount of compression exerted onto the cage 17
and/or the bone growth promoting material contained therein. As
should be appreciated, the distance between the screw-receiving
openings 34, 36 in the plate 26 controls the height of the
intervertebral space formed between the vertebral endplate 11P,
12P, and also serves to control the amount of compression exerted
onto the cage 17 and the bone growth promoting material contained
therein by the vertebral endplate 11P, 12P. The plate 26 therefore
functions in a strut-like manner to control the amount of
compression exerted onto the cage 17 and the bone growth promoting
material. Additionally, the plate 26 may also function to resist
tensile loads and/or to limit extension or separation of the
vertebral bodies 11, 12 at the surgical site during subsequent
patient activity (e.g., during extension of the vertebral bodies
11, 12 adjacent the surgical site).
[0024] Following rotation of the cage 17 to the second operational
configuration illustrated in FIGS. 3 and 4, the tool 57 may be
removed from the passages 44, 46 in the cage 17. Additionally, the
fastener 27 is further threaded into the passage 22 in the cage 17,
thereby resulting in displacement of the cage 17 in the direction
of arrow 57 toward the plate 26 (FIGS. 2 and 4). Displacement of
the cage 17 in the direction of arrow 57 in turn results in the
positioning of the pins 23, 24 extending from the cage 17 within
the passages 37, 38 formed in the plate 26. Positioning of the pins
23, 24 within the passages 37, 38 serves to prevent further
rotation and/or lateral movement of the cage 17 relative to the
plate 26. Additionally, since the plate 26 is securely engaged to
the vertebral bodies 11, 12 via the bone screws 48, 49, positioning
of the pins 23, 24 within the passages 37, 38 likewise serves to
prevent rotation and/or lateral movement of the cage 17 relative to
the vertebral bodies 11, 12.
[0025] In one embodiment of the invention, the cage 17 is provided
with a transition feature between the primary side portions 17L,
17P and the secondary side portions 17T, 17B to aid in the rotation
of the cage 17 between the first and second operational
configurations. In the illustrated embodiment, the transition
feature comprises a rounded corner 61 defining a convex outer
surface (FIGS. 1 and 3). In effect, the rounded corners 61 provide
a smooth transition between the primary side portions 17L, 17P and
the secondary side portions 17T, 17B. The rounded corners 61
thereby serve to eliminate the sharp corners or edges otherwise
associated with the rectangular-shaped cage 17, thereby allowing
for rotation of the cage 17 between the first and second
operational configurations without undue interference by or
disturbance of the adjacent vertebral bodies 11, 12. In the
illustrated embodiment, the transition surfaces 61 are
semi-cylindrical surfaces and extend the entire length of the cage
17 from the front portion 17F to the rear portion 17R. However,
other shapes and configurations of the transition surfaces 61 are
also contemplated as would occur to one of ordinary skill in the
art. Additionally, although the illustrated embodiment of the cage
17 includes a transition surfaces 61 at each of its four corners,
it should be understood that in another embodiment, only the
opposite corners of the cage 17 that directly contact the vertebral
endplates 11P, 12P during rotation of the cage 17 need necessarily
be provided with a transition surface 61.
[0026] While the invention has been illustrated and described in
detail in the drawings and foregoing description, the same is to be
considered as illustrative and not restrictive in character, it
being understood that only the preferred embodiments have been
shown and described and that all changes and modifications that
come within the spirit of the invention are desired to be
protected.
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