U.S. patent application number 15/884452 was filed with the patent office on 2018-05-31 for modular anchor bone fusion cage.
The applicant listed for this patent is Zimmer Biomet Spine, Inc.. Invention is credited to Andrew Lamborne, Jared Walkenhorst.
Application Number | 20180147068 15/884452 |
Document ID | / |
Family ID | 48430251 |
Filed Date | 2018-05-31 |
United States Patent
Application |
20180147068 |
Kind Code |
A1 |
Walkenhorst; Jared ; et
al. |
May 31, 2018 |
MODULAR ANCHOR BONE FUSION CAGE
Abstract
A modular anchor bone fusion cage is provided. The cage includes
a spacer configured to fit into a space between the faces of two
bones that are to be fused together. A fusion plate having at least
a main body portion is coupled to the spacer by a connector.
Fasteners extend through the fusion plate to engage the bone. At
least some of the fasteners also extend through the spacer to
engage the opposed faces of the bone. A cover plate is coupled to
the fusion plate to inhibit the fasteners from backing out prior to
fusion of the bones.
Inventors: |
Walkenhorst; Jared; (Denver,
CO) ; Lamborne; Andrew; (Golden, CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Zimmer Biomet Spine, Inc. |
Westminster |
CO |
US |
|
|
Family ID: |
48430251 |
Appl. No.: |
15/884452 |
Filed: |
January 31, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15157671 |
May 18, 2016 |
9913729 |
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15884452 |
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14359070 |
May 16, 2014 |
9370435 |
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PCT/US2012/065912 |
Nov 19, 2012 |
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15157671 |
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61561119 |
Nov 17, 2011 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2002/30593
20130101; A61F 2002/3041 20130101; A61F 2220/0016 20130101; A61F
2/4455 20130101; A61F 2002/30495 20130101; A61F 2002/3083 20130101;
A61F 2002/30492 20130101; A61F 2002/30375 20130101; A61F 2/4465
20130101; A61F 2002/30507 20130101; A61F 2002/30616 20130101; A61F
2002/30777 20130101; A61F 2002/30433 20130101; A61F 2002/30785
20130101; A61F 2310/00359 20130101; A61F 2002/30904 20130101; A61F
2310/00203 20130101; A61F 2002/30517 20130101; A61F 2002/2835
20130101; A61F 2002/30622 20130101; A61F 2/30744 20130101; A61F
2310/00131 20130101; A61F 2002/3023 20130101; A61F 2002/30576
20130101; A61F 2/447 20130101; A61F 2002/30578 20130101; A61F
2002/3008 20130101; A61F 2310/00023 20130101; A61B 17/7059
20130101; A61F 2310/00329 20130101; A61B 17/8047 20130101; A61F
2002/30607 20130101; A61F 2310/00017 20130101; A61F 2002/30797
20130101; A61F 2002/30787 20130101; A61F 2310/00071 20130101; A61F
2310/00161 20130101; A61F 2002/3082 20130101; A61B 17/8645
20130101; A61F 2310/00239 20130101; A61F 2002/2817 20130101; A61F
2310/00293 20130101 |
International
Class: |
A61F 2/44 20060101
A61F002/44; A61B 17/70 20060101 A61B017/70 |
Claims
1. An implant configured to be interposed between opposing faces of
two bones to be fused together, the implant comprising: a spacer
configured to fit between the opposing faces of the two bones to
promote fusion of the two bones, the spacer having a forward
portion, a rearward portion, a top portion, a bottom portion, and
two side portions; the rearward portion comprising at least one
cavity, the spacer having at least one spacer channel extending
from the rearward portion to at least one of the top portion or the
bottom portion; a fusion plate coupled to the spacer, the fusion
plate comprising a main body portion and a first extension side
portion, the main body portion comprising a forward face, a
rearward face opposed to the forward face, and a sidewall
connecting the forward face and the rearward face, the forward face
and at least a portion of the sidewall to be received in the at
least one cavity, the first extension side portion configured to
extend beyond at least one of the top portion or the bottom portion
of the spacer, the fusion plate comprising at least a first bore
aligned with the at least one spacer channel and extending from the
rearward face to the forward face of the fusion plate and a second
bore in the first extension side portion extending from the
rearward face to the forward face; a plurality of fasteners
comprising at least a first fastener extending through the first
bore, extending through the at least one spacer channel, and
exiting the top portion or the bottom portion and configured to
couple the implant to an endplate of a first bone, and at least a
second fastener extending through the second bore to couple the
implant to a second bone; and a lock coupled at least to the fusion
plate to inhibit movement of the plurality of fasteners out of the
first and second bones.
Description
BACKGROUND
[0001] The human spine contains a series of bony segments separated
by discs and coupled together with muscle, ligaments, and other
connective tissues. A large number of ailments may afflict one or
more of these components. One exemplary ailment generally occurs
with age as the spinal discs begin to break down, or degenerate
resulting in the loss of fluid in the discs, and consequently, the
discs become less flexible. Likewise, the discs become thinner
allowing the vertebrae to move closer together. Degeneration also
may result in tears or cracks in the outer layer, or annulus, of
the disc. Degeneration of the annulus may allow the disc to begin
to bulge outwardly. In more severe cases, the inner material of the
disc, or nucleus, may extrude out of the disc. In addition to
degenerative changes in the disc, the spine may undergo changes due
to trauma from automobile accidents, falls, lifting, and other
activities. Furthermore, in a process known as spinal stenosis, the
spinal canal narrows due to excessive bone growth, thickening of
tissue in the canal (such as ligament), or both. In all of these
conditions, the spaces through which the spinal cord and the spinal
nerve roots pass may become narrowed leading to pressure on the
nerve tissue which can cause pain, numbness, weakness, or even
paralysis in various parts of the body. Finally, the facet joints
between adjacent vertebrae may degenerate and cause localized
and/or radiating pain. All of the above conditions, as well as
others not specifically mentioned, are collectively referred to
herein as spine disease.
[0002] Conventionally, surgeons treat spine disease by attempting
to restore the normal spacing between adjacent vertebrae. This may
be sufficient to relieve pressure from affected nerve tissue.
However, it is often necessary to surgically remove disc material,
bone, or other tissues that impinge on the nerve tissue and/or to
debride the facet joints. Most often, the restoration of vertebral
spacing is accomplished by inserting a rigid spacer made of bone,
metal, or plastic into the disc space between the adjacent
vertebrae and allowing the vertebrae to grow together, or fuse,
into a single piece of bone. The vertebrae are typically stabilized
during this fusion process with the use of bone plates and/or
pedicle screws fastened to the, adjacent vertebrae.
[0003] Although techniques for placing intervertebral spacers,
plates, and pedicle screw fixation systems have become less
invasive in recent years, they still require the placement of
hardware deep within the surgical site adjacent to the spine. The
hardware is frequently related to the intervertebral spacer,
itself, along with additional hardware to immobilize the vertebral
segment associated with the fusion. The additional hardware also
inhibits the spacer from exiting the space. Recovery from such
surgery can require several days of hospitalization and long, slow
rehabilitation to normal activity levels.
[0004] Thus, it would be desirable to provide an implantable
intervertebral spacer that presented as low a profile as possible
while still providing sufficient hardware to facilitate
immobilizing the vertebral segment being fused.
SUMMARY
[0005] This Summary is provided to introduce a selection of
concepts in a simplified and incomplete manner highlighting some of
the aspects further described in the Detailed Description. This
Summary, and the foregoing Background, is not intended to identify
key aspects of essential aspects of the claimed subject matter.
Moreover, this Summary is not intended for use as an aid in
determining the scope of the claimed subject matter.
[0006] In sonic aspects of the technology disclosed by the present
application, an implant is provided.. The implant generally relates
to fusing two boney segments together using as low a profile as
possible. In one aspect of the technology, the implant has a spacer
and a fusion plate that may be coupled to the spacer. The spacer is
configured to fit between the two boney segments and promote fusion
therebetween. The fusion plate couples to a rear (sometimes an
anterior) portion of the spacer. The fusion plate includes a main
body portion generally conforming in size and shape to the rear
portion of the spacer and a first extension side extending from the
main body portion of the fusion plate to overlie a portion of the
bones to be fused together. The implant is coupled by fasteners
extending through the fusion plate. Some of the fasteners may
intersect with the rear portion of the spacer and extent through
the top or bottom portion of the spacer. Some of the fasteners may
extend through the fusion plate directly into the bone, although a
portion of the fastener may interest with the rear portion of the
spacer.
[0007] In still other aspects of the technology provided by the
present application a cover plate may further be provided. The
cover plate may be coupled to the fusion plate to inhibit the
fasteners from reverse threading to promote the immobilization of
the boney segment.
[0008] In certain embodiments, the spacer will be provided with a
cavity where the main body portion of the fusion plate fits within
the cavity to allow a. portion of the fusion plate to reside in the
space between the boney segments. In these embodiments, the first
extension side will angle or flare from the main body portion of
the fusion plate to allow the first extension side to reside along
one of the adjacent bones. The first extension side may be
straight, curved, sinusoidal, or a combination thereof.
[0009] In certain embodiments provided by the technology of the
present application the spacer will have a spacer bore that is
coupled to a first end of a connector. In certain aspects, the
spacer bore will have a thread that cooperatively engages an
external thread of the connector, such as, for example, a set
screw. The fusion plate will correspondingly have an aligned plate
bore that is coupled to a second end of the connector. In certain
aspects, the plate bore will have a shoulder and the second end of
the connector will have a plurality of protrusions with outturned
lips. The second end will be elastically deformable to form a snap
fit between the outturned lips of the second end of the connector
and the shoulder of the plate bore. In certain aspects a cover
plate will further have a cover plate bore with a thread. The cover
plate bore aligns with the plate bore. A connecting pin couples the
cover plate to the fusion plate. In certain aspects of the
technology, the connecting pin has a head and a shaft. The shaft
has a first thread proximate to the head and a second thread distal
to the head. An intermediate portion of the shaft may be
non-threaded to separate the first thread from the second thread.
The second thread may cooperatively engage an internal thread of
the connector and the first thread may cooperatively engage the
thread of the cover plate bore to couple the cover plate to the
fusion plate.
[0010] This summary provides only a general outline of some aspects
of the technology disclosed herein. The above and other aspects of
the technology of the present application will be apparent after
consideration of the Detailed Description and Figures herein. It is
to be understood, however, that the scope of the application shall
be determined by the claims as issued and not by whether given
subject matter addresses any or all issues noted in the Background
or includes any features or aspects highlighted in the Summary,
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Various examples of the present invention will be discussed
with reference to the appended drawings. These drawings depict only
illustrative examples of the invention and are not to be considered
limiting of its scope.
[0012] FIG. 1 is a side view of three adjacent vertebra having an
implant consistent with the technology of the present
application;
[0013] FIG. 2 is perspective view of a spacer consistent with the
technology of the present application;
[0014] FIG. 3 is a top plan view of the spacer of FIG. 2;
[0015] FIG. 4 is a cross-sectional view along line A-A of FIG.
3;
[0016] FIG. 5 is rearward portion elevation view of the spacer of
FIG. 2;
[0017] FIG. 6 is a perspective view of a fusion plate consistent
with the technology of the present application;
[0018] FIG. 7 is another perspective view of the fusion plate of
FIG. 6;
[0019] FIG. 8 is perspective view of a threaded connector shown in
FIG. 7 consistent with the technology of the present
application;
[0020] FIG. 9 is perspective view of a fastener consistent with the
technology of the present application;
[0021] FIG. 10 is a perspective view of a lock usable with the
technology of the present application;
[0022] FIG. 11 is a perspective view of a cover plate consistent
with the technology of the present application;
[0023] FIG. 12 is perspective view of a connector pin consistent
with the technology of the present application;
[0024] FIG. 13 is a perspective view of an implant consistent with
the technology of the present application;
[0025] FIG. 14 is a perspective view of a fusion plate consistent
with the technology of the present application;
[0026] FIG. 15 is a side elevation view of the fusion plate of FIG.
14;
[0027] FIG. 16 is a perspective view of a cover plate consistent
with the technology of the present application;
[0028] FIG. 17 is a side elevation view of the cover plate of FIG.
16;
[0029] FIG. 18 is a perspective view of an implant consistent with
the technology of the present application;
[0030] FIG. 19 is a perspective view of a fusion plate consistent
with the technology of the present application;
[0031] FIG. 20 is a side elevation view of the fusion plate of FIG.
19;
[0032] FIG. 21 is a perspective view of a cover plate consistent
with the technology of the present application;
[0033] FIG. 22 is a side elevation view of the cover plate of FIG.
21; and
[0034] FIG. 23 is a perspective view of an implant consistent with
the technology of the present application.
DETAILED DESCRIPTION
[0035] The technology of the present patent application will now be
explained with reference to various figures and the like. While the
technology of the present application is described with respect to
implants that facilitate spinal fusion, such as, for example,
anterior lumbar interbody fusion (ALIF) implants, one of ordinary
skill in the art would recognize on reading the disclosure that the
technology is applicable to other implants. For example, the
technology as described herein may be used for implants to
facilitate fusion of other spinal fusions, such as a transforaminal
lumbar interbody fusion (TLIF), anterior cervical discectomy (ACD),
posterior lumbar interbody fusion (PLIF), lateral thoracolumbar
fusions, and other skeletal fusions, such as long bones or the
like. Moreover, the technology of the present patent application
will be described with reference to certain exemplary embodiments
herein. The word "exemplary" is used herein to mean "serving as an
example, instance, or illustration." Any embodiment described
herein as "exemplary" is not necessarily to be construed as
preferred or advantageous over other embodiments or examples absent
a specific indication that such an embodiment or example is
preferred or advantageous over other embodiments. Moreover, in
certain instances, only a single "exemplary" embodiment is
provided. A single example is not necessarily to be construed as
the only embodiment. The detailed description includes specific
details for the purpose of providing a thorough understanding of
the technology of the present patent application. However, on
reading the disclosure, it will be apparent to those skilled in the
art that the technology of the present patent application may be
practiced with or without these specific details. In some
descriptions herein, generally understood structures and devices
may be shown in diagrams to aid in understanding the technology of
the present patent application without obscuring the technology
herein.
[0036] Referring first to FIG. 1, three vertebrae 40, 42, and 44
are provided. Each of the vertebrae 40, 42, and 44 have an anterior
side 46, a posterior side 48 and lateral sides 50 (only one shown).
The three vertebrae 40, 42, and 44 each have a spinous process
60.
[0037] In a normal spine, discs would reside between each of the
endplates 55 of vertebrae 40 and 42, and vertebrae 42 and 44. The
endplates 55 form opposed bony surfaces for spinal application, but
use of the technology to be described herein is applicable to any
bony segments to be fused across opposed facing bony surfaces. For
convenience of illustration, the discs are not included in the
figures. However, injury, age, disease, or other trauma may cause
the discs to degenerate for one reason or another. To restore
proper height to a disc, for example, a surgeon would remove all or
a portion of the disc and replace it with a spacer. For example, as
shown in FIG. 1, a spacer 52 may be surgically implanted in the
space between vertebrae 40 and 42. As shown, spacer 52 is implanted
from the anterior side of the patient. A fusion plate 54, as will
be explained further below, is coupled to the spacer 52 and extends
over only one of the vertebrae 40 and 42 in the exemplary
embodiment of the technology shown in FIG. 1. While shown in a
spinal application, the technology of the present application is
usable to facilitate the fusion of other bones.
[0038] Referring now to FIGS. 2 and 3, an exemplary spacer 52 is
shown. The spacer 52 is generally shaped to fit within the
intervertebral space and has a forward portion 102, which may be
referred to as a posterior portion 102, a rearward portion 104,
which may be referred to as an anterior portion 104, a top portion
106, which may be referred to as a superior portion 106, a bottom
portion 108, which may be referred to as an inferior portion 108,
and side portions 110. The spacer 52 may have apertures 112 to
receive radio opaque plugs 114, which are useful for tracking when
using computer assisted surgery, and as marking for fluoroscopy or
other imaging techniques in which the bulk of spacer 52 may be
difficult to visualize. The orientation of the front (posterior),
rear (anterior), left, right, top (superior), and bottom
(inferior), or the like are provided for reference and should not
be construed to limit the technology of the present application.
The spacer 52 is provided to fit entirely in the intervertebral
space; although in certain embodiments, the rearward portion 104
may extend beyond the anterior ends of the vertebrae.
[0039] As shown in FIG. 3, the forward portion 102 is shaped to
have a concave, convex, and concave portion forming a recess 118.
The recess 118 is configured to avoid the dura in spinal
applications, but would not be necessary for other applications of
the technology. The rearward portion 104 is generally shaped to
have a concave shape consistent with the anterior aspect of the
vertebrae 40, 42 between which it is implanted. The rearward
portion 104 comprises a cavity 120 having a depth D.sub.1 to
receive a fusion plate as will be explained further below. The side
portions 110 provide a concave portion transitioning between the
forward portion 102 and the rearward portion 104. The spacer 52, as
shown, has a first and a second void 122, 124 separated by a
central strut 126 providing the spacer 52 with a vaguely "B" shape.
Other shapes and types of spacers 52 are possible, such as, for
example, other fusion cages, dowels, and the like. The first void
122 and second void 124 may be packed with material to facilitate
bone growth and fusion of the vertebrae 40, 42. The first and
second voids 122, 124 are both generally greater than 20% of the
surface area of the spacer 52. Alternatively to the large first and
second voids 122, 124, a large number of smaller bone growth
channels are possible.
[0040] A number of protrusions 116 may be provided on the top
portion 106, the bottom portion 108, or a combination thereof. As
best seen in FIG. 4, which is a cross-sectional view across line
A-A in FIG. 3, the protrusions 116 form a generally shark-tooth
shape that angles from the forward portion 102 towards the rearward
portion 104. The protrusions 116 generally resist movement of the
spacer 52 out of the intervertebral space between vertebrae 40, 42.
As shown in the cross-section, the top portion 106 and bottom
portion 108 may be convex shapes providing the spacer 52 with a
bi-convex shape from the forward portion 102 to the rearward
portion 104 forming a dome shape close to a lordotic curvature or
positioning of the vertebrae. The forward portion 102 (or posterior
portion 102) has a taper 128 to facilitate insertion of the spacer
52. The forward portion 102 expands symmetrically on both sides to
a thicker section. The spacer 52, in this exemplary embodiment, is
generally thickest in the rearward portion 104, but generally
forward of cavity 120. Instead of a bi-convex, domed shape, the
spacer 52 may form a more conventional wedge shape or have a planar
top portion 106, a planar bottom portion 108, or a combination
thereof.
[0041] Still with reference to FIG. 4, the protrusion 116 are
formed by a first surface 130 forming an obtuse angle with a
surface of the spacer 52. The first surface 130 extends to an
engaging surface 132 of the protrusion 116. The engaging surface
132 is adapted to engage the endplates of the vertebrae 40, 42. The
engaging surface 132 may be formed to a line contact, a point
contact, or to a flat or convex surface formed generally parallel
to the body surface. In particular, the engaging surface 132 may be
formed and shaped to conform to the anatomical shape of the
associated endplates. A surface formed by connecting the engaging
surface 132 on the top and bottom portion 106, 108, may be shaped
to conform to the anatomical shape of the associated endplates as
well. A second surface 134 extends from the engaging surface 132
back to the surface of the spacer 52. The second surface 134 also
forms an obtuse angle, but may form a right angle or be slightly
undercut. The protrusions 116 are generally of a unified
construction with the body. The protrusions 116 are separated by a
flat or scooped gap 136 between each protrusion and generally
extend over the entire superior and inferior surface of the
implant. However, the forward portion 102 has a portion without
protrusions, generally associated with the taper 128. In a
particular embodiment, protrusions 116 have a shape as generally
disclosed in U.S. Pat. Nos. 7,041,137 or 7,427,294, both of which
are assigned to the assignee of the present application and the
complete disclosures of which are incorporated herein by reference
for all purposes.
[0042] Referring now to FIG. 5, an elevation view of the rearward
portion 104 of spacer 52 is provided. Cavity 120 has a length
L.sub.1 and a height H.sub.1, and is sized to cooperatively engage
a fusion plate, which will be explained further below. A threaded
spacer bore 138 is in the cavity 120. The threaded spacer bore 138
is used, as will be explained further below, to couple the spacer
52 and the fusion plate. The threaded spacer bore 138 may have an
undercut. The threaded spacer bore 138 extends into the central
strut 126. The threaded spacer bore 138 has a first thread The
cavity 120 has an upper edge 140 at a transition to the top portion
106 and a lower edge 142 at a transition to the bottom portion 108.
A spacer channel 144 is accessible from cavity 120 and exists in
each of the upper edge 140 and the lower edge 142. As shown, there
are two spacer channels 144 proximate the upper edge 140 and two
spacer channels 144 proximate the lower edge 142. The spacer
channels 144 are shown as having generally half-cylindrical shapes,
such as a half pipe, U shapes, or V shapes that provides a guide
for a fastener, which will be explained further below. The spacer
channels 144 may be bores as well. The spacer channels 144 are
shown on both the upper and lower edge 140, 142 of the spacer 52.
In certain aspects of the technology, the spacer channels 144 may
only be oriented on the upper edge 140 or the lower edge 142.
[0043] As can be appreciated on reading the above, the spacer 52 is
provided with a length L.sub.2 and a height H.sub.1 to provide an
implant having a reasonably low profile to fit within the
intervertebral space with the spacing desired by the surgeon. To
anchor the spacer 52 to the superior and inferior vertebrae, a
fusion plate 54 (FIG. 1) is provided in certain aspects of the
technology of the present application. In many embodiments, the
plate provided has as low a profile as possible.
[0044] Referring now to FIGS. 6 and 7, a low profile fusion plate
200 consistent with the technology of the present application is
provided. The low profile fusion plate 200 has a forward face 202
and a rearward face 204 opposite the forward face 202. A sidewall
206 extends between the forward face 202 and the rearward face 204.
The edges of sidewall 206 may be beveled or chamfered to reduce
trauma. The low profile fusion plate 200 has a length L.sub.3, a
height H.sub.2, and a depth D.sub.2 to allow low profile fusion
plate 200 to cooperatively engage cavity 120. The low profile
fusion plate 200 has a plurality of fastener bores 208 that
generally correspond to the spacer channels 144 associated with the
spacer 52. The fastener bores 208 have an internal sidewall 210
forming a concave surface for cooperative engagement with a
fastener as will be described below. In some embodiments, the
concave surface formed by internal sidewall 210 generally is a
spherical shape or curvature. The forward face 202 may have a
plurality of protrusions 212 extending therefrom to cooperatively
engage the spacer channels 144. As shown, the protrusions 212 are
generally shaped as partial cylindrical surfaces.
[0045] The low profile fusion plate 200 further comprises a plate
bore 214. The plate bore 214 is adapted to be aligned with threaded
spacer bore 138. The plate bore 214 has an inner wall 216 and an
outer wall 218 (shown in FIG. 7) extending from forward face 202
into threaded spacer bore 138. The plate bore 214 at a distal end
thereof may have an outwardly turned lip 220. The plate bore 214
may be fitted to the spacer 52 by causing outwardly turned lip 220
to engage an undercut in the threaded spacer bore 138. Moreover,
the inner wall 216 may be provided with a shoulder 222, which may
be a ledge extending into the bore or a groove extending into the
wall.
[0046] In one aspect of the technology, the low profile fusion
plate 200 is coupled to the spacer 52 using a threaded connector
224 as shown in FIGS. 7 and 8. The threaded connector 224 has a
slotted head end 226. The slots form a number of compressible
protrusions 228 with outwardly turned lips 230. The threaded
connector 224 also has a threaded shaft 232. The threaded shaft 232
has an outer thread T.sub.2 adapted to cooperatively engage the
threads T.sub.1 of threaded spacer bore 138. The threaded connector
224 also comprises an inner threaded bore 234 having inner threads
T.sub.3 as will be explained further below.
[0047] The threaded connector 224 is coupled to the low profile
fusion plate 200 by inserting the slotted head end 226 of the
threaded connector 224 into the plate bore 214. The head end
compresses until the outwardly turned lips 230 extend past the
shoulder 222, at which point the slotted head expands to form a
snap lock between the threaded connector 224 and the low profile
fusion plate 200. In alternative embodiments, the threaded
connector 224 is coupled to the fusion plate 200 with a C-ring, a
split ring, or the like. The threaded connector 224 is next
threaded into the threaded spacer bore 138 to couple the low
profile plate to the spacer 52.
[0048] The spacer 52 and the low profile fusion plate 200 are
coupled to the superior and inferior vertebrae in this exemplary
aspect by a plurality of fasteners 236. The fasteners 236 may be
any conventional fasteners, such as, for example, a bone screw 236
as shown in FIG. 9. The bone screw 236 may comprise a head 238 and
a shaft 240 having threads T. The head 238 may be provided with a
convex lower surface 242 to cooperatively engage the internal
sidewall 210 of the fastener bores 208 in the low profile fusion
plate 200. The fasteners 236 are adapted to be threaded into the
endplates of the vertebrae 40, 42 by extending from the fastener
bores into the rearward portion 104 of the spacer 52 and out of at
least one of the top portion 106 or bottom portion 108.
[0049] The fasteners 236, as is conventionally known, may have a
tendency to reverse thread or back-out of the vertebrae 40, 42, the
spacer 52, and the fusion plate 54. A lock may be provided to
inhibit the fasteners 236 from reverse threading. In certain
aspects of the technology, the lock is similar to bushing 244 as
shown in FIG. 10. The bushing 244 comprises a top edge 246, a
bottom edge 248, and a bushing wall 250 extending between the top
and bottom edges 246, 248. The bushing sidewall 250 would have an
outer surface 252 to cooperatively engage internal sidewall 210 of
the fusion plate 54 and an inner surface 254 to cooperatively
engage the convex lower surface 242 of the head 238 of the fastener
236. The diameter 256 of the bushing may vary from the top edge 246
to the bottom edge 248.
[0050] As shown, in this exemplary embodiment, the bushing is
generally cylindrical in shape, but other shapes are possible. The
bushing 244 would have a diameter consistent with the diameter of
the plate bore 214 and fit between the head 238 of the fastener 236
and the internal sidewall 210 of the plate bore 214. As is
conventionally known, the bushing 244 may have a gap 258 to allow
the bushing 244 to be compressed and fitted into plate bore 214.
Moreover, the bushing 244 may have a number of slots 259 shown in
the bottom portion of the bushing 244, which could be in the top
portion of bushing 244 or a combination thereof as well. The slots
260 allow portions of the bushing 244 to flex to facilitate
implanting the fasteners 236. The hushing 244, as a fastener lock,
helps secure fastener 236 to plate 54.
[0051] Alternatively to bushings, the lock may be a cover plate.
Referring now to FIG. 11, a cover plate 260 is provided that is
usable with the low profile fusion plate 200. The cover plate 260
has a first face 262 and a second face 264 opposite the first face
262. The cover plate 260 may be shaped to fit into a recess 266 in
the low profile fusion plate 200, as shown in FIG. 6. The cover
plate 260, as shown, generally has a main body portion 268 with a
cover plate bore 270, which is shown as countersunk region 272. The
cover plate bore 270 includes a shoulder 274 separating a threaded
portion 276 having threads T.sub.4 of the cover plate bore 276 from
a non-threaded portion.
[0052] A connecting pin, which will be explained further below,
couples the cover plate 260 to the low profile fusion plate 200.
The cover plate bore 270 aligns with the plate bore 214 described
above. A plurality of arms 278 or flared extensions 280 extend from
the main body portion 268. The arms 278 extend from the main body
portion a sufficient distance such that at least a distal end 282
of the arm extends over fastener bore 208. The distal end 282 of
the arm, thus, resists the ability of the fastener 236 to reverse
thread from the implant. The flared extension(s) 280 extends from
the main body portion a sufficient distance such that at least a
distal end 282 of the flared extension(s) 280 extends over fastener
bore 208. The distal end 282 of the arm, thus, resists the ability
of the fastener 236 to reverse thread from the implant.
[0053] As can be appreciated, the shape, size, and whether arms or
flared extensions are associated with cover plate 260 depends in
part on the shape and size of fusion plate 54 (shown in FIG. 1).
The shape and size of the cover plate 260 specifically shown in
FIG. 11 is designed for use with the low profile fusion plate 200
shown in FIGS. 6 and 7. Generally, arms on cover plate 260 are
associated with a single fastener bore 208 and flared extension(s)
280 are associated with multiple fastener bores 208.
[0054] As described above, the cover plate bore 270 generally
aligns with the plate bore 214. The cover plate 260 is coupled to
the low profile fusion plate 200 using a connecting pin 286 as
shown in FIG. 12. The connecting pin 286 has a head 288 and a shaft
290. The head 288 has a lip 292 that abuts either the second face
262 or, if the cover plate bore 270 is countersunk, the shoulder
274. The shaft 290 has a proximal portion 294 proximate to the head
288, a distal portion 296 distal from the head 288, separated by a
medial portion 298. The proximal portion 294 has a first thread
T.sub.5 that is designed to cooperatively engage the threads
T.sub.4 of the cover plate 260. The medial portion 298 is shown as
being threadless and provides a transition from the proximal
portion to the distal portion. The distal portion 296 has a second
thread T.sub.6 that is designed to cooperatively engage the threads
T.sub.3 of the inner threaded bore 234 of the threaded connector
224. The connecting pin 286 has length L.sub.4 and couples the
cover plate 260 to the low profile fusion plate 200.
[0055] Referring now to FIG. 13, a low profile implant 300
consistent with the above is provided. The low profile implant 300
includes spacer 52 having the rearward portion 104 (or the anterior
portion for the exemplary spinal application) with voids 122 and
124 separated by a central strut 126. The protrusions 116 are shown
on the top (or superior) portion. The cavity 120 in the rearward
portion 104 has the low profile fusion plate 200 therein. The
fastener bores 208 of the low profile fusion plate 200 are aligned,
generally, with the spacer channels 144. The fasteners 236 extend
through the fastener bores 208, spacer channels and extend out of
the top portion and bottom portion of the spacer 52. The cover
plate 260 is provided with arms 278 covering two of the fastener
bores 208 and flared extensions 280 covering the other two of the
fastener bores 208. The connecting pin 286 is then moved into cover
plate bore 270. In a particular embodiment, the overall height of
plate 200 (treasured along the inferior to superior direction) is
similar to or the same as the overall height of the spacer 52. In
this embodiment, the implant 300 is a "zero profile" implant in
that the plate 200 does not extend above or below the height of the
disc space into which spacer 52 is disposed.
[0056] The low profile fusion plate 200 may not be usable in
certain aspects of the technology. For example, the end plate or
size of the vertebrae may not support a fastener in such a manner,
the angle necessary to facilitate the fastener 236 extending from
the rearward portion 104 through the top portion 106 or bottom
portion 108 may not be possible, to name but two situations in
which the low profile construction as shown in FIG. 13 may not be
possible or desirable. In these cases, it may be necessary to
provide a fusion plate with a slightly higher profile than the low
profile fusion plate 200, sometimes referred to as a middle profile
fusion plate 400 of "single flange plate" as shown in FIGS. 14 and
15.
[0057] The middle profile fusion plate 400 has a main body portion
401 similar in construction to the low profile fusion plate 200
including a forward face 402 and a rearward face 404 opposite the
forward face 402. A sidewall 406 extends between the forward face
402 and the rearward face 404. The edges of sidewall 406 may be
beveled or chamfered to reduce trauma. The forward face 402 is
generally sized to fit the cavity 120 of the spacer 52. Thus, the
forward face 402 may have a length L.sub.3, a height H.sub.2, and a
depth D.sub.2 to allow middle profile fusion plate to cooperatively
fit in cavity 120. The middle profile fusion plate 400 also has a
first extension side 408 that extends from the main body portion
401 beyond the height H.sub.2 in only one of the superior or
inferior directions, which in this exemplary embodiment, is shown
as extending in the inferior direction. A distal edge of the first
extension side 408 may have a concave shape. The first extension
side 408 has an angled forward face 402 and an angled rearward face
404. The first extension side 408 is angled at an angle 410 (shown
in FIG. 15) with respect to the rearward face 404 to allow for the
first extension side 408 to overlap one of the bones to be fused.
The angle 410 provides that the portion of first extension side 408
distal from the rearward face 404 is offset from the spacer 52
rearward portion 104. While described as an angle for convenience,
the first extension side 408 may have a slight curvature or
sinusoidal shape rather than a straight angled surface. In a
particular embodiment, the first extension side 408 is curved in a
manner such that the distal tip portion of extension side 408 is
generally parallel to main body portion 401.
[0058] As can be appreciated, the middle profile fusion plate 400
has a plurality of fastener bores 412 in the forward and rearward
faces 402, 404 that cooperate with spacer channels in the implant
to allow a set of fasteners to extend from the middle profile
fusion plate 400 through the spacer 52 into the endplates of the
associated vertebrae 40, 42. While the spacer could be formed
consistent with spacer 52 above, the spacer in this exemplary
embodiment may be provided, with spacer channels 144 on the upper
edge 140 and no spacer channels 144 on the lower edge 142 as a
design option.
[0059] A second plurality of fastener bores 414 are provided in the
first extension side 408. The fastener bores 414 are arranged to
allow the fastener 236 to extend through the angled forward face
402 and the angled rearward face 404 directly into, for example, a
pedicle of the inferior vertebrae 42. The fastener bores 412, 414
have an internal sidewall 416 forming a concave surface for
cooperative engagement with the convex lower surface 242 of head
238 of fastener 236. The middle profile fusion plate 400 includes a
plate bore 418 similar to plate bore 214 to receive the threaded
connector 224 that couples the middle profile fusion plate 400 to
the spacer 52.
[0060] Referring now to FIGS. 16 and 17, a perspective view and
side elevation view of a middle profile cover plate 120 is shown.
The cover plate 420 has a first face 422 and a second face 424
opposite the first face 422, which is similar to cover plate 260
described above. The cover plate 420 may be shaped to fit into a
recess 426 in the middle profile fusion plate 400, as shown in FIG.
14. The cover plate 420, as shown, generally has a main body
portion 428 with a cover plate bore 430, which may be constructed
similar to cover plate bore 270 described above to receive the
connecting pin 286 to couple the cover plate 420 to the middle
profile fusion plate 400. The middle profile fusion plate 400
comprises a plurality of arms 432 extending at an angle 410
extending from main body portion 428 and a flared extension 434
extending from the main body portion 428. The arms 128 are angled
to coincide with the angle 410 of the first extension side 408 such
that the arms 432 extend over a portion of the fastener bores 414.
The arms 432 may have a web of material (not shown) between them to
form a flared extension instead of arms as a matter of design
choice. Also, the arms 432 are designed to cooperatively engage the
recess 426 and, as such, may have a curvature or sinusoidal
shape.
[0061] The arms extend from the main body portion a sufficient
distance such that at least a distal end 436 of the arm extends
over fastener bores 414. The distal end 436 of the arm, thus,
resists the ability of the fastener 236 to reverse thread from the
implant. The flared extension(s) 434 extends from the main body
portion a sufficient distance such that at least distal ends 438 of
the flared extensions) 434 extend over fastener bores 412. The
distal ends 438, thus, resist the ability of the fasteners 236 to
reverse thread from the implant.
[0062] As can be appreciated, the shape, size, and whether arms or
flared extensions are associated with cover plate 420 depends in
part on the shape and size of fusion plate 54 (shown in FIG. 1).
The shape and size of the cover plate 420, specifically shown in
FIGS. 16 and 17, is designed for use with the middle profile fusion
plate 400 shown in FIGS. 14 and 15. Generally, arms on cover plate
432 are associated with a single fastener bore 414 and flared
extension(s) 434 are associated with multiple fastener bores
412.
[0063] Referring now to FIG. 18, a middle profile implant 450
consistent with the above is provided. The middle profile implant
450 includes spacer 52 having the rearward portion 104 (or the
anterior portion for the exemplary spinal application with voids
122 and 124 separated by a central strut 126. The protrusions 116
are shown on the top (or superior) portion. The cavity 120 in the
rearward portion 104 has the middle profile fusion plate 400
therein. The fastener bores 412 of the middle profile fusion plate
400 are aligned, generally, with the spacer channels 144. The
fasteners 236 extend through the fastener bores 412 and spacer
channels and extend out of the top portion and bottom portion of
the spacer 52. The fastener bores 414 in the first extension side
408 of the middle profile fusion plate 400 are aligned with the
inferior vertebrae 42 in this example, but the fastener bores 414
may be aligned with the superior vertebrae 40 or other bone
surfaces depending on the use. The fasteners 236 extend through the
fastener bores 414 and into the pedicle or anterior side 46 of the
inferior vertebrae 42. Depending on the dimensions, the fasteners
236 extending through the fastener bores 414 may not pass through
spacer channels 144, and in those cases, the spacer channels may be
removed. In a particular embodiment, the fasteners 236 extending
through fastener bores 414 are generally parallel to spacer 52
surface. In this manner, fasteners 236 may be generally orthogonal
to the bony surface to which they are coupled. In alternative
embodiments, fasteners 236 extending through fastener bores 414 are
at a diverging or converging angle relative to spacer 52 upper or
lower surfaces. The cover plate 260 is provided with arms 432
covering two of the fastener bores 414 and flared extensions 434
covering the other two of the fastener bores 412. Generally, the
arms 432 are associated with the bores on the first extension side
and the flared extension is associated with the bores on the
remainder of the fusion plate. The connecting pin 286 couples the
cover plate 420 to the middle profile fusion plate 400.
[0064] In some applications, the middle profile fusion plate 400
may not be usable or desirable for any number of reasons, in these
cases, it may be necessary to provide a fusion plate with a
slightly higher profile than the middle profile fusion plate 400,
sometimes referred to as a high profile fusion plate 500 or "two
flange plate" as shown in FIGS. 19 and 20. The high profile fusion
plate 500 has a main body portion 501 similar in construction to
the low profile fusion plate 200 including a forward face 502 and a
rearward face 504 opposite the forward face 502. A sidewall 506
extends between the forward face 502 and the rearward face 504. The
edges of sidewall 506 may be beveled or chamfered to reduce trauma.
The forward face 502 is generally sized to fit the cavity 120 of
the spacer 52. Thus, the forward face 502 may have a length
L.sub.3, a height H.sub.2, and a depth D.sub.2 to allow the high
profile fusion plate to cooperatively engage cavity 120.
[0065] The high profile fusion plate 500 also has a first extension
side 508 that extends beyond the height H.sub.2 in one of the
superior or inferior directions, which in this exemplary embodiment
is shown as extending in the inferior direction and a second
extension side 509. The first and second extension sides 508, 509
may be pinched such that a distal edge of the first and second
extension sides 508, 509 has a concave shape. The first extension
side 508 has an angled forward face 502.sub.1 and an angled
rearward face 504.sub.1. The second extension side has an angled
forward face 502.sub.2 and an angled rearward face 504.sub.2. The
first extensions side 508 and the second extension side 509 are
angled at an angle 510 with respect to the rearward face 504 to
allow for each of the first and second extension sides 508, 509 to
overlap opposite ones of the bones to be fused. The angle 510
provides that the portions of the first and second extension sides
508, 509 distal from the rearward face 504 are offset from the
spacer 52 rearward portion 104. While described as an angle for
convenience, the first and second extension sides 508, 509 may have
a slight curvature or sinusoidal shape rather than a straight
angled surface. One or both extension sides 508, 509 may have an
orientation or curvature, and/or fastener bores similar to that
described for first extension side 408 above. Moreover, while
described as symmetrical, the first extension side 508 and the
second extension side 509 may be asymmetrical and may be
necessarily so under certain anatomical conditions.
[0066] As can be appreciated, the high profile fusion plate 500 has
a plurality of fastener bores 512 in the first and second extension
sides 508, 509 that cooperate with a set of fasteners to extend
from the high profile fusion plate 500 into the pedicle or anterior
side of the associated vertebrae 40, 42. While the spacer could be
formed consistent with spacer 52 above, the spacer in this
exemplary embodiment may be provided without spacer channels 144 on
the upper and lower edges 140, 142 as a design option. The fastener
bores 512 have an internal sidewall 514 thrilling a concave surface
for cooperative engagement with the convex lower surface 242 of
head 238 of fastener 236. The high profile fusion plate 500
includes a plate bore 518 similar to plate bore 214 to receive the
threaded connector 224 that couples the high profile plate 500 to
the spacer 52.
[0067] Referring now to FIGS. 21 and 22, a perspective view and
side elevation view of a high profile cover plate 520 is shown. The
cover plate 520 has a first face 522 and a second face 524 opposite
the first face 522, which is similar to cover plates 260, 420
described above. The cover plate 520 may be shaped to fit into a
recess 526 in the fusion plate 500, as shown in FIG. 19. The cover
plate 520, as shown, generally has a main body portion 528 with a
cover plate bore 530, which is may be constructed similar to cover
plate bore 270, 430 described above to receive the connecting pin
286 to couple the cover plate 520 to the high profile fusion plate
500.
[0068] The cover plate 520 comprises a plurality of arms 532
extending at an angle 510 extending from main body portion 528. The
arms 532 are angled to coincide with the angle 510 of the first and
second extension sides 508, 509 such that the arms 532 extend over
a portion of the fastener bore 512. The arms 532 may have a web of
material 534 there between. The web of material 534 may be extended
from a flared extension instead of arms as a matter of design
choice. Also, the arms 532 are designed to cooperatively engage the
recess 526 and, as such, may have a curvature or sinusoidal shape.
The arms extend from the main body portion a sufficient distance
such that at least a distal end 536 of the arm extends over
fastener bores 512. The distal end 536 of the arm, thus, resists
the ability of the fastener 236 to reverse thread from the implant.
As shown in FIGS. 21 and 22, the distal end 536 of the arms 532 may
have pads 538 that extend from the arms 532 into the fastener bores
512 to contact the fastener heads 238. The pads 538 shown herein
may be provided on any of the arms or flared extensions described
above.
[0069] As can be appreciated, the shape, size, and whether arms or
flared extensions are associated with cover plate 520 depends in
part on the shape and size of fusion plate 54 (shown in FIG. 1).
The shape and size of the cover plate 520, specifically shown in
FIGS. 21 and 22, is designed for use with the high profile fusion
plate 500 shown in FIGS. 19 and 20. Generally, arms on cover plate
520 are associated with a single fastener bore 512 and flared
extension(s) having the web of material 534 may be associated with
multiple fastener bores 512.
[0070] Referring now to FIG. 23, a high profile implant 550
consistent with the above is provided. The high profile implant 550
includes spacer 52 having the rearward portion 104 (or the anterior
portion for the exemplary spinal application) with voids 122 and
124 separated by a central strut 126. The protrusions 116 are shown
on the top (or superior) portion. The cavity 120 in the rearward
portion 104 has the high profile fusion plate 500 therein. The
fastener bores 512 in the first and second extension sides 508, 509
of the high profile fusion plate 500 are aligned with the pedicles
or the anterior sides of the inferior and superior vertebrae 42, 40
in this example, but the fastener bores 512 may be aligned with
other bone surfaces depending on the use. The fasteners 236 extend
through the fastener bores 512 and into the pedicle or anterior
side 46 of the superior and inferior vertebrae 40, 42. Depending on
the dimensions, the fasteners 236 extending through the fastener
bores 512 may not pass through spacer channels 114, and in those
cases, the spacer channels may be removed. The fasteners 236 may be
generally orthogonal to anterior sides 46 of vertebrae 40, 42, or
may alternatively enter the vertebrae at divergent or convergent
angles in one or more planes. The cover plate 520 is provided with
arms 532 covering the fastener bores 512. The connecting pin 286
couples the cover plate 520 to the high profile fusion plate
500.
[0071] Notice that the above described implant was described with
reference to a low profile fusion plate, a middle profile fusion
plate, and a high profile fusion plate. On reading the disclosure,
one of ordinary skill in the art will now recognize that the use of
low profile, middle profile, and high profile are relative terms to
distinguish the above described embodiments and are provided for
reference and should not be construed to limit the technology of
the present application.
[0072] The technology of the present application also includes
methods for implanting the apparatus described above. While the
methodology is provided in certain discrete steps, one of ordinary
skill in the art will recognize that the steps identified may be
broken into multiple steps or multiple steps may be combined into a
single step. Moreover, the sequence of events provided may be
altered or rearranged without departing from the technology of the
present application. With that in mind, the surgeon would first
determine the appropriate spacer to be used. In spinal
applications, the spacer may be sized to restore the height
corresponding to the height of a health vertebra. In other
applications, the spacer may be sized to most readily promote
fusion or the like.
[0073] Once the appropriate spacer is identified, the threaded
connector may be threaded into the spacer bore, although the
threaded connector may already be threaded to the spacer. The
surgeon would next implant the spacer and threaded connector to the
fusion site. Notice the threaded connector may be threaded when the
spacer is in the fusion site as a matter of surgical technique.
Next the surgeon would determine whether a low, middle, or high
profile fusion plate is appropriate for the patient's anatomy. The
fusion plate would be coupled to the threaded connector. For
example, the protrusions on the slotted head may be compressed and
fitted into the fusion bore until a snap fit is formed between the
slotted head and the fusion plate. The fusion plate may be fitted
to the threaded connector such that the spacer and fusion plate are
placed at the fusion site at the same time.
[0074] The surgeon would next use fasteners to couple the implant
to the honey segments, such as the superior and inferior vertebrae
for a spinal application. Finally, a cover plate that corresponds
to the fusion plate is selected and coupled to the fusion plate.
For example, the connecting pin may be threaded through the cover
plate bore and fusion plate bore into the internal threads of the
threaded connector to couple the cover plate, fusion plate, and
spacer.
[0075] The implant may be supplemented with bone growth promoting
substances to facilitate fusion of adjacent vertebrae between
spinous processes, laminae, transverse processes, facets, and/or
other spinal structures. The bone growth promoting substances may
be spaced from the implant, placed adjacent the implant, sandwiched
between the implant and underlying bone, placed inside the implant,
coated onto the implant, and/or otherwise placed relative to the
implant. If it is coated onto the implant, it may cover the entire
implant or only selected portions of the implant such as the
extensions, fasteners, spinous process contacting portions of the
spacer, and/or other portions.
[0076] As used herein, bone growth promoting substances may include
bone paste, bone chips, hone strips, structural bone grafts,
platelet derived growth factors, bone marrow aspirate, stem cells,
bone growth proteins, bone growth peptides, bone attachment
proteins, bone attachment peptides, hydroxylapatite, calcium
phosphate, other suitable bone growth promoting substances, and/or
combinations thereof.
[0077] The implant and any associated cerclage or other components
may be made of any suitable biocompatible material including among
others metals, resorbable ceramics, non-resorbable ceramics,
resorbable polymers, and non-resorbable polymers. Some specific
examples include stainless steel, titanium and its alloys including
nickel-titanium alloys, tantalum, hydroxylapatite, calcium
phosphate, bone, zirconia, alumina, carbon, bioglass, polyesters,
polylactic acid, polyglycolic acid, polyolefins, polyamides,
polyimides, polyacrylates, polyketones, fluoropolymers, and/or
other suitable biocompatible materials and combinations
thereof.
[0078] Various methods, systems and devices for treating spinal
fractures are disclosed. While detailed descriptions of one or more
embodiments have been provided above, various alternatives,
modifications, and equivalents are possible. Therefore, the above
description should not be taken as limiting the scope of possible
embodiments, which is defined by the appended claims.
* * * * *