U.S. patent application number 12/961858 was filed with the patent office on 2011-03-31 for vertebral fusion implants and methods of use.
This patent application is currently assigned to Warsaw Orthopedic, Inc.. Invention is credited to Eric S. Heinz.
Application Number | 20110077741 12/961858 |
Document ID | / |
Family ID | 38712973 |
Filed Date | 2011-03-31 |
United States Patent
Application |
20110077741 |
Kind Code |
A1 |
Heinz; Eric S. |
March 31, 2011 |
Vertebral Fusion Implants and Methods of Use
Abstract
A vertebral implant for use in vertebral fusion surgeries
includes a body with an exterior surface and an interior surface.
The interior surface defines an interior cavity into which bone
growth promoting materials such as bone graft are insertable. The
body also includes a plurality of apertures that extend from the
exterior surface to the interior surface. Further, the vertebral
implant includes a cutting feature to decorticate bone that
protrudes outward from the exterior surface at each aperture. The
cutting feature is shaped so that as a cutting force is applied to
move the implant in a cutting direction, the removed bone matter is
directed through the apertures and into the interior cavity.
Inventors: |
Heinz; Eric S.; (Mountain
View, CA) |
Assignee: |
Warsaw Orthopedic, Inc.
Warsaw
IN
|
Family ID: |
38712973 |
Appl. No.: |
12/961858 |
Filed: |
December 7, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11403348 |
Apr 13, 2006 |
7850736 |
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12961858 |
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Current U.S.
Class: |
623/17.16 |
Current CPC
Class: |
A61B 17/1671 20130101;
A61F 2002/30322 20130101; A61F 2/446 20130101; A61F 2/447 20130101;
A61F 2230/0069 20130101; A61F 2002/30225 20130101; A61F 2310/00011
20130101; A61F 2002/448 20130101; A61F 2002/30252 20130101; A61F
2002/30133 20130101; A61F 2/4465 20130101; A61F 2002/30593
20130101; A61F 2002/30841 20130101; A61F 2310/00179 20130101; A61F
2002/30784 20130101; A61F 2/44 20130101; A61F 2/4455 20130101; A61F
2002/4629 20130101; A61F 2230/0015 20130101; A61F 2230/0073
20130101; A61F 2002/2835 20130101; A61F 2250/0026 20130101 |
Class at
Publication: |
623/17.16 |
International
Class: |
A61F 2/44 20060101
A61F002/44 |
Claims
1. An implant for insertion into a patient between first and second
vertebral members, the implant comprising: a hollow body with an
enclosed interior cavity, the body including a first side
configured to contact against the first vertebral member and a
second side configured to contact against the second vertebral
member after the implant has been inserted into the patient; a
plurality of apertures and cutting features positioned about the
first and second sides, each of the apertures extending through one
of the first and second sides, and each of the cutting features
extending outward from the body at one of the plurality of
apertures, each of the cutting features including a tapered shape
that terminates at a pointed tip that cuts into one of the first
and second vertebral members; the enclosed interior cavity
configured to capture and maintain portions of the first and second
vertebral members that are cut by the cutting features and enter
the enclosed interior cavity through the plurality of
apertures.
2. The implant of claim 1, wherein each of the cutting features
includes a leading surface relative to a cutting direction that
extends at least partly around the corresponding aperture and is
concave relative to the aperture.
3. The implant of claim 1, further comprising a plurality of second
cutting features that each extend outward from one of the first and
second sides and are spaced away from each of the plurality of
apertures.
4. The implant of claim 1, wherein the plurality of cutting
features positioned on the first side include different
heights.
5. The implant of claim 1, wherein the cutting features in
proximity to a leading end of the body include a smaller height
than the cutting features in proximity to an opposing trailing end
of the body.
6. The implant of claim 1, wherein the body includes a leading end
and a trailing end that are parallel to each other.
7. The implant of claim 1, wherein the plurality of cutting
features on the first side are equidistant from a common point on
the first side.
8. The implant of claim 1, wherein the body includes an exterior
geometry that is different than an interior geometry with the body
having different thicknesses at various sections around the
interior cavity.
9. An implant for insertion into a patient between first and second
vertebral members, the implant comprising: a hollow body with an
enclosed interior cavity, the body including a first section
configured to contact against the first vertebral member and a
second section configured to contact against the second vertebral
member after the implant has been inserted into the patient; a
plurality of apertures and cutting features positioned about the
first section, each of the apertures extending through the first
section and into the interior cavity, and each of the cutting
features extending outward from the first section at one of the
plurality of apertures; a first one of the cutting features
includes a first leading surface facing a first direction and a
second one of the cutting features includes a second leading
surface facing a different second direction; the enclosed interior
cavity configured to capture and maintain portions of the first and
second vertebral members that are cut by the cutting features and
enter the enclosed interior cavity through the plurality of
apertures.
10. The implant of claim 9, wherein the first leading surface and
the second leading surface face in opposing directions.
11. The implant of claim 9, wherein the body further includes a
leading end and a trailing end each extending between the first and
second sections, the first leading surface facing towards the
leading end and the second leading surface facing towards the
trailing end.
12. The implant of claim 9, further including a second plurality of
apertures and cutting features positioned about the second section,
each of the apertures extending through the second section and into
the interior cavity and each of the cutting features extending
outward from the second section at one of the plurality of
apertures.
13. The implant of claim 9, wherein each of the cutting features
includes a tapered shape that terminates at a pointed tip and is
configured to cut into the first vertebral member.
14. The implant of claim 9, wherein a height of the plurality of
cutting features increases from a leading end of the body to a
trailing end of the body.
15. An implant for insertion into a patient between first and
second vertebral members, the implant comprising: a hollow body
with an enclosed interior cavity, the body including a first side
configured to contact against the first vertebral member and a
second side configured to contact against the second vertebral
member after the implant has been inserted into the patient, the
first side including an inner surface that faces into the interior
cavity and an opposing outer surface; a plurality of paired cutting
features positioned about the first side, each of the paired
cutting features including an aperture that extends through the
first side and into the interior cavity and a tooth at the aperture
that extends outward from the outer surface; the body having
different thickness over the first side with the inner surface of
the first side having a different geometry than the outer surface
of the first side; the enclosed interior cavity configured to
capture and maintain portions of the first vertebral member that
are cut by the plurality of paired cutting features and enter the
enclosed interior cavity through the plurality of apertures.
16. The implant of claim 15, wherein the body includes a
cylindrical shape with the plurality of paired cutting features
extending around an exterior surface that includes the first and
second sides.
17. The implant of claim 15, wherein the body includes a tapered
shape that changes in height between a leading end and a trailing
end.
18. The implant of claim 15, wherein a first portion of the
plurality of paired cutting features are oriented in a first
direction and a second portion of the plurality of paired cutting
features are oriented in a different second direction.
19. The implant of claim 15, further comprising a second plurality
of paired cutting features positioned about the second side, each
of the second plurality of paired cutting features includes an
aperture that extends through the second side and into the interior
cavity and a tooth at the aperture that extends outward.
20. The implant of claim 15, wherein the body includes a
substantially rectangular cross-sectional shape.
Description
RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/403,348, filed on Apr. 13, 2006, and
incorporated in its entirety herein by reference.
BACKGROUND
[0002] Vertebral implants are often used in the surgical treatment
of spinal disorders such as degenerative disc disease, disc
herniations, curvature abnormalities, and trauma. Many different
types of treatments are used. In some cases, spinal fusion is
indicated to inhibit relative motion between vertebral bodies.
Motion between vertebral bodies is naturally provided in part by
the flexible disc material that resides between adjacent vertebral
bodies. Spinal fusion often involves the removal of the vertebral
disc and insertion of an interbody implant to create a fused
junction between a pair of vertebral bodies. Fusion may also occur
at multiple vertebral levels or between vertebral bodies that are
several levels apart. Interbody implants may be coated, filled, or
surrounded by growth promoting materials such as BMP, DBM,
allograft, autograft or other osteoinductive growth factors to
facilitate fusion between the vertebral bodies and the implant.
[0003] Conventionally, interbody implants are inserted into the
space between vertebral bodies after the disc material has been
removed and after the vertebral end plates are prepared. This end
plate preparation may include shaping, planing, scraping, or other
decorticating processes in which bone matter is removed and blood
flow is initiated to enhance bone growth into the interbody
implant. Ideally, new bone matter forms and bridges the gap between
the vertebral bodies and the growth promoting material. In certain
instances, particularly where the growth promoting material is
contained within the interbody implant, new bone matter does not
sufficiently span the gap between the vertebral endplate and the
growth promoting material. Consequently, the fusion site may be
compromised.
SUMMARY
[0004] Illustrative embodiments disclosed herein are directed to a
vertebral implant for use in vertebral fusion surgeries. The
vertebral implant includes a body with an exterior surface and an
interior surface. The body may be shaped for use in ALIF, PLIF, and
TLIF surgeries.
[0005] The implant may include a hollow body with an enclosed
interior cavity. The body may include a first side configured to
contact against the first vertebral member and a second side
configured to contact against the second vertebral member after the
implant has been inserted into the patient. A plurality of
apertures and cutting features may be positioned about the first
and second sides. Each of the apertures may extend through one of
the first and second sides. Each of the cutting features may extend
outward from the body at one of the plurality of apertures. Each of
the cutting features may include a tapered shape that terminates at
a pointed tip that cuts into one of the first and second vertebral
members. The enclosed interior cavity may be configured to capture
and maintain portions of the first and second vertebral members
that are cut by the cutting features and enter the enclosed
interior cavity through the plurality of apertures.
[0006] The implant may include a hollow body with an enclosed
interior cavity. The body may include a first section configured to
contact against the first vertebral member and a second section
configured to contact against the second vertebral member after the
implant has been inserted into the patient. A plurality of
apertures and cutting features may be positioned about the first
section. Each of the apertures may extend through the first section
and into the interior cavity. Each of the cutting features may
extend outward from the first section at one of the plurality of
apertures. A first one of the cutting features may include a first
leading surface facing a first direction and a second one of the
cutting features may include a second leading surface facing a
different second direction. The enclosed interior cavity may be
configured to capture and maintain portions of the first and second
vertebral members that are cut by the cutting features and enter
the enclosed interior cavity through the plurality of
apertures.
[0007] The implant may include a hollow body with an enclosed
interior cavity. The body may include a first side configured to
contact against the first vertebral member and a second side
configured to contact against the second vertebral member after the
implant has been inserted into the patient. The first side may
include an inner surface that faces into the interior cavity and an
opposing outer surface. A plurality of paired cutting features may
be positioned about the first side. Each of the paired cutting
features may include an aperture that extends through the first
side and into the interior cavity and a tooth at the aperture that
extends outward from the outer surface. The body may have different
thickness over the first side with the inner surface of the first
side having a different geometry than the outer surface of the
first side. The enclosed interior cavity may be configured to
capture and maintain portions of the first vertebral member that
are cut by the plurality of paired cutting features and enter the
enclosed interior cavity through the plurality of apertures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a perspective view of a vertebral implant
according to one embodiment;
[0009] FIG. 2 is a side section view, including a partial detail,
of a vertebral implant according to one embodiment;
[0010] FIG. 3 is a side section view of a vertebral implant
according to one embodiment shown relative to vertebral bodies;
[0011] FIG. 4 is a side section view of a vertebral implant
according to one embodiment shown relative to vertebral bodies;
[0012] FIG. 5 is a side section view of a vertebral implant
according to one embodiment shown relative to vertebral bodies;
[0013] FIG. 6 is a front view of a vertebral implant according to
one embodiment;
[0014] FIG. 7 is a side view of a vertebral implant according to
one embodiment;
[0015] FIG. 8 is a side view of a vertebral implant according to
one embodiment shown relative to vertebral bodies;
[0016] FIG. 9 is a side view of a vertebral implant according to
one embodiment shown relative to vertebral bodies;
[0017] FIG. 10 is a top view of a vertebral implant according to
one embodiment shown relative to a vertebral body;
[0018] FIG. 11 is a perspective view of a vertebral implant
according to one embodiment;
[0019] FIG. 12 is a front view of a vertebral implant according to
one embodiment;
[0020] FIG. 13 is a top view of a vertebral implant according to
one embodiment;
[0021] FIG. 14 is a side view of a vertebral implant according to
one embodiment;
[0022] FIG. 15 is a side view of a vertebral implant according to
one embodiment;
[0023] FIG. 16 is a side view of a vertebral implant according to
one embodiment;
[0024] FIG. 17 is a partial section view of a vertebral implant
illustrating a profile of a cutting feature according to one
embodiment;
[0025] FIG. 18 is a partial section view of a vertebral implant
illustrating a profile of a cutting feature according to one
embodiment;
[0026] FIG. 19 is a partial section view of a vertebral implant
illustrating a profile of a cutting feature according to one
embodiment;
[0027] FIG. 20 is a partial section view of a vertebral implant
illustrating a profile of a cutting feature according to one
embodiment;
[0028] FIG. 21 is a top view of a vertebral implant according to
one embodiment; and
[0029] FIG. 22 is a side section view of a vertebral implant
according to one embodiment.
DETAILED DESCRIPTION
[0030] The various embodiments disclosed herein relate to a
vertebral implant in which bone-contact surfaces are constructed
with cutting features that remove bone matter from vertebral bodies
in the human spine. Further, the cutting features are configured to
guide the removed bone matter through apertures in the vertebral
implant and into contact with bone-growth-promoting material
contained therein. Reference number 10 in FIG. 1 generally
identifies one example of an implant with cutting features on the
bone-contact surfaces. The representative vertebral implant 10 is
illustrated as a disc replacement implant that is inserted between
vertebral bodies of a patient as part of a disc replacement
surgery. The exemplary vertebral implant 10 includes a perimeter
wall 12 that extends between a superior surface 14 and an inferior
surface 16. The superior surface 14 and inferior surface 16 are
bone-contact surfaces in that they are positioned adjacent to and
face a vertebral endplate once the vertebral implant 10 is inserted
into a patient.
[0031] The vertebral implant 10 shown in FIG. 1 includes a simple
disc shape, though other shapes and contours may be used. In
further embodiments, the vertebral implant 10 may take on other
types of configurations, such as, for example, a circular shape,
kidney shape, semi-oval shape, bean-shape, D-shape,
elliptical-shape, egg-shape, or any other shape that would occur to
one of skill in the art. The vertebral implant 10 may take on
substantially solid configurations, such as, for example,
block-like or plate-like configurations that do not define an open
inner region. In other embodiments, the vertebral implant 10 could
also be described as being annular, U-shaped, C-shaped, V-shaped,
horseshoe-shaped, semi-circular shaped, semi-oval shaped, or other
similar terms defining an implant including at least a partially
open or hollow construction.
[0032] The vertebral implant 10 may be constructed from
biocompatible metal alloys such as titanium, cobalt-chrome, and
stainless steel. The vertebral implant 10 may be constructed from
non-metallic materials, including for example, ceramics, resins, or
polymers, such as UHMWPE and implantable grade polyetheretherketone
(PEEK) or other similar materials (e.g., PAEK, PEKK, and PEK). The
vertebral implant 10 may be constructed of synthetic or natural
bone or bone composites. Those skilled in the art will comprehend a
variety of other material choices that are suitable for the
illustrated vertebral implant 10.
[0033] The exemplary vertebral implant 10 includes a plurality of
apertures 18 disposed about the superior surface 14. The apertures
18 are shown as substantially cylindrical, though it should be
understood that other shapes, including for example, square, hex,
triangular, diamond, crescent, elliptical apertures may be used.
Additional apertures 18 are also disposed about the inferior
surface 16, though their existence is not immediately apparent from
FIG. 1. In an alternative embodiment, the apertures 18 are disposed
about one of the superior 14 and inferior 16 surfaces but not the
other. The vertebral implant 10 also includes one or more side
apertures 26 disposed about the perimeter wall 12. The side
apertures 26 provide a passage from the exterior of the vertebral
implant into an interior cavity 30 that is more clearly visible in
FIG. 2 and discussed in greater detail below. The side apertures 26
may also provide a location at which to grasp the vertebral implant
10 during surgical installation.
[0034] In the illustrated embodiment, a cutting feature 20 is
associated with each aperture 18. In other embodiments, the
vertebral implant 10 may have apertures without associated cutting
features 20 or cutting features 20 without associated apertures 18.
The cutting features 20 may be implemented as teeth, hooks,
serrations, blades, or other features adapted to remove cortical
bone from a vertebral body as the vertebral implant 10 is inserted.
The cutting features 20 may be constructed of the same material as
the remainder of the vertebral implant 10 as described above. In
one embodiment, the cutting features 20 are constructed of rigid,
hardened materials such as titanium, ceramic, or polymers
impregnated with carbon fibers. In the embodiment illustrated in
FIG. 1, the cutting features 20 are oriented in a common direction
so as to define a cutting direction C. As described below, this
cutting direction C may coincide with the insertion direction.
Accordingly, the vertebral implant 10 may include an insertion
feature 36 to which an insertion tool (see FIG. 4) may be attached.
The insertion feature 36 may be an aperture, such as a threaded
hole or a slot that is engageable by a male insertion tool.
Alternatively, the insertion features 36 may be a protruding
feature that is engageable by a female insertion tool.
[0035] The lateral cross section view of the vertebral implant 10
provided in FIG. 2 shows the aforementioned interior cavity 30.
This cavity 30 is defined in part by an interior surface 28. In the
embodiment shown, the interior surface 28 follows a contour similar
to the outer surfaces 12, 14, 16 of the vertebral implant such that
the thickness T of wall 34 is approximately the same throughout. In
other embodiments, the interior cavity 30 may include a different
shape than the outer geometry of the vertebral implant 10. In
either case, the interior cavity 30 is configured to receive bone
growth promoting material such as BMP, DBM, allograft, autograft or
other osteoinductive growth factors to facilitate fusion between
vertebral bodies and the implant 10. The apertures 18 disposed
about the superior surface 14 and inferior surface 16 provide a
passage through which blood and removed bone material may pass from
outside the vertebral implant 10 to the interior cavity 30 where
the bone growth promoting material is placed. This removed bone
material may be scoured by the cutting features 20 and diverted
through the apertures 18 into the interior cavity 30 as denoted by
the arrows labeled B.
[0036] The right side of FIG. 2 also depicts a detail view of the
exemplary cutting features 20. The cutting features 20 extend
generally outward from the superior surface 14 and inferior surface
16. Relative to the cutting direction C, the cutting features 20
include a leading surface 24 and a trailing surface 32. The leading
surface 24 and trailing surface 32 curve generally towards the
cutting direction C. This curvature improves the overall strength
and cutting ability of the cutting features 20. Further, the
leading surface 24 and the trailing surface converge at a cutting
edge 22 that is advantageously sharpened to allow the cutting
feature 20 to remove bone material from vertebral bodies during
implant 10 insertion. Notably, the cutting feature 20 is raked in
the cutting direction such that the cutting edge 22 is disposed at
least partly above the aperture 18 with which the cutting feature
20 is associated.
[0037] In the depicted embodiment, the leading surface 24 of the
cutting feature 20 extends generally upward from the aperture 18 in
the walls 34 of the vertebral implant 10. In this configuration,
the leading surface 24 and aperture 18 share a common wall. Thus,
the cutting feature 20 curves at least partly around the aperture.
In other embodiments, the aperture 18 may have straight sides and
the leading surface 24 may share one or more sides of the aperture
18. Further, the leading surface 24 is generally concave, bent, or
curved in the direction of the aperture 18. Consequently, through
motion of the vertebral implant 10 in the cutting direction C, the
leading surface 24 tends to divert removed bone matter through the
aperture 18, past the interior surface 28 and into the interior
cavity 30. FIGS. 3, 4, and 5 illustrate this sequence, which occurs
as the vertebral implant 10 is inserted into a patient.
[0038] Specifically, FIG. 3 shows two vertebrae 102, 104 and a disc
116 therebetween. Each vertebra 102, 104 includes a generally
cylindrical body 106, 108 that contributes to the primary
weight-bearing portion of the spine 100. Further, each vertebra
102, 104 includes various bony processes 110, 112 extending
posterior to the body 106, 108. Adjacent vertebrae 102, 104 may
move relative to each other via facet joints 114 and due to the
flexibility of the disc 116. For instances where the disc 116 is
herniated or degenerative, the entire disc 116 may be replaced with
the vertebral implant 10 using an anterior approach as shown.
[0039] Initially, the disc 116 is removed from the space between
the vertebrae 102, 104. Also, the vertebral implant 10 is packed
with a bone growth promoting material such as those described
above. The bone growth promoting material is identified by numeral
40 in FIG. 4. FIG. 4 also shows an insertion tool 42 attached to
the vertebral implant 10. Using the insertion tool 42, the
vertebral implant 10 is guided towards and between the vertebral
bodies 106, 108. An insertion force is applied in the direction of
the arrow labeled N. This insertion force causes the cutting
features 20 to engage and remove bone matter from the vertebral
bodies 106, 108. This bone matter is identified by number 44 in
FIG. 4. The shape and configuration of the cutting feature 20, and
specifically leading surface 24, tend to guide the removed bone
matter 44 from the exterior of the vertebral implant 10, through
the apertures 18, into the interior cavity 30, and into contact
with the bone growth promoting material 40.
[0040] Ultimately, once the vertebral implant 10 is inserted
completely between the vertebral bodies 106, 108 as shown in FIG.
5, the insertion tool 42 may be removed. At this juncture, bone
matter 44 has been removed by the cutting features 20 and packed
through the apertures 18. Some of the removed bone matter 44
travels through the apertures 18 and into contact with the bone
growth promoting materials 40. Some of the removed bone matter 44
remains in the apertures 18. Further, some of the removed bone
matter 44 remains near the cutting features 20 and adjacent to the
vertebral bodies 106, 108. Accordingly, a bridge comprising bone
matter 44 is formed between the vertebral bodies 106, 108 and the
bone growth promoting material 40.
[0041] FIG. 6 shows a frontal view of the exemplary vertebral
implant 10. In this orientation, the cutting direction C described
above is directed out of the page. FIG. 6 specifically illustrates
an overlapping configuration for the plurality of cutting features
20 and leading surfaces 24 on both the superior surface 14 and
inferior surface 16. The overlap is in a direction T that is
substantially parallel to the superior surface 14 (and inferior
surface 16), but transverse to the cutting direction C. The cutting
features 20 may be disposed in a staggered configuration such that
they overlap across multiple rows oriented in the transverse
direction T. In other words, the cutting features 20 shown in FIG.
6 may be arranged in a single row in the transverse direction T or
at different depths into or out of the page to achieve the
overlapping configuration. As a result, the cutting features 20 are
able to remove significant amounts of bone matter from the
vertebral bodies 106, 108 as the vertebral implant 10 is inserted
in the cutting direction C.
[0042] In one embodiment, the cutting features 20 overlap one
another in the transverse direction T by an amount that leaves a
nominal space 46 between the cutting features 20. This space 46 may
permit the removed bone matter 44 to fill gaps between the
vertebral implant 10 and the vertebral bodies 106, 108. That is,
the space 46 strikes a balance between directing all removed bone
matter 44 into the interior cavity 30 of the vertebral implant 10
and allowing the removed bone matter 44 to fill gaps between the
vertebral implant 10 and the vertebral bodies 106, 108.
[0043] Embodiments described above included a plurality of cutting
features 20 arranged along a common cutting direction C. In the
embodiment of the vertebral implant 110 shown in FIG. 7, some of
the cutting features 20 are arranged in a first cutting direction C
while other cutting features 20 are arranged in a second, different
cutting direction C'. With the cutting features 20 configured in
this manner, a surgeon may be able to remove additional bone matter
44 by imparting a reciprocating motion as indicated by the arrows
labeled B in FIG. 8. The reciprocating motion B may be imparted
through an insertion tool 42. With each pass in the forward and
backward direction, the cutting features 20 are able to remove more
bone matter 44. Ultimately, as FIG. 9 shows, if enough bone matter
44 is removed, the cutting features 20 dig into the cortical bone
of the vertebral bodies 106, 108 by an amount sufficient to bring
the vertebral bodies (in the directions D, D') into close proximity
with the superior surface 14 and the inferior surface 16 of the
vertebral implant 110.
[0044] The cutting features 20 may be incorporated on different
types of fusion implants, including ALIF cages similar in structure
to the above-described embodiments. The cutting features 20 may be
incorporated in PLIF or TLIF cages as well. FIGS. 10, 11, 12, and
13 illustrate embodiments of this type that may be inserted from a
posterior, transforaminal, or lateral direction. FIG. 10 shows one
implementation where vertebral implants 210 are inserted using a
posterior approach. Accordingly, the vertebral implants 210 include
a plurality of cutting features 20 adapted as described above to
remove bone matter from vertebral body 106 as the vertebral
implants 210 are inserted in the cutting direction C. Concurrent
with the action of cutting bone matter from the vertebral body 106,
the cutting features 20 direct at least some of the bone matter
through the apertures 18 into an interior cavity (not shown) in the
vertebral implant 210.
[0045] The vertebral implants 210 may include a generally
rectangular shape as depicted in the perspective view in FIG. 11.
In this embodiment, the cutting features 20 are included in one or
both of the superior surface 214 and inferior surface 216. The
lateral surfaces 212 may include apertures 18 and/or cutting
features 20, though neither is shown in FIG. 11.
[0046] In one embodiment shown in FIGS. 12 and 13, the vertebral
implants 310, 410 include a generally cylindrical shape. In each
embodiment, the cylindrically shaped implant 310, 410 extends along
a longitudinal axis A. Each vertebral implant 310, 410 may be
inserted along this longitudinal axis A. FIG. 12 shows an end view
of a vertebral implant 310 where cutting features 20 are disposed
about the cylindrical outer wall 312. Furthermore, the cutting
features 20 are arranged to create two different cutting directions
C and C' that traverse a substantially arcuate path. Specifically,
the cutting features on the left side of the dashed line 48 in FIG.
12 are oriented in a first direction associated with cutting
direction C. The cutting features on the right side of the dashed
line in FIG. 12 are oriented in a second direction associated with
cutting direction C'. Notably, the cutting directions C, C' do not
necessarily coincide with the direction of insertion, which may be
along the longitudinal axis A.
[0047] The vertebral implant 310 may include an insertion feature
336 to which an insertion tool (not shown) may be attached. The
insertion feature 336 may be elongated or may comprise multiple
features disposed on opposite sides of the longitudinal axis A.
This type of insertion feature may allow a surgeon to impart a
rotating, reciprocating motion about axis A, in the two different
cutting directions C and C' to remove bone matter along a generally
cylindrical pattern. This rotating motion is in contrast with the
non-rotating motion imparted on previously described embodiments to
remove the bone matter.
[0048] FIG. 13 shows another embodiment of a cylindrically-shaped
vertebral implant 410. In embodiments disclosed above, cutting
features 20 that are facing different cutting directions were
generally grouped in different portions of the implant (see e.g.,
FIG. 7 or FIG. 12). However, as FIG. 13 shows, the cutting features
20 may be oriented so that different cutting directions C, C' are
interspersed about the vertebral implant 410. This configuration
may be implemented in the different types of vertebral implants,
including the PLIF, TLIF, and ALIF implants.
[0049] The cutting features 20 may be arranged at gradually
increasing heights in a manner similar to a broach. FIGS. 14 and 15
illustrate examples of vertebral implants 510, 610 where the
cutting features 20 are arranged at progressively taller heights.
In both embodiments of the vertebral implant 510, 610, the cutting
height increases from a leading end 522, 622 (relative to the
cutting direction C) to a trailing end 524, 624 of the implant 510,
610. That is, the cutting features 20 disposed towards the leading
end 522, 622 include a first associated height H1. However, the
cutting features 20 disposed towards the trailing end 524, 624
include a larger, second associated height H2.
[0050] In the first exemplary embodiment, the cutting features 20
are substantially the same size. Therefore, the increase in height
of the cutting features 20 primarily derives from an increase in
the height of the implant body 512 from a first height D1 at the
leading end 522 to a larger second height D2 at the trailing end
524. Alternatively, the increase in height may be obtained through
different size cutting features 20a, 20b, 20c as shown in FIG. 15.
In this embodiment, the height D3 of the implant body 612 remains
substantially the same. However the cutting features 20a disposed
near the leading end 622 of the vertebral implant 610 are smaller
than cutting features 20b, 20c disposed towards the trailing end
624 of the vertebral implant 610. In one embodiment, the increase
in height of the cutting features 20 may be obtained through a
combination of a change in contour of the implant body 610 and a
change in size of the cutting features 20.
[0051] Embodiments described above related to vertebral implants
that are implanted into the space normally occupied by a vertebral
disc. In other procedures, such as vertebrectomies or corpectomies,
one or more vertebral bodies are removed and an implant is inserted
in the space left by the removed vertebrae. These types of devices,
such as the vertebral implant 710 shown in FIG. 16, include
multiple components, including spacers, a cage, rods, or other
fixed or expandable members 700 spanning a distance between first
and second end plates 702, 704. The various types and arrangements
for the cutting features 20 described above may be used with these
types of devices as well as those disclosed above. That is, the
cutting features 20 may be disposed on separate end plates 702, 704
and not on the same body as disclosed in other embodiments.
[0052] The cutting features 20 illustrated in FIGS. 1-16 include
similar geometries. As described above, the leading surface 24 and
trailing surface 32 of the cutting feature 20 intersect at a
generally arcuate leading edge 22. In other embodiments, the
cutting features may include different geometries that include
straight, tapered, flared, or blunt geometries. FIGS. 17-20
illustrate some exemplary geometries that may be used for the
cutting features. For instance, the cutting feature 220 may be
triangular, pyramid-like, or diamond-like as shown in FIG. 17. In
FIG. 18, the exemplary cutting feature 320 is generally dome or
oval-shaped. FIG. 19 depicts an embodiment where the cutting
feature 420 is squared while FIG. 20 depicts a generally
trapezoidal cutting feature 520. Accordingly, the shape of the
cutting features may be varied to achieve different cutting
characteristics and/or to remove different amounts and different
sizes of bone fragments. Each of these exemplary cutting features
may be raked towards the cutting direction as in previously
described embodiments. Further each of these exemplary cutting
features may extend at least partially around the aperture with
which the cutting feature is associated.
[0053] In one embodiment shown in FIGS. 21 and 22, the vertebral
implant 810 includes a generally cylindrical shape with a generally
circular outer perimeter 812, 816. A cylindrical column 814 that
includes a smaller diameter compared to the outer perimeter 812,
816 is disposed in a central portion of the vertebral implant 810,
between end surfaces 830, 840. The vertebral implant 810 further
includes an interior volume 850 that may be packed with a bone
growth promoting material as previously described. The vertebral
implant 810 includes superior 830 and inferior 840 surfaces that
are positioned adjacent to vertebral endplates when the implant is
inserted. As with previously described embodiments, the vertebral
implant 810 includes cutting features 20 associated with apertures
18 that permit bone material to pass from the cutting features 20
and into an interior volume 850. The cutting features 20 may be
disposed on both superior 830 and inferior 840 surfaces.
[0054] As FIG. 21 shows, the cutting features 20 are disposed in a
radial manner so that the cutting direction follows an arcuate path
defined by the orientation of the cutting features 20. The cutting
features 20 may include substantially similar heights or may
gradually increase or decrease in height around the perimeter 812,
816 of the implant 810 as described above. Though not illustrated,
additional cutting features may be disposed interior to the
depicted cutting features 20. Further the cutting features 20 may
be oriented along the same cutting direction or different cutting
directions than those illustrated in FIG. 21. The vertebral implant
810 may be inserted between vertebral bodies and rotated in the
cutting direction by engaging the implant 810, for example at
surface 814, with an unillustrated insertion tool. As described
above, the cutting features 20 may be aligned along a common
cutting direction or different cutting directions.
[0055] Spatially relative terms such as "under", "below", "lower",
"over", "upper", and the like, are used for ease of description to
explain the positioning of one element relative to a second
element. These terms are intended to encompass different
orientations of the device in addition to different orientations
than those depicted in the figures. Further, terms such as "first",
"second", and the like, are also used to describe various elements,
regions, sections, etc and are also not intended to be limiting.
Like terms refer to like elements throughout the description.
[0056] As used herein, the terms "having", "containing",
"including", "comprising" and the like are open ended terms that
indicate the presence of stated elements or features, but do not
preclude additional elements or features. The articles "a", "an"
and "the" are intended to include the plural as well as the
singular, unless the context clearly indicates otherwise.
[0057] The present invention may be carried out in other specific
ways than those herein set forth without departing from the scope
and essential characteristics of the invention. For instance, aside
from the disclosed apertures 18 and cutting features 20,
embodiments disclosed above have not included any particular
surface geometry, coating, or porosity as are found in
conventionally known vertebral implants. Surface features such as
these are used to promote bone growth and adhesion at the interface
between an implant and a vertebral body. Examples of features used
for this purpose include, for example, teeth, scales, keels,
knurls, and roughened surfaces. Some of these features may be
applied through post-processing techniques such as blasting,
chemical etching, and coating, such as with hydroxyapatite. The
superior and inferior bone interface surfaces of the vertebral
implant may also include growth-promoting additives such as bone
morphogenetic proteins. Alternatively, pores, cavities, or other
recesses into which bone may grow may be incorporated via a molding
process. Other types of coatings or surface preparation may be used
to improve bone growth into or through the bone-contact surfaces.
The present embodiments are, therefore, to be considered in all
respects as illustrative and not restrictive, and all changes
coming within the meaning and equivalency range of the appended
claims are intended to be embraced therein.
* * * * *