U.S. patent application number 11/030459 was filed with the patent office on 2005-06-02 for anterior impacted bone graft and driver instruments.
This patent application is currently assigned to SDGI Holdings, Inc.. Invention is credited to Buskirk, Dayna, DeRidder, Steven D., Lange, Eric C., McGahan, Thomas V..
Application Number | 20050119753 11/030459 |
Document ID | / |
Family ID | 22674883 |
Filed Date | 2005-06-02 |
United States Patent
Application |
20050119753 |
Kind Code |
A1 |
McGahan, Thomas V. ; et
al. |
June 2, 2005 |
Anterior impacted bone graft and driver instruments
Abstract
Instrument and implants are disclosed which provide for
insertion of an implant into an intervertebral disc space from
multiple approaches to the spine. Specifically, as a preferred
aspect of the invention the implant includes a tapered portion and
the implant may be inserted from multiple approaches to the spine
with the orientation and taper properly oriented in the disc space
regardless of the approach.
Inventors: |
McGahan, Thomas V.;
(Memphis, TN) ; DeRidder, Steven D.; (Bartlett,
TN) ; Buskirk, Dayna; (Gainesville, FL) ;
Lange, Eric C.; (Germantown, TN) |
Correspondence
Address: |
WOODARD, EMHARDT, MORIARTY, MCNETT & HENRY LLP
BANK ONE TOWER/CENTER
111 MONUMENT CIRCLE
SUITE 3700
INDIANAPOLIS
IN
46204-5137
US
|
Assignee: |
SDGI Holdings, Inc.
Wilmington
DE
|
Family ID: |
22674883 |
Appl. No.: |
11/030459 |
Filed: |
January 5, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11030459 |
Jan 5, 2005 |
|
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10213328 |
Aug 6, 2002 |
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10213328 |
Aug 6, 2002 |
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PCT/US01/05638 |
Feb 22, 2001 |
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60183930 |
Feb 22, 2000 |
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Current U.S.
Class: |
623/17.16 ;
623/17.11 |
Current CPC
Class: |
A61F 2/442 20130101;
A61F 2310/00017 20130101; A61F 2002/3023 20130101; A61F 2002/2839
20130101; A61F 2/4465 20130101; A61F 2310/00179 20130101; A61F
2002/30593 20130101; A61F 2310/00359 20130101; A61F 2002/4627
20130101; A61F 2230/0069 20130101; A61F 2002/30879 20130101; A61F
2310/00023 20130101; A61F 2/28 20130101; A61F 2002/30892 20130101;
A61F 2002/30774 20130101; A61F 2/4611 20130101; A61F 2002/30787
20130101; A61F 2002/30904 20130101 |
Class at
Publication: |
623/017.16 ;
623/017.11 |
International
Class: |
A61F 002/44 |
Claims
What is claimed is:
1. A spinal implant for implanting into a disc space of a spine,
comprising: an implant body having three pairs of substantially
parallel sidewalls constructed and arranged to permit insertion of
said implant body into the disc space at least from a direct
anterior approach to the spine and an oblique angle to the spine;
and wherein said implant body is tapered.
2. The implant of claim 1, wherein said implant body has an upper
anti-migration surface and a lower anti-migration surface adapted
to minimize implant migration.
3. The implant of claim 1, wherein: said implant body is formed of
bone; and a portion of said implant body includes unmachined donor
implant bone portion.
4. The implant of claim 1, wherein said implant body has a first
bore defined therein and a second bore defined therein parallelly
spaced apart from said first bore, said second bore being adapted
to receive a pin to minimize implant rotation.
5. The implant of claim 4, wherein: said implant body further
includes an angled driving wall in which said second insertion tool
bore is defined; and said angled driving wall defines a recess
surface that extends substantially perpendicular with respect to
one of said pairs of sidewalls.
6. The implant of claim 4, wherein said implant body defines a
third bore parallelly spaced apart from said first bore, said third
bore being smooth to receive a pin for minimizing implant
rotation.
7. The implant of claim 1, wherein said implant body has a central
opening defined therein.
8. The implant of claim 7, wherein said implant body is formed of
bone having a medullary canal, and said central opening conforms
generally to said medullary canal.
9. The implant of claim 1, wherein a distance between each pair of
said three pairs of sidewalls is the same.
10. A spinal implant for implanting into a disc space of a spine,
comprising: an implant body having three pairs of substantially
parallel sidewalls; and wherein two of said three pairs of
sidewalls are disposed at an oblique angle with respect to one
another to permit insertion of said implant body into the disc
space at least from a direct anterior approach to the spine and an
oblique angle to the spine.
11. The implant of claim 10, wherein said implant body is
tapered.
12. The implant of claim 10, wherein said implant body defines a
first insertion tool bore and a second insertion tool bore, said
first tool bore extending substantially parallel to one pair of
said sidewalls, said second tool bore extending substantially
parallel to another pair of said sidewalls.
13. The implant of claim 10, wherein: said implant body is formed
of bone; and a portion of said implant body includes an unmachined
donor implant bone portion.
14. The implant of claim 13, wherein said implant body has a
central opening defined therein.
15. The implant of claim 14, wherein said bone has a medullary
canal, and said central opening conforms generally to said
medullary canal.
16. A spinal implant for implanting into a disc space of a spine,
comprising: an implant body having means for permitting insertion
of said implant body into the disc space at least from a direct
anterior approach to the spine and an oblique angle to the
spine.
17. The implant of claim 16, wherein: said means for permitting
insertion of said implant body includes three pairs of
substantially parallel sidewalls; and wherein two of said three
pairs of sidewalls are disposed at an oblique angle with respect to
one another.
18. The implant of claim 17, wherein said means for permitting
insertion of said implant body further includes a first tool
insertion bore defined in said implant body and a second tool
insertion bore defined in said implant body, said first tool bore
extending substantially parallel to one of said three pairs
sidewalls, said second tool bore extending substantially parallel
to another of said three pairs sidewalls.
19. The implant of claim 16, wherein said implant body is
tapered.
20. The implant of claim 16, wherein: said implant body is formed
of bone; and a portion of said implant body includes unmachined
donor implant bone portion.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a divisional of U.S. patent
application Ser. No. 10/213,328 filed Aug. 6, 2002 entitled
"Anterior Impacted Bone Graft and Driver Instruments", which is a
continuation of PCT patent application Ser. No. PCT/US01/05638
filed Feb. 22, 2001 entitled "Anterior Impacted Bone Graft and
Driver Instruments" which was published in English under Article
21(2) and which claims the benefit of U.S. Provisional Patent
Application Ser. No. 60/183,930 filed Feb. 22, 2000 entitled
"Instruments and Implants for Multi-Directional Insertion of a
Vertebral Spacer" which are hereby incorporated by reference in
their entirety.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to instruments and
implants for intervertebral spacing. More specifically, the present
invention provides instruments and implants that may be utilized to
provide multi-directional insertion techniques to establish and
maintain intervertebral spacing. Still more preferably, the present
invention provides implants made of bone adapted to be inserted
from more than one direction while maintaining proper orientation
in the disc space.
[0003] The removal of damaged or diseased discs and restoration of
disc space height to treat chronic back pain and other ailments, is
well-known. Spacers are often utilized to maintain or reestablish
disc space height after removal of all or a portion of the disc.
Such spacing implants may include those promoting fusion between
adjacent vertebral bodies, inert implants, and artificial disc
implants. Such implants are typically designed to be inserted from
an anterior, posterior or lateral approach. However, such implants
are often designed for insertion only from one of the particular
approaches to the spine. This is particularly true where implants
are intended to maintain non-parallel angulation between adjacent
vertebrae. Therefore, multiple implants each designed for insertion
from one of the various approaches to the spine must be maintained
in inventory to accommodate the various surgical demands of each
procedure. Maintaining multiple implant designs may create
inventory problems for both manufacturers and their customers.
Moreover, the complications of creating multiple implants to
accomplish the same desired spacing is compounded when implants are
made of a scarce resources, such as allograft bone.
[0004] Therefore, there remains a need for instruments, techniques,
and implants that reduce implant inventory without sacrificing
desired implant configurations.
SUMMARY OF THE INVENTION
[0005] The present invention provides for instruments to implant a
single implant design from multiple approaches to the disc space.
In a preferred aspect of the present invention, instruments are
provided for inserting an implant from a direct anterior approach
to the spine and from an oblique-anterior approach to the
spine.
[0006] In a further aspect of the present invention, an implant is
provided that includes features permitting insertion into the disc
space from multiple directions. In a preferred aspect of the
present invention, the implant may be configured for insertion from
a direct anterior approach as well as an anterior-lateral approach
to the spine. Still more preferably, the anterior-lateral approach
to the spine is from an oblique angle with respect to the sagittal
plane.
[0007] In still a further aspect of the present invention, a
multi-faceted implant is provided comprising an implant body having
a first pair of substantially parallel side walls and a second pair
of substantially parallel side walls. The second pair of
substantially parallel side walls are disposed at an oblique angle
with respect to the first pair of substantially parallel side
walls. The angulation between the first and second set of parallel
side walls permits insertion of the implant into the disc space
from multiple directions. Further in one preferred embodiment the
distance between the first pair of side walls is substantially
identical to the distance between the second pair of side walls.
One choice is to dispose the second pair of side walls at an angle
of approximately 30 degrees with respect to the first pair of side
walls. In a more preferred aspect of the present invention, the
implant body has upper and lower bone engaging surfaces that are
tapered to maintain angulation between adjacent vertebrae. In still
further preferred aspects of the invention, one of each of the
first and second pair of side walls includes an insertion tool
bore.
[0008] In yet a further aspect of the present invention, a method
of making an implant of boney material is provided. The method
comprises forming a first pair of substantially parallel side walls
on the boney material. A second pair of substantially parallel side
walls is formed at an oblique angle with respect to the first pair
of side walls. In one aspect the method further includes forming a
plurality of driving surfaces on the donor bone. Still more
preferably, the upper and lower bone engaging surfaces are disposed
at an angle with respect to each other.
[0009] In still a further aspect of the invention an implant
inserter is provided. Preferably, the implant inserter includes
anti-rotation components to limit rotation of the implant about the
longitudinal axis of the inserter and rotation about the axis of
the implant itself. In one preferred embodiment, the anti-rotation
components comprise a pair of angled side walls on the inserter
adapted to engage a pair of corresponding surfaces on the implant.
In still a further preferred aspect, a threaded post engages a
corresponding opening on the implant and the angled surfaces are
spaced from the opening to limit stress placed on the implant
adjacent the opening.
[0010] These and other objects of the present invention will become
apparent from the following description of the preferred
embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a perspective view of an implant according to the
present invention.
[0012] FIG. 2(a) is a side view of the implant of FIG. 1.
[0013] FIG. 2(b) is an enlarged view of a portion of FIG. 2(a).
[0014] FIG. 3 is an end view of the implant of FIG. 1.
[0015] FIG. 4 is a cross-sectional view taken along line 4-4 of
FIG. 2(a).
[0016] FIG. 5 is a top view of an implant inserter according to the
present invention.
[0017] FIG. 6 is a side view of the implant inserter of FIG. 5.
[0018] FIG. 7 is a perspective view of a distal guide of the
implant inserter of FIG. 5.
[0019] FIG. 8 is a perspective view of an implant and an implant
inserter according to the present invention.
[0020] FIG. 9 is a top view of the combination shown in FIG. 8.
[0021] FIG. 10 is a top view of a further embodiment of an implant
inserter according to the present invention.
[0022] FIG. 11 is a side view of the implant inserter of FIG.
10.
[0023] FIG. 12 is an end view of the distal guide of FIG. 10.
[0024] FIG. 13 is a perspective view of the distal guide of FIG.
12.
[0025] FIG. 14 is a cross-sectional view taken along line 14-14 of
FIG. 12.
[0026] FIG. 15(a) is a top view of an implant and an implant
inserter according to the present invention.
[0027] FIG. 15(b) is an enlarged perspective view of a portion of
FIG. 15(a).
[0028] FIG. 16 is a top view of a further embodiment of an implant
according to the present invention.
[0029] FIG. 17 is an end view of the implant of FIG. 16.
[0030] FIG. 18 is a cross-sectional view taken along line 18-18 of
FIG. 17.
[0031] FIG. 19(a) is a side view of the implant of FIG. 16.
[0032] FIG. 19(b) is a perspective view of the implant of FIG.
16.
[0033] FIG. 20(a) is a top view of a further embodiment of an
implant inserter according to the present invention.
[0034] FIG. 20(b) is a side view of the implant inserter of FIG.
20(a).
[0035] FIG. 21(a) is a perspective view of the distal guide of the
implant inserter of FIG. 20(a).
[0036] FIG. 21(b) is an end view of the distal guide of FIG.
21(a).
[0037] FIG. 21(c) is a cross-sectional view of the distal guide of
FIG. 21(b) taken along line 21(c)-21(c).
[0038] FIG. 22(a) is a top view of an implant inserter and an
implant according to the present invention.
[0039] FIG. 22(b) is an enlarged perspective view of a portion of
the drawing FIG. 22(a).
[0040] FIG. 23(a) is a perspective view of an implant inserter,
implant, and guide tube according to the present invention.
[0041] FIG. 23(b) is an enlarged perspective view of a portion of
FIG. 23(a).
[0042] FIG. 24(a) is a perspective view of an implant positioned
adjacent a vertebral body according to the present invention.
[0043] FIG. 24(b) is a top view of the implant and vertebral body
of FIG. 24(a).
[0044] FIG. 24(c) is a further perspective view of the implant and
vertebral body of FIG. 24(a).
[0045] FIG. 25(a) is a top view of an alternative embodiment of an
implant inserter according to the present invention.
[0046] FIG. 25(b) is a side view of the implant inserter of FIG.
25(a).
[0047] FIG. 26 is a perspective view of a distal guide of the
implant inserter of FIG. 25(a).
[0048] FIG. 27(a) is an end view of the distal guide of FIG.
26.
[0049] FIG. 27(b) is a side view of the distal guide of FIG.
26.
[0050] FIG. 27(c) is a rear end view of the distal guide of FIG.
26.
[0051] FIG. 28 is a cross-sectional view of the distal guide taken
along line 28-28 of FIG. 27(b).
[0052] FIG. 29(a) is a top view of an implant and an implant
inserter according to the present invention.
[0053] FIG. 29(b) is an enlarged perspective view of a portion of
FIG. 29(a).
[0054] FIG. 30(a) is a perspective view of an implant, implant
inserter, and guide tube according to one aspect of the present
invention.
[0055] FIG. 30(b) is an enlarged top view of a portion of FIG.
30(a).
[0056] FIG. 31(a) is a perspective view of an implant positioned
adjacent a vertebral body according to the present invention.
[0057] FIG. 31(b) is a top perspective view of the implant and
vertebral body of FIG. 31(a).
[0058] FIG. 31(c) is a further perspective view of the implant and
vertebral body of FIG. 31(a).
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0059] For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to the
embodiments illustrated in the drawings and specific language will
be used to describe the same. It will nevertheless be understood
that no limitation of the scope of the invention is thereby
intended, such alterations and further modifications in the
illustrated devices, and such further applications of the
principles of the invention as illustrated therein being
contemplated as would normally occur to one skilled in the art to
which the invention relates.
[0060] The present invention provides implants and instruments for
multi-directional implantation of an intervertebral spacer.
Additional instrumentation and techniques for disc space
preparation are disclosed in Provisional Application entitled
"Instruments and techniques for Disc Space Preparation," filed Feb.
22, 2000. The disclosure of the referenced Provisional Application
is incorporated herein by reference in its entirety. Referring now
to FIGS. 1-4, there is shown an implant according to a preferred
embodiment of the present invention. Implant 10 includes an upper
bone engaging surface 12, a lower bone engaging surface 14, and a
central opening 16 extending from upper surface 12 to lower surface
14. While it is contemplated that implant 10 may be formed of any
suitable bio-compatible material (e.g. steel, titanium, composites,
ceramics, zenograft, composite bone material, etc.), in a preferred
aspect of the invention, implant 10 is formed of allograft bone.
Referring specifically to FIG. 4, outline 36 represents a typical
outline of an allograft ring suitable for use to form an implant
according to the present invention. It will be understood that
central opening 16 conforms generally to the medullary canal,
typically found in an allograft ring.
[0061] Implant 10 includes a pair of opposing side walls 24 and 26
formed in substantial parallel alignment with longitudinal axis 64.
A further pair of oblique angled side walls 20 and opposing side
wall 28 are formed at an angle A5 with respect to side walls 26 and
24. In a preferred embodiment, angle A5 is approximately 30
degrees. In a preferred aspect, from driving wall 18 extends
substantially perpendicular to longitudinal axis 64 and at an angle
of A4 with respect to angled surface 20. In a preferred embodiment,
angle A4 is substantially 60 degrees. Implant 10 includes a front
face 18 and an opposing end face 30. While not required, front face
18 and face 30 are planar surfaces in substantially parallel
alignment. Further, front face 18 is substantially parallel to end
face 30. A first opening 40 is formed in implant 10 and is
internally threaded to received an externally threaded post.
Internally threaded opening 40 extends substantially along
longitudinal axis 64 and in substantial alignment with side walls
24 and 26. A second bore 42 has an axis 66 extending substantially
parallel to axis 64 and spaced at a distance D9 therefrom. Bore 42
is adapted to receive a substantially smooth pin. It will be
understood that a pin extending in bore 42 will limit the tendency
of implant 10 to rotate as an externally threaded rod is inserted
into threaded opening 40. In a preferred aspect, distance D9 is
approximately 5 mm.
[0062] Referring now to FIG. 4, front face 18 and opposing end face
30 are substantially parallel and spaced by distance D2. In a
preferred aspect, opposing side walls 24 and 26 are substantially
parallel and spaced by a distance of D3. Opposing angled walls 20
and 28 are substantially parallel and spaced by a distance D6. In a
preferred embodiment, distances D2, D3, and D6 are approximately
equal. Still more preferably, in at least one preferred embodiment
adapted for implantation in the lumbar spine, distances D2, D3, and
D6 are approximately 26 mm.
[0063] Referring still further to FIG. 4, an angled driving wall 22
is provided at an approximately 30 degree angle with respect to
front wall 18. Internally threaded bore 44 extends through angled
wall 22 along axis 62. Axis 62 is substantially parallel to side
walls 20 and 28.
[0064] As shown most clearly in FIG. 4, the multi-faceted implant
provides three pairs of substantially parallel side walls. A
reference point 60 is provided on the drawing as an indication of
the starting point of the formation of the various walls of the
implant. Side wall portions 32 and 34 are not machined, thereby
preserving at least a portion of the original configuration of the
donor bone. It will be understood that the amount of machining
required to form an implant according to the present invention
depends in large measure on the configuration of the donor bone
available and the dimensions of the implant intended to be
manufactured from the available donor bone. As will be explained
further herein, it is advantageous in a preferred embodiment that
the maximum outer dimensions of the implant permit the implant to
be inserted from a direct anterior approach to the spine, an
oblique angle to the spine and, while not specifically shown in the
drawings, a lateral approach to the spine.
[0065] Dimensions of donor bone vary depending on the source of the
bone, as well as the specific location of the source of an
allograft ring taken along a bone, such as the femur. In one aspect
of the invention, intended for use in the lumbar spine, it is
preferred that the implant have certain minimal dimensions for the
safety and efficacy of the device. While such dimensions are
disclosed herein, it is contemplated that dimensions may be altered
for various implants in the lumbar, thorasic, and cervical spine
without deviating from the present invention provided that the
implant provides the desired strength and stability. Specifically,
minimum dimensions are given from the surface of the outer side
walls to central channel 16. As previously indicated, central
channel 16 is preferably defined by the naturally occurring
medullary canal. However, it may be altered or increased by
additional machining to form a channel having desired dimensions or
shapes. Side wall 19 has a dimension D5. Side wall 25 has a
dimension D7. Side wall 31 has a dimension D4. Side wall 27 has a
dimension D8. In a preferred aspect, dimensions D5, D7, and D8 are
limited to a minimum thickness of 4 mm. Dimension D4 may have an
even smaller minimum thickness of approximately 3 mm.
[0066] Referring now to FIG. 2(a), implant 10 includes end wall 30
having a height H2 and front wall 18 having a height H1. In a
preferred aspect, height H1 is substantially greater than height
H2. Furthermore, opposing bone engaging surfaces 12 and 14
substantially, uniformly taper from height H1 at end wall 30 to
height H2 at front wall 18. In a preferred embodiment, height H1 is
approximately 17 mm. Further, the substantially uniform taper
between the upper and lower surfaces 12 and 14 creates an angle A1.
In a particular application, angle A1 is approximately 8
degrees.
[0067] In a preferred embodiment, upper surface 12 includes
buttressed ridges 13 providing an anti-migration surface to engage
adjacent vertebral bone upon insertion and limit movement out of
the disc space. In a similar fashion, lower bone engaging surface
14 includes a plurality of buttressed bone engaging ridges 15. Bone
engaging ridges 15 are shown in greater detail in FIG. 2(b). The
bone engaging ridges include a leading angled surface 50 and a
trailing surface 54 disposed substantially perpendicular to the
intervening flat surface 52 disposed between ridges. Angled surface
50 is disposed at an angle A3, which in a preferred embodiment is
substantially 30 degrees. Trailing surface 54 is disposed at an
angle A2, which in a preferred embodiment is substantially 90
degrees. Individual ridges have a height of approximately H3, which
in a preferred embodiment is approximately 0.5 mm. Further,
individual ridges are spaced by a distance of approximately 1.5 mm,
as shown by dimension D1.
[0068] The present invention further includes an implant inserter,
such as that shown in FIGS. 5 and 6. Implant inserter 80 includes
an outer shaft 82 and an inner shaft 85 rotatably disposed therein.
Inner shaft 85 includes a thumb wheel 84 connected to its proximal
end and an externally threaded portion 90 on the distal end.
Implant inserter 80 further includes a proximal guide 86, a distal
guide 88, and a stop 87. The proximal and distal guides are
intended to guide and maintain alignment of the inserter within an
outer guide sleeve (not shown) while stop 87 provides the function
of limiting further movement of the implant inserter into the outer
guide sleeve (see FIG. 23a), thereby limiting the advancement of
the implant into the disc space. While the implant inserter is
shown with features suitable for use with a guide sleeve, it is
contemplated that the inserter may be used without a guide
sleeve.
[0069] Distal guide 88 includes upper and lower tapered guiding
surfaces 89 and 95, respectively. Guide 88 also includes
substantially parallel opposed side walls 91 and 93. Guide 88 has a
width W1 extending between side walls 91 and 93. Further, with
reference to FIG. 7, a substantially smooth pin 92 extends from
opening 96 while inner shaft 85 extends through opening 94 of guide
88. Guide 88 includes a substantially planar bearing wall 98
extending substantially perpendicular to the longitudinal axis of
the implant inserter.
[0070] Referring now to FIGS. 8 and 9, the implant inserter of
FIGS. 5 and 6 is shown interconnected with the implant of FIGS.
1-4. Implant inserter 80 is interconnected with implant 10 by
threaded engagement of externally threaded portion 90 of inner
shaft 85 with the internally threaded opening 40 of implant 10.
Further, pin 92 may be inserted into bore 42 to limit rotation of
implant 10 while externally threaded portion 90 is threadedly
inserted into internally threaded bore 40. Pin 92 also limits
rotation of the implant about its own axis as force is applied to
advance the implant into the disc space. Front face 18 is in
substantial abutting engagement with bearing wall 98 such that
implant 10 may be impacted into a disc space by forcing bearing
wall 98 against front face 18. Furthermore, substantially parallel
side walls 24 and 26 of the implant are in substantial alignment
with side walls 91 and 93 of the implant inserter. In a preferred
aspect, the width W1 of distal guide 88 is substantially equal to
or greater than the width D3 of implant 10. The implant inserter
FIGS. 8 and 9 may be referred to as a straight inserter as it is
intended to function in a preferred aspect of the invention from a
direct or straight anterior approach to the spine.
[0071] In still another aspect of the invention, an oblique
inserter is shown in FIGS. 10 and 11. The oblique inserter is
configured for engaging the implant of FIGS. 1-4 to permit
insertion from an oblique angle to the spine. As a general
reference, this approach may be carried out by approaching the disc
space in substantial alignment with the axial plane and at an
oblique angle with respect to the sagittal plane. Oblique inserter
110 includes an outer shaft 112 and an inner shaft 115 movably
disposed therein. Inner shaft 115 includes a proximal thumb wheel
114 and has a distal end 120 with an external thread pattern.
Inserter 110 includes proximal guide 116, distal guide 118, and
stop 117. Distal guide 118 includes opposing tapered surfaces 132
and 134 tapering from opposing upper and lower surfaces 136 and
138, respectively. Distal guide 118 has a maximum width W2
extending from opposing side surfaces 122 and 124. The features of
implant 110 are substantially similar to the features of implant
inserter 180 with the exception of the driving surfaces of distal
guide 118.
[0072] Referring now to FIGS. 12-14, distal guide 118 includes a
central driving surface 128 substantially perpendicular to
longitudinal axis 131 and the planes of side walls 122 and 124.
Distal guide 118 further includes a first oblique driving surface
126 disposed at an angle A6 with respect to surface 128. In a
preferred aspect, angle A6 is approximately 30 degrees. Distal
guide 118 further includes a second angled driving surface 130
disposed at an angle A7 with respect to driving surface 126. In a
preferred embodiment, angle A7 is approximately 90 degrees.
[0073] Referring now to FIGS. 15(a) and 15(b), implant inserter 110
is shown here connected with implant 10. Implant 10 is coupled to
implant inserter 110 by engagement of externally threaded portion
120 of the inner shaft with internally threaded opening 44. Driving
surfaces 126, 128, and 130 of distal guide 118 substantially engage
surfaces 26, 22, and 18, respectively, of implant 10. It will be
understood that driving surfaces of distal guide 118 are configured
to substantially mate with the external surfaces of implant 10 such
that force transmitted on the implant inserter tending to urge the
implant into the disc space is substantially transmitted to implant
10. Additionally, angled side walls 126 and 130 inhibit rotation of
implant 10. Further, in a preferred aspect, substantially parallel
side walls 20 and 28 of implant 10 are in substantial parallel
alignment with opposing parallel side walls 122 and 124 of distal
guide 118. Width W2 of distal portion 118 is substantially equal to
or greater than the width D6 between opposing side walls 20 and 28
of implant 10.
[0074] Referring now to FIGS. 16-19(b), a further embodiment of an
implant according to the present invention is shown. Implant 200
includes an upper bearing surface 228 and opposing lower bearing
surface 230. Each of the upper and lower bearing surfaces include
anti-migration members. In a preferred aspect of the invention, the
anti-migration members are comprised of buttressed ridges extending
substantially perpendicular to side walls 212 and 220. Still more
preferably, upper and lower bearing surfaces 228 and 230 extend at
an angle A25 with respect to one another forming a tapered implant.
It is contemplated that angle A25 may have a variety of angles, but
in a preferred embodiment specifically adapted for establishing and
maintaining lumbar lordosis, angle A25 is approximately 8 degrees.
Further, the implant has a maximum height of H20, which in a
preferred aspect is approximately 21 mm.
[0075] As with the implant according to the first embodiment shown
in FIG. 1, implant 200 includes two pair of opposing parallel side
walls. Specifically, side wall 212 opposes substantially parallel
side wall 220. Similarly, angled side walls 214 and opposing angled
side wall 222 are in substantially parallel alignment. Side wall
222 extends at an angle A23 with respect to side wall 220. Angled
side wall 214 extends at an angle A21 with respect to side wall
212. In a preferred aspect, angles A21 and A23 are substantially
identical. Still more preferably, angles A21 and A23 are
approximately 30 degrees. Implant 200 further includes end wall 216
and unmachined portion 215 extending between end wall 216 and
angled wall 214. A further unmachined portion maintaining
substantially the natural shape of donor bone 202 includes wall
portion 218 extending between end wall 216 and side wall 220.
[0076] The driving walls of implant 200 have been modified in
comparison to the implant of FIG. 1. Specifically, implant 200
includes a short drive wall 206 extending generally perpendicular
to longitudinal axis 223. An internally threaded opening 224 is
formed extending substantially along and in alignment with
longitudinal axis 223. It is contemplated that driving wall 206 may
be substantially unmachined and may include arcuate portions such
as those found in the naturally occurring outer portion of donor
bone 202. Referring to FIG. 16, angled driving walls 210 and 208
extend away from reference line 227 at an angle of A20 and A24,
respectively. In a preferred embodiment, angles A20 and A24 are
substantially identical. Still more preferably, angles A20 and A24
are substantially 18 degrees. Angled driving wall 210 further
includes a recess surface 229 extending into surface 210 at an
angle of A22. Preferably, angle A22 is approximately 12 degrees,
thereby making surface 229 substantially perpendicular to angled
side walls 214 and 222. Referring more specifically to FIG. 18, an
internally threaded bore 226 is defined through the implant
extending along axis 231. Axis 231 extends in substantial parallel
alignment with side walls 214 and 222. In a preferred aspect,
implant 200 is asymmetrical about axis 231. More specifically, in a
preferred aspect of the invention axis 231 is approximately 12 mm
from angled side wall 214 and approximately 14.5 mm from angled
side wall 222. Implant 200 further includes central opening 204,
which as previously described, will typically be defined by the
naturally occurring medullary canal formed in the donor bone
graft.
[0077] Referring now to FIGS. 20(a)-21(c), a straight implant
inserter according to another aspect of the present invention is
illustrated. Implant inserter 250 is substantially identical to the
implant inserter of FIG. 5 with the exception of distal guide 252.
Distal guide 252 includes a first angled drive surface 256 and an
opposing angled drive surface 258 separated from the first drive
surface by a concave surface 260. Surfaces 256 and 258 each extend
at an angel A26 with respect to reference line 261 (FIG. 21(c)).
Reference line 261 is substantially perpendicular to the surface of
side walls 257 and 259. In a preferred aspect, angle A26 is
substantially 18 degrees to matingly engage corresponding surfaces
on implant 200. Distal guide 252 further includes an internal bore
262 extending through surface 260 adapted to receive the inner
shaft. The inner shaft has an externally threaded portion 254
extending beyond distal guide 252.
[0078] Referring now to drawing FIGS. 22(a) and 22(b), implant
inserter 250 is shown selectively coupled to implant 200. Distal
guide 252 abuttingly engages implant 200. More specifically, angled
drive surfaces 256 and 258 abuttingly engage angled drive surfaces
210 and 208, respectively. It will be understood that angled
surfaces act to inhibit rotation of implant 200. Angled surfaces
256 and 258 limit rotation of the implant about the longitudinal
axis of the inserter as the threaded post is engaged to implant 200
and rotation of the implant about itself as force is applied to
urge the implant into the disc space. Thus, the angled drive
surfaces provide secure engagement with the implant without the
need for additional openings that may weaken the implant walls.
Concave surface 260 is intended to be spaced from naturally
occurring surface 206 such that machining of surface 206 is not
required to provide the requisite clearance. Further, by spacing
the driving walls from the wall having the threaded opening, force
applied to the implant during insertion is concentrated away from
the implant opening thereby having less tendency to cause fracture.
This may be particularly beneficial where somewhat brittle
materials, such as bone or ceramics, are used to form the implant.
As shown in FIGS. 22(a)-(b), with implant 200 securely engaged with
driver 250, opposing implant side walls 200 and 220 are in
substantial alignment with implant driver side walls 257 and 259.
It will be understood that by providing angled driving surfaces
rather than a single planar drive surface, more of the natural
architecture of the bone may be maintained, thereby increasing the
strength of the implant. While angled drive surfaces are shown as
substantially planar surfaces it will be understood that they may
also be arcuate, concave, convex, or complex surfaces.
[0079] Implant 200 may be inserted into a vertebral disc space
properly prepared for receipt from a direct anterior approach. As
shown in FIG. 23(b), a distraction window 268 is disposed adjacent
a vertebral body V1 with distraction extensions 270 and 272
extending into the vertebral disc space (the opposing upper
vertebra is not shown). Guide tube 262 is selectively coupled to
distraction window 268. Distraction window and guide tube define a
substantially rectangular working channel (not shown) substantially
confirming to the dimensions of the distal guide 252. Inserter 250
with selectively coupled implant 200 attached thereto may then be
inserted through guide tube 266 and distraction window 268 and
guided to the disc space. Implant inserter is slidably advanced in
the guide tube 266 with distal guide maintaining alignment until
stop 271 engages the distal end 273 of guide tube 266. Implant 200
will thereby be positioned in the proper location in the disc space
with the intended orientation. The thumb wheel of implant inserter
250 may then be rotated to threadedly disengage the inserter from
implant 200. Once implant inserter 250 has been disengaged from
implant 200. The inserter may be removed from the guide tube and
distraction window. Guide tube 266 and distraction window 268 may
then be removed from the disc space.
[0080] Referring now to FIGS. 24(a)-24(c), implant 200 is shown
disposed in a prepared end plate of vertebral V1. It will be
understood that an opposed vertebra is disposed above the implant
creating a disc space, but the upper opposed vertebra has been
removed from the illustration for the purpose of clarity. Implant
200 is shown disposed in channel C1 defined in the end plate of
vertebra V1. One method of forming channel C1 is disclosed in
Provisional Application entitled "Instruments and Techniques for
Disc Space Preparation," filed on Feb. 22, 2000, which is
incorporated herein by reference. Channel C1 extends in a direction
extending from the anterior to the posterior portion of the
vertebra and is configured for direct anterior insertion of an
implant. End surface 216 is shown in substantial alignment with
posterior portion 274 of channel C1. Thus, end surface 216 is
disposed substantially adjacent the posterior portion 275 of
vertebra V1. Side walls 212 and 220 are disposed laterally with
respect to vertebra V1. Thus, implant 200 is disposed in the disc
space between vertebra V1 and the upper opposed vertebra (not
shown) such that the taper between opposed bone engaging surfaces
228 and 230 is in proper alignment and orientation to maintain the
appropriate angular relationship between the opposing vertebral
bodies.
[0081] Referring now to FIGS. 25(a)-28, there is shown an implant
inserter 300 adapted for insertion of implant 200 from an
anterior-oblique approach to the spine. Inserter 300 includes
features also found in implant inserter 250 with the exception that
distal guide 302 has been configured to permit engagement with an
implant for oblique insertion. Distal guide 302 includes a first
angled drive surface 310 disposed at an angle A33 with respect to
side wall 306. In a preferred embodiment, A33 is approximately 42
degrees. A second angled drive surface 314 is disposed at an angle
A32 with respect to side wall 308. In the preferred aspect, A32 is
approximately 30 degrees. A third angled surface 312 is disposed at
an angle A30 with respect to angled drive surface 310 and an angle
A31 with respect to angled drive surface 314. In a preferred
embodiment, angle A30 is approximately 144 degrees and angle A31 is
approximately 108 degrees. Additionally, an internal bore 316 is
formed through distal guide 302. Bore 316 is formed a distance D30
from side wall 308 and a distance D31 from side wall 306. In a
preferred aspect of the invention, D31 is greater than the distance
D30 such that bore 316 is offset with respect to the longitudinal
axis of guide 302. More specifically, distance D30 is approximately
12 mm and distance D31 is approximately 15 mm.
[0082] Referring to FIGS. 29(a) and 29(b), implant inserter 300 is
shown selectively coupled to implant 200. Angled driving surfaces
310 and 314 are in abutting engagement with driving surfaces 212
and 208. It will be noted that angled surface 312 and 310 have
sufficient length such that side wall 206 is not intended to be in
substantial contact with the implant driver. Further, it is
contemplated that surface 312 may be spaced slightly from wall 210
to limit stress on the implant adjacent opening 226. Implant 200 is
aligned with distal guide 302 such that opposing side walls 214 and
222 are in substantial alignment with side walls 308 and 306,
respectively, of distal guide 302. Moreover, angled driving
surfaces 310 and 314 cooperate to limit implant rotation.
[0083] Referring now to FIGS. 30(a)-31(c), a distraction window 342
is disposed in a disc space created by vertebra V2 and an opposing
upper vertebra (not shown) with distraction extensions 344 and 346
extending into the disc space. Distraction window 342 is positioned
in the disc space from an anterior-oblique angle approach to the
spine. Specifically, reference line 348 represents a direct
anterior approach to the spine, in substantial alignment with the
sagittal plane. In the anterior-oblique approach, distraction
window 342 is positioned into the disc space from an angled
approach shown by angle A35. In a preferred embodiment, with
opposing angled side walls disposed at an approximately 30 degree
angle, angle A35 is approximately 30 degrees. A guide tube 340 is
selectively coupled to distraction window 342, thereby forming a
substantially rectangular working channel into the disc space.
Inserter 300 with interconnected implant 200 is then inserted
through guide sleeve 340 until implant 200 is disposed in the disc
space in preformed channel C2. The guide sleeve has dimensions
substantially corresponding to the implant dimensions, thereby
limiting the amount of tissue, vessels and other structures that
must be removed or retracted for placement of the implant. The
inner shaft is then rotated to release implant inserter from
implant 200. The implant inserter, guide tube, and distraction
window may then be removed. The orientation of implant 200 in
comparison to vertebra V2 is substantially identical to the
orientation of implant 200 with respect to vertebra V1 shown in
FIGS. 24(a)-24(c). End wall 216 is in substantial alignment with
posterior portion 274 of channel C2. End wall 216 is disposed
substantially adjacent posterior portion 275 of vertebra V2.
Further, opposed side walls 212 and 250 are in substantial lateral
alignment with the lateral portions of vertebra V2. Thus, it will
be understood that implant 200 is positioned in the disc space with
the tapering surfaces 228 and 230 extending in the proper
orientation to provide maintenance of angulation between vertebra
V2 and the opposing upper vertebra (not shown).
[0084] While not shown by illustration, it will be understood that
the implants described herein may be inserted from a direct lateral
approach to the spine. The same orientation in the disc space may
be achieved regardless of the direction of insertion and the
guiding instruments used.
[0085] Thus, the present invention provides an implant having
multiple facets or substantially parallel side walls allowing
uniform orientation of the implant in the disc space although it is
inserted by multiple, often guided, approaches to the spine.
Specifically, the embodiments of the implants according to the
present invention permit insertion from a direct anterior,
oblique-anterior and a direct lateral approach to the spine. While
preferred embodiments of the invention has disclosed three pair of
substantially parallel side walls disposed at a various angles, it
is contemplated that more than three pair of substantially parallel
side walls could be utilized to provide for implant insertion from
a plurality of angles. Further, while a particular angle of 30
degrees has been utilized for the purposes of illustration in a
preferred embodiment, it will be understood that any oblique angle
might be utilized to provide for insertion from multiple approaches
from the spine.
[0086] While the invention has been illustrated and described in
detail in the drawings and foregoing description, the same is to be
considered as illustrative and not restrictive in character, it
being understood that only the preferred embodiments have been
shown and described and that all changes and modifications that
come within the spirit of the invention are desired to be
protected.
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