U.S. patent application number 10/417974 was filed with the patent office on 2003-10-16 for methods and instrumentation for vertebral interbody fusion.
Invention is credited to Boyd, Lawrence M., Burkus, J. Kenneth, Dorchak, John D., Estes, Bradley T., Ray, Eddie F..
Application Number | 20030195520 10/417974 |
Document ID | / |
Family ID | 22380775 |
Filed Date | 2003-10-16 |
United States Patent
Application |
20030195520 |
Kind Code |
A1 |
Boyd, Lawrence M. ; et
al. |
October 16, 2003 |
Methods and instrumentation for vertebral interbody fusion
Abstract
A method and instrumentation particularly adapted for disc space
preparation from an anterior approach to the spine. The invention
provides an improved guide sleeve defining a channel having
overlapping cylindrical working channel portions and lateral
non-distracting extensions extending from reduced thickness wall
portions. The guide sleeve has an overall reduced width
configuration adjacent the distal end due to the overlapping
working channel portions and reduced thickness wall portions. A
pair of distractors are provided. A first distractor includes a
shaft and distal tip, each having convex walls. A second distractor
includes a shaft and distal tip including a recessed area at least
along the tip. The first distractor is at least partially received
within the recessed area of the second distractor when the first
and second distractors are in side-by-side relation and a reduced
overall width of the distractors is obtained. Preferably, the first
and second distractors are used with the guide sleeve. A method of
using the disclosed instruments is also provided.
Inventors: |
Boyd, Lawrence M.; (Memphis,
TN) ; Ray, Eddie F.; (Cordova, TN) ; Estes,
Bradley T.; (Memphis, TN) ; Burkus, J. Kenneth;
(Columbus, GA) ; Dorchak, John D.; (Midland,
GA) |
Correspondence
Address: |
Woodard, Emhardt, Moriarty, McNett & Henry LLP
Bank One Center/Tower
Suite 3700
111 Monument Circle
Indianapolis
IN
46204-5137
US
|
Family ID: |
22380775 |
Appl. No.: |
10/417974 |
Filed: |
April 17, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10417974 |
Apr 17, 2003 |
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09498426 |
Feb 4, 2000 |
|
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6575981 |
|
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60118793 |
Feb 4, 1999 |
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Current U.S.
Class: |
606/90 |
Current CPC
Class: |
A61B 2017/0256 20130101;
A61F 2002/4627 20130101; A61B 2090/034 20160201; A61F 2/4611
20130101; A61F 2002/30871 20130101; A61F 2002/448 20130101; A61F
2002/4681 20130101; A61F 2002/30604 20130101; A61F 2/446 20130101;
A61B 17/1671 20130101; A61F 2002/3082 20130101; A61F 2250/0063
20130101; A61F 2/4603 20130101; A61B 90/94 20160201; A61F
2002/30904 20130101; A61F 2/442 20130101; A61F 2002/4687 20130101;
A61F 2002/30593 20130101; A61F 2002/3085 20130101; A61B 17/1735
20130101; A61B 17/1757 20130101; A61B 17/025 20130101 |
Class at
Publication: |
606/90 |
International
Class: |
A61F 002/36 |
Claims
What is claimed is:
1. A surgical instrument for distracting a spinal disc space,
comprising: a distractor having a length and including: a shaft and
a first distractor tip connected to an end of said shaft,
including: a first surface and an opposite second surface defining
a distraction height; and a recessed area extending between said
first and second surfaces along at least a portion of said
length.
2. The instrument of claim 1, wherein said shaft includes a
recessed area adjacent to and coplanar with said recessed area of
said distractor tip along a portion of a length of said shaft.
3. The instrument of claim 2, wherein said recessed area of said
distractor tip and said recessed area of said shaft extend along
substantially the entire length of said distractor.
4. The instrument of claim 3, wherein said recessed areas are
concave surfaces.
5. The instrument of claim 2, wherein said recessed areas are
concave surfaces.
6. The instrument of claim 1, wherein said first surface and said
second surface are substantially parallel.
7. The instrument of claim 6, wherein said first surface and said
second surface are each substantially planar.
8. The instrument of claim 1, wherein said recessed area is
configured to permit rotation of a surgical device positioned
adjacent thereto.
9. The instrument of claim 1, wherein said distractor tip is
integrally formed with said shaft.
10. The instrument of claim 1, wherein said recessed area is a
concave surface extending between said first and second
surfaces.
11. The instrument of claim 10, wherein said distractor tip
includes a convex surface opposite said concave surface extending
between said first and second surfaces.
12. The instrument of claim 1, wherein said distractor tip includes
a rounded leading end extending between said first and second
surfaces.
13. The surgical instrument of claim 1, further comprising: a
second distractor having a second length and including: a second
shaft extending along a portion of said second length; a second
distractor tip connected to an end of said second shaft, including:
a first surface and an opposite second surface defining a second
distraction height; and wherein said second distractor is
positionable adjacent said distractor with at least a portion of
said second distractor being received within said recessed area of
said distractor to define an overlap region.
14. The instrument of claim 13, wherein said second distractor
includes a pair of opposite convex surfaces extending between said
first surface and said second surface.
15. The surgical instrument of claim 13, wherein said shaft of said
distractor includes a recessed area adjacent to and coplanar with
said recessed area of said distractor tip along the length of said
shaft, and said second shaft of said second distractor is
positionable adjacent said distractor shaft with said second
distractor shaft at least partially received in said recessed
area.
16. The instrument of claim 15, wherein said distractor shaft
includes a pair of notches in said recessed area and said second
distractor shaft includes a locking member positionable in said
pair of notches to lock said first distractor and said second
distractor together.
17. The instrument of claim 13, wherein said shaft includes an
opening and said second shaft includes a second opening, and
further including a clip securable to each of said opening and said
second opening to couple said distractor adjacent to said second
distractor.
18. The instrument of claim 13, further comprising a driving cap
for placement over the other end said distractor and the other end
of said second distractor for transmitting a driving force to said
instrument during insertion.
19. A surgical instrument for distracting a spinal disc space,
comprising: a first distractor having a first shaft and a first
distractor tip extending from said first shaft, said first
distractor tip including opposite first and second surfaces
defining a first distraction height and including a recessed area
extending between said first and second surfaces; a second
distractor having a second shaft and a second distractor tip
extending from said second shaft, said second distractor tip
including opposite first and second surfaces defining a second
distraction height substantially equal to said first distraction
height; and a guide sleeve having a wall defining a working
channel, wherein said first and second distractors are received in
said working channel of said guide sleeve.
20. The surgical instrument of claim 19, wherein: said first
distractor includes a convex surface opposite said recessed area
extending between said first and second surfaces of said first
distractor tip; and said second distractor includes a pair of
opposite convex surfaces extending between said first and second
surfaces of said second distractor tip.
21. The instrument of claim 20, wherein said second distractor is
positionable adjacent said first distractor with one of said convex
surfaces of said second distractor tip received at least partially
in said recessed surface to define an overlap region.
22. The instrument of claim 19, wherein said working channel
extends between a proximal working end and a distal end of said
guide sleeve.
23. The instrument of claim 19, wherein said distal end of said
guide sleeve includes a pair of opposite flanges extending from a
distal end of said guide sleeve said wall along each side of said
working channel for insertion into a distracted disc space.
24. The instrument of claim 23, further comprising a number of
spikes extending from said distal end of said guide sleeve
intermediate said pair of flanges for engaging vertebrae on either
side of the distracted disc space.
25. The instrument of claim 23, wherein said wall of said guide
sleeve includes a reduced thickness portion along each side of said
working channel extending from said distal end toward a proximal
end of said guide sleeve, whereby said guide sleeve has a first
width at said proximal end and a second width at said reduced
thickness portions, said first width being greater than said second
width.
26. The instrument of claim 25, wherein each of said flanges has a
thickness corresponding to said reduced thickness portion.
27. The instrument of claim 19, wherein said guide sleeve includes
a visualization window extending proximally from a distal end of
said guide sleeve.
28. The instrument of claim 19, wherein said guide sleeve includes
a flange ring at said proximal end.
29. The instrument of claim 19, wherein said working channel
includes a first working channel portion for receiving said first
distractor and a second working channel portion for receiving said
second distractor.
30. The instrument of claim 29, wherein said first working channel
portion and said second working channel portion form a working
channel having a figure eight shape.
31. The instrument of claim 29, wherein each of said first and
second working channel portions has a truncated circular shape,
wherein said truncated portions are positioned adjacent one
another.
32. A method for distracting a spinal disc space, comprising:
gaining access to the disc space; providing a first distractor
having a first distractor tip with a recessed area extending along
its length; providing a second distractor having a second
distractor tip; positioning the second distractor adjacent the
first distractor with the second distractor tip at least partially
received in the recessed area; and inserting the distractor tips
into the disc space to distract the disc space.
33. The method of claim 32, further comprising: providing a guide
sleeve having a working channel extending therethrough between a
proximal end and a distal end; positioning the first and second
distractors within the working channel; and applying a driving
force to the first and second distractors and to the guide sleeve
to insert the first and second distractor tips into the disc
space.
34. The method of claim 33, further comprising: applying a driving
force only to the guide sleeve to advance the guide sleeve towards
the disc space until the distal end is positioned adjacent the disc
space.
35. The method of claim 34, wherein the guide sleeve is provided
with a pair of flanges extending from the distal end, the flanges
being positioned in the disc space when the distal end is
positioned adjacent the disc space.
36. The method of claim 34, wherein the flanges have a height that
is not greater a height of the distracted disc space.
37. The method of claim 34, wherein the guide sleeve is provided
with a number of spikes extending from the distal end, the number
of spikes engaging the vertebral bodies on either side of the disc
space when the distal end is positioned adjacent the disc
space.
38. The method of claim 34, further comprising: removing the second
distractor from the guide sleeve to form a substantially
cylindrical working space through the guide sleeve adjacent the
first distractor tip.
39. The method of claim 38, further comprising: reaming the disc
space adjacent the recessed area of the first distractor tip;
providing a first implant having a concave side surface; and
inserting the first implant into the reamed disc space with the
concave side surface facing the first distractor tip.
40. The method of claim 39, further comprising: tapping threads
into this reamed disc space before inserting the implant; and
threading the first implant into the tapped disc space.
41. The method of claim 39, further comprising: removing the first
distractor from the disc space; reaming the disc space adjacent the
inserted implant; and inserting a second implant adjacent the
inserted implant.
42. The method of claim 41, the inserted second implant has a
convex side surface positioned adjacent the concave side surface of
the first implant.
43. The method of claim 42, wherein the second implant has a
concave side surface facing the concave side surface of the first
implant to define a cavity therebetween; and further comprising
placing bone growth material within the cavity.
44. The method of claim 33, wherein the guide sleeve includes a
flange ring on the proximal end, wherein the driving force to the
guide sleeve is applied to the flange ring.
45. The method of claim 32, further comprising: removing the second
distractor from the disc space to form a working space adjacent the
first distractor tip.
46. The method of claim 45, further comprising: reaming the disc
space adjacent the recessed area of the first distractor tip;
providing a first implant having a concave side surface; and
inserting the first implant into the reamed disc space with the
concave side surface facing the first distractor tip.
47. The method of claim 46, further comprising: tapping threads
into this reamed disc space before inserting the implant; and
threading the first implant into the tapped disc space.
48. The method of claim 46, further comprising: removing the first
distractor from the disc space; reaming the disc space adjacent the
inserted implant; and inserting a second implant adjacent the
inserted implant.
49. The method of claim 48, the inserted second implant has a
convex side surface positioned adjacent the concave side surface of
the first implant.
50. The method of claim 49, wherein the second implant has a
concave side surface facing the concave side surface of the first
implant to define a cavity therebetween; and further comprising
placing bone growth material within the cavity.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 09/498,426, filed on Feb. 4, 2000, which claims the
benefit of the filing date of Provisional Application Serial No.
60/118,793, filed Feb. 4, 1999, each of which are incorporated
herein by reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to surgical
procedures for spinal stabilization and more specifically to
instrumentation adapted for inserting a spinal implant within the
intervertebral disc space between adjacent vertebra. More
particularly, while aspects of the invention may have other
applications, the present invention is especially suited for disc
space preparation and implant insertion into a disc space from an
anterior surgical approach to the spine.
[0003] Various surgical methods have been devised for the
implantation of fusion devices into the disc space. Both anterior
and posterior surgical approaches have been used for interbody
fusions. In 1956, Ralph Cloward developed a method and
instrumentation for anterior spinal interbody fusion of the
cervical spine. Cloward surgically removed the disc material and
placed a tubular drill guide with a large foot plate and prongs
over an alignment rod and then embedded the prongs into adjacent
vertebrae. The drill guide served to maintain the alignment of the
vertebrae and facilitated the reaming out of bone material adjacent
the disc space. The reaming process created a bore to accommodate a
bone dowel implant. The drill guide was thereafter removed
following the reaming process to allow for the passage of the bone
dowel which had an outer diameter significantly larger than the
reamed bore and the inner diameter of the drill guide. The removal
of the drill guide left the dowel insertion phase completely
unprotected.
[0004] More recent techniques have advanced this concept and have
provided further protection for sensitive tissue during disc space
preparation and dowel insertion. Such techniques have been applied
to an anterior approach to the lumbar spine.
[0005] An initial opening or openings are made in the disc space
and the height of the disc space is distracted to approximate
normal height. Typically, a first distractor is inserted with a
height estimated by radiological examination. If additional
distraction is required, the first distractor is removed and a
second, larger distractor is inserted. However, since the
positioning of the distractors is performed without the benefit of
protective guide sleeves, the switching of distractors increases
the potential for damage to neurovascular structures and may
correspondingly increase the time of the procedure.
[0006] For bilateral procedures, a double barrel sleeve may be
inserted over the distractors, with a central extension extending
into the disc space to maintain distraction. One limitation on
guide sleeve placement is the amount of neurovascular retraction
that must be achieved to place the guide sleeves against the disc
space. For some patients, a double barrel sleeve may not be used
because there is insufficient space adjacent the disc space to
accept the sleeve assembly. Thus, there remains a need for guide
sleeves requiring less neurovascular retraction for proper
placement and providing greater protection to adjacent tissue.
[0007] While the above-described techniques are advances,
improvement is still needed to reduce the procedure time by
utilization of improved instruments and techniques, to reduce the
potential for damage to sensitive tissue adjacent the disc space,
and to limit the amount of vessel retraction necessary to utilize
the protective instrumentation. The present invention is directed
to this need and provides more effective methods and
instrumentation for achieving the same.
SUMMARY OF THE INVENTION
[0008] The present invention relates to methods and instrumentation
for vertebral interbody fusion. In one aspect of the invention, the
instruments define a reduced width configuration that allows
bilateral insertion of implants into the disc space.
[0009] In one aspect of the invention, a distractor is provided
that includes a distractor shaft with a length. A distractor tip
extends from on end of the shaft. The distractor tip has opposite
first and second surfaces that define a distraction height between
the surfaces. The distractor tip has a recessed area, preferably a
concave surface, that extends between the first and second
surfaces. Optionally, the distractor shaft may include a recessed
area along its length that is an extension of the recessed area of
the distractor tip. The recessed area of the distractor and/or
shaft may permit the passage of and rotation of surgical devices
adjacent thereto.
[0010] In another aspect of the present invention, a guide sleeve
has a wall that defines a protected passageway to a distracted disc
space. The guide sleeve includes a proximal end and a distal end. A
pair of overlapping working channels extends between the ends. The
sleeve has a first width at the proximal end and a second width at
the distal end. The first width is greater than the second width.
The reduced second width is provided by reducing the exterior wall
thickness of the sleeve at the distal end. Preferably, a first
flange and a second flange extend from the distal end at the
reduced wall thickness portions. Preferably, the flanges have a
thickness that corresponds to the reduced wall thickness. Still
more preferably, the first and second lateral extensions have a
height less than the height of the distracted disc space, and
inhibit encroachment of adjacent tissue into the distracted disc
space. In another form, the guide sleeve may include spikes
projecting from the sleeve distal end between the flanges to engage
the adjacent vertebral bodies. In a further form, the overlapping
working channels are substantially cylindrical.
[0011] In another aspect, there is provided a guide sleeve
assembly. The assembly includes a sleeve defining a working
channel. A first distractor has a first distractor tip with a
recessed area along a portion of its length, and a second
distractor has a second distractor tip. With the first distractor
disposed in the working channel of the sleeve in side-by-side
relation with the second distractor, the recessed surface of the
first distractor tip receives at least a portion of the second
distractor tip. In one form, the recessed area of the first
distractor tip is defined by a concave surface and the second
distractor tip has opposite convex surfaces, one of which is
positioned adjacent the concave surface of the first distractor
tip. In another form, the first and second distractors define an
overlap region in the guide sleeve working channel.
[0012] In a method according to the present invention, access is
gained to a disc space. A first distractor having first distractor
tip with a recessed area and a second concave distractor having a
second distractor tip are disposed in side-by-side relation with
the distractor tips inserted adjacent the disc space. Preferably,
the distractors are also engaged within the working channel of an
outer sleeve. The distractors distract and maintain the disc space
at the desired height during the procedure. Once the desired
distraction of the disc space has been achieved, the outer sleeve
is advanced toward the disc space until disposed adjacent the disc
space. If necessary, a driving cap may be positioned over the
proximal end of the outer sleeve to apply a driving force
thereto.
[0013] The outer sleeve is then driven into position so that
opposing side flanges are positioned in the disc space and spikes
on the outer sleeve enter the vertebral bodies. Preferably, the
side flanges do not perform any distraction of the disc space. Once
the outer sleeve is positioned, the second distractor may be
removed and a substantially cylindrical working space is provided
through the sleeve to the disc space adjacent the first distractor.
Preferably, the working space defines an area that is greater than
one half of the area of the working channel of the guide
sleeve.
[0014] Various surgical procedures are performed through the
working space, such as reaming, tapping and inserting a threaded
implant into the disc space. Once the first implant is inserted,
the second distractor is removed, and the first implant maintains
the disc space distraction and defines a working space adjacent the
inserted implant. Preferably, the first implant has a concave side
wall to define a portion of a substantially cylindrical working
space. The surgical procedures are then repeated to insert a second
implant adjacent the first implant. In one embodiment, the second
implant has a circular cross-section. In another embodiment, the
implant has a cross-section that mirrors that of the first implant
after insertion.
[0015] Although various sleeves are known in the art, in a
preferred embodiment, outer sleeves according to the present
invention have a reduced width portion adjacent the bone engaging
distal end to limit the amount of retraction of the surrounding
vasculature and neural tissue required for the procedure. The
reduced width portion, preferably in combination with the
previously described overlapping working channels, combine to
greatly reduce the overall width of the sleeve. In a preferred
form, a sleeve assembly includes a pair of opposite side flanges or
lateral extensions having a first height. The lateral extensions
provide protection from encroachment of tissue into the working
area of the disc space. Preferably, the side flanges of the outer
sleeve are not used to maintain distraction of the disc space and
thus do not experience the forces of disc space distraction. As a
result, the flanges and adjacent side walls may be formed with a
reduced wall thickness.
[0016] A further aspect includes the provision of a visualization
window along the centerline of the outer sleeve for visual access
to the interior working channel while instruments are in the
working channel. Even without the use of an imaging system, the
present invention contemplates the use of manually adjustable depth
stop that is to control the steps of trephining, reaming, tapping,
and implant insertion. The term implant is used in a broad sense
throughout the disclosure and is intended to encompass bone dowels,
metallic cages and spacers, and other implants used for interbody
fusion regardless of shape or material of construction.
[0017] Related objects, advantages, aspects, forms, and features of
the present invention will be apparent from the following
description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1a is a perspective view of a distractor according to
the present invention.
[0019] FIG. 1b is an enlarged front view of the tip of the
distractor of FIG. 1a.
[0020] FIG. 1c is an enlarged side view of the tip of the
distractor of FIG. 1a.
[0021] FIG. 2a is a perspective view of a distractor according to
another aspect of the present invention.
[0022] FIG. 2b is an enlarged front view of the tip of the
distractor of FIG. 2a.
[0023] FIG. 2c is an enlarged side view of the tip of the
distractor of FIG. 2a.
[0024] FIG. 2d is an elevation view of a distractor clip.
[0025] FIG. 3 is a perspective view of a guide sleeve according to
another aspect of the present invention.
[0026] FIG. 4 is a front view of the guide sleeve of FIG. 3.
[0027] FIG. 5 is a side view of the guide sleeve of FIG. 3.
[0028] FIG. 6 is a perspective view of a guide sleeve assembly
according to another aspect of the present invention.
[0029] FIG. 7 is an enlarged end view of the distal end of the
guide sleeve assembly of FIG. 6.
[0030] FIG. 8 is an enlarged end view of the proximal end of the
guide sleeve assembly of FIG. 6.
[0031] FIG. 9 is an anterior to posterior view of a guide sleeve
assembly according to FIG. 3, the guide sleeve assembly is
positioned in relation to a pair of adjacent vertebral bodies and
blood vessels.
[0032] FIG. 10 is a partial cross-sectional view of the disc space
through line 10-10 of FIG. 9.
[0033] FIG. 11 is a perspective view of the guide sleeve assembly
during insertion of the distractors into the disc space.
[0034] FIGS. 11a and 11b are front and rear elevation views,
respectively, of a distractor driver cap for driving the
distractors into the disc space.
[0035] FIGS. 12a-12b are perspective views of the guide sleeve
assembly 150 with an impactor cap disposed thereon prior to seating
the guide sleeve.
[0036] FIGS. 13 is a perspective view of the guide sleeve assembly
with an impactor cap disposed thereon.
[0037] FIG. 14 is a perspective view of the guide sleeve assembly
with a slap hammer disposed on one of the distractors.
[0038] FIGS. 15a-15b are a perspective view and an end view,
respectively, of the guide sleeve assembly with a distractor
removed.
[0039] FIGS. 16a-16b are a perspective view and an end view,
respectively, of the guide sleeve assembly with a reamer disposed
adjacent a distractor.
[0040] FIGS. 17a-17c are a perspective view, detail view and end
view, respectively, of the guide sleeve assembly with a tap
disposed adjacent a distractor.
[0041] FIGS. 18a-18c are a perspective view, detail view and end
view, respectively, of the guide sleeve assembly with an implant
disposed adjacent a distractor.
[0042] FIGS. 19a-19c are perspective views and an end view,
respectively, of the guide sleeve assembly showing withdrawal of
the other distractor.
[0043] FIGS. 20a-20b are a perspective view and an end view,
respectively, of the guide sleeve assembly with a reamer disposed
adjacent an implant.
[0044] FIGS. 21a-21c are a perspective view, detail view and end
view, respectively, of the guide sleeve assembly with a tap
disposed adjacent an implant.
[0045] FIGS. 22a-22c are a perspective view, detail view and end
view, respectively, of the guide sleeve assembly with an implant
disposed adjacent an implant.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0046] 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 device, 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.
[0047] The present invention relates to methods and instrumentation
for performing vertebral interbody fusion. Specifically, although
aspects of the present invention may have other uses either alone
or in combination, the instruments and methods disclosed herein are
particularly useful for anterior lumbar interbody fusion. However,
the surgical instruments and methods according to the present
invention are not limited to such an approach, and may find
application in, but without limitation, lateral and
anterior-lateral approaches to the spine as well. Also, the
surgical instruments and methods of the present invention may find
application at all vertebral segments of the spine, and in areas
other than spinal surgery.
[0048] Referring now to FIGS. 1a-c, there is shown a convex or
first disc space distractor 50 according to one aspect of the
present invention. Distractor 50 includes a proximal end 53
configured for engagement with conventional tools and handles (not
shown) used in operative procedures on the spine. A shaft 54 is
joined with a distractor tip 56. In the illustrated embodiment,
shaft 54 has a hollow interior and a clip hole 55 communicating
with the hollow interior; however, the present invention also
contemplates a solid shaft 54. Also, while an integral shaft and
head are shown, head 56 may be removably attached to shaft 54. One
such removable attachment is more fully disclosed in U.S. patent
application entitled METHOD AND INSTRUMENTATION FOR VERTEBRAL
INTERBODY FUSION, Ser. No. 09/287,917, filed Apr. 7, 1999, which is
incorporated herein by reference in its entirety (hereinafter
referred to as the '917 patent application.) Distractor tip 56 is
designed such that it can be inserted in a disc space to establish
a first working distraction height 72 (see FIG. 1b). More
specifically, distractor tip 56 has a rounded leading edge 62 that
extends to opposing inclined surfaces 58 and 59, which in turn
extend more proximally and blend into substantially planar opposing
surfaces 60 and 61, respectively. Extending between planar surfaces
60 and 61 and proximal the rounded tip 62 are opposite convex
surfaces 64 and 66.
[0049] Planar surfaces 60 and 61 extend in a substantially parallel
alignment along a longitudinal axis A of distractor 50 and define
height 72 therebetween. It should be understood that the inclined
surfaces 58 and 59 cooperate to aid insertion of the distractor tip
56 into the disc space and to initially distract the disc space to
at least a height 72. If first distraction height 72 is sufficient,
further procedures as known in the art may then be carried out to
accomplish implant insertion. While a specific distractor has been
described in detail, it is contemplated that other known distractor
configurations may be substituted for the same without deviating
from the scope of this invention.
[0050] Referring now to FIGS. 2a-c, there is shown a second disc
space distractor 80 according to one aspect of the present
invention. Distractor 80 includes a proximal end 83 configured for
engagement with conventional tools and handles (not shown). A shaft
84 is joined with a distractor tip 86. In the illustrated
embodiment, shaft 84 has a hollow interior and a hole 85
communicating therewith. While an integral shaft and head are
shown, head 86 may be removably attached to shaft 84, as similarly
described with respect to the removable attachments disclosed in
the '917 patent application. Similar to distractor tip 56 of
distractor 50, distractor tip 86 is designed such that it can be
inserted in a disc space to establish a first working distraction
height 72' (see FIG. 2b) that is preferably the substantially the
same as working height 72. More specifically, distractor tip 86 has
a rounded leading edge 92 that extends to opposing inclined
surfaces 88 and 89 which, in turn, extend more proximally and blend
into substantially planar opposing surfaces 90 and 91,
respectively.
[0051] Planar surfaces 90 and 91 extend substantially parallel to
longitudinal axis B of distractor 80 to define height 72'
therebetween. Extending between planar surfaces 90 and 91 are
convex surface 94 and a recessed area defined by opposite concave
surface 96. Along the distractor shaft 84, there is defined a
concave surface 98 that is adjacent to and coplanar with concave
surface 96 of distal tip 86 to define a concave surface extending
along the length of distractor 80. In the illustrated embodiment,
surface 98 has a slot 87 formed therein communicating with the
hollow interior of shaft 84; however, it the present invention also
contemplates a solid shaft 84 and a shaft 84 without slot 87. As
explained more fully below, concave surfaces 96, 98 are configured
to receive convex surface 64 or 66 of distractor 50 to reside
therein when distractors 50 and 80 are disposed in side-by-side
relation. Concave surfaces 96, 98 also partially define a working
space that allows operative procedures to be performed
therethrough.
[0052] It should be understood that the inclined surfaces 88 and 89
cooperate to aid insertion of distractor tip 86 into the disc
space, and to distract the disc space and maintain disc space
distraction to at least a height 72, 72'. To further aid in
distractor insertion, in FIG. 2d there is shown a distractor clip
75 having a cross member 76 with first clip member 77 and second
clip member 78 extending therefrom. Clip members 77 and 78 are each
received in a corresponding one of holes 55 and 85 to couple
distractor 50 to distractor 80. Clip 75 prevents splaying and
maintains the relative positioning of distractors 50, 80 during
insertion into the disc space. If first distraction height 72 is
sufficient, further procedures as known in the art may then be
carried out to accomplish implant insertion. It should be further
understood that second distractor 80 has a second width 74 that is
less than a first width 70 of first distractor 50.
[0053] Specifically, but without limitation, the distractor heads
56, 86 may be formed with heights 72 ranging from 6 mm to 24 mm.
Preferably, height 72 of the next sized distractor increases or
decreases in 2 mm increments. Other variations and may be provided
as long as the working distractor height provided approximates the
disc height in a normal spine and accommodates insertion of an
implant into the disc space as more fully described below.
[0054] Referring now to FIG. 3, there is shown a guide sleeve 100
that is useful with the distractors 50 and 80 described above.
Guide sleeve 100 has a wall 110 defining a working channel 130
having a figure eight shaped cross-section (FIG. 9) extending in a
substantially unobstructed manner from a proximal end 102 to a
distal end 104. Sleeve 100 includes upper windows 106 and 108
formed in wall 110 on at least one side of sleeve 100 for
engagement by a removal tool to remove sleeve 100. The sleeve 100
also includes lower elongated visualization window 112 centered
about the longitudinal axis L with an elongated slot 111 extending
proximally window 112. Window 112 provides the surgeon with the
ability to visualize the instruments inserted in guide sleeve 100
as well as the openings in the disc space and vertebral bodies,
without entirely removing instrumentation from guide sleeve 100.
The reduce width of sleeve 100 allows the use of one window 112 for
visualization of implant insertion into its respective bilateral
location in the disc space, and separate windows along each
insertion path are not necessary. However, it should be understood
that any number of visualization windows and configurations thereof
are contemplated herein, such as those described in the '917 patent
application. The present invention also contemplates that covers
may be used for visualization windows, as described in greater
detail in the '917 patent application.
[0055] At proximal end 102 is provided a flange ring 155. Flange
ring 155 strengthens sleeve 100 and provides a load transfer member
to facilitate transfer of a driving force to sleeve 100, as
described more fully below. Adjacent distal end 104, the material
thickness along the exterior outer edge of wall 110 is reduced in
order to provide a reduced thickness wall portion 114 and an
opposite reduced thickness wall portion (not shown). The reduced
thickness wall portions define a smaller cross-sectional area for
the sleeve 100 as well as a reduced width extending transverse to
the longitudinal axis L. The reduced cross-sectional area and
smaller width of guide sleeve 100 reduces the amount of vasculature
and neural tissue retraction adjacent the disc space that would
otherwise be required to place a similarly sized guide sleeve
without the width reduction.
[0056] Distal end 104 includes a pair of flanges 118 and 120
extending from wall 110 on opposite sides of working channel 130.
Flanges 118 and 120 are configured to extend partially into the
disc space. Flanges 118, 120 are each formed by and are an
extension of the corresponding reduced thickness wall portions 114
described above. In a preferred embodiment, flanges 118 and 120 do
not provide distraction of the disc space but are primarily
provided to protect surrounding vessels and neurological structures
from damage during the procedures. Since the lateral flanges do not
provide structural support for distraction, the material thickness
of the flanges and adjacent side walls may be reduced.
Additionally, distal end 104 includes spikes 122, 124, positioned
between flanges 118, 120 and a third spike 126 and a fourth spike
128 positioned opposite spikes 122, 124 between flanges 118, 120 as
shown in FIG. 7. These spikes may be urged into the bone of the
adjacent vertebral bodies to hold guide sleeve 100 in a fixed
position relative to the vertebral bodies.
[0057] Referring to FIGS. 4 and 5, guide sleeve 100 is shown in
front and side views, respectively, to further illustrate an
additional aspect of the invention. A proximal end 102 the guide
sleeve 100 has a maximum width W1. At distal end 104 of sleeve 100,
wall 110 has a reduced wall thickness at side walls 114 and 113
defining a width W2 that is less than width W1. The side walls 113,
114 are preferably not entirely flat and have a slight curvature.
Side walls 113, 114 provide a reduction in wall thickness of wall
110 and taper to the full wall thickness of wall 110 at the
termination of side walls 113 and 114. The reduction in width of
wall 110 decreases the amount of vasculature and neural tissue
retraction in the area adjacent the disc space. The desirable
reduction in width is accomplished with little reduction in the
required strength of the device since distractors 50, 80 are used
to distract and maintain the distraction of the vertebral bodies
instead of the extensions or side flanges 118, 120 of guide sleeve
100.
[0058] There are also shown in FIGS. 4 and 9 a first working
channel portion 107, defined about axis L1, and a second working
channel portion 109, defined about axis L2. These working channel
portions 107, 109 are positioned on either side of longitudinal
axis L of sleeve 100. There is no wall or other structure
separating working channel portions 107 and 109. Working channel
portion 107 is that portion of working channel 130 about axis L1
between longitudinal axis L and inside surface of 116 of guide
sleeve 100. Similarly, working channel portion 109 is that portion
of working channel 130 about axis L2 between longitudinal axis L
and inside surface 116. Thus, working channel portions 107 and 109
are substantially equal in area, and each has a truncated circular
shape, with the truncated portions of each working channel 107 and
109 positioned adjacent one another.
[0059] Referring now to FIG. 6, there is illustrated a
distractor/guide sleeve assembly 150 that includes distractors 50
and 80 disposed within working channel 130 of guide sleeve 100 in
side-by-side relation. Distractors 50, 80 reside within sleeve 100
with each distractor substantially occupying all or a portion of a
corresponding one of working channel portions 107 and 109 of
working channel 130. Each distractor 50, 80 extends from proximal
end 102 to distal end 104 of the guide sleeve 100. Flange ring 155
is in the form of a flange extending about the proximal end 102 of
guide sleeve 100 and contacts a driving cap positioned on
distractors 50, 80 in order to maintain the relative positioning
between sleeve 100 and distractors 50, 80 during insertion of
assembly 150.
[0060] Referring now to FIG. 7, there is illustrated an end view at
distal end 104 of the assembly 150 showing distractors 50 and 80 in
side-by-side relation. More particularly, shaft 54 of distractor 50
is received within concave portion 98 of distractor shaft 84. As
also illustrated in this view, concave portion 96 of distractor tip
86 is coextensive with concave surface 98 to form a concave surface
that extends the length of the distractor 80. The concave surface
of distractor 80 has a radius of curvature R that is preferably
about one half the diameter of the cage or implant to be inserted
into the disc space. For example, an 18 mm diameter implant
requires use of a distractor 80 having a radius of curvature R of
about 9 mm.
[0061] When distractor 50 is removed from guide sleeve 100, there
is defined a cylindrical working space through the working channel
130 adjacent and along the recessed areas of distractor 80. The
cylindrical working space includes that portion of the working
channel 130 between concave surfaces 96, 98 and inside wall 116 of
the guide sleeve 100. Thus, the working space occupies
substantially all of working channel portion 107, (FIG. 4) and a
portion of working channel portion 109. The area of the portion of
the working channel portion 109 occupied by the cylindrical working
space is indicated in FIG. 7 by the hatched area A, and is
hereinafter referred to as the overlap region. This overlap region
A allows operative procedures to be performed in the working space
adjacent the distractor 80 using conventionally sized tools and
implements while providing a guide sleeve 100 of reduced overall
width. The amount of width reduction achieved is approximately the
maximum width of overlap region A. It should be understood that
shaft 84 need not have a recessed area to provide a cylindrical
working space in the disc space, but rather can be provided with a
reduced diameter or size that maintains access to the overlap
region A in the disc space.
[0062] In FIG. 8 there is shown a top view of the guide sleeve
assembly 150, looking down on proximal ends 53, 83 of the
distractors 50, 80 and the proximal end 102 of guide sleeve 100. In
one embodiment, there is provided adjacent proximal end 53 of
distractor 50 a locking segment 140 formed with and extending from
the distractor shaft 54. Locking segment 140 has a first projection
142 and a second projection 144. First and second projections 142,
144 are received within corresponding notches 146, 148 defined in
concave surface 98 of shaft 84 of distractor 80 to prevent rotation
of distractors 50 and 80 with respect to one another. The present
invention also contemplates other mechanisms for engaging
distractors 50 and 80 to prevent rotation relative to one another
as would occur to those of ordinary skill in the art. For example,
the above described distractor clip 75 can be used to couple the
distractors 50, 80 together. Moreover, it is contemplated that the
distractors 50, 80 may be inserted without any locking
mechanism.
[0063] The present invention contemplates that access to the disc
space has heretofore been provided by known surgical techniques and
therefore will not be further described herein. The use of
intraoperative templates for providing access to the disc space is
known in the art. One example of a procedure for gaining access to
the disc space is disclosed in the '917 patent application. Another
reference including techniques for template positioning and disc
space distraction using a starter distractor to initially distract
the disc space is the surgical technique brochure entitled Reduced
Profile Instrumentation published in 1999 by Sofamor Danek, said
brochure being incorporated by reference herein in its entirety
(hereinafter the Danek brochure.) The present invention also
contemplates the use and application of other procedures for
gaining access to the disc space in conjunction with the procedures
and instruments discussed below as would occur to those skilled in
the art. The templates contemplated herein define the area
necessary for placement of implants and instruments having a
specific configuration and size. While in a preferred embodiment,
templates are provided for cylindrical implants having diameters
ranging from 16 mm to 24 mm, it is contemplated that other
diameters of implant and templates for use therewith may be used
and other shapes, such as, but without limitation, squares and
rectangles.
[0064] Access to an anterior portion of the spinal column is
achieved by known methods. Blood vessels, particularly the aorta,
vena cava, and branches thereof are mobilized to provide space for
bilateral implant placement. The template is inserted into the body
and advanced until the pins are disposed adjacent a disc space. The
circumference of the template is selected to correspond to the
circumference needed for bilateral placement of a pair of implants.
More specifically, the area of the template closely approximates
the area needed for placement of the guide sleeve disclosed herein,
such as that shown in FIG. 7. It is contemplated that a guide
sleeve 100 need not necessarily be used, and tissue to the surgical
site is retracted by other means while the disc space is distracted
by distractors 50 and 80. The surgical procedures are then
performed in the working space defined by the distractors 50, 80 as
discussed below without use of a guide sleeve.
[0065] Referring to FIG. 9, a cross section through guide sleeve
100, with distractors 50, 80 removed for clarity, is provided.
Sleeve 100 is inserted into a disc space D between two adjacent
vertebra V1 and V2. Disposed adjacent guide sleeve 100 are vessels
560 and 562 graphically representing portions of the aorta or vena
cava. Referring to FIG. 10, a cross-section through line 10-10 of
FIG. 9, sleeve 100, flanges 118, 120 on guide sleeve 100 extend
into the disc space where the surgical procedures are being
performed. Flanges 118, 120 and sleeve 100 inhibit contact between
vessels and tissue surrounding the disc space and the tools used
during the surgical procedure. Spikes 122, 124, 126, and 128 may be
inserted into the bone of the corresponding vertebral body V1,
V2.
[0066] Various tools and implements are usable with guide sleeve
100 including distractors 50, 80 disclosed herein and more
specifically within the working spaces defined by the working
channel 130 of guide sleeve 100. Several of these tools are
disclosed in the Danek brochure and in the '917 patent application,
while other tools are known to those skilled in the art to which
the present invention relates.
[0067] In accordance with a preferred method of using the apparatus
of the present invention, reference will now be made to FIGS. 11
through 22. In FIG. 11, the sleeve assembly is assembled and
prepared for insertion through the skin and to the disc space.
Distractor driver cap 250 of FIGS. 1a and 1b is positioned on
proximal end 53, 83 of distractors 50, 80. Driver cap 250 includes
a body 252 having T-shaped slots 253 and 254 configured to receive
flanged posts 53a and 83a of distractors 50 and 80, respectively.
Opposite slots 253, 254 are windows 256 and 257. Preferably, the
flanged portion of posts 53a and 83a extend into a corresponding
one of the windows 256 and 257 and also into a corresponding one of
the upper portions 253a and 254a of slots 253 and 254 to secure
driver cap 250 to distractors 50, 80.
[0068] In use, distractor cap 250 contacts flange ring 155 with
distractors 50, 80 in sleeve 100 such that distractor tips 56, 86
can be driven into the disc space while flanges 118, 120 remain
positioned outside the disc space. The driving force applied to
distractor cap 250 is transmitted to flange ring 155, and drives
sleeve 100 towards the disc space along with distractors 50, 80.
Alternatively, if distractors 50, 80 are not positioned in guide
sleeve 100, distractor cap 250 is secured to proximal ends 53, 83
and distractor tips 56, 86 are driven into the disc space.
Distractor cap 250 is then removed and sleeve 100 placed over the
inserted distractors 50, 80 and the procedure continues as
discussed below. In this alternate technique, clip 75 may be used
to couple distractors 50, 80 together during insertion. In a
further variation, alternating insertion of distractors 50, 80 is
not precluded by the present invention. However, insertion of
distractors 50, 80 into the disc space simultaneously enables the
surgeon maintain the positioning of distractors 50, 80 and control
the depth of insertion of distractor tips 56, 86 with respect to
one another.
[0069] In FIG. 12a, an impactor cap 160 is disposed about proximal
end 102 of sleeve 100 over flange ring 155. Sleeve 100 is now
relatively free to move with respect to distractors 50, 80. A
driving force is applied to impactor cap 160 to drive sleeve 100
towards the disc space and position flanges 118 and 120 therein
adjacent the distractor tips 56, 86 already positioned into the
disc space as shown in FIG. 12b. Preferably, flanges 118 and 120 do
not distract the disc space and prevent migration of tissue into
the working space when distractor 50, 80 is removed from sleeve
100.
[0070] As shown in greater detail and enlarged FIG. 13, impactor
cap 160 is positioned around and contacts the flange ring 155.
Flange ring 155 is preferably of uniform size and shape for various
sized guide sleeves 100, thus providing a modular attachment to
each of the various sized guide sleeves for a single impactor cap
160. Impactor cap 160 has a hollow interior 161 for receiving
proximal ends 53, 83. Hollow interior 161 has a depth d sufficient
to allow movement of guide sleeve 100 into the disc space while the
position of distractors 50, 80 is maintained.
[0071] In FIG. 14, a slap hammer 165 is engaged to distractor 50 in
order to withdrawal distractor 50 from the disc space. In FIG. 15a
the distractor 50 is removed from the working channel 130 of sleeve
110 using the slap hammer 165. The distractor tip 86 of concave
distractor 80 remains disposed in the disc space to maintain the
disc space distraction height during subsequent operative steps. In
an alternate embodiment, it is contemplated that shaft 84 of
distractor 80 is removably connected to tip 86, in which case the
shaft may be withdrawn while leaving tip 86 in place. In a further
embodiment, shaft 84 has a reduced size to accommodate insertion
and rotation of devices into overlap region A of the disc space.
With a removable or smaller diameter shaft, only tip 86 requires a
recessed area.
[0072] In FIG. 15b, the withdrawn distractor 50 leaves a working
space comprised of working channel portion 109 and an overlap
portion, indicated by hatched area A. Thus, the concave surfaces
96, 98 of distractor 80 and inside surface 116 of sleeve 110 define
a substantially cylindrical working space for completion of further
operative procedures as described further below. The working space
defines a substantially circular cross section along guide sleeve
100 that is adapted for receiving surgical tools therethrough to
prepare the disc space for insertion of an implant. The overlapping
configuration of distractors 50, 80 provides a reduced overall
width for guide sleeve 100.
[0073] In FIGS. 16a-16b, there is shown a reamer 170 disposed
through guide sleeve 110. A cutting head 171 has threads as known
in the art to ream the disc space. As shown in FIG. 16b, reamer 170
is positioned within the working space adjacent distractor 80,
while distractor tip 86 maintains the disc space distraction.
Concave surface 98 of shaft 84 of distractor 80 and the inside
surface 116 of sleeve 110 acts as a guide for insertion and/or
withdrawal of reamer 170. The depth of reaming can be controlled
with a depth stop 172 and verified via fluoroscopy
[0074] In FIGS. 17a-17c, the reamer 170 is withdrawn and replaced
by a tapping tool 175 with a head 176 to prepare the space for a
threaded implant. As shown in FIGS. 17b and 17c, tapping tool 175
is positioned within the working space adjacent the concave
distractor 80, while distractor tip 86 maintains the disc space
distraction. The concave surface 98 of shaft 84 of distractor 80
and inside surface 116 of sleeve 110 acts as a guide for insertion
of tapping tool 175. Tapping tool 175 has a depth stop 178 to
control the tapping depth in the disc space. Depth and sagittal
alignment can also be verified via fluoroscopy during tapping.
[0075] In FIGS. 18a-18c, the tapping tool 175 is withdrawn and
replaced by an implant insertion device 190 with a threaded implant
200 engaged on a distal end thereof. Threaded implant 200 and
insertion device 190 may be any one of the types and configuration
disclosed in a first pending PCT Application No. PCT/US00/00590
filed on Jan. 11, 2000 and a second PCT Application No.
PCT[US00/00604, also filed Jan. 11, 2000; each claiming priority to
U.S. Provisional Application No. 60/115, 388, filed Jan. 11, 1999,
each of said above referenced PCT applications being incorporated
by reference herein in its entirety. Further, the implants of the
present invention may be any other known implant and insertion
device, so long as at least one implant has at least one recessed
side wall. The implants may be formed of any biocompatible
material. Concave surface 98 of shaft 84 of distractor 80 and
inside surface 116 of sleeve 110 acts as a guide for insertion of
the implant into the disc space.
[0076] Inserter 190 includes a thumbscrew 191 having a threaded
shaft (not shown) extending through inserter 190 to couples implant
200 thereto via an internally threaded opening in a slotted end 201
(FIG. 19) of implant 200. T-handle 192 is used to rotate implant
200 and thread it into the disc space, as shown in the enlarged
view of FIG. 18b. As shown more clearly in the enlarged view of
FIG. 18c, implant 200 is inserted so that a concave face 202 is
disposed toward concave surface 96 of distractor 80. This
positioning of concave face 202 can be confirmed by providing
alignment markings on insertion device 190 and sleeve 100. Further,
insertion device 190 includes countersink marking 193 to provide an
indication of the countersink of implant 200 into the disc space.
To facilitate implant rotation, inserter 190 can be provided with a
movable slide at its distal end that occupies the recessed area of
concave surface 202 providing a round construct for threading.
While implant 200 is threaded into place, distractor tip 86
maintains the disc space distraction.
[0077] In FIGS. 19a-19b, when implant 200 is placed in the desired
position, and implant inserter 190 is removed from guide sleeve
100, distractor tip 86 is withdrawn from the disc space.
Preferably, a slap hammer 165 is engaged to distractor 80 in order
to withdraw distractor tip 86 from the disc space and distractor 80
from guide sleeve 100. As shown in FIGS. 19b-19c, distractor 80 is
removed from working channel 130 of sleeve 110. Implant 200 remains
disposed in the disc space to maintain the disc space distraction
height during subsequent operative steps. The withdrawn distractor
80 leaves a working space comprised of working channel portion 107
and an overlap region A. Thus, concave surface 202 of implant 200
and inside surface 116 of sleeve 110 define a cylindrical working
space in the disc space for further procedures as described below.
The working space defines a circular cross section that is adapted
for receiving conventionally sized surgical tools to prepare the
disc space for insertion of a second implant adjacent implant 200,
while providing a reduced overall width.
[0078] In FIGS. 20a-20b, the above described reamer 170 is disposed
through guide sleeve 110. Cutting head 171 has threads as known in
the art to ream the disc space. As shown in FIG. 20b, reamer 170 is
positioned within the working space adjacent the concave surface
201 of implant 200, while implant 200 maintains the disc space
distraction. The concave surface 201 of implant 200 and inside
surface 116 of sleeve 110 acts as a guide for insertion and
operation of reamer 170.
[0079] In FIGS. 21a-21c, reamer 170 is withdrawn and replaced by
the above-described tapping tool 175 with head 176 to prepare the
space for a second threaded implant. As shown in FIGS. 21b and 21c,
head 176 of tapping tool 175 is positioned within the working space
adjacent concave surface 201 of implant 200, while implant 200
maintains the disc space distraction. The concave surface 201 and
inside surface 116 of sleeve 110 acts as a guide for insertion of
tapping tool 175.
[0080] In FIGS. 22a-22c, the tapping tool is withdrawn and replaced
by the above described implant insertion device 190, with a
threaded implant 210 engaged on a distal end thereof. Threaded
implant 210 may either have a circular cross-section, such as that
shown in solid lines in enlarged FIGS. 22b and 22c, or have a
cross-section identical to implant 200 with a concave surface 202
as shown in hidden lines. In either event, concave surface 201 of
implant 200 acts as a guide for threading of implant 210 into the
disc space.
[0081] If an implant like that of implant 200 is used, it is
preferred to position implant 210 so that its concave surface 212'
is disposed towards concave surface 202 of implant 200, forming a
cavity 215' therebetween as indicated in dashed lines in FIG. 22c.
The cavity may then be packed with bone growth promoting material.
T-handle 192 is used to rotate implant 210 and thread it into the
disc space, as shown in FIG. 22b, adjacent to implant 200. If a
circular implant similar to that shown in FIG. 22c is used, implant
210 is nested within concave surface 201 of implant 200. Bone
growth material can be placed in cavity 204 of implant 200 and in
cavity 213 of implant 210.
[0082] While the use of threaded implants has been primarily
discussed, the present invention likewise contemplates using
push-in type implants and/or expandable implants in the disc space.
Also, while it is preferred that the present invention be utilized
for insertion of two implants at bilateral locations within the
disc space, insertion of a single implant into the disc space is
also contemplated herein.
[0083] Of course, the present invention makes use of depth stops
and other devices for measuring and controlling the depth of the
various procedures performed in the disc space. These devices and
procedures are more fully explained in the Danek brochure and in
the '917 patent application. Additionally, the present invention is
not limited to use with the tools and instruments described above,
and guide sleeve 100 and distractors 50, 80 may be used with other
such devices as would normally occur to those skilled in the art to
which the invention relates.
[0084] 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 embodiment has been shown
and described and that all changes and modifications that come
within the spirit of the invention are desired to be protected.
* * * * *