U.S. patent application number 10/438249 was filed with the patent office on 2004-01-22 for apparatus and method for spinal stabilization.
This patent application is currently assigned to Sulzer Spine-Tech Inc.. Invention is credited to Kohrs, Douglas W., Yonemura, Kenneth S..
Application Number | 20040015168 10/438249 |
Document ID | / |
Family ID | 25444763 |
Filed Date | 2004-01-22 |
United States Patent
Application |
20040015168 |
Kind Code |
A1 |
Yonemura, Kenneth S. ; et
al. |
January 22, 2004 |
Apparatus and method for spinal stabilization
Abstract
A surgical method and apparatus for implanting a spinal fusion
implant includes a rigid centering guide having a distal end sized
to be inserted into the disc space with the guide extending along a
longitudinal axis from a distal end to a proximal end. The guide
includes a first external guide surface which extends at least
partially between the distal end and the proximal end. The external
guide surface is shaped complimentary to an external guided surface
of a drill guide. The external guide surface and the guided surface
are nested such that the guided surface slides against the external
guide surface along a path of travel parallel to the longitudinal
axis.
Inventors: |
Yonemura, Kenneth S.;
(Seattle, WA) ; Kohrs, Douglas W.; (Edina,
MN) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Assignee: |
Sulzer Spine-Tech Inc.
Minneapolis
MN
|
Family ID: |
25444763 |
Appl. No.: |
10/438249 |
Filed: |
May 13, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10438249 |
May 13, 2003 |
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09717531 |
Nov 21, 2000 |
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6562041 |
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09717531 |
Nov 21, 2000 |
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09364127 |
Jul 30, 1999 |
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6156040 |
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09364127 |
Jul 30, 1999 |
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08921001 |
Aug 29, 1997 |
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6086595 |
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Current U.S.
Class: |
606/86A ;
606/247; 606/279; 623/17.11 |
Current CPC
Class: |
A61B 90/39 20160201;
A61F 2002/30787 20130101; A61F 2002/448 20130101; A61B 17/025
20130101; A61F 2002/30593 20130101; A61B 17/1757 20130101; A61F
2002/30868 20130101; A61F 2/442 20130101; A61F 2002/30235 20130101;
A61B 2017/0256 20130101; A61F 2/4611 20130101; A61F 2230/0069
20130101; Y10S 606/914 20130101; A61F 2002/4627 20130101; A61B
2090/062 20160201; A61F 2002/30785 20130101; A61F 2/446 20130101;
A61F 2002/2835 20130101; A61F 2002/4687 20130101 |
Class at
Publication: |
606/61 |
International
Class: |
A61F 002/30; A61B
017/56; A61B 017/58 |
Claims
What is claimed is:
1. A surgical method for implanting a spinal fusion implant into a
disc space separating a first vertebra and a second vertebra, said
method comprising: inserting a distal end of a rigid centering
guide into said disc space with said guide extending along a
longitudinal axis from said distal end to a proximal end exterior
of said disc space and with said guide having a first external
guide surface of predetermined geometry; placing an implement
against said centering guide with said implement having an external
guided surface shaped complementary to said first external guide
surface for said first external guide surface and said guided
surface to be nested with said guided surface sliding against said
first guide surface along a path, of travel parallel to said
longitudinal axis; sliding said implement toward said vertebrae
with said first guide surface and said guided surface maintaining
movement of said implement along said path of travel.
2. A method according to claim 1 comprising selecting said distal
end to be sized to distract said disc space upon insertion of said
distal end into said disc space and distracting said disc space by
insertion of said distal end into said disc space.
3. A method according to claim 2 comprising inserting said distal
end from an anterior approach and selecting said distal end to have
opposite side edges defining an angle approximate to a desired
angle of lordosis between said disc space.
4. A method according to claim 2 comprising inserting said distal
end from a posterior approach and selecting said distal end to have
opposite side edges defining an angle approximate to a desired
angle of lordosis between said disc space, said distal end inserted
by first inserting said distal end into said disc space with said
side edges rotated to oppose said disc space and subsequently
rotating said distal end within said disc space for said side edges
to oppose and distract said vertebra.
5. A method according to claim 1 wherein said guide includes said
first external guide surface and a second external guide surface,
said first and second external guide surfaces positioned on
opposite sides of said longitudinal axis with each of said first
and second external guide surfaces shaped complementary to said
external guided surface of said implement for a selected one of
said first and second external guide surfaces to nest with said
guided surface for said guided surface to slide against said
selected one along said path of travel, and wherein said implement
is a drill guide adapted to axially guide a drill, said method
further comprising: sliding said drill guide toward said vertebrae
against said first guide surface; inserting a drill through said
drill guide and boring a first bore; inserting an implant into said
first bore; sliding a drill guide toward said vertebrae against
said second guide surface; inserting a drill through said drill
guide and boring a second bore; and inserting an implant into said
second bore.
6. A method according to claim 1 wherein said guide includes an
external second surface on a side of said longitudinal axis
opposite said first guide surface, said second surface being convex
to present a smooth surface opposing a dura, said method including:
retracting a dura before inserting said distal end into said disc
space; and placing said distal end into said disc space with said
second surface opposing said dura.
7. An apparatus for use in implanting a spinal fusion implant into
a disc space separating a first vertebra and a second vertebra,
said apparatus comprising: a rigid centering guide having a distal
end sized to be inserted into said disc space with said guide
extending along a longitudinal axis from said distal end to a
proximal end exterior of said disc space; a first external guide
surface extending at least partially between said distal end and
said proximal end; and said external guide surface shaped
complementary to an external guided surface of an implement for
said first external guide surface and said guided surface to be
nested with said guided surface sliding against said first guide
surface along a path of travel parallel to said longitudinal
axis.
8. An apparatus according to claim 7 wherein said distal end is
sized to distract said disc space upon insertion of said distal end
into said disc space.
9. An apparatus according to claim 8 wherein said distal end
includes side edges spaced apart by a desired distraction and with
said side edges defining an angle approximate to a desired lordosis
angle between said first and second vertebrae.
10. An apparatus according to claim 9 wherein said angle is
selected for an anterior approach with said distal end having a
narrowest spacing between said side edges at said distal end.
11. An apparatus according to claim 9 wherein said angle is
selected for a posterior approach with said distal end having a
narrowest spacing between said side edges at a location spaced
rearwardly from said distal end.
12. An apparatus according to claim 7 wherein said guide includes
said first external guide surface and a second external guide
surface, said first and second external guide surfaces positioned
on opposite sides of said longitudinal axis with each of said first
and second external guide surfaces shaped complementary to said
external guided surface of said implement for a selected one of
said first and second external guide surfaces to nest with said
guided surface for said guided surface to slide against said
selected one along said path of travel.
13. An apparatus according to claim 7 wherein said guide includes
an external second surface on a side of said longitudinal axis
opposite said first guide surface, said second surface being convex
to present a smooth surface opposing a dura.
15. An apparatus according to claim 7 wherein said guide includes a
plurality of x-ray detectable indicia at a plurality of positions
at said distal end.
16. An apparatus according to claim 7 wherein said drill guide is
cylindrical and said first external guide surface is a convex arc
taken in cross-section orthogonal to said longitudinal axis and
having a radius of curvature approximate to an external radius of
said implement.
Description
I. BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention pertains to spinal stabilization surgical
procedures and apparatus for performing such procedures. More
particularly, this invention pertains to an apparatus and method
for implanting a fusion spinal implant between two vertebrae.
[0003] 2. Description of the Prior Art
[0004] Chronic back problems cause pain and disability for a large
segment of the population. In many cases, chronic back problems are
attributed to relative movement between vertebrae in the spine.
[0005] Orthopedic surgery includes procedures to stabilize
vertebrae. Common stabilization techniques include fusing the
vertebrae together.
[0006] Recently, spinal implants have been developed to facilitate
successful fusion of vertebrae. In such procedures, a bore is
formed between opposing vertebrae to be fused. An implant, commonly
containing bone growth-inducing material such as harvested bone
chips, is placed within the bore.
[0007] In order to enhance the successful procedure, a bore should
be formed centrally between the vertebrae such that the bore cuts
equally into both vertebrae. Also, from time to time, it is
desirable to place two implants within the same disc space. In such
procedures, it is desirable that the vertebrae be spaced apart by a
minimum spacing sufficient to prevent the implants from contacting
one another during the implanting procedure. In the prior art,
numerous methods have been disclosed for performing spinal
stabilization procedures.
[0008] A spinal implant and stabilization procedure is taught in
U.S. Pat. Nos. 5,015,247 and 5,484,437 both to Michaelson, dated
May 14, 1991 and Jan. 16, 1996, respectively. That patent teaches a
threaded spinal implant as well as a method of implantation
including certain tools to form a bore into which the implant is
threaded. An implant and surgical method are also shown in U.S.
Pat. No. 4,961,740 to Ray, et al., dated Oct. 9, 1990, as well as
U.S. Pat. No. 5,026,373 to Ray, et al., dated Jun. 25, 1991. The
latter patent teaches preparing a bore for the implant by drilling
over a pilot rod.
[0009] In addition to cylindrical threaded implants such as those
shown in U.S. Pat. No. 5,015,247, implants may take on different
geometries, including non-cylindrical implants such as those shown
in U.S. Pat. No. 5,609,636 dated Mar. 11, 1997. Also, conical
implants have been suggested, where the conical implants have a
conical angle approximating a desirable lordosis between the
opposing vertebrae.
[0010] In surgical procedures involving implants, it is desirable
that the surgical procedure be performed accurately to ensure
central positioning of the implant within the disc space between
the opposing vertebrae. U.S. Pat. No. 5,489,307 to Kuslich, et al.,
dated Feb. 6, 1996, teaches a plurality of instruments and a
surgical method for preparing a bore for receiving an implant. That
procedure results in accurately positioning an implant centrally
between the opposing vertebrae while avoiding certain disadvantages
with other prior art techniques as discussed more fully in the '307
patent. Unfortunately, the method and procedure of the '307 patent
requires a large number of instruments which must be accurately
selected and manipulated throughout the procedure. It is an object
of the present invention to provide an apparatus and method for
performing spinal stabilization using a reduced number of
instruments in order to simplify the procedure without sacrificing
the accuracy achieved with the procedure of the '307 patent.
Furthermore, it is an object of the present invention to provide a
surgical procedure that can be performed posteriorly, anteriorly,
laterally, or as a laparoscopic procedure.
II. SUMMARY OF THE INVENTION
[0011] According to the preferred embodiment of the present
invention, an apparatus and method are disclosed for implanting a
spinal fusion implant into a disc space separating a first vertebra
and a second vertebra. The method comprises inserting a distal end
of a rigid centering guide into the disc space. The guide extends
along a longitudinal axis from a distal to a proximal end. The
guide has a first external guide surface with a predetermined
geometry. A drill guide is placed against the centering guide. The
drill guide is adapted to axially guide a drill. The drill guide
has an external guided surface which is shaped complementary to the
external guide surface of,the centering guide. The external guide
surface and the guided surface are mutually nested with the guided
surface sliding against the external guide surface along a path of
travel parallel to the longitudinal axis of the centering guide.
The drill guide is slid toward the vertebrae with the guide surface
and the guided surface maintaining movement of the drill guide
along the desired path of travel.
III. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a side elevation view of a prior art implant for
use with the method of the present invention;
[0013] FIG. 2 is a view of the implant of FIG. 1 with the implant
rotated 90.degree. about its axis;
[0014] FIG. 3 is a view taken along line 3-3 of FIG. 1;
[0015] FIG. 4 is a view taken along line 4-4 of FIG. 3;
[0016] FIG. 5 is a view taken along line 5-5 of FIG. 2;
[0017] FIG. 6 is a view taken along line 6-6 of FIG. 3;
[0018] FIG. 7 is a side elevation of a first embodiment of a
centering guide according to the present invention for use in a
posterior approach and without a lordotic distal end;
[0019] FIG. 8 is a view taken along line 8-8 of FIG. 7;
[0020] FIG. 9 is a top plan view of the centering guide of FIG.
7;
[0021] FIG. 10 is a side elevation view of a second embodiment of a
centering guide according to the present invention for use in an
anterior approach and without a lordotic distal end;
[0022] FIG. 11 is a view taken along line 11-11 of FIG. 10;
[0023] FIG. 12 is a top plan view of the centering guide of FIG.
10;
[0024] FIG. 13 is a side elevation view of a third embodiment of a
centering guide according to the present invention for use in an
anterior approach and with a lordotic distal end;
[0025] FIG. 14 is a view taken along line 14-14 of FIG. 13;
[0026] FIG. 15 is a top plan view of the centering guide of FIG.
13;
[0027] FIG. 16 is a side elevation view of a fourth embodiment of
the centering guide according to the present invention for use in a
posterior approach and with a lordotic distal end;
[0028] FIG. 17 is a view taken along line 17-17 of FIG. 16;
[0029] FIG. 18 is a top plan view of the centering guide of FIG.
16;
[0030] FIG. 19 is a side elevation tube of a prior art drill tube
for use with the present invention;
[0031] FIG. 20 is a view taken along line 21-21 of FIG. 19;
[0032] FIG. 21 is an enlarged side elevation view of a distal end
of the drill tube of FIG. 19;
[0033] FIG. 22 is a side elevation view of a prior art boring tool
for use with the present invention;
[0034] FIG. 23 is an elevation view of a proximal end of the boring
tool of FIG. 22;
[0035] FIG. 24 is an enlarged view of a boring head of the boring
tool of FIG. 22;
[0036] FIG. 25 is an end elevation view of a distal end of the
boring head of FIG. 24;
[0037] FIG. 26 is a side elevation view of a prior art tap for use
with the present invention;
[0038] FIG. 27 is a view taken along line 27-27 of FIG. 26;
[0039] FIG. 28 is an enlarged sectional view of threaded cutting
teeth on the tool of FIG. 26;
[0040] FIG. 29 is a side elevation view of an implant driver for
use with the present invention;
[0041] FIG. 30 is an end view of a hub on a distal end of the tool
of FIG. 29;
[0042] FIG. 31 is a view taken along line 31-31 of FIG. 29;
[0043] FIG. 32 is a side elevation view of a shaft of a tool of
FIG. 29 showing an attachment collet;
[0044] FIG. 33 is a cross sectional view of FIG. 32 taken along
line 33-33;
[0045] FIG. 34 is a side elevation view of a protective sleeve for
use on the drill tube of FIG. 19;
[0046] FIG. 35 is an end elevation view of the sleeve of FIG.
34;
[0047] FIG. 36 is a schematic posterior to anterior view of two
vertebrae separated by a disc space and showing a dura extending
centrally along a mid line between the vertebrae;
[0048] FIG. 37 is the view of FIG. 30 with a dura retracted to a
left side;
[0049] FIG. 38 is the view of FIG. 37 with a centering guide of the
present invention such as that shown in FIG. 7 inserted into the
disc space between the vertebrae prior to the centering guide being
rotated to a distraction position;
[0050] FIG. 39 is the view of FIG. 38 with the centering guide
rotated to a distraction position;
[0051] FIG. 40 is a plan view of a disc space showing the elements
of FIG. 39;
[0052] FIG. 41 is a view taken along line 41-41 of-FIG. 40;
[0053] FIG. 42 is the view of FIG. 39 with a drill tube of FIG. 19
inserted into position and guided by the centering guide;
[0054] FIG. 43 is a plan view of the elements of FIG. 42 with the
drill tube shown in section;
[0055] FIG. 44 is the view of FIG. 43 following formation of a bore
in the disc space and vertebrae and showing retraction of a boring
tool through the drill tube;
[0056] FIG. 45 is the view of FIG. 44 following formation of a
tapped thread in the bore of FIG. 44 and showing removal of the
tapping tool through the drill tube;
[0057] FIG. 46 is the view of FIG. 45 showing an implant inserted
into the threaded bore of FIG. 45 and showing removal of the
implant driving tool through the drill tube;
[0058] FIG. 47 is a posterior-to-anterior view showing a dura
retracted to a right side over an inserted implant and with the
centering guide reversed and with a drill tube positioned against
the centering guide prior to formation of a bore on the left side
of the vertebra;
[0059] FIG. 48 is a plan view of the elements of FIG. 47 with the
drill tube shown in section;
[0060] FIG. 49 is an anterior-to-posterior view of two vertebrae
separated by a disc space and showing a non-lordotic, anterior
approach centering guide of the present invention (such as that
shown in FIG. 10) and shown inserted into the disc space between
the vertebrae and with a drill tube being guided by the centering
guide;
[0061] FIG. 50 is the view of FIG. 49 showing an implant inserted
into a formed bore on a left side of the vertebrae and with the
drill tube moved to be guided by an opposite side of the centering
guide prior to formation of a bore on the right side of the
vertebra;
[0062] FIG. 51 shows a drill tube of FIG. 19 and a protective
sleeve of FIG. 34 guided by a posterior centering guide of FIG.
7;
[0063] FIG. 52 shows a still further embodiment of a centering
guide;
[0064] FIG. 53 is a side elevation view of an alternative
embodiment of a drill tube for use with the centering guide of the
present invention;
[0065] FIG. 54 is a view taken along line 54-54 of FIG. 53;
[0066] FIG. 55 is the view of FIG. 53 with drill tube rotated
90.degree. about its longitudinal axis; and
[0067] FIG. 56 is a view taken along line 56-56 of FIG. 53.
IV. DESCRIPTION OF THE PREFERRED EMBODIMENT
A. Implant
[0068] Referring now to the several drawing figures in which
identical elements are numbered identically throughout, a
description of the preferred embodiment of the present invention
will now be provided. For purposes of illustrating the preferred
embodiment, a description of the surgical procedure will be give
with respect to an implant 10 such as that shown and described in
commonly assigned U.S. Pat. No 5,489,307. It will be appreciated
that the present surgical procedures and apparatus can apply to a
wide variety of implants including threaded implants such as those
shown in U.S. Pat. Nos. 5,489,307 and 5,015,247, non-cylindrical
implants such as those shown in U.S. Pat. No. 5,609,636 as well as
conical implants for use in maintaining a desired lordosis. The
term "implant" as used herein may also include bone implants as
well as metallic implants.
[0069] The implant 10 (FIGS. 1-6) is a hollow cylinder 12 having
male, square-profile threads 14 exposed on the exterior cylindrical
surface of cylinder 12. The cylinder includes a forward interior
chamber 16 and a rear interior chamber 17 separated by a
reinforcing rib 19. A bond slurry or bone chips may be compacted
into chambers 16,17.
[0070] A first plurality of holes 18 extend radially through the
cylinder wall and communicate with the chambers 16,17. A second
(and enlarged) plurality of holes 21 are disposed on diametrically
opposed sides of the implant 10.
[0071] A rear end 22 of the implant has a slot 24 which
communicates with the chamber 17. The slot 24 allows the bone
slurry or bone chips to be impacted into the implant 10. A slot 25
is defined by rib 19. The slot 25 is sized to receive a distal end
of a tool (as will be more fully described) to place the implant
within a bore formed between opposing vertebrae. End caps (not
shown) may be used with the implant. Such end caps are shown in
U.S. Pat. No. 5,489,307.
[0072] In a preferred embodiment the technique of the present
invention will be performed with a prescribed kit of tools. For the
purpose of illustrating the preferred embodiment, the tools of the
kit will now be described. It will be appreciated that the method
of surgery can be practiced using a wide variety of tools of
different size and shapes.
[0073] Each of the tools of a kit necessary to perform the surgery
as described in this application will be separately described. The
use of the tools will become apparent with the description of the
method of the invention in Section IV.3 of this application. Unless
otherwise specified, all tools are formed of stainless steel.
[0074] Since vertebrae size and disc space vary from
patient-to-patient (and since such sizes vary along the length of
the spine of any give patient), several sizes of implants 10 are
anticipated. Presently, implants 10 having minor outside diameters
(D.sub.m) of 3 mm, 5 mm, 7 mm, 9 mm, 11 mm, 13 mm, 15 mm, 17 mm, 19
mm and 21 mm with lengths (L) of 10 mm, 12 mm, 14, mm 16 mm, 18 mm,
20 mm, 24 mm, 28 mm, 30 mm, 32 mm, 34 mm, 38 mm, 42 mm and 44 mm,
respectively, are anticipated to accommodate various spine
locations and sizes. The major outside diameters (D.sub.M) of the
implants 10 are 2.5 mm larger than the minor outside diameters
D.sub.m.
[0075] Several of the tools to be described (e.g., a reaming tool
126) are sized for particular sizes of implants. Namely, the
reaming tool 126 must form a bore sized to receive the implant.
Since ten sizes of implants are anticipated, ten sizes of boring
tools 126 are anticipated as will become apparent to one of
ordinary skill in the art.
B. Centering Guide
[0076] 1. Non-Lordotic Anterior
[0077] The present invention utilizes a novel centering guide to
ensure accurate positioning of a drill tube prior to forming a bore
and placing an implant. With initial reference to FIGS. 10-12, a
centering guide 100 is shown for use in an anterior approach where
a surgeon is approaching the disc space from an anterior side of
the patient.
[0078] The centering guide 100.sub.1 is a rigid rod extending from
a distal end 102.sub.1 to a proximal end 104.sub.1 along a
longitudinal axis X.sub.1-X.sub.1. The distal end 102.sub.1 is
rounded to facilitate easy insertion of the distal end 102.sub.1
into the disc space.
[0079] The anterior guide 100.sub.1 has, in cross section, a major
transverse axis Y.sub.1-Y.sub.1 with the guide being symmetrical
about the axis Y.sub.1-Y.sub.1 and axis X.sub.1-X.sub.1. At the
distal end 102.sub.1, the guide 100.sub.1 has a distraction portion
106.sub.1. The distraction portion 106.sub.1 is defined by parallel
and spaced-apart side edges 108.sub.1 which are spaced apart by a
distance equal to desired distraction of the vertebrae.
[0080] The side edges 108.sub.1 act against the end plates of the
opposing vertebrae to urge the vertebrae apart. The end plates hold
the centering guide 100.sub.1 with the axis X.sub.1-X.sub.1
centrally positioned between the end plates. While the tool
proximal end 104.sub.1 can be moved left or right relative to the
vertebrae, the precise central positioning of the proximal end
104.sub.1 can be determined through x-ray analysis following
placement of the centering guide 100.sub.1 such that a surgeon can
be assured that the longitudinal axis X.sub.1-X.sub.1 extends
perpendicular to a transverse plane of the vertebrae.
[0081] The distraction portion 106.sub.1 is provided with a
plurality of indicia 110.sub.1 in the form of grooves positioned at
5 millimeter increments from the distal end 102.sub.1. The grooves
110.sub.1 are detectable in x-ray films to permit a surgeon to
measure the degree of insertion of the distal end 102.sub.1 into a
disc space. The guide 100.sub.1 includes a stop 109.sub.1 on edges
108.sub.1. The stop 109.sub.1 abuts vertebrae to prevent further
insertion of guide 100.sub.1 beyond full insertion of portion
106.sub.1.
[0082] Extending between the side edges 108.sub.1 and extending the
length from end 102.sub.1 to end 104.sub.1 are left and right (or
first and second) guide surfaces 112.sub.1,114.sub.1. The guide
surfaces 112.sub.1,114.sub.1 are concave and have a radius of
curvature equal to a radius of curvature of a drill tube al will be
described. While the preferred embodiment of the present invention
will be described with reference to using a drill tube having a
geometry which is complimentary to the guide surfaces 112.sub.1,
114.sub.1, it will be appreciated that the present invention could
be performed without a drill tube and by using a drill, tap or
other implement to facilitate insertion of an implant where the
implement has a curved geometry to match the radius of curvature of
the guide surfaces 112.sub.1, 114.sub.1 in which case the implement
is directly guided by the guide surface, rather than being guided
by an intermediate drill tube.
[0083] The proximal end 104.sub.1 is provided with a hole 105.sub.1
to permit a surgeon to place a tool (not shown) into the hole
105.sub.1 to twist the centering guide 100.sub.1 to release the
centering guide 100.sub.1 if necessary. Also, an angled hole
107.sub.1 is provided near portion 106.sub.1 to permit insertion of
a rod (not shown) into hole 107.sub.1 to permit a surgeon to force
the guide 100.sub.1 to the mid-line of vertebrae. With the
centering guide 100.sub.1 of FIG. 7 the end plates of the vertebrae
will be distracted in parallel spaced apart relation since the side
walls 108.sub.1 are parallel at the distraction portion
106.sub.1.
[0084] 2. Non-Lordotic Posterior
[0085] FIGS. 7-9 show a centering guide 100.sub.2 similar to that
of FIGS. 10-13 but differing due to the fact that centering guide
100.sub.1 of FIGS. 7-9 is intended for use in a posterior approach
where a surgeon approaches the vertebrae from the posterior side of
the patient. In the embodiments of FIGS. 7-18, simple elements are
numbered similarly with the addition of subscripts to distinguish
the embodiments.
[0086] Like the centering guide 100.sub.1 of FIGS. 10-12, the
centering guide 100.sub.2 of FIGS. 7-9 is for a non-lordotic
parallel distraction appliance where the side edges 108.sub.2 are
spaced apart in parallel alignment at the distraction portion 1062.
Unlike the centering guide 100.sub.1 of FIGS. 10-12, the centering
guide 100.sub.2 of FIGS. 7-9 is not symmetrical about its major
transverse axis Y.sub.2-Y.sub.2 (although it is symmetrical about
axis X.sub.2-X.sub.2. Instead, the centering guide 100.sub.2 of
FIGS. 7-9 includes only a first concave guiding surface 112.sub.2
extending on one side of the centering guide 100.sub.2. The
opposite surface 114.sub.2 is a convex surface to present a smooth
surface opposing a dura following insertion of the centering guide
100.sub.2 as will be described.
[0087] 3. Lordotic Posterior
[0088] The centering guides 100.sub.1,100.sub.2 of FIGS. 7-12 both
show distraction portions 106.sub.1,106.sub.2 having distracting
edges 108.sub.1,108.sub.2 which are parallel and spaced apart. From
time to time, it may be desirable to ensure that end plates of
opposing vertebrae are retained at a desired degree of lordosis
(i.e., with a non-parallel angle between end plates of the opposing
vertebrae).
[0089] FIGS. 16-18 show a centering guide 100.sub.3 for a posterior
approach and having a lordotic distraction portion 106.sub.3. The
distraction portion 106.sub.3 has side edges 108.sub.3 placed at an
angle, A, equal to the desired degree of lordosis. In all other
respects, the centering guide 100.sub.3 of FIGS. 16-18 is identical
to that of FIGS. 7-9.
[0090] 4. Lordotic Anterior
[0091] FIGS. 13-15 show a lordotic centering guide 100.sub.4 for
use in an anterior approach. The distractor end 106.sub.4 of the
tool 100.sub.4 has distracting side edges 108.sub.4 set at a
lordotic angle, A', equal to but reverse that of the embodiment of
FIGS. 16-18. In all other respects, the centering guide 100.sub.4
of FIGS. 13-15 is identical to that of FIGS. 10-12.
[0092] 5. Laparoscopic
[0093] Laparoscopic versions of both the lordotic and non-lordotic
centering guides can also be provided. Although not shown in the
drawings, such laparoscopic centering guides would have a shorter
length than the non-laparoscopic centering guides shown in the
drawings. For example, a non-lordotic, laparoscopic anterior
centering guide would be identical to that of guide 100.sub.1 (FIG.
10) but have its axial length detachable so that the terminal end
104.sub.1 is spaced from the distal tip 102.sub.1 by about 3
inches. After insertion of the portion 106.sub.1 into the disc
space, approximately 1.5 inches of the guide surfaces 112.sub.1,
144.sub.1 would protrude beyond the vertebrae and provide a guide
surface for directing a laparoscopic drill tube. The design would
also permit the maintenance of insufflation.
C. Drill Tube
[0094] A drill tube 92 (FIGS. 20-22) is provided in the form of a
hollow cylindrical tube 94. The distal end 96 of the tube 94 is
provided with axially projecting teeth 98. The proximal end 99 of
the tube 94 is flared outwardly. As will be apparent, ten sizes of
tube 92 are required with inside diameters D.sub.DT to slip in
close tolerance over ten sizes of implants 10 (i.e., D.sub.DT is
0.5 mm larger than D.sub.m).
[0095] The teeth 98 each have a length, T.sub.L, of preferably 3
mm. The valleys 97 are flat to provide stop surfaces to hit bone as
teeth 98 are forced into vertebrae. This helps prevent the drill
tube 92 from being forced too far into bone. The drill tube 92 is
identical to that shown in U.S. Pat. No. 5,489,307.
[0096] An alternative embodiment of a drill tube 192 is illustrated
in FIGS. 53-56. The drill tube is a hollow cylindrical tube 194
with an outside diameter having a radius of curvature to match the
radius of curvature of the guide surfaces 112.sub.1, 114.sub.1. The
distal end 196 of the tube 194 includes diametrically opposed and
axially projecting sharpened teeth 198 for penetration into
vertebrae. Diametrically opposed and axially extending retraction
paddles 199 are provided ninety degrees offset from the teeth 198
(with reference to the longitudinal axis (X'.sub.D-X'.sub.D). The
paddles 199 have a width (W in FIG. 54) equal to the desired
distraction of the vertebrae. The proximal end 197 of the tube 194
is a handle to be gripped by a surgeon. The tube 194 has a length
L.sub.D measured from the base of the teeth 198 and retraction
paddles 199 to the base of the handle 197. The length L.sub.D is
equal to the length of a centering guide (such as the length of
guide 100.sub.1 of FIG. 10) between the proximal end 104.sub.1 and
the insertion portion 106.sub.1. Therefore, when the insertion
portion 106.sub.1 is fully inserted into the disc space, the end
104.sub.1 buts against the handle 197 when the teeth 198 are forced
into the vertebrae.
D. Vertebral Reamer
[0097] A vertebral reamer 126 (or boring tool) (FIGS. 22 through
25), is provided for forming a bore. The reamer 126 is such as that
shown in U.S. Pat. No. 5,489,307. The reamer 126 includes a shaft
128. A distal end of the shaft is provided with a reamer end 130
having side and end cutting blades 131. A proximal end of the shaft
is provided with an outwardly flared hub 132. Extending from hub
132 is an axial shaft 134. For ten sizes of implants 10 ten sizes
of reamers 126 are required with the kit. The outside diameter
D.sub.R of reamer 126 equals the minor outside diameter D.sub.m of
implants 10. The diameter D.sub.RG of the guide hub 133 equals the
inner diameter of the drill tube D.sub.DT.
E. Bone Tap
[0098] In the event a threaded implant is utilized (as is the case
in the preferred embodiment of the present invention), the bores
for the implants are partially pre-threaded. To pre-thread, a bone
tap 142 (FIGS. 26-28) is provided, having a shaft 144. The top 142
is such as that shown in U.S. Pat. No. 5,489,307. At the distal end
of the shaft 144 is a tapping head 146 having tapping threads 148.
Near the proximal end of the shaft 144 is an enlarged diameter
portion 156 having an outwardly flared flange 158. A handle 160 is
secured to an enlarged portion 156. The shaft 144 is also enlarged
at portion 162 adjacent tapping head 146. The enlarged portion 156
is sized with diameter D.sub.8 to be received, in close tolerance,
within the drill tube 92 such that the tube 92 will guide the tap
142 as will be more fully described.
[0099] Since ten sizes of implants 10 are intended to be utilized,
ten sizes of bone taps 142 are required. Diameter D.sub.T is equal
to the major outside diameter D.sub.M of implant 10. The head 146
has a minor outside diameter D.sub.t (i.e., the diameter without
threads 148) equal to the minor outside diameter D.sub.m of the
implants 10.
F. Implant Driver
[0100] To place implant 10 an implant driver 164 (FIGS. 29 through
33) is provided. The driver 164 is such as that shown in U.S. Pat.
No. 5,487,307. A driver is also shown in U.S. Pat. No. 5,609,636.
The driver 164 includes a shaft 166 having a reduced diameter
distal portion 166a. A distal end of the shaft 166 is provided with
a hub 168 sized to be received within slot 24 of the implant 10 to
urge the implant 10 to rotate as the implant driver 164 is rotated.
The implant driver 164 includes a stepped enlarged portion 170
including a first diameter portion 172, a second diameter portion
174 and a third diameter portion 176 to accommodate the different
diameters of drill tubes 92. A handle 178 is secured to the shaft
164. Grooves 180,180a are formed on the shafts 166,166a and extend
along their axial lengths. The grooves 180 provide a means for a
surgeon to sight the alignment of the implant.
[0101] FIGS. 32-33 show the implant driver 164 with a collet 171.
The collet 171 has a cylindrical, knurled body 173 slidably carried
on shaft 166a. A pin 175 extending from body 173 into groove 180a
permits collet 171 to slide on shaft 166 but not rotate. Four
prongs 177 extend axially from body 173 toward hub 168.
[0102] In use, shaft 166 is passed through end opening 24 of
implant 10. Hub 168 is received within slot 25. The prongs 177 are
forced by a surgeon pushing on body 171 for the prongs 177 to be
urged between opposing surfaces of the implant 10 and shaft 166a to
thereby securely capture the implant 10 on driver 164. As a result,
the implant 10 cannot inadvertently fall off. (For ease of
illustration, the Figures showing the method of the invention,
e.g., FIG. 46, does not show use of collet 171).
G. Drill Tube Sheath
[0103] Drill tube 92 is passed through a patient's body to an
implant site. To avoid risk of teeth 98 damaging vessels, nerves or
organs, a drill tube sheath 300 is provided (FIGS. 34,35). The
sheath 300 is such as that shown in U.S. Pat. No. 5,489,307. The
sheath 300 is a hollow tube with inside diameter D.sub.S slightly
smaller than the outside diameter of drill tube 92 (accordingly,
ten sizes of sheath 300 are required). The sheath 300 has an axial
slit 301 extending its entire length. The sheath 300 has a blunt
distal end 302 and a flared proximal end 304.
[0104] The sheath is slipped onto the drill tube 92 with end 302
extending beyond the teeth 98. As the drill tube 92 is passed to an
implant site the blunt end 302 covers the teeth and prevents the
unwanted cutting of vessels, nerves or organs. When pressed against
vertebrae, the end 302 abuts the vertebrae. With continued
advancement of the tube 92 toward the vertebrae, the sheath 300
slides on the tube 92 until teeth 98 abut the vertebrae.
[0105] In the method of the invention, sheath 300 remains in place
whenever drill tube 92 are used. However, for ease of illustration,
sheath 300 is not shown in FIGS. 42-50.
H. Posterior Technique
[0106] The present invention will first be described with reference
to use in a posterior approach. In a posterior approach, a surgeon
seeks access to the spine through the back of the patient. Another
alternative approach is the lateral approach, where the patient is
on his side and a single cage is inserted across the disk space. An
alternative approach is an anterior approach where the surgeon
seeks access to the spine through the abdomen of a patient. The
approaches can be done through open surgery or through laparoscopic
surgery.
[0107] While a posterior approach will be described in detail, it
will be appreciated that the present invention can be used in an
anterior or lateral approach for both laparoscopic or
non-laparoscopic procedures.
[0108] With initial reference to FIG. 36, once a surgeon has
identified two vertebrae 200,200' which are to be fused together,
the surgeon identifies an implant 10 of desired size and the
surgeon determines the desired amount of distraction of the disc
space 202 to be required before placement of the implant 10. In
selecting the implant size, the surgeon should ensure that the
device will remain within the lateral borders of the intervertebral
disc space 202 while also penetrating at least 3 mm into the
vertebral bodies 200,200' cephalad and caudal to the disc.
[0109] In the posterior technique, a patient is placed on the
operating table in either a prone or kneeling-sitting position. At
the discretion of the surgeon, the spine is flexed slightly.
Anesthesia is administered.
[0110] Exposure of the intervertebral disc is obtained through any
suitable technique well-known in the art. The facet of the
vertebrae is removed in as limited amount as possible to permit
insertion of the instruments and the implants. Preferably, bone
dissected from the lamina, facets and spinous process are preserved
for later use as bone graft.
[0111] FIG. 36 shows two vertebrae 200,200' separated by a disc
space 202. For ease of illustration, disc material is not shown in
space 202 having an undistracted thickness T.sub.R. In the
posterior P to anterior A view, a dura 204 extends between the
vertebrae 200,200' and is centrally positioned along a medial line,
M, between the vertebrae 200,200'. The line M separates the disc
space 202 and vertebrae 200,200' into a left side L and right side
R corresponding to the patient's left and right sides.
[0112] As shown in FIG. 37, the dura 204 is first retracted to the
left through any suitable means to expose the disc space 202 and
vertebrae 200,200' at the medial line, M. A distal end 102.sub.2 of
the centering guide 100.sub.2 of FIGS. 7-9 is inserted into the
disc space 202 in the manner illustrated in FIG. 38 with the
distracting side edges 108.sub.2 opposing and in line with the disc
space 202.
[0113] After initial insertion of the distal end 102.sub.2 into the
disc space, the centering tool 100.sub.2 is rotated 90.degree. to
the position shown in FIG. 39 such that the side edges 108.sub.2 of
the distraction portion 106.sub.2 oppose and distract the vertebrae
and the convex surface 114.sub.2 is opposing the dura 204 to
prevent damage to the dura 204. The vertebrae 200,200' are now
distracted to a spacing of T.sub.D equal to the distance between
side edges 108.sub.2.
[0114] The distraction portion 106.sub.2 of the guide 100.sub.2 is
forced into the disc space 202 at the mid line M of the disc space
202. The size (i.e., the spacing between the side edges 108.sub.2)
of the centering guide 100.sub.2 is selected to distract the
annulus fibrosus without causing damage to the surrounding
vertebral bone, annular fibers or spinal nerves. Accordingly, it is
recommended that a surgeon initially insert a relatively narrow
distal end centering guide (e.g., 6 millimeters) followed by
successively larger guides until the annulus is distracted to the
surgeon's satisfaction.
[0115] Once the correct maximum size distraction portion 106.sub.2
has been chosen, it is left in place. The disc space 202 has now
been stretched so that a parallel distraction of the end plates
201,201' of the vertebrae 200,200' has occurred on both the left
and right sides of the vertebrae. The distraction portion 106.sub.2
is fully inserted such that the indicia 110.sub.2 are flush or
slightly recessed within the disc space.
[0116] Following placement of the distracting centering guide
100.sub.2, the drill tube 92 is placed against the centering guide
100.sub.2. Since the guiding surface 112.sub.2 of the centering
guide 100.sub.2 is concave with a radius of curvature matching the
outer radius of curvature of the drill tube 92, the drill tube 92
can be slid along the length of the guide 100.sub.2 into precise
position with the axis X.sub.D-X.sub.D of the drill tube 92
centrally positioned between the end plates 201,201' of the
vertebrae 200,200'.
[0117] In a preferred embodiment, the drill tube 92 will be
surrounded by a sliding protective sleeve 300 such as that shown in
FIGS. 34-35 and described fully in U.S. Pat. No. 5,489,307. The
thin wall of the drill sleeve 300 has substantially the same radius
of curvature as the drill tube 92 and does not materially affect
the positioning. At most, the addition of the protective sleeve 300
increases the spacing of the axis X.sub.D-X.sub.D of the drill tube
92 from the axis X.sub.2-X.sub.2 of the guide 100.sub.2 (FIG. 51)
but does not alter the central positioning of the axis
X.sub.D-X.sub.D of the drill tube 92 between the end plates
201,201'. For ease of illustration, the drill sleeve protective
sleeve is not shown in FIGS. 42-50.
[0118] With the drill tube 92 in place, the preparation of the
implant bore 206 is completed by inserting the reamer 126 into the
drill tube 92 (FIG. 44). The reamer 126 is rotated with any
suitable driver (such as driver 136 shown in U.S. Pat. No.
5,489,307).
[0119] Since the drill tube 92 is centrally placed with the axis
X.sub.D-X.sub.D of the drill tube 92 centrally positioned between
the end plates 201,201', the reamer 126 will bore into the disc
space 202 and bore equally into and through the end plates 201,201'
of the opposing vertebrae. The reamer 126 is selected to form a
bore 206 having a diameter D.sub.m equal to the minor outside
diameter of the implant 10 (in the case of a cylindrical implant
such as that shown in FIGS. 1-6).
[0120] For use with a threaded implant 10 such as that shown in
FIGS. 1-6, a bone tap 142 is passed through the drill tube 92 and
rotated to at least partially pretap the bore (FIG. 45). The tap is
then removed to expose a tapped bore 207 with the drill tube 92
remaining in place. The implant 10 may then be packed with a bone
graft material. The graft may be autograft obtained previously from
the iliac crest or some other graft material (e.g., allograft or
artificial bone). The implant 10 is attached to the implant driver
164 by placing the hub 168 within the slot 25 and securing the
implant 10 with the collet 171. The implant 10 is then passed
through the drill tube 92. The implant 10 is threaded into the bore
207 with the implant driver 164 by the surgeon rotating the driver
164 and advancing it into the drill tube 92. As disclosed in U.S.
Pat. No. 5,489,307, it is desirable that the larger holes of the
implant are oriented in a superior-inferior direction (i.e., the
larger holes are facing the vertebrae 200,200').
[0121] After the implant 10 is fully in place, the implant driver
164 is removed through the drill tube 92 (FIG. 47). The drill tube
92 is then removed. The dura 204 is retracted slightly and the
centering guide 100 is then removed. The dura 204 is then retracted
to the opposite side and the centering guide 100.sub.2 is
repositioned with the disc space 204 but rotated 180.degree.
relative to FIG. 39 so that the rounded side 114.sub.2 is facing
both the dura 204 and the previously placed implant 10 and the
guide surface 112.sub.2 is facing the opposite side of the disc
space 202. The procedure can then be repeated by placing the drill
tube 92 against the vertebrae with the drill tube 92 aligned by the
guide 100.sub.2 as previously described (FIG. 47).
I. Anterior Approach
[0122] The foregoing discussion illustrates the use and method of
an apparatus of the invention in a posterior approach. It will be
noted that for placing two implants 10, the centering guide
100.sub.2 is removed and reinserted into the disc space 202 to
reorient the guiding surface 112.sub.2.
[0123] When performing an anterior approach, the surgeon uses the
anterior guide 100,100.sub.4 which has concave guiding surfaces
112,114 on opposite sides of the centering guide 100. With such
structure, the anterior centering guide 100 is placed at the mid
line M and a drill tube 92 is guided by a first 112 of the guiding
surfaces 112,114 so that a first bore can be formed, tapped and an
implant 10 inserted through the drill tube (FIG. 50). After the
implant 10 is inserted, the centering guide 100 remains in place
but the drill tube 92 is moved to the opposite side and guided into
position by the second guiding surface 114 (FIG. 51). With the
drill tube 92 in position on the second side, a bore 206 is then
formed by passing the reamer and tap through the drill tube and a
second implant is inserted through the drill tube.
J. Lateral Approach
[0124] The present invention is particularly suited for a lateral
approach where an elongated single implant is to be placed in the
inner vertebral space. The present invention requires smaller
access space to the disc space which is of particular advantage in
a lateral approach where there is substantial anatomic structure
limiting access to the disc space in a lateral approach at certain
vertebrae locations.
K. Additional Embodiments
[0125] In the foregoing description, the guide surface has been
shown as a concave surface 112 having the same radius of curvature
of the guided surface of the cylindrical drill tube. It will be
appreciated that while a circular arc of a guide surface
corresponding to a radius of curvature of a cylindrical drill tube
is preferred, a plurality of complementary geometries could be used
for the guide surface and the guiding surface.
[0126] In the present invention, if the surgeon were to place the
drill tube 92 such that the axis X.sub.D-X.sub.D of the drill tube
92 is not parallel to the longitudinal axis X.sub.2-X.sub.2 of the
centering guide 100.sub.2, such misalignment could be detected at
the proximal end 104.sub.2 of the guide 100.sub.2 and be indicated
by a spacing between the centering guide 100.sub.2 and the drill
tube 92. An alternative embodiment would be to provide a guiding
surface on the centering guide which locks with a guided surface on
the drill tube such that non-parallel alignment of the axis of the
drill tube and the centering guide is not possible. For example,
the guide surface 112' on the centering guide 100' could be
dovetail grooved and the guided surface on the drill tube 92' could
be a complementary shaped dovetail rail 93' which slides within the
dovetail groove 112'. Such a modification would preclude
non-parallel alignment of the axis X.sub.D'-X.sub.D' of the drill
tube 92' and the longitudinal axis X'-X' of the centering guide
100'. However, such a modification would require accurate alignment
of the drill tube 92', whereas in the preferred embodiment
previously disclosed, the drill tube 92 may be rotated about its
axis X.sub.D-X.sub.D.
[0127] From the foregoing detailed description of the present
invention it has been shown how the objects of the invention have
been obtained in a preferred manner. However, modifications and
equivalence of the disclosed concepts such as those which would
occur to one of ordinary skill in the art are intended to be
included within the scope of the present invention.
* * * * *