U.S. patent application number 10/336647 was filed with the patent office on 2003-11-20 for spinal surgery instruments and methods.
This patent application is currently assigned to Sulzer Spine-Tech Inc.. Invention is credited to Emstad, Erik E., Grabowski, John J., Guenther, Kevin V., Longhini, Ross, Pohndorf, Peter J..
Application Number | 20030216744 10/336647 |
Document ID | / |
Family ID | 27024719 |
Filed Date | 2003-11-20 |
United States Patent
Application |
20030216744 |
Kind Code |
A1 |
Longhini, Ross ; et
al. |
November 20, 2003 |
Spinal surgery instruments and methods
Abstract
Instruments and methods for insertion of one or more spinal
implants into an intervertebral space between opposing vertebral
bodies are disclosed. Instruments according to the invention
include a guide for preparing a spinal fusion implant site, a guide
starter, implant depth gauges, reamers, taps and implant drivers.
The instruments and methods disclosed provide improved
visualization of the surgical field and enhanced precision of
placement of spinal fusion implants between vertebral bodies.
Inventors: |
Longhini, Ross; (Woodbury,
MN) ; Grabowski, John J.; (Bloomington, MN) ;
Guenther, Kevin V.; (Carver, MN) ; Emstad, Erik
E.; (St. Paul, MN) ; Pohndorf, Peter J.;
(Stilwater, MN) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Assignee: |
Sulzer Spine-Tech Inc.
Minneapolis
MN
|
Family ID: |
27024719 |
Appl. No.: |
10/336647 |
Filed: |
January 2, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10336647 |
Jan 2, 2003 |
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09484045 |
Jan 18, 2000 |
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6524318 |
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09484045 |
Jan 18, 2000 |
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09420070 |
Oct 18, 1999 |
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Current U.S.
Class: |
606/99 |
Current CPC
Class: |
A61B 2017/0256 20130101;
A61B 2090/034 20160201; A61B 17/1757 20130101; A61B 2017/0046
20130101 |
Class at
Publication: |
606/99 |
International
Class: |
A61B 017/58 |
Claims
What is claimed is:
1. A guide for preparing a spinal fusion implant site between
opposing vertebral bodies, the guide comprising: a ring wall, said
ring wall having a first end, a second end and a first internal
ring wall forming a first lumen having a first lumen diameter; said
ring wall having a first ring wall length (R.sub.L1) extending from
said first end to said second end of said ring wall; said guide
having an aspect ratio of less than about 4:1; a first projection
extending from said first end of said ring wall, said projection
having a first projection length (L.sub.P1) at least as great as
said first ring wall length.
2. A guide according to claim 1 wherein said ring wall is
complete.
3. A guide according to claim 1 wherein said first projection
length is greater than said first ring wall length.
4. A guide according to claim 1 having a ratio of L.sub.P:R.sub.L
of about 1:4 to 3:1.
5. A guide according to claim 1 having a ratio of L.sub.P:R.sub.L
of about 1:4 to 1:2.5.
6. A guide according to claim 4 wherein said aspect ratio is about
0.5:1 to 3:1.
7. A guide according to claim 1 wherein said ring wall has a second
ring wall length extending from said first end to said second end
of said ring wall, said second ring wall length being less than
said first ring wall length.
8. A guide according to claim 1 having a second projection
extending from said first end of said ring wall.
9. A guide according to claim 8 wherein said second projection has
a second projection length (L.sub.P2) such that a ratio of
L.sub.P2:R.sub.L1 is about 1:1 to 1:2.5.
10. A guide according to claim 9 wherein said first and second
projections are co-linear with said first ring wall.
11. A guide according to claim 7 further comprising an anchoring
arrangement at said first end of said ring wall.
12. A guide according to claim 11 wherein said anchoring
arrangement comprises at least one tooth.
13. A guide according to claim 11 wherein said anchoring
arrangement comprises a plurality of teeth.
14. A guide according to claim 1 further comprising a handle.
15. A guide according to claim 14 wherein said handle is
selectively removable from said ring wall.
16. A guide according to claim 7 wherein said first end of said
ring wall is in a first plane and said second end of said ring wall
is in a second plane and said first plane and said second plane
form an angle therebetween of about 0.degree. to 30.degree..
17. A guide according to claim 1 wherein said ring wall further
includes a second internal ring wall forming a second lumen having
a second lumen diameter.
18. A guide according to claim 17 wherein said first lumen diameter
and said second lumen diameter are equal.
19. A guide according to claim 17 wherein said first projection
extending from said first end of said ring wall extends between
said first and second lumens.
20. A guide according to claim 1 having a second projection
extending from said first end of said ring wall, each of said first
and second projections being tapered.
21. A surgical instrument comprising: a tubular sleeve comprising
an outer wall surrounding a lumen and having a first end and a
second end a shaft sized to pass into said lumen of said tubular
sleeve and comprising a working end which can protrude a plurality
of predetermined distances beyond said first end of said tubular
sleeve; a depth adjustment arrangement for selectively controlling
said predetermined distances said working end protrudes beyond said
first end of said tubular sleeve.
22. The surgical instrument according to claim 21 wherein said
depth adjustment arrangement comprises a plurality of stops
positioned on said shaft and incrementally spaced a distance from
said working end of said shaft, each stop corresponding to one of
said predetermined distances said working end protrudes beyond said
first end of said tubular sleeve.
23. The surgical instrument according to claim 22 wherein said
shaft is circular in transverse cross section and said stops are
circumferentially positioned around said shaft.
24. The surgical instrument according to claim 23 wherein said
stops are positioned in a stair-step arrangement around said
shaft.
25. The surgical instrument according to claim 24 wherein each stop
is associated with a groove which is configured to interdigitate
with a pin protruding into said lumen of said tubular sleeve near
said second end of said tubular sleeve.
26. The surgical instrument according to claim 24 wherein said
predetermined distances are selectively controlled by moving said
tubular sleeve towards said working end of said shaft and rotating
said tubular sleeve.
27. The surgical instrument according to claim 21 wherein said
outer wall of said tubular sleeve includes an exterior surface
having at least two different cross sectional dimensions forming a
lip near said first end of said tubular sleeve.
28. The surgical instrument according to claim 26 wherein said
tubular sleeve is biased relative to said shaft.
29. The surgical instrument according to claim 28 wherein said bias
is provided by a helical spring.
30. The surgical instrument according to claim 21 wherein said
working end is a reamer.
31. The surgical instrument according to claim 21 wherein said
working end is a tap.
32. A kit for placement of a spinal implant between opposing
vertebral bodies, the kit comprising: (a) a first guide for
preparing a spinal fusion implant site between said opposing
vertebral bodies, said first guide comprising: a first ring wall,
said first ring wall having a first end, a second end and a first
internal ring wall forming a first lumen having a first lumen
diameter; said first ring wall having a first ring wall length
extending from said first end to said second end of said first ring
wall; said guide having an aspect ratio of less than about 4:1; a
first projection extending from said first end of said first ring
wall, said projection having a first projection length at least as
great as said first ring wall length; and (b) a guide starter, said
guide starter comprising: a first guide end, said first guide end
having a first guide diameter sized for insertion within said first
lumen diameter and a second guide diameter which is greater than
said first guide diameter.
33. A kit according to claim 32 further comprising a reamer.
34. A kit according to claim 33 wherein the reamer is
adjustable.
35. A kit according to claim 32 further comprising, a second guide
for preparing a spinal fusion implant site between said opposing
vertebral bodies, said second guide comprising: a second ring wall,
said second ring wall having a first end, a second end and a second
internal ring wall forming a second lumen having a second lumen
diameter, said second lumen diameter different from said first
lumen diameter.
36. A kit according to claim 35 wherein said guide starter
comprises: a second guide end longitudinally spaced from said first
guide end along a shaft, said second guide end having a third guide
diameter sized for insertion within said second lumen diameter and
a fourth guide diameter which is greater than said second lumen
diameter.
37. A kit according to claim 32 wherein said first ring wall
further includes a second internal ring wall forming a second lumen
having a second lumen diameter.
38. A kit according to claim 37 wherein said first lumen diameter
is equal to said second lumen diameter.
39. A method for preparing a site for implanting a spinal implant
into a disc space between adjacent first and second vertebral
bodies the method comprising: distracting said first and second
adjacent vertebrae; applying a guide over said disc space between
distracted first and second adjacent vertebrae, said guide
comprising: (i) a ring wall, said ring wall having a first end, a
second end and a first internal ring wall forming a first lumen
having a first lumen diameter; (ii) said ring wall having a first
ring wall length extending from said first end to said second end
of said ring wall; (iii) said guide having an aspect ratio of less
than about 4:1; passing a reamer through said internal ring wall to
said disc space and reaming a site for implanting said spinal
implant.
40. A method according to claim 39 wherein said guide further
comprises a first projection extending from said first end of said
ring wall, said projection having a first projection length at
least as great as said first ring wall length.
41. A method according to claim 39 further comprising a step of:
removing said guide; and inserting said implant into said implant
site.
42. A method according to claim 41 wherein said implant is inserted
into said implant site before said guide is removed.
43. An adjustable guide tube comprising: a guide housing having a
distal end and a proximal end, said proximal end including a
proximal cutout having a proximal shoulder and a plurality of
grooves and stops; an adjustable sleeve having a proximal rim and a
distal ridge forming a distal shoulder and a pin protruding from an
inner surface of said adjustment sleeve; and a biasing arrangement
to bias said proximal rim away from said distal end.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to U.S. Ser. No.
09/420,070, filed Oct. 18, 1999, the entire disclosure of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention pertains to vertebral body fusion.
Specifically, the invention is directed to instrumentation and
methods for insertion of spinal implants between opposing vertebral
bodies to facilitate fusion of the bodies.
BACKGROUND OF THE INVENTION
[0003] Chronic neck and back problems can cause pain and disability
for a large segment of the population. Frequently, the cause of the
pain is traceable to diseased disc material between opposing
vertebrae. When the disc material is diseased, the opposing
vertebrae may be inadequately supported, resulting in persistent
pain.
[0004] Surgical devices and techniques have been developed for
removing diseased disc material and fusing the joint between
opposing vertebral bodies. Arthrodesis of the intervertebral joint
can reduce the pain associated with movement of a joint having
diseased disc material. Some fusion techniques involve removal of
the diseased disc, drilling a bore for receiving a fusion implant
into the bore and inserting the implant between the opposing
vertebral bodies.
[0005] Spinal fusion implants and related surgical instruments for
implanting a fusion device are known and disclosed in, for example,
U.S. Pat. Nos. 5,741,253; 5,658,337; 5,609,636; 5,505,732;
5,489,308; 5,489,307; 5,484,437; 5,458,638; 5,055,104; 5,026,373;
5,015,247; and 4,961,740, the disclosures of which are incorporated
herein by reference.
[0006] Procedures for fusing an intervertebral joint space include
removing disc material and preparing a bore for placement of one or
more implants in the disc space by removing bone from opposing
vertebrae which are adjacent to the disc space. Currently two of
the most common approaches for preparing the bore are free-hand
preparation using a powered boring device and manual or powered
boring through a hollow guide tube. Systems which provide for
preparing the implant site bore through a hollow guide tube are
described in, for example, U.S. Pat. Nos. 5,484,437 and 5,489,307.
Preparing the implant site by passing instruments, such as reamers
or taps, through a hollow guide tube advantageously provides an
isolated surgical field with reduced chance of injury to tissues
surrounding the surgical site.
[0007] However, free-hand preparation of the implant site and some
of the available hollow guide tube systems often do not provide a
means for ensuring that an equal amount of bone is removed from the
adjacent vertebral bodies during formation of the bore. This is
particularly true for current systems used to fuse cervical
vertebrae. In addition to other problems, removal of unequal
amounts of bone can result in over reaming of one vertebra relative
to the adjacent vertebra. Also, free-hand preparation and most
hollow tube systems do not adequately ensure that reaming of the
bore is performed parallel to the vertebral endplates. Failure to
ream parallel to the endplates and/or over reaming of the vertebral
bodies can result in misplacement of the fusion device or
subsidence of the joint space post operatively.
[0008] Moreover, many of the available hollow tubes presently used
as guides are relatively long, some having lengths that can be 10
to 30 times greater than the diameter of the bore. This length
obscures direct visualization of the surgical site and prevents the
surgeon from being able to continuously monitor, and adjust as
needed, during the reaming or tapping procedure. In addition, while
some presently available hollow tubes include paddles for insertion
into the disc space, the paddles typically are short relative to
the length of the hollow tube (e.g., having a paddle length:tube
length ratio of about 1:6 to 1:35). Long hollow tubes relative to
short paddles can introduce a significant lever arm effect. In such
arrangements, small movements at the proximal end of the hollow
tube can significantly alter the trajectory of a reamer or other
instruments guided by the hollow tube. In addition to hollow
instrument guides, the precision and ease of use of the instruments
which are passed through the guide can also affect surgical
outcome.
[0009] Thus, there is a continuing need for greater precision,
safety and ease of use of instrumentation used for placement of
spinal fusion implants. The present invention is directed to
addressing these needs.
SUMMARY OF THE INVENTION
[0010] The present invention is directed to increasing the ease and
enhancing the precision of placement of spinal fusion implants
between opposing vertebral bodies. In particular, the invention
provides instruments and methods for performing a spinal surgical
procedure through a hollow guide wherein the guide has a low lever
arm effect and can provide greater visibility when the guide is
placed over a surgical site.
[0011] The invention also provides novel instrument guides, implant
gauges, guide starters, reamers, taps and other associated
instruments which can be used alone or combined in a kit to perform
a spinal surgical procedure. The principles underlying some of the
adjustable features of the instruments of the invention may also be
advantageously applied for use with prior art hollow guide
systems.
[0012] Methods for implanting a spinal implant into a disc space
between opposing vertebral bodies using instruments and kits of the
invention are also disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1a is a perspective view of a spinal implant suitable
for use according to the invention;
[0014] FIG. 1b is a side view of the spinal implant of FIG. 1a;
[0015] FIG. 1c is a trailing end view of the implant of FIG.
1a;
[0016] FIG. 2a is a top plan view of an implant gauge according to
the invention;
[0017] FIG. 2b is a side view of the implant gauge of FIG. 2a;
[0018] FIG. 3a is a side view of one embodiment of a guide
according to the invention;
[0019] FIG. 3b is a side view of an alternative configuration for
the handle shown in FIG. 3a;
[0020] FIG. 4 is a top view of the guide of FIG. 3;
[0021] FIG. 5 is a close up side view of the distal end of the
guide of FIG. 3;
[0022] FIG. 6 is a front view of the guide of FIG. 5;
[0023] FIG. 7 is a side view of the distal end of an alternative
embodiment of a guide according to the invention;
[0024] FIG. 8 is a front view of the guide of FIG. 7;
[0025] FIG. 9 is a side view of the distal end of an alternative
embodiment of a guide according to the invention;
[0026] FIG. 10 is a front view of the guide of FIG. 9;
[0027] FIG. 11a is one embodiment of a guide according to the
invention having a removable handle and shown without a handle;
[0028] FIG. 11b is a side view of one embodiment of a removable
handle which can be used with the guide of FIG. 11a;
[0029] FIG. 11c is a top plan view of the handle of FIG. 11b;
[0030] FIG. 11d is a front view of the handle of FIG. 11b;
[0031] FIG. 12 is an alternative embodiment of a guide according to
the invention;
[0032] FIG. 13 is a diagrammatic view of the embodiment of a guide
of FIG. 12 illustrating planes in which the first and second end of
the guide reside in;
[0033] FIG. 14 is a side view of one embodiment of a dual lumen
guide according to the invention;
[0034] FIG. 15 is a top view of the guide of FIG. 14;
[0035] FIG. 15a is a top view of an alternative embodiment of a
dual lumen guide;
[0036] FIG. 16 is a close up side view of the distal end of the
guide of FIG. 14;
[0037] FIG. 17 is a front view of the guide of FIG. 15;
[0038] FIG. 18 is a side view of an alternative embodiment of a
guide according to the invention;
[0039] FIG. 19 is a side view of an alternative embodiment of a
guide according to the invention;
[0040] FIG. 19a is a side view of an alternative embodiment of a
guide according to the invention;
[0041] FIG. 20 is a side view of an embodiment of a guide starter
according to the invention;
[0042] FIG. 21 is a side view of one embodiment of a reamer
according to the invention;
[0043] FIG. 22 is a side view of the reamer of FIG. 21 with the
adjustable nut and lock nut removed;
[0044] FIG. 23 is a side view of an alternative embodiment of a
reamer according to the invention;
[0045] FIG. 24 is a longitudinal cross section through the reamer
of FIG. 23;
[0046] FIG. 25 is a side view of a shaft of the reamer of FIG.
23;
[0047] FIG. 26 is a laid-out view of an embodiment of stops for a
depth adjustment arrangement suitable for the reamer of FIG.
23;
[0048] FIG. 27 is a side view of one embodiment of a tap suitable
for use according to the methods of the invention;
[0049] FIG. 28 is a side view of an embodiment of an adjustable tap
according to the invention;
[0050] FIG. 29 is a longitudinal cross section view of the tap of
FIG. 28;
[0051] FIG. 30 is an alternative embodiment of a reamer according
to the invention;
[0052] FIG. 31 is a side view of a cleaning probe of the
invention;
[0053] FIG. 32a is a side view of an embodiment of a handle
according to the invention;
[0054] FIG. 32b is a distal end view of the handle of FIG. 32a;
[0055] FIG. 33a is a side view of an implant driver suitable for
the invention;
[0056] FIG. 33b is a longitudinal cross section through the implant
driver of FIG. 33a;
[0057] FIG. 33c is a distal end view of the implant driver of FIG.
33b;
[0058] FIG. 34 is a side view of the adjustable guide tube;
[0059] FIG. 35 is a longitudinal cross section through the
adjustable guide tube of FIG. 35;
[0060] FIG. 36 is a side view of the guide housing of the
adjustable guide tube of FIG. 34;
[0061] FIG. 37 is a side view of the guide housing of the
adjustable guide tube of FIG. 34 with a helical spring in
place;
[0062] FIG. 38 is a side view of an adjustable guide tube of FIG.
34 with a reaming tool passed therethrough;
[0063] FIG. 39 is a front view of an alternative embodiment of a
dual lumen guide according to the invention;
[0064] FIG. 40 is a side view of the guide of FIG. 39; and
[0065] FIG. 41 is a bottom plan view of the guide of FIG. 39 with
an incomplete handle.
DETAILED DESCRIPTION
[0066] The present invention is directed to devices and methods
which improve visualization and enhance the ease and precision of
placement of spinal fusion implants between opposing vertebral
bodies.
[0067] Throughout the specification, guidance may be provided
through lists of examples. In each instance, the recited list
serves only as a representative group. It is not meant, however,
that the list is exclusive.
[0068] As used herein, the "depth" of a vertebrae is defined as the
anterior posterior dimension of the vertebrae. The "width" of the
vertebrae is the dimension from the right lateral edge to the left
lateral edge. The "height" of the disc space is the dimension from
the superior endplate to the inferior endplate of opposing
vertebrae.
[0069] The instruments of the invention can be advantageously used
for fusion of all types of joints. In some embodiments, the
instruments and methods disclosed are particularly advantageous for
preparing an implant site for fusing cervical vertebrae. Typical
cervical vertebral joints fused are C.sub.2-C.sub.3 through
C.sub.7-T.sub.1. Thus, for exemplary purposes, the invention will
be described with reference to fusion of a cervical vertebral
joint. However, it will be appreciated that the disclosed
instruments and methods can also be used for fusion of vertebrae at
other spinal locations.
[0070] The invention provides instruments, including guides, guide
starters, implant depth gauges, reamers, taps and implant drivers
and methods for preparing a spinal implant site. The invention also
provides kits including instruments of the invention. Because the
herein disclosed instruments are suitable for implanting various
size implants, the kits can include multiple guides, starter
guides, depth gauges, reamers, taps, etc. for different implant
sizes.
[0071] A guide of the invention can be placed across an
intervertebral joint space to facilitate placement and axial
alignment of other instruments used to prepare a site for insertion
of the implant between adjacent vertebrae. Accurate placement and
alignment of instruments used to prepare the implant site helps
reduce the chance of post-operative problems, including implant
displacement, joint space subsidence, joint instability, non-union
of the fusion site, etc. In general, the guide includes an external
ring wall surrounding at least one lumen through which instruments
can be passed for preparing the implant site. The lumen is defined
by an internal ring wall. The internal ring wall, which can be
complete or incomplete, also defines the diameter of the lumen.
[0072] The ring wall has a first ring wall length measured from a
first end of the ring wall to a second end. In some embodiments,
the ring wall has a second ring wall length, measured from the
first end of the ring wall to the second end, which is different
than the first ring wall length. Thus, in some embodiments the
length of the ring wall is not the same around the circumference of
the ring wall. However, in general, the greatest length of the ring
wall preferably provides an aspect ratio of less than about 4:1. As
used herein, "aspect ratio" refers to the ratio of ring wall
length:lumen diameter. Thus, a ring wall with a 4:1 aspect ratio
has a ring wall length that is four times the diameter of the
lumen. In preferred embodiments, the aspect ratio is about 0.5:1 to
3:1 typically about 0.8:1 to 1:2.5. In some embodiments, the guide
can include dual-lumens for placement of two implants in parallel
alignment. In such embodiments, the external ring wall can surround
both lumens with each lumen having separate internal ring walls.
Typically, each lumen of a dual-lumen guide has an aspect ratio
within the above stated ranges of aspect ratios.
[0073] In some preferred embodiments, the guide includes one or
more projections or paddles extending from an end of the ring wall.
Typically, the guide includes two diametrically opposed paddles
which have a projection length extending from the first end of the
ring wall to the end of the paddle. However, in some dual lumen
guides, a single paddle located between the lumens may be used. In
addition to other features, the paddles can advantageously maintain
distraction of the disc space, enhance stabilization of the guide
within the joint space and facilitate removal of equal amounts of
bone from the vertebrae during reaming. Unlike prior art paddles,
the length of the paddles of the present guides are preferably
selected such that the length is greater than 50% of the depth the
vertebrae between which the guide is placed. In addition, the
length of the paddles are selected to reduce the lever arm effect
of prior systems. Thus, in most embodiments, the length of the
paddles, relative to the ring wall length (i.e., paddle length:ring
wall length) can be reduced to about 1:4 to 3:1. Typically, the
ratio of paddle length:ring wall length can be about 1:3 to 3:1,
and, in preferred embodiments, about 1:1 to 1:2.5.
[0074] The width of the paddles among different guides can vary. In
some embodiments, the inner surface of the paddles is arcuate and
defines a radius of curvature substantially equal to the radius of
curvature of the lumen. For a particular application, the width of
the paddles, throughout a major portion of the length of the
paddles, can be selected to correspond to the height of the
distracted disc space. The paddle width can also vary from the
proximal to distal aspect of the paddle. For example, a paddle can
be convergently tapered from a proximal aspect to a distal aspect
of the paddle to facilitate ease of insertion into an
intervertebral space. The distal most aspect of a tapered paddle
can further include a more acute taper to facilitate initial
insertion into the disc space. A taper of the distal most aspect of
a substantially non-tapered paddle can also be advantageously
used.
[0075] In some embodiments, the length dimension of the paddle can
be parallel to an axis passing through the lumen of the guide. In
other embodiments, the length dimension of the paddles can converge
towards, or, more likely, diverge away from an axis passing through
the lumen of the guide. In still other embodiments, the distance
between opposing paddles can be greater than the diameter of the
lumen of the guide.
[0076] In general, multiple guides will be available which have
paddles with varied widths. For cervical applications, a typical
range of paddle widths is approximately 2 mm to 12 mm, in 1 mm
increments. For a given guide, the paddle width is preferably about
1 mm to 3 mm less than the minor diameter of the implant to be
inserted at the site prepared with the guide.
[0077] The paddles can be inserted into the disc space after
distraction of the disc space or the paddles can be used to
distract and maintain the distracted disc space. By selecting a
paddle having a maximum width equal to the desired disc space
height, the paddles can maintain distraction of the disc space
during implant site preparation. In addition, due to the length of
the paddles relative to the ring wall length, the paddles of the
present guides provide increased stabilization of the guide to
reduce the likelihood of movement during implant site preparation
and further facilitate preparation of an implant site that is
parallel to the joint space with substantially equal amounts of
bone removed from the adjacent vertebral endplates.
[0078] The guide can also include an anchoring arrangement to
anchor the guide to the vertebral bodies and a handle for holding
and manipulating the guide. Suitable anchoring arrangements include
one or more teeth, pins, tines, etc., which can penetrate into the
vertebral body. The handle can be fixed or removable from the
guide.
[0079] A guide starter can be used for placement of the guide in
the intervertebral space. In general a portion of the guide starter
can be positioned within a lumen of the guide and provide for
substantially equal pressure to be applied around the circumference
of the ring wall during placement of the guide in the disc space.
As will be described, preferably, the starter guide includes a
shoulder which can seat on an edge of the ring wall to apply equal
pressure around the ring wall when the guide is placed into the
disc space.
[0080] Novel implant gauges, reamers, taps, implant drivers and
other instruments which are suitable for use according to the
invention are also described. In one embodiment, the invention
provides reamers and taps which are adjustable for selectively
controlling reaming and tapping to predetermined depths. As will be
further described, selective control can be provided by incremental
stops which can be fixed for a particular instrument or selectively
predetermined by the user. It will be appreciated that many of the
principles disclosed herein for selective control of reaming and
tapping depths can be applied to known hollow guide tubes to
provide hollow guide tube systems which provide selective control
of depth of penetration into a disc space when used with known
reamers, taps, etc.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
[0081] The invention will be described with reference to the
accompanying drawings, wherein like reference numerals identify
similar or corresponding components throughout the several views.
The illustrated embodiments and description are for exemplary
purposes to facilitate comprehension of the invention and should
not be construed to limit the scope of the invention. In addition,
for purposes here, the invention will be described with reference
to insertion of a spinal implant into a cervical disc space between
cervical vertebrae. However, it will be appreciated that many of
the described instruments and procedures are also suitable for
insertion of implants at other intervertebral disc space
locations.
[0082] FIG. 1a illustrates a perspective view, FIG. 1b a side view
and FIG. 1c a trailing end view of one example of a spinal implant
10 suitable for insertion in an intervertebral disc space using
instruments and methods of the invention. Referring to FIG. 1b,
D.sub.M is defined as the major diameter and D.sub.m is the minor
diameter of implant 10. Implants having various diameters, lengths,
thread patterns, etc., are available and can be used in accordance
with the invention. Examples of sizes of the minor diameter D.sub.m
of an implant for use in cervical fusions are 6 mm, 8 mm, 10 mm and
12 mm. The major diameter D.sub.M is typically 2-3 mm greater than
the minor diameter D.sub.m. The instruments of the invention can be
sized for a particular size of implant.
[0083] FIG. 2a is a top plan view and FIG. 2b is a side view of an
embodiment of an implant gauge 20 for measuring the disc height of
an intervertebral disc space. In some embodiments, the minor
diameter D.sub.m of an implant 10 is selected to be approximately
2-3 mm greater than the measured disc height. X-ray, CT or MRI
films can be used to determine the size of an implant to be used at
a particular location.
[0084] Implant gauge 20 includes a first end 21 and second end 22.
First end 21 includes two measuring regions, a distal first end
region 23 having a height D.sub.H1 and a proximal first end region
24 having a height D.sub.H2. The second end 22 also includes two
measuring regions, a distal second end region 25 having a height
D.sub.H3 and a proximal second end region 26 having a height
D.sub.H4. Additional measuring regions can also be included. Other
markings, for example measurement guide 27, can be present on gauge
20 for the surgeon's convenience. As will be described below,
implant gauge 20 can be used to determine the disc space height of
an intervertebral joint space to be fused. A kit of the invention
can include multiple implant gauges having varied end region
heights for measuring a range of disc heights. Typically, for
cervical vertebral fusions the range of heights of the end regions
which will be used for measuring disc space height which can be in
1 mm increments from about 2 mm to about 12 mm.
[0085] FIG. 3 is a side view of one embodiment of a guide 30
according to the invention. In this embodiment, guide 30 includes a
ring wall 31 having a first end 32 and a second end 33, projections
34 and anchoring arrangement 35. Handle 36 comprises a proximal
portion 37 and a distal portion 38 which is mounted to ring wall
31.
[0086] FIG. 4 is a top plan view illustrating that ring wall 31 has
an internal ring wall 40 which defines a lumen 41 having a diameter
D.sub.I. In some preferred embodiments, to prepare an implant bore
for an implant having a minor diameter D.sub.m lumen 41 is selected
such that the D.sub.I equals D.sub.m. In the illustrated
embodiment, ring wall 31 of guide 30 is complete. However, in
alternative embodiments, ring wall 31 need not be complete around
the circumference of the ring wall. The wall thickness of ring wall
31 provides a first end edge 42 and a second end edge 43. The
second end edge 43, is also referred to as the proximal edge.
[0087] Referring again to FIG. 3, distal portion 38 of handle 36
forms an angle .alpha. of about 0.degree. to 30.degree. with axis
A.sub.L passing through lumen 41. The angle .alpha. between axis
A.sub.L and distal portion 38 facilitates visualization of the
surgical site. FIG. 3a illustrates an alternative configuration for
handle 36. In other embodiments, the handle can be malleable to
allow the surgeon to adjust the angle as necessary for a particular
procedure. Also, it will be noted that in the embodiments of FIGS.
3-6, handle 36 is positioned relative to projections 34 such that
when projections 34 are inserted into the disc space handle 36 is
oriented perpendicular to the axis of the spine. However, in
alternative embodiments, handle 36 can be oriented relative to
paddles 34, such that when paddles 34 are inserted into the disc
space, handle 36 is substantially parallel to the axis of the
spine. Handle orientations between perpendicular and parallel can
also be used.
[0088] Referring to FIGS. 3, 5 and 6, guide 30 will be further
described. FIG. 5 is an enlarged side view of ring wall 31 and FIG.
6 is a front view rotated 90.degree. from the view of FIG. 5 (i.e.,
viewed from opposite handle 36).
[0089] Projections 34 comprise opposing paddles 50 and 51 which
extend from the first end 32 of ring wall 31. In the illustrated
embodiment, anchor arrangement 35 comprises teeth 52, 53 to anchor
guide 30 to the vertebral bodies. The width W.sub.P of paddles 50
and 51 can vary. However, in preferred embodiments, width W.sub.P
of paddles 50 and 51 is selected to be substantially equal to the
disc height determined with implant gauge 20. The paddle length
L.sub.P of paddles 50 and 51 is preferably at least 50% of the
depth of the vertebral bodies adjacent the intervertebral disc
space to be fused.
[0090] As discussed above, the paddle length L.sub.P is selected to
reduce the lever arm effect of prior systems. In the embodiment of
FIGS. 3-6, ring wall length R.sub.L is the same around the entire
ring wall 31. Also, paddle length L.sub.P is equal to lumen
diameter D.sub.I and both are greater than ring wall length
R.sub.L.
[0091] FIGS. 7 and 8 illustrate an alternative embodiment of a
guide 30 having a ring wall 31 wherein the ring wall length R.sub.L
is the same around the entire ring wall 31 and ring wall length
R.sub.L is equal to lumen diameter D.sub.I, both of which are less
than paddle length L.sub.P.
[0092] FIGS. 9 and 10 illustrate another embodiment of a guide 30
having a ring wall 31 wherein ring wall length R.sub.L is the same
around the entire ring wall 31 and ring wall length R.sub.L is
greater than lumen diameter D.sub.I and both are less than paddle
length L.sub.P.
[0093] FIG. 11a illustrates an alternative embodiment of a guide 70
wherein ring wall 71 has an exterior surface 72 including a groove
73 for cooperatively mounting to a removable handle 75 such as
illustrated in FIGS. 11b-d. As illustrated, handle 75 includes a
proximal end 76 for operating handle 75 and a distal end attachment
77 for mounting the handle 75 to the guide 70. The size of the
opening of distal end attachment 77 can be locked into a selected
position by use of, for example, known ratchet locking systems
78.
[0094] FIGS. 12 and 13 illustrate alternative embodiments of a
guide 100 of the invention. As illustrated in FIG. 13, a plane
P.sub.1 passing through first end 101 of ring wall 103 forms an
angle .beta. with a plane P.sub.2 passing through the second end
102 of ring wall 103. Thus, ring wall 103 has a first ring wall
length R.sub.L1, measured from first end 101 to second end 102,
which is greater than second ring wall length R.sub.L2, measured
from first end 101 to second end 102 at a point diametrically
opposed to R.sub.L1. The advantage of this configuration for some
applications is discussed below.
[0095] FIG. 12 is a side view of guide 100 (handle not shown)
showing paddle 105 (opposing paddle not visible in this view)
inserted into intervertebral disc space IS between adjacent
cervical vertebrae C.sub.X and C.sub.Y. "A" indicates the anterior
vertebral surfaces and "P" indicates posterior surfaces. As
illustrated, within the cervical spinal region, the intervertebral
disc space IS is generally not perpendicular to the anterior
margins of the vertebral bodies. Also, the inferior end plate 150
of superior cervical vertebrae C.sub.X is typically concave. The
superior end plate 151 of inferior cervical vertebrae C.sub.Y is
typically flat to slightly concave.
[0096] The configuration of guide 100 facilitates boring an implant
site substantially parallel to disc space IS and removal of equal
amounts of bone from the opposing end plates 150, 151, during
reaming when the end plates are not parallel and the disc space IS
is not perpendicular to the vertebral margins. Creating a bore
having a longitudinal axis parallel to the disc space facilitates
removal of equal amounts of the endplate bone of opposing yertebrae
and reduces the likelihood of, for example, post-surgical
subsidence of the vertebrae.
[0097] Referring to FIG. 13, typically planes P.sub.1 and P.sub.2
form an angle .beta. of about 0.degree. to 30.degree., and in some
preferred embodiments, about 5.degree. to 20.degree.. This
angulation between the first end 101 and second end 102 of guide
100 ensures that a reamer passed into the lumen of guide 100 will
be aligned to create an implant bore substantially parallel to the
disc space IS. The elongate paddle length P.sub.L of paddle 105,
relative to the depth of vertebrae C.sub.X and C.sub.Y, reduces the
likelihood of inadvertent displacement of the position of guide 100
by providing a small lever arm relative to ring wall length R.sub.L
(or ring wall lengths R.sub.L1, R.sub.L2). In addition, the length
P.sub.L of paddle 105, relative to the depth of vertebrae C.sub.X
and C.sub.Y, reduces the chances that the surface contours of the
endplates 150, 151 will cause formation of an implant bore that is
not parallel to the intervertebral disc space IS.
[0098] FIGS. 14-17 illustrate an alternative embodiment of a guide
200. FIG. 14 is a side view of guide 200 having a ring wall 201
including dual lumens 203 and 204. FIG. 15 is a top plan view
showing that in the illustrated embodiment, the diameter D.sub.I of
lumens 203 and 204 are equal. However, the lumen sizes need not be
equal. As illustrated for some previous embodiments of a guide,
guide 200 includes a handle 205, paddles 206, 207 and anchoring
arrangement 208. In the illustrated embodiment, lumen diameter
D.sub.I is less than ring wall length R.sub.L which is less than
paddle length L.sub.P. However, it will be appreciated that other
lumen diameter, ring wall and paddle length sizes can be used as
previously described.
[0099] FIG. 15a illustrates that in some embodiments, the internal
walls 210, 211 of lumens 203, 204, respectively, need not be
complete. Rather, a contiguous space 212 can exist between lumens
203, 204.
[0100] FIGS. 39-41 illustrate an alternative embodiment of a
dual-lumen guide 900. FIG. 39 is a front view and FIG. 40 is a side
view of guide 900 having an external ring wall 901 including dual
lumens 902 and 903. The thickness of ring wall 901 provides a first
edge 904 and a second edge 905. The first edge 904 is also referred
to as a proximal edge 906. In the embodiment illustrated here the
second edge 905 has a concave surface 907. Concave surface 907 can
advantageously provide for the dual-lumen guide to more closely
follow the curved contours of the vertebral bodies when in use.
[0101] Also in this embodiment, a single paddle 909 located between
lumens 902 and 903 extends from second edge 905. Referring to FIG.
41, the bottom plan view shows that the paddle 909 includes
bilateral concave surfaces 910a and 910b. In this embodiment, the
concave surfaces 910a and 910b of paddle 909 have a curved radius
which is the same as the radius of lumens 902 and 903. However, the
concave surfaces need not have radiuses which are the same as the
radius of the lumens. Moreover, it will be appreciated that
although the bilaterally concave paddle surfaces 910a and 910b are
advantageous in certain circumstances, a single central paddle such
as paddle 909 having non-concave surfaces (e.g., linear) could also
be used.
[0102] Guide 900 can also include an anchoring arrangement 911
comprising teeth 912a-912d (or other previously described anchoring
arrangement) extending from second edge 905. Guide 900 can also
include a handle 915. Handle 915 can be positioned relative to the
external ring wall 901 in any of the various positions previously
discussed for other embodiments of the invention. In addition, the
length of the ring wall and paddle relative to one another and
relative to the lumen diameters can vary as described for other
embodiments of the invention.
[0103] As previously described, paddle 909 can be inserted into the
disc space after distraction of the disc space or the paddle can be
used to distract and maintain the distracted disc space. By
selecting a paddle width equal to the desired disc space height,
the paddle can maintain distraction of the disc space during
implant site preparation. As with other embodiments of the
invention, due to the length of the paddle relative to the ring
wall length, the paddle provides increased stabilization of the
guide to reduce the likelihood of movement during implant site
preparation and can facilitate preparation of an implant site that
is parallel to the joint space.
[0104] Typically, a dual lumen guides can enhance the accuracy of
parallel alignment between two implants inserted into the
intervertebral disc space by providing early and continued
maintenance of parallel operating fields at both implant sites.
[0105] FIGS. 18, 19 and 19a illustrate additional embodiments of a
guide 250, 260 and 270. FIG. 18 illustrates that guide 250 includes
paddles 251 and 252 which diverge away from axis A.sub.L of lumen
257 from the proximal end 253, 254, to the distal end 255, 256 of
paddles 251, 252, respectively. In FIG. 19, the distance P.sub.D
between the interior surfaces 263, 264 of paddles 261, 262,
respectively, is greater than the diameter D.sub.I of lumen 265 of
guide 260. The configurations of FIGS. 18 and 19 can advantageously
provide greater retraction of soft tissue structures away from the
surgical field within lumens 257, 265.
[0106] The guide 270 of FIG. 19a illustrates paddles (only one
visible) having a taper. That is, the width at the proximal end 272
(W.sub.P272) of paddle 271 is greater that the width at the distal
end 273 (W.sub.P273). The tapered configuration of paddle 271
facilitates use of guide 270 to more easily be passed into and
distract an intervertebral disc space. For any specific procedure,
the width of paddle 271 at the proximal end 272 (W.sub.P272) can be
selected to provide the selected height of a distracted disc space.
According to the invention, a guide having paddles tapered as for
guide 270 can also include any of the previously described features
of a guide as well as additional paddle configurational features
shown for other guides including, for example, those illustrated in
FIGS. 3-5, 7-10, 11a-19, 39-41, etc.
[0107] FIG. 20 is a side view of a guide starter 300 according to
the invention. Guide starter 300 includes a starter shaft 301
having a first end 302 and second end 303. First end 302 includes a
distal end region 304 having a distal end region diameter D.sub.D
and a proximal end region 305 having a proximal end region diameter
D.sub.P. The junction of distal end region 304 and proximal end
region 305 form a shoulder 306. Distal end region diameter D.sub.D
is sized to fit within a guide lumen (e.g., 41 of FIG. 4) such that
shoulder 306 rests on proximal edge 43 (FIG. 4) of ring wall 31.
Thus, by tapping on second end 303, shoulder 306 provides for
substantially equal pressure to be applied around the circumference
of ring wall 31 to force the paddles (e.g., 50, 51) of a guide
(e.g., 30, 100, 200) into the intervertebral disc space. It will be
appreciated that the second end 303 of guide starter 300 can also
include a distal end region 310 and a proximal end region 311 to
form a shoulder 312. Each distal and proximal end regions having a
different diameter. Multiple guide starters each having different
size distal and proximal region diameters can be provided in a kit
to match guides having corresponding lumen diameters.
[0108] FIGS. 21 and 22 illustrate one embodiment of an adjustable
reamer suitable for use according to the invention. Adjustable
reamer 350 includes a proximal end 351, and a distal end 352 having
a working end 353 comprising a cutting end 354 for reaming an
implant bore between adjacent vertebrae. In the illustrated
embodiment, the bore depth of reamer 350 can be selectively
adjusted to a predetermined depth by adjustment arrangement 360
comprising threads 361, adjustment nut 362 and lock nut 363.
[0109] Referring to FIG. 22, adjustment nut 362 and lock nut 363
have been removed to show that reamer 350 also includes a proximal
shaft region 365 providing spacing between cutting end 354 and
adjustment threads 361. Adjustment threads 361 provide for
threadedly moving locking nut 363 to a selected position which can
be guided by, for example, depth markings 364. In the illustrated
embodiment, depth markings 364 correspond to a particular implant
bore-depth. The position of adjustment nut 362 can be fixed by
threading adjustment nut 362 against the distal end 366 of lock nut
363. In use, the depth of reaming is controlled by the affirmative
stop which occurs when the distal edge 367 of adjustment nut 362
contacts the proximal edge of a ring wall (e.g., 43 of FIG. 4). In
an alternative embodiment, the diameter of the distal end region
368 of adjustment nut 362, can be sized to fit within the lumen of
the guide such that contact of lip 369 with proximal edge 43 of the
guide affirmatively stops the depth of reaming.
[0110] FIGS. 23-26 illustrate an alternative embodiment of an
adjustable reamer 500 according to the invention. Referring to
FIGS. 23-25, adjustable reamer 500 includes a proximal end 503, a
distal end 504, a tubular sleeve 501 and a shaft 550 in the lumen
502 of tubular sleeve 501.
[0111] Tubular sleeve 501 has a first end 505 and a second end 506.
In the illustrated embodiment, wall 507 of tubular sleeve 501 has a
first outer diameter 508 and a second outer diameter 509 forming
lip 510 at first end 505. In use, lip 510 acts to affirmatively
stop the passage of reamer 500 through the lumen 41 of ring wall 31
(e.g., FIG. 4) when the proximal lip 510 of reamer contacts the
proximal edge 43 of ring wall 31. However, (as discussed and
illustrated below with the discussion of a tap) in an alternative
embodiment with an appropriate size guide lumen, distal edge 511
can also act as an affirmative stop. When using a reamer 500 having
a tubular sleeve 501 configured to include a lip 510, the lumen 41
diameter D.sub.I of a guide 30 is selected such that diameter
D.sub.I is of a size sufficient to permit passage of first outer
diameter 508 into lumen 41.
[0112] Referring now to FIG. 25, shaft 550 includes a working end
551 and an operating end 552. Working end 551 comprises a cutting
head 553.
[0113] The diameter D.sub.C of cutting end 553 is sized to permit
passage into lumen 502. In use, D.sub.C is typically selected to
equal D.sub.m of implant 10. Thus, according to this embodiment the
diameter D.sub.I of lumen 41 of a guide 30 is selected for close
tolerance passage of first outer diameter 508, rather than close
tolerance with diameter D.sub.C of cutting end 553. A handle
described below, can be mounted to the operating end 552 to rotate
the shaft for boring an implant site with the cutting head 553.
Shaft 550 can also include a stabilizer 554 for controlling lateral
stability of shaft 550 when within lumen 502 of tubular sleeve 501.
The function of fixed ring 555 is further described below. Shaft
550 also includes a portion of depth adjustment arrangement 575
having stops 560 and slots 561 which are seen in FIG. 25 and shown
in laid out form in FIG. 26.
[0114] Referring to FIG. 26, it will be appreciated that stops 560
are positioned an incremental distance from cutting end 553 (and
first end 505 of tubular sleeve 501) and are the terminal point of
slots 561. Each of the incremental positions of stops 560
correspond to an incremental position by which working end 551 can
protrude from the first end 505 of tubular sleeve 501.
[0115] Referring again to FIG. 24, the operation of adjustable
reamer 500 will be described. At the proximal end 503 of adjustable
reamer 500, tubular sleeve 501 includes a pin 515 which passes into
the lumen 502 of the second end 506 of tubular sleeve 501. The
stair step arrangement 563 of stops 560 and slots 561 permits pin
515 to interdigitate with the slots 561 and contact stops 560 to
fix the protrusion of cutting head 553 at a predetermined position
beyond the first end 505 of tubular sleeve 501. Thus, by sliding
tubular sleeve 501 towards the working end 551 of shaft 550, pin
515 can be advanced out of a particular slot 560 such that when
tubular sleeve 501 is axially rotated pin 515 can be repositioned
to pass into an alternative slot. Once rotated to a selected slot
position, sleeve 501 can retract away from working end 551, and pin
515 can retract to the corresponding stop 560, by use of a biasing
force, such as helical spring 564, to bias tubular sleeve 501 in a
direction toward the proximal end 503 of adjustable reamer 500.
Helical spring 564 provides a biasing force by acting against fixed
ring 555 and shoulder 516 within lumen 502. Referring to FIG. 26,
in the illustrated embodiment, stop 560a is positioned for
convenient cleaning of adjustable reamer 500 by permitting tubular
sleeve 501 to move a sufficient distance proximally to permit easy
access to all aspects of cutting head 553.
[0116] Thus, positioning pin 515 against a selected stop 560 allows
for selective positioning of working end 553 relative to shoulder
510 (or distal edge 511). The position of cutting head 553,
relative to shoulder 510, determines the depth of an implant bore
by controlling the depth of penetration of cutting head 553 into
the disc space before the reamer is affirmatively stopped by
proximal edge 43 of guide 30.
[0117] Referring to FIG. 23, in the illustrated embodiment, pin 515
is located in groove 567. Groove 567 can be positioned to align
with numerical markings 565 (in FIG. 26), such that each numerical
marking provides quick correlation of a particular bore depth to be
used for a particular implant length.
[0118] After reading the foregoing discussion, it will be
appreciated that alternative configurations for the pins, slots and
grooves of the depth adjustment arrangement can be utilized and are
within the scope of the invention.
[0119] In some procedures, it may be desirable to tap the implant
bore prior to placement of an implant. FIG. 27 illustrates one
example of a tap 600 suitable for the invention. According to this
embodiment, tap 600 includes a working end 601, specifically a
tapping head 602 at end 603 which is spaced a distance from an
operating end 604 at proximal end 605. A handle can be mounted to
operating end 604 for operating tap 600. Tap 600 also includes a
lip 606 which can act as an affirmative stop to limit depth of
tapping when lip 606 contacts proximal edge 43 of guide 30.
[0120] Referring to FIGS. 28 and 29, in an alternative embodiment,
a tap according to the invention can be an adjustable tap 650.
Similar to adjustable reamer 500, adjustable tap 650 includes a
tubular sleeve 651 having a lumen 652 through which is passed a
shaft 653. Shaft 653 includes a working end 654 comprising a
tapping head 655. The operating end 656 of shaft 653 can be
configured for attachment to a handle as described below. Tubular
sleeve 651 has a distal edge 657 which acts as an affirmative stop
to the depth of tapping when it contacts the proximal edge 43 of
guide 30. The components of a depth adjustment arrangement
described for adjustable reamer 500 are also present in adjustable
tap 650.
[0121] FIG. 30 illustrates a side view of an embodiment of an
adjustable reamer similar to reamer 500 of FIGS. 23-26, but wherein
the configuration of tubular sleeve 576 is similar to tubular
sleeve 651 of tap 650 in FIGS. 28-29. That is, tubular sleeve 576
has a distal edge 577 and only a single outer diameter size at the
distal end. One purpose of FIG. 30 is to illustrate another
arrangement of a guide according to the invention which provides
further selectivity for the surgeon. Specifically, in the event
that a surgeon desires both the visibility advantage of a low
profile ring wall, e.g., 71 of guide 70, and greater lateral
support when reaming, spacing sleeve 580 can be used.
[0122] In the illustration of FIG. 30, spacing sleeve 580 includes
a distal end region 581 having an outside diameter D.sub.SS sized
to pass into lumen 78 of guide 70. Spacing sleeve 580 also includes
a proximal lip 582 of distal end region 581 which abuts against
proximal edge 79 of guide 70 when spacing sleeve 580 is inserted
into guide 70. The proximal end 583 of spacing sleeve 580 includes
a proximal edge 584. During use, the depth of reaming by reamer 575
is affirmatively stopped when distal edge 577 contacts proximal
edge 584 of spacing sleeve 580. It will be appreciated that the
arrangement of a guide and spacing sleeve can also be used to
provide guidance for a tap, implant driver or other instrument used
according to the invention.
[0123] FIG. 31 is a side view of a cleaning probe 590 according to
the invention. As illustrated, cleaning probe 590 includes an
operating end 591, a shaft 592 and a distal tip 593. Cleaning probe
590 can be used to remove bone material which collects within the
flutes 578 of the cutting end 579 of a reamer such as reamer 575 in
FIG. 30. In addition, although not shown, any of the reamers of the
invention (e.g., 350, 500 or 575) or taps (e.g., 600, 650) can
include a bore through the longitudinal axis of reamer for passage
of cleaning probe 590 therethrough. The bony debris can be
collected and used to pack into the chamber of an implant 10.
[0124] FIGS. 32a and 32b show a handle 675 suitable for operation
of a reamer, tap or driver according to the invention. In this
embodiment handle 675 provides a ratchet function using known
technology. Non-ratchet handles also be used.
[0125] FIGS. 33a-c illustrate an implant driver assembly 700 for
inserting an implant (e.g. FIG. 1) in a reamed or reamed and tapped
bore. Implant driver 700 includes a proximal end 701 for attaching
to a handle (e.g., 675 of FIGS. 32a and 32b) for operating the
implant driver 700. Implant driver 700 also has a distal end 702
for mounting of an implant 10 to the implant driver 700. FIG. 33c
is a distal end view of implant driver 700 illustrating four
protuberances 704a-d which can be inserted into apertures 11a-d at
the trailing end 12 of implant 10. The distal end 702 of shaft 705
includes threads 706 for mounting implant driver assembly 700 into
threaded bore 13 at the trailing end 12 of implant 10. Once the
implant 10 is mounted to implant driver 700, the handle can be
rotated so that external threads 14 of implant 10 are threadedly
inserted into the implant site bore. Implant driver 700 also can
include an adjustable stop 710 which is positioned to affirmatively
stop the depth of advancement of an implant 10 into the bore when
the distal edge 711 of adjustable stop 710 contacts the proximal
edge of a guide or spacing sleeve.
[0126] According to the method of the invention, the approximate
size of an implant can be determined from x-ray, CT or MRI images
of the affected intervertebral disc space. A properly sized implant
preferably fits within the perimeter margins of the vertebral
bodies. Typically, the appropriate implant size will be based upon
the disc height of the affected disc space.
[0127] For fusion of a cervical intervertebral space, the patient
can be placed in the supine position with support under the
cervical spine. The patient can be draped and prepped in the usual
manner for an Anterior Cervical Decompression and Fusion (ACDF)
surgery. A complete anterior cervical discectomy using conventional
methods can be performed. Any bone pieces removed during
decompression can be saved for packing into the implant to
facilitate fusion.
[0128] Based on templating from x-ray, CT or MRI images, the disc
space to be fused is distracted using a distraction system such as
a Caspar Retractor (Aesculap) or similar retractor. The retractor
can be removed or remain in place until the implant has been
implanted. The disc space can then be measured by inserting an
implant gauge 20 to determine the appropriate disc height.
Preferably, the reamer cutting diameter is selected to be
approximately 2 to 3 mm greater than the measured disc height.
[0129] The paddles of the guide are inserted between the vertebral
bodies, and, if an anchoring arrangement is present, the anchoring
arrangement is positioned for penetration into the superior and
inferior vertebral bodies. To snug the guide into appropriate
position, a guide starter is selected having a distal end diameter
selected to fit within the lumen of the guide with the shoulder of
the guide starter resting on the proximal edge of the ring wall.
The end of the guide starter away from the guide can then be tapped
with a small mallet to force the paddles into the intervertebral
space and wedge the anchoring arrangement into the vertebral
bodies. The guide starter can then be removed.
[0130] The affirmative stop on the reamer (e.g., lip or distal
edge) can be adjusted until the appropriate reaming depth is set.
While firmly holding the handle of the guide, the cutting end of
the reamer is passed through the lumen of the guide and the reamer
advanced until the reamer is affirmatively stopped by the proximal
edge of the guide. A lateral x-ray can be taken to inspect the
depth of reaming. Typically, in a cervical fusion procedure, ideal
reaming is to a depth of about 2 to 3 mm from the posterior margin
of the vertebral body. If an insufficient reaming depth has been
achieved, the affirmative stop position of the reamer can be
adjusted to allow for deeper reaming. To prevent excessive reaming,
it is best to make incremental reaming adjustments to achieve the
desired depth.
[0131] The reamer is then removed from the guide and bone material
present in the cutting end can be removed and packed into the
implant. The bore can then be tapped. However, in some embodiments
of the invention, particularly in methods involving cervical
vertebrae, tapping may not be necessary.
[0132] After tapping the bore, or if the bore is not tapped, the
implant can be mounted to the distal end of an implant driver. The
leading end of the implant is inserted into the bore and the
implant driver rotated until the implant has been positioned at an
appropriate depth. Depending on the size of the components, the
guide can be removed prior to inserting the implant or the guide
can remain in place and the implant inserted into the bore through
the guide.
[0133] If two implants are to be inserted, after insertion of the
first implant on one side of the intervertebral disc space, the
above described procedure is repeated at the second side of the
intervertebral disc space. Alternatively, if a dual lumen guide is
used, after placement of the guide in the intervertebral disc
space, the first implant site can be prepared and, before or after
insertion of the first implant into the first implant site, the
second implant site prepared. After the implants are inserted, the
surgical wound can be closed using known methods.
[0134] In a further embodiment, the invention also provides a depth
adjustment arrangement, which can advantageously be used to provide
for selective control of instrument depth penetration through known
elongate hollow guide tubes. In one such embodiment, known taps,
reamers and implant guides providing an affirmative stop
arrangement at the proximal end of the instrument can be used with
the novel hollow guide systems described below.
[0135] FIGS. 34-38 illustrate one embodiment of an adjustable guide
tube 800 according to the invention. FIG. 34 is a side view of the
adjustable guide tube 800, FIG. 35 is a longitudinal cross section
through the adjustable guide tube of FIG. 35. FIG. 36 is a side
view of the guide housing of the adjustable guide tube of FIG. 34.
FIG. 37 is a side view of the guide housing of FIG. 36 with a
helical spring and FIG. 38 is a side view of an adjustable guide
tube of FIG. 34 with a reaming tool passed therethrough.
[0136] As illustrated, adjustable guide tube 800 has a distal end
801, a proximal end 802 and a lumen 803 passing therethrough.
Adjustable guide tube 800 also includes a guide housing 804 and an
adjustable sleeve 805. Guide housing 804 includes an inner surface
806 which defines lumen 803 and an outer surface 807 having a
proximal cutout 808 which forms a proximal shoulder 809. Adjustable
sleeve 805 also has an outer surface 810 and an inner surface 811.
Inner surface 811 includes an axially protruding ridge 812 forming
a distal shoulder 813.
[0137] FIG. 36 illustrates guide housing 804 with adjustable sleeve
805 removed. It will be appreciated that proximal cutout 808
includes a plurality of slots, e.g., 820-823. Each of slots 820-823
include a terminal stop 824-827 which is incrementally positioned a
predetermined distance from the distal end 801 of guide housing
804.
[0138] Referring again to FIG. 35, the proximal shoulder 809 of
guide housing 804 and distal shoulder 813 of adjustable sleeve 805
are biased away from each other by helical spring 830. Adjustable
sleeve 805 also includes a pin 831 which protrudes towards inner
surface 811 and a proximal rim 832 surrounding opening 833 through
which a surgical instrument can pass into the adjustable guide
tube. As illustrated in FIG. 26 for adjustable reamer 500, stops
824-827 of adjustable guide tube 800 are preferably oriented in a
stair step arrangement spaced around guide housing 804. The stair
step arrangement of stops 824-827 permits pin 831 to interdigitate
with slots 820-823 and contact stops 824-827 to fix the overall
distance between rim 832 of adjustable sleeve 805 and the contact
edge 835 of guide housing 804. By sliding adjustment sleeve 805
towards the proximal end 802 of adjustable guide tube 800, pin 831
can be retracted out of a slot (e.g., 820-823) so that when
adjustment sleeve 805 is axially rotated, pin 831 can be realigned
to pass into an alternate slot.
[0139] Once rotated to a selected slot position, adjustable sleeve
805 can slide away from proximal end 802, and pin 831 will advance
into the slot to the corresponding stop (e.g., 824-827), by the
biasing force of helical spring 830. It will be appreciated that
although the foregoing discussion describes four slots 820-823 and
four stops 824-827, any number of slots and stops can be used.
[0140] According to this embodiment of the invention, once rim 832
of adjustable sleeve 805 is positioned at a selected distance from
contact edge 835, adjustable guide tube 800 provides lateral
guidance for reamers, taps, implant drivers, etc. which are passed
through lumen 803 of adjustable guide tube 800. FIG. 38 illustrates
a reamer 850 having a cutting end 851 and a flange 852 which acts
as to affirmatively stop penetration of the reamer (or other
instrument) when flange 852 contacts rim 832 of adjustment sleeve
805. The distal end 801 of adjustable guide tube 800 can include an
anchoring arrangement, paddles, or other features, e.g.,
longitudinal slots in guide housing 804 for cleaning, present in
known hollow guide tube systems.
[0141] From the foregoing detailed description and examples, it
will be evident that modifications and variations can be made in
the devices and methods of the invention without departing from the
spirit or scope of the invention. Therefore, it is intended that
all modifications and verifications not departing from the spirit
of the invention come within the scope of the claims and their
equivalents.
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