U.S. patent application number 11/764997 was filed with the patent office on 2009-01-29 for intervertebral cage designs.
Invention is credited to Mark H. Falahee.
Application Number | 20090030519 11/764997 |
Document ID | / |
Family ID | 32659274 |
Filed Date | 2009-01-29 |
United States Patent
Application |
20090030519 |
Kind Code |
A1 |
Falahee; Mark H. |
January 29, 2009 |
INTERVERTEBRAL CAGE DESIGNS
Abstract
Cage systems that improve upon the prior art in various ways. In
the preferred embodiments, devices are radiolucent, with markers,
thereby allowing visualization of placement without excessive
obscuration. Devices according to the invention eliminate multiple
steps, instruments and trays, while being capable of a custom fit.
The devices according to the invention permit easier and greater
access to end plate surface area, and can be used with autografts,
allografts, and biologics.
Inventors: |
Falahee; Mark H.; (Ann
Arbor, MI) |
Correspondence
Address: |
GIFFORD, KRASS, SPRINKLE,ANDERSON & CITKOWSKI, P.C
PO BOX 7021
TROY
MI
48007-7021
US
|
Family ID: |
32659274 |
Appl. No.: |
11/764997 |
Filed: |
June 19, 2007 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10691854 |
Oct 23, 2003 |
7232463 |
|
|
11764997 |
|
|
|
|
60420616 |
Oct 23, 2002 |
|
|
|
Current U.S.
Class: |
623/17.16 ;
623/17.11 |
Current CPC
Class: |
A61B 90/92 20160201;
A61F 2002/30904 20130101; A61F 2/447 20130101; A61B 17/1659
20130101; A61F 2002/30433 20130101; A61F 2002/4627 20130101; A61F
2/30744 20130101; A61F 2250/0087 20130101; A61F 2/4603 20130101;
A61F 2002/3008 20130101; A61F 2/30965 20130101; A61F 2250/0009
20130101; A61B 2017/0256 20130101; A61F 2002/30507 20130101; A61F
2/4601 20130101; A61F 2002/30593 20130101; A61B 17/1671 20130101;
A61F 2250/0098 20130101; A61B 2017/00464 20130101; A61F 2/4611
20130101; A61F 2220/0091 20130101; A61B 17/00234 20130101; A61B
17/86 20130101; A61B 17/1757 20130101; A61F 2220/0041 20130101;
A61F 2002/3071 20130101; A61B 17/1735 20130101; A61F 2002/30579
20130101; A61F 2002/30471 20130101; A61F 2220/0025 20130101; A61F
2002/2835 20130101; A61F 2002/4629 20130101; A61F 2002/30616
20130101; A61F 2002/30556 20130101; A61B 17/8875 20130101; A61F
2002/4635 20130101 |
Class at
Publication: |
623/17.16 ;
623/17.11 |
International
Class: |
A61F 2/44 20060101
A61F002/44 |
Claims
1.-9. (canceled)
10. An implant for promoting intervertebral fusion, comprising: a
cage having two sidewalls, a posterior back wall, an open top, an
open bottom, and an open front; and wherein the back wall is
expandable such that the sidewalls can be brought closer together
for insertion and spread apart during implantation.
11. The implant of claim 10, wherein the side walls are
substantially parallel during insertion and when spread apart.
12. The implant of claim 10, wherein: the cage is comprised of two
L-shaped pieces, each with a first section forming a respective one
of the side walls and a second section forming a portion of the
back wall; and wherein the second sections of each L-shaped piece
overlap in sliding engagement enabling the sidewalls to be brought
closer together for insertion and spread apart during
implantation.
13. The implant of claim 10, wherein: the back wall is composed of
two hinged sections hinged sections that collapse against the side
walls for insertion and become substantially straightened out
during implantation.
14. The implant of claim 10, wherein each sidewall has a convex
upper edge and a substantially flat lower edge, such that when
viewed from the side, the upper and lower edges conform to
outwardly curved and flat planes, respectively.
15. The implant of claim 10, further including a physically
separate, rigid gate element for closing the open front.
16. The implant of claim 15, wherein the cage and gate are
constructed of a radiolucent material.
17. The implant of claim 15, wherein the cage and gate are
constructed of carbon fiber.
18. The implant of claim 15, wherein: the cage is constructed of a
radiolucent material; and further including one or more radiopaque
markers on the cage.
19. The implant of claim 10, wherein the backwall is indented to
minimize neurocompression.
20. The implant of claim 10, wherein: the sidewalls have a
posterior height and an anterior height; and wherein the posterior
height is less than the anterior height, thereby forming a
trapezoid.
21. The implant of claim 10, wherein the anterior height, posterior
height, or both, are sized to accommodate a particular vertebral
level.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/691,854, filed Oct. 23, 2003, which claims
priority from U.S. Provisional Patent Application Ser. No.
60/420,616, filed Oct. 23, 2002, the entire content of both of
which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates generally to spinal implants and, in
particular, to improved intervertebral cage designs.
BACKGROUND OF THE INVENTION
[0003] There are many intervertebral implants to assist with
stabilization and fixation, including pre-assembled mesh rings of
varying size; cylindrical threaded cages; carbon fiber boxes; and
bone dowels, rings, and wedges. However, all existing devices have
certain drawbacks, including the requirement of multiple steps and
tools to prepare and mold the intervertebral plates for acceptance
of the devices.
[0004] Existing implants also exhibit the need to remove/move a
distraction device such as a spreader or plugs around a
decorticate. Such plugs/distraction devices often get in the way of
cage placement. Mesh cages in bone materials can deform or break
with attempts to force them into the inner space. Typically, only a
small surface of the end plate is exposed to bone graft, this being
dictated by the size and position of the cage. Existing devices
also require large trays with many instruments and many cages, and
it is difficult to see the bone fused in mass inside metal cages,
which are radiopaque.
SUMMARY OF THE INVENTION
[0005] This invention resides in cage systems that improve upon the
prior art in various ways. In the preferred embodiments, devices
are radiolucent, with markers, thereby allowing visualization of
placement without excessive obscuration. Devices according to the
invention eliminate multiple steps, instruments and trays, while
being capable of a custom fit. The devices according to the
invention permit easier and greater access to end plate surface
area, and can be used with autografts, allografts, and
biologics.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a drawing that shows a preferred embodiment of the
invention;
[0007] FIG. 2A is a drawing which shows a contoured, wedge-shaped
retractor;
[0008] FIG. 2B shows a side view of a U-shaped introducer;
[0009] FIG. 2C shows a top view of the U-shaped introducer;
[0010] FIG. 2D shows the U-shaped introducer received within a
cage;
[0011] FIG. 2E is a side view of a graft impactor;
[0012] FIG. 2F is a side view of the graft impactor but with an end
view of the impactor tip;
[0013] FIG. 2G shows a gate holder with a screw mechanism used to
capture and release a gate;
[0014] FIG. 2H is a drawing of a screwdriver;
[0015] FIG. 3A shows cage shapes for levels L2-L5;
[0016] FIG. 3B shows cage shapes for levels L5/S1;
[0017] FIG. 3C shows cage shapes for levels T/L2;
[0018] FIG. 4A shows how disc material is removed to determine the
lateral extent of a disc space;
[0019] FIG. 4B is a drawing that shows a disc space being dilated
to a desired height using distracters which are preferably color
coded;
[0020] FIG. 4C shows a cage being inserted;
[0021] FIG. 4D illustrates how, with the implant released and the
introducer tool removed, easy access is available to the end
plates;
[0022] FIG. 4E shows how end plates are prepared, and grafting
material, biologics, and so forth are packed in;
[0023] FIG. 5A is a first view of an implant according to the
invention;
[0024] FIG. 5B is a second view of an implant according to the
invention;
[0025] FIG. 6A is a drawing that shows how a proximal guide sleeve
is attached onto one vertical side wall of the cage and drilled and
tapped as necessary;
[0026] FIG. 6B shows a locking screw in position;
[0027] FIG. 6C shows how a universal screw driver/holder is used to
place distal screws into the cage;
[0028] FIG. 6D depicts the lower aspect of a cage being locked into
a distal vertebrae;
[0029] FIG. 6E is a lateral view of a cage in place;
[0030] FIG. 6F is an anterior-posterior (AP) view of a cage in
place;
[0031] FIG. 7A begins a series of drawings that depict an
alternative embodiment of the invention including a different form
of anterior fixation;
[0032] FIG. 7B shows how a fixation jig is used to introduce a
screw or similar device through the intervertebral body proximally
into the superior cage walls
[0033] FIG. 7C shows how inferior fixation is accomplished with a
ratchet screwdriver/holder to deliver a fastener through the
inferior wall of the cage into the vertebral body
[0034] FIG. 7D is a drawing that shows how the screw preferably
angles out laterally;
[0035] FIG. 7E depicts a fixed cage in place;
[0036] FIG. 8A shows the anchoring screw being pushed;
[0037] FIG. 8B shows the pins advanced;
[0038] FIG. 8C shows the device in-situ;
[0039] FIG. 9A shows the hinged contoured back wall with the
inserter prior to use;
[0040] FIG. 9B shows the back wall being straightened and the side
walls being spaced apart;
[0041] FIG. 10A illustrates a different embodiment involving a
sliding lateral expandable cage with locking screws; and
[0042] FIG. 10B shows an expanded condition with the locking screws
being used to stabilize the structure at a desired level of
expansion.
DETAILED DESCRIPTION OF THE INVENTION
[0043] A first preferred embodiment of the invention is depicted in
FIG. 1. This design includes an open-faced cage 102, which is
constructed of carbon fiber or other radiolucent material but for
small dot radiopaque markers (not shown). The device includes a
contoured dome-shaped side walls 104, 104' with a flat trapezoidal
undersurface. Separate cages and tools may be used for the L5-S1
levels with more pronounced trapezoidal shapes. An indented back
wall 110 is used to prevent neurocompression. The side walls
preferably include a recessed face with nippled intents 112 and
screw holes 114 to receive a locking screw 116. A closing face gate
120 is provided with non-slip nipples and locking screw holes as
well.
[0044] In addition to the dome-shaped contours of the upper end
plate, different shapes for the L5-S1 levels, and the indented back
wall, the use of an open-face plate with gate and locking screw
mechanism allows the device to be packed and closed in-situ,
thereby effectively assembling the cage between the vertebrae. Note
that although this design includes numerous features which are
believed to be novel, they need not be used entirely in
combination, but may be used separately or combined in subsets. The
side view at the right in FIG. 1 illustrates the optional use of
sawtooth features 125 on the upper surface 130, which is preferably
dome-shaped, and the lower surface 140, which is preferably
flat.
[0045] FIG. 2 is a series of drawings which shows the instruments
used to implant devices according to the invention. Most or all are
removably attached able to a ratchet handle 200. The set includes a
screwdriver 202 (FIG. 2H); contoured, wedge-shaped retractors 206,
preferably including a color-coded raised centering mark or ridge
207 (FIG. 2A); U-shaped introducers 208 (FIG. 2B), preferably
including retractable wings 209 (FIG. 2C) to release a cage 210
(FIG. 2D) using control 211; graft impactors 220 (FIGS. 2E, 2F) and
gate holder 230 including a screw mechanism 232 used to capture and
release a gate 240 (FIG. 2G). The impactors 230 are generally 25 in
length, and preferably come in different sizes, such as 0.8 cm at
one end and 1-2 cm at the other, 0.5 cm at one end and 1 cm or less
at the other, and so forth.
[0046] FIG. 3 shows how cage shapes would preferably be varied for
different vertebral levels. FIG. 3A shows cage shapes for L2-L5;
FIG. 3B shows cage shapes for L5/S1; and FIG. 3C shows cage shapes
for T/L2. In each case, the implants would preferably utilize some
or all of the other geometries described herein, including a
general U-shaped construction, crescent-shaped side walls, domed
tops, indented back wall, carbon fiber or other radiolucent
construction with markers, serrated or tooth-edged, end-plate
surfaces, and so forth. The devices would also preferably include
correspondingly sized anterior gates, also utilizing carbon fiber
or other radiolucent material, with non-slip nipples, locking screw
holes and associated screws.
[0047] FIG. 4 is a series of drawings which show a method involving
an anterior approach to the intervertebral space. In FIG. 4A, disc
material is removed with tool 402 to determine the lateral extent
of the space. In FIG. 4B, the disc space is dilated to a desired
height using distracters 206 which are preferably color coded. The
final distracter is removed and replaced with the same color-coded
implant introducer instrument 208, with the cage being inserted as
shown in FIG. 4C. The implant is released and the introducer tool
removed, allowing easy access 410 to the end plates as shown in
FIG. 4D.
[0048] In FIG. 4E, the end plates are prepared, and grafting
material, biologics, and so forth are packed in. In FIG. 4F, a
correspondingly sized anterior gate is locked into position using
the gate holder and locking screws and screwdriver, and the wound
is closed. FIG. 5 begins a series of drawings which shows an
alternative embodiment of the invention which allows for an in-situ
cage to act as a stand-alone radiolucent cage system. In addition
to the instruments previously described, this embodiment utilizes
proximal left/right guide sleeves, a drill and universal head
screwdriver. In terms of the implant itself, proximal and distal
screws are used in conjunction with an in-situ cage having a
locking gate, in this case modified to accept proximal screws and
guide inferior screws. Different views of the implant are shown in
FIGS. 5A and 5B.
[0049] In terms of the operative procedure, the steps previously
described involving cage insertion are followed. However, in this
case, a proximal guide sleeve is attached onto one vertical side
wall of the cage and drilled and tapped as necessary, as shown in
FIG. 6A. The locking screw is shown in place in FIG. 6B. The
universal screw driver/holder is used to place distal screws into
the cage, as shown in FIG. 6C, allowing the lower aspect of the
cage to be locked into the distal vertebrae as shown in FIG. 6D.
FIG. 6E is a lateral view of the cage in place, and FIG. 6F is an
A-P view.
[0050] Now turning to FIGS. 7 and higher, which depict yet a
further alternative embodiment including a different form of
anterior fixation. As shown in this case, a fixation jig 700 is
used to introduce a screw or similar device through the
intervertebral body proximally into the superior cage walls, as
shown in FIG. 7B. Inferior fixation is accomplished with a ratchet
screwdriver/holder 702 , which delivers the fastener through the
inferior wall of the cage into the vertebral body as shown in FIG.
7C. The screw preferably angles out laterally, as shown in FIG. 7D,
with the fixed cage in place in FIG. 7E. FIG. 8 is a series of
drawings which shows internal fixation using an advancing screw to
push a fixation pin into the cortical end plate. FIG. 8A shows the
anchoring screw 802 being pushed, FIG. 8B shows the pins 804
advanced, and FIG. 8C shows the device in-situ.
[0051] FIG. 9 shows yet a different alternative embodiment of the
invention in the form of a collapsing cage suitable for endoscopic
placement. The cage is hinged enabling it to be laterally
expandable with an expandable cage inserter. FIG. 9A shows the
hinged contoured back wall 902 with the inserter prior to use, and
FIG. 9B shows the back wall being straightened and the side walls
being spaced apart. FIG. 10 shows a different embodiment involving
a sliding lateral expandable cage 10 with locking screws 12. Again,
an expandable cage inserter is used to move the side walls apart
from the condition in FIG. 10A to the expanded condition in FIG.
10B with the locking screw being used to stabilize the structure at
a desired level of expansion.
* * * * *