U.S. patent application number 10/973481 was filed with the patent office on 2006-04-27 for surgical instruments and method of using same.
Invention is credited to Charanpreet S. Bagga, Peter F. JR. Ullrich.
Application Number | 20060089649 10/973481 |
Document ID | / |
Family ID | 36207086 |
Filed Date | 2006-04-27 |
United States Patent
Application |
20060089649 |
Kind Code |
A1 |
Ullrich; Peter F. JR. ; et
al. |
April 27, 2006 |
Surgical instruments and method of using same
Abstract
Certain preferred embodiments of the present invention relate to
surgical instruments particularly suitable for preparing vertebral
endplates during spinal interbody surgical procedures. Methods of
using such instruments are also disclosed. In one embodiment, the
surgical instrument includes a first portion which serves as a
rasp, and a second portion serving as a device guide for a reaming
device.
Inventors: |
Ullrich; Peter F. JR.;
(Neenah, WI) ; Bagga; Charanpreet S.;
(Phoenixville, PA) |
Correspondence
Address: |
WOODCOCK WASHBURN LLP
ONE LIBERTY PLACE, 46TH FLOOR
1650 MARKET STREET
PHILADELPHIA
PA
19103
US
|
Family ID: |
36207086 |
Appl. No.: |
10/973481 |
Filed: |
October 26, 2004 |
Current U.S.
Class: |
606/85 |
Current CPC
Class: |
A61B 17/1757 20130101;
A61B 17/1671 20130101 |
Class at
Publication: |
606/085 |
International
Class: |
A61B 17/16 20060101
A61B017/16 |
Claims
1. A surgical instrument for use in spinal surgery comprising a
first portion connected to a second portion; wherein said first
portion and second portion are longitudinally offset from each
other; said first portion is generally D-shaped in transverse
cross-section and further comprises a top and bottom surface having
rasp teeth; said first portion further including at least one
aperture that extends the entire transverse length of said first
portion; said second portion is generally rectangular shaped and
further comprises an access port for guiding a reamer device; and
said second portion is adapted for removable attachment to a
holder.
2. The surgical instrument of claim 1, wherein at least one of said
first and second portion further comprises at least one contact
member.
3. The surgical instrument of claim 2, wherein said at least one
contact member is at least one of slidably and rotatably connected
to said first portion, said second portion, or combinations
thereof.
4. The surgical instrument of claim 2, wherein said at least one
contact member is extendable from at least one of said first and
second portion.
5. The surgical instrument of claim 1, wherein said at least one
first portion further comprises at least one graded marking.
6. The surgical instrument of claim 1, wherein said at least one
second portion further comprises at least one graded marking.
7. The surgical instrument of claim 1, wherein said second portion
is integrally connected to a holder
8. The surgical instrument of claim 1, wherein said instrument is
comprised of a durable material.
9. The surgical instrument of claim 8, wherein the durable material
is at least one of a pure metal and metal alloy.
10. The surgical instrument of claim 1, wherein said access port is
controllably extendable from said second portion.
11. The surgical instrument of claim 10, wherein said access port
is telescoping.
12. The surgical instrument of claim 1, wherein said access port is
threaded.
13. A surgical instrument for use in spinal surgery comprising a
first portion connected with a second portion; said first portion
having top and bottom surfaces wherein at least one of said
surfaces comprises rasp teeth; and said second portion including a
device guide.
14. The surgical instrument of claim 13, wherein said first portion
is removably connectable to said second portion.
15. The surgical instrument of claim 13, wherein said device guide
is controllably extendable from said second portion.
16. The surgical instrument of claim 15, wherein said device guide
is telescoping.
17. The surgical instrument of claim 13, wherein the device guide
is an access port.
18. The surgical instrument of claim 17, wherein said access port
is threaded.
19. The surgical instrument of claim 13, wherein the device guide
is a frame.
20. The surgical instrument of claim 13, wherein the device guide
is a track.
21. The surgical instrument of claim 13, wherein the first portion
is generally D-shaped.
22. The surgical instrument of claim 13, further comprising at
least one contact member connected to at least one of said first
and second portion.
23. The surgical instrument of claim 22, wherein said at least one
contact member is at least one of slidably and rotatably
connected.
24. The surgical instrument of claim 22, wherein said at least one
contact member is extendable from at least one of said first and
second portion.
25. The surgical instrument of claim 13, wherein at least one of
said first portion and second portion further comprise at least one
graded marking.
26. The surgical instrument of claim 13, wherein said first portion
is substantially planar.
27. The surgical instrument of claim 13, wherein said first portion
is substantially cylindrical.
28. The surgical instrument of claim 13, wherein said first portion
and said second portion are longitudinally offset from each
other.
29. The surgical instrument of claim 13, wherein said second
portion is removably connectable to a holder.
30. The surgical instrument of claim 13, wherein said second
portion is integrally connected to a holder.
31. The surgical instrument of claim 13, wherein said first portion
further includes at least one aperture that extends the entire
transverse length of said first portion.
32. A kit for performing spinal surgery comprising: a surgical
instrument comprising at least one first portion being connectable
or connected with at least one second portion; the first portion
comprising top and bottom surfaces wherein at least one of said
surfaces has rasp teeth; and the second portion including a device
guide.
33. The kit of claim 32, wherein said device guide is an access
port.
34. The kit of claim 32, wherein said device guide is a frame.
35. The kit of claim 32 wherein said device guide is a track.
36. The kit of claim 32, wherein the first portion is generally
D-shaped.
37. The kit of claim 32, further comprising at least one contact
member connected to at least one of said first and second
portion.
38. The kit of claim 37, wherein said at least one contact member
is extendable from at least one of said first and second
portion.
39. The kit of claim 37, wherein said at least one contact member
is slidably, rotatably, or combinations thereof, connected to at
least one of said first and second portion.
40. The kit of claim 32, wherein said at least one first or second
portion further includes at least one graded marking.
41. The kit of claim 32, wherein said at least one first portion is
substantially planar.
42. The kit of claim 32, wherein said at least one first portion is
substantially cylindrical.
43. The kit of claim 32, wherein said at least one first and second
portion are longitudinally offset from each other.
44. The kit of claim 32, wherein said at least one second portion
is integrally connected to a holder.
45. The kit of claim 32, wherein said at least one first portion
further includes at least one aperture that extends the entire
transverse length of said first portion.
46. The kit of claim 32, wherein said at least one second portion
is removably connectable to a holder.
47. A method of performing spinal surgery comprising the steps of:
providing a surgical instrument comprising a first portion being
connected or connectable with a second portion; the first portion
including top and bottom surfaces wherein at least one of said
surfaces has rasp teeth; the second portion including a device
guide; exposing the spine and identifying the center of at least
one target vertebral disc; removing the anterior annulus of said at
least one vertebral disk and performing at least a partial
discectomy, thus creating at least one intervertebral cavity;
removing a sufficient amount of spinal endplate cartilage to expose
underlying bone; distracting at least one intervertebral cavity;
using the first portion of said surgical instrument to prepare at
least one of the posterior-lateral and anterior-lateral regions of
one or more spinal endplates; providing a reamer through the device
guide of the surgical instrument to further prepare said one or
more spinal endplates.
48. The method of claim 47, wherein the step of exposing the spine
comprises an anterior surgical approach.
49. The method of claim 47, wherein a complete discectomy is
performed.
50. The method of claim 47 further comprising the step of impacting
at least one successively sized first-portion of the surgical
instrument into the intervertebral cavity.
51. The method of claim 47, wherein the step of lateral preparation
of one or more spinal endplates, comprises the step of
contra-laterally rotating said surgical instrument.
52. The method of claim 47, wherein the step of providing a reamer
comprises the steps of providing the reamer under fluoroscopic
guidance.
53. The method of claim 47 further comprising the step of placing
an appropriately sized implant into the prepared intervertebral
cavity.
54. The method of claim 47, wherein said device guide is an access
port.
55. The method of claim 47, wherein said device guide is a
frame.
56. The method of claim 47, wherein said device guide is a
track.
57. The method of claim 47, wherein said first portion is generally
D-shaped.
58. The method of claim 47, further comprising at least one contact
member connected to at least one of said first and second
portion.
59. The method of claim 58, wherein said contact members are at
least one of slidably and rotatably connected.
60. The method of claim 58, wherein said at least one contact
member is extendable from said at least one of first and second
portion.
61. The method of claim 47, wherein said first portion is
substantially planar.
62. The method of claim 47, wherein said first portion is
substantially cylindrical.
63. The method of claim 47, wherein said second portion is
removably connectable to a holder.
64. The method of claim 47, wherein said first portion further
includes at least one aperture that extends the entire transverse
length of said first portion.
65. The method of claim 47, wherein said device guide is
controllably extendable from said second portion.
66. The method of claim 54, wherein said access port is
telescoping.
67. The method of claim 54, wherein said access port is
threaded.
68. The method of claim 47, wherein said reamer further comprises a
collet.
69. The method of claim 47, wherein said reamer is operatively
engaged with said device guide.
Description
FIELD OF THE INVENTION
[0001] This invention relates to surgical instruments and methods
of using such instruments. The instruments are particularly
suitable for preparing vertebral endplates during spinal interbody
implant procedures.
BACKGROUND OF THE INVENTION
[0002] In the simplest terms, the spine is a column made of
vertebrae and discs. The vertebrae provide the support and
structure of the spine while the spinal discs, located between the
vertebrae, act like cushions or "shock absorbers." These discs also
contribute to the flexibility and motion of the spinal column. Over
time, the discs may become diseased, infected, develop deformities
such as tears/cracks, or simply lose structural integrity, for
example bulge or flatten. These impaired discs can affect the
anatomical functions of the vertebrae, due to the resultant lack of
proper biomechanical support, and are often associated with chronic
back pain. Chronic back pain afflicts a large percentage of the
world's population and often interferes with one's ability
participate in regular daily activities.
[0003] Several surgical techniques have been developed to address
spinal defects, such as disc degeneration and/or deformity. Spinal
fusion has become a recognized surgical procedure for restoring
biomechanical and anatomical integrity to the spine. Spinal fusion
techniques involve the removal, or partial removal, of at least one
intervertebral disc and preparation of the disc space for receiving
an implant by shaping the exposed vertebral endplates, an implant
is then inserted between the opposing endplates. Vertebral
endplates can have complex shapes due to various anatomical and
biological factors. For example, a vertebral endplate may be
concave in some portions. The vertebral endplates may also have
surface irregularities and even bony protuberances, or osteophytes,
which can be difficult to remove. These osteophytes, found
predominately about the posterior-lateral portions of the endplate,
are especially problematic as they can painfully impinge on nearby
anatomical structures and reduce the useable implant-seating
surface to primarily the medial-anterior portion of the disc space.
This reduction in seating area may compromise biomechanical
integrity by reducing the area in which to distribute mechanical
forces, thus increasing the apparent stress experienced by both the
implant and vertebral endplate.
[0004] Proper endplate preparation is important to successful
spinal fusion surgery procedures. To achieve fusion, it is
generally necessary to expose bleeding endplate bone stock. This
initiates the biological healing process of the bone and encourages
implant integration. The surgeon must also conform or shape the
endplate to, at least, approximate the implant geometry thereby
ensuring proper seating of the spinal implant in the disc space.
One of the many challenges of preparing the endplates is the
discrepancy between the shape of the endplates and the implant.
While the spinal endplates may have a complex surface topography,
the mating surfaces of spinal implants are generally flat. Thus,
the surgeon may initially desire to provide the maximum surface
area for proper implant seating by simply razing enough endplate
bone stock to ensure a relatively flat surface.
[0005] In addition to maximizing the surface area available for
implant seating, the surgeon should also preserve as much surface
vertebral endplate bone as possible by minimizing the amount of
bone removed since this subchondral bone is generally much stronger
than the underlying cancellous bone. Preservation of the endplate
bone stock ensures biomechanical integrity of the endplates and
minimizes the risk of implant subsidence. Thus, the surgeon should
provide for optimal seating of the implant while still maximizing
the amount of available securing endplate bone stock.
[0006] The surgeon may rely on a number of instruments during
complex spinal surgical procedures. With the advent of spinal
fusion surgery and the development of spinal implants, there is an
increasing need for complimentary instruments. These complimentary
instruments should reduce the "instrument load" on the surgeon
while increasing the efficiency and precision of the surgical
procedure. These instruments should also compliment the final size
and shape of the implant to be used; again increasing the
efficiency of the surgical procedure, while decreasing the overall
need for multiple instruments. While there are many instruments
that may be required for such complex spinal surgical procedures,
there is a need in the art for a single instrument suitable for
preparing vertebral endplates to properly receive a spinal implant
for spinal surgery procedures.
[0007] Methods of endplate preparation have traditionally been
performed "by-hand" using a variety of instruments. Traditional
free-hand instruments such as box chisels, osteotomes, curettes,
drills, milling instruments and the like, which aid in shaping the
endplate, also aggressively, and sometimes unevenly, remove bone.
Even when used by the most skilled surgeons, these traditional
free-hand instruments may prove difficult to control in order to
achieve uniform and reproducible results during endplate
preparation. The surgeon must also avoid damaging nearby anatomical
structures, such as the spinal cord or vertebral arteries. These
previously known "by-hand" methods and instruments are generally
cumbersome, lack precision, and may lead to the removal of
excessive amounts of vertebral endplate bone stock.
[0008] None of these approaches provide a single multi-purpose
surgical instrument, as is now taught, for allowing controlled and
precise preparation of vertebral endplates while preserving
endplate bone stock. Thus, there is a need in the art for a single
spinal surgical instrument which reduces the instrument load and
the number of operating steps for a surgeon, improves visualization
of the disc space while minimizing exposure of the disc space, and
improves surgical safety by increasing the precision of
complimentary free-hand instruments while reducing the risk of
damage to nearby anatomical structures.
[0009] There is a further need in the art for an instrument for the
improved preparation of spinal endplates, especially one which can
be used to prepare the posterior-lateral regions of the endplates
and/or the entire endplate. There is also a need for a single
instrument that can be flipped about its longitudinal axis outside
of the disc space, and re-inserted to address features of both the
left and right posterior-lateral regions of a vertebral endplate.
For example, a single multi-purpose instrument capable of preparing
both the lateral and contra-lateral sides of a vertebral endplate.
Still further there is a need for a single instrument capable of
preparing both the left and right posterior-lateral regions of
vertebral endplates and for removing osteophytes.
SUMMARY OF THE INVENTION
[0010] The present invention is directed to surgical instruments
and methods of using such instruments. The instruments are
particularly suitable in spinal surgeries for preparing a vertebral
endplate during an anterior approach procedure.
[0011] Certain preferred embodiments of the present invention
provide for precise and controlled preparation of vertebral
endplates using free-hand surgical instruments. Certain preferred
embodiments of the present invention also provide for improved
safety in addressing features of the vertebral endplate
posterior-lateral regions, including the removal of
posterior-lateral osteophytes. Still other preferred embodiments
allow for improved visualization of the disc space during surgical
procedures while minimizing exposure of the operating space.
[0012] Certain embodiments of the present invention include a
surgical instrument having both a rasp and a guide body. The
instrument has a generally D-shaped first portion which is
longitudinally offset from, and connected to, a generally
rectangular shaped second portion. The first portion serves as a
rasp, while the second portion includes an access port that serves
as a device guide. As used herein, a device for use in accordance
with certain embodiments of the present invention may be, without
limitation, any free-hand instruments including a reamer, box
chisel, osteotome, curette, drill, milling instrument or the like,
which aid in preparing vertebral endplates. The second portion may
also include any number of housings or structures capable of
guiding a device such as, for example and without limitation,
through-holes, access ports, frames, carriages, tracks, etc. Still
further, the device may be controllably advanced along the
longitudinal axis of the second portion. The second portion may
further include a threaded opening for attachment to a threaded
holder.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1A shows a perspective view of an embodiment of one
surgical instrument of the invention (10) having a generally
D-shaped first portion (20) and a second portion (30). FIG. 1B
further depicts a top view of the same embodiment. Lastly, FIG. 1C
depicts a side view of the embodiment showing a transverse aperture
(50) of the D-shaped portion (20). FIG. 2A is a perspective view of
an embodiment of the surgical instrument (10) having a contact
member (90). FIG. 2B further depicts an embodiment having a contact
member only on the upper surface, while FIG. 2C depicts contact
members (90) on both the upper and lower surfaces.
[0014] FIG. 3A depicts a top view of an embodiment of the surgical
instrument (10) configured to accept a reamer (200) though device
guide (80). FIG. 3B depicts a side view of the surgical instrument
(10) showing visualization of the reamer through the transverse
aperture (50).
[0015] FIG. 4 illustrates a perspective view of an embodiment of
the surgical instrument (10) configured to accept a box chisel
(300).
DETAILED DESCRIPTION OF ILLUSTRATIVE EMODIMENTS
[0016] Certain presently preferred aspects of the present invention
may be used for the preparation of spinal endplates for a variety
of interbody implant procedures. These procedures include, but are
not limited to, spinal fusion, vertebral body replacement, and
artificial disc procedures. Thus, certain embodiments of the
present invention are directed to an instrument and method for use
in spinal surgery procedures. Certain embodiments of the surgical
instrument are particularly suitable for procedures in which an
implant is placed between adjacent vertebrae, such as in spinal
fusion procedures, or those which use an implant to replace all or
part of one or more vertebral bodies such as during vertebral body
replacement procedures. For either procedure, stability of the
implant is a major concern, thus implant loosening and/or motion
should be avoided as either condition may impair implant
performance, result in anatomical damage, present substantial pain
to the patient, and may result in implant expulsion from the disc
space. As such, proper preparation of the disc space and,
particularly, the spinal endplates is critical.
[0017] In accordance with certain embodiments of the present
invention, a surgical instrument is provided comprising both a rasp
and a device guide. As shown in FIG. 1, the instrument (10)
includes a generally D-shaped first portion (20) which is
longitudinally offset, and connected, to a generally rectangular
shaped second portion (30). The posterior-lateral-most aspect of
the first portion (20) is rounded such that its contour matches the
posterior-lateral aspects of the interbody implant for good
conformity. Both the top and bottom surfaces of the first portion
include rasp (40) for endplate preparation. Alternatively, first
portion (20) may have a rasp (40) on either the top or bottom
surfaces. Rasp (40) may cover any degree of the top and/or bottom
surfaces, but preferably cover the entire top and bottom surface of
the first portion. The first portion (20) also includes an aperture
(50) that extends the entire transverse length of the first portion
(20), thus the first portion may be predominantly hollow.
Alternatively, first portion 20 may include a plurality of
apertures (50) having uniform or varied size/shape. These apertures
(50) aid in the fluoroscopic visualization of a device, such as
reamer (200), during a surgical procedure as either an embodiment
of the surgical instrument of the present invention or a reamer is
advanced into the disc space. The second portion (30) includes a
threaded opening (60) on the most proximal end surface, or front
face, (70) for attachment to a threaded holder (not shown). The
second portion (30) also includes an access port that serves as a
device guide (80) adjacent the threaded opening (60). Device guide
(80) is particularly useful for controlling the trajectory of
free-hand devices, thus increasing the precision of the surgical
procedure while also providing for controlled removal of bone in
the posterior-lateral regions. First portion (20) may be
substantially planar or substantially cylindrical. First portion
(20) may also act as a stabilizing element in reducing vibration,
and other unwanted movement, while improving free-hand instrument
balance and precision. First portion (20), including rasp portion
(40), may further serve as a standard rasp for initial preparation
and roughening of the vertebral endplate surface with minimal bone
removal. The surgeon may therefore choose to skip an initial
rasping step using a standard free-hand rasp, and may instead use
certain embodiments of the present invention for rasping as well as
targeted bone removal. The first portion and/or second portion may
also have at least one graded marking or measurement, to gauge the
depth of penetration into the disc space.
[0018] Certain embodiments of the present invention may also
include at least one raised shoulder or contact member (90). The
contact members may be any variety of sizes or shapes, so designed
to abut at least one adjacent vertebral body. The contact members
may also be slidably and/or rotatably connected to second portion
(40). Still further, contact member (90) may be extendable to abut
a plurality of adjacent vertebrae, as needed. Contact member (90)
may be particularly useful in preventing or minimizing damage to
nearby anatomical structures.
[0019] Preferred embodiments of the present invention are
particularly suited for shaping the lateral aspects of the
posterior portion of the endplate. The instruments of the present
invention can be used with a variety of implants. In particular,
those implants having a generally annular shape with rounded
corners, for example elliptical or "D" shaped, may be used in
accordance with the present invention. In still other preferred
embodiments of the present invention device guide (80) may be used
with a reamer. In use, a reamer (200) is inserted through the
device guide (80) and used to precisely shape the lateral aspects
of the posterior portion of the endplate to match the corresponding
geometry of the implant. The reamer also aids in the removal of
posterior osteophytes and may be provided with a depth control
feature such as collet or shoulder to prevent the reamer from
breaching the disc space and damaging nearby anatomical structures.
For the remainder of the endplate preparation, the rasp portion
(40) of the instrument (10) is used. Thus, the present invention
allows easy and precise reaming of the lateral corners of the
posterior endplate, while at the same time provides a rasp for
preparing the remainder of the endplate. The instrument can be
flipped 180.degree. about the longitudinal axis of device guide
(80) (an imaginary line which runs orthogonal to the front face
(70) of the instrument (10) to the distal end of the instrument and
would run parallel to the longitudinal centerline of an inserted
reamer device). In this manner, the instrument can first be used to
prepare the left side of the endplate, removed from the disc space,
rotated 180.degree., and re-inserted to the disc space to prepare
the right side of the endplate. This "flipping" action is
particularly convenient in cases where there are posterior-lateral
osteophytes which require removal prior to preparing the disc
space. Thus, certain preferred embodiments of the present invention
can be flipped to remove osteophytes on both sides of the endplate,
then used to properly ream and prepare the disc space.
[0020] In certain embodiments of the present invention, the second
portion (30) may also include a threaded opening (60) on the most
proximal end surface, or front face, (70) for attachment to a
threaded holder (not shown). Still further, second portion (30) may
be removably attached to a holder by a variety of engagement
structures including, but not limited to, interlocking components
or snug-fit mating components. In other embodiments, the present
invention is integral with a holder (not shown). And yet in other
embodiments, the first portion (20), second portion (30), and
holder are all modular components that are assembled during
surgery.
[0021] In still other embodiments of the present invention, second
portion may also include any number of housings or structures
capable of guiding a device such as, for example and without
limitation, through-holes, access ports, frames, carriages, tracks,
etc. Embodiments of device guide (80) may be any number of shapes
including, circular, rectangular, irregular, or custom shaped to
particular device. Still further, the device may be controllably
advanced along the longitudinal axis of the second portion. The
second portion may further have any number of mechanisms or
structures which facilitate controllable device advancement
therefrom. For example, and without limitation, the second portion
(30) may contain a threaded access port (80) to accept a threaded
reamer; a track, carriage or frame that may be controllably
extended from the second portion; an access port (80) having an
internal ratchet or other stop-motion mechanism operatively engaged
with a reamer; and/or a telescoping access port (80). Thus, second
portion (30) may provide for controlled reamer (200) advancement,
and controlled reaming depth, into the disc space. Controlled depth
of reaming may be particularly useful in preventing, minimizing or
even eliminating damage to the surrounding anatomical structures.
An alternate embodiment of the present instrument may be configured
for use with a free-hand box chisel, or similar instrument. In this
manner, access port (80) of second portion (30) serves as a device
guide for improved safety, uniformity, and precision of a chisel
device.
[0022] Embodiments of the present surgical instrument are
preferably made of a durable material such as stainless steel,
stainless steel alloy, titanium, or titanium alloy, but can also be
made of other durable materials such as, but not limited to,
polymeric, ceramic or composite materials. Durable materials may
also consist of any number of pure metals and/or metal alloys.
Certain embodiments of the present invention may also include more
than one material. For example, the first portion may be made of a
metal alloy and the second portion may be made of a ceramic
material.
[0023] Certain preferred embodiments of the present invention may
include a rasp portion (40) of various sizes. In certain
embodiments of the invention, modular rasp portion (40) may be
provided in varying sizes, shapes, and/or degrees of coarseness,
which may be connected to the remaining modular components during
surgery. For example, first portions (20) of various size, etc. may
be removably connectable to a single base second portion (30), or
alternatively may be assembled to various second portions (30). In
yet still another embodiment, there may be multiples, or series, of
instrument (10) each having a rasp portion (40) of various sizes,
or shapes and/or degrees of coarseness, which are made available
during surgery. Still further, rasp portion (40) may act as a
spacer to maintain a desired intradiscal height while the lateral
aspects of the endplates are prepared to a desired shape using a
reamer or other suitable tool. Thus, the entire spinal endplate
final geometry can be conveniently prepared to match a desired
implant geometry for optimal seating of the implant in the disc
space.
[0024] Different sizes of rasp portion (40) may cover various
percentages of the available medial-lateral disc space. For
example, one embodiment of rasp portion (40) may cover the entire
medial-lateral width of the disc space. While other embodiments of
rasp portion (40) may cover 50%, or more, of the medial-lateral
width of the disc space with the remainder of the instrument
serving as a guide for a reamer designed particularly for
preparation of the spinal endplate, including removal of
posterior-lateral osteophytes in the disc space. In yet another
embodiment of the present invention, the entire width of the
instrument is equivalent to the entire width of the implant to be
inserted.
[0025] Those skilled in the art will appreciate that numerous
changes and modifications can be made to the many embodiments of
the invention and that such changes and modifications can be made
without departing from the spirit of the invention. It is therefore
intended that the appended claims cover all such equivalent
variations as falling within the true spirit and scope of the
invention
EXAMPLE 1
[0026] A certain embodiment of the present invention was used to
prepare spinal endplates to receive a vertebral body replacement.
In this surgical procedure, the spine was first exposed via an
anterior approach and the center of the target disc was identified.
The anterior annulus was then removed and a complete discectomy was
performed. Residual cartilage was removed from the spinal endplates
to expose bleeding bone. The resultant disc space was distracted by
impacting sequentially larger heights of distractors/trial spacers
into the disc space, until a tight feel was obtained.
[0027] Spinal endplate preparation started with a standard general
rasp which was impacted into the disc space for initial coarse
rasping and then removed. A size-specific rasp-reamer guide
instrument (10) of the present invention was then used to remove
strong osteophytes in the posterior-lateral region of the spinal
endplate. The size specific rasp-reamer guide instrument (10) was
impacted into the disc space via the end face of an optional
instrument holder connected via opening (60).
[0028] A size-specific reamer (200) was advanced through the
opening (80) of size specific rasp-reamer guide instrument (10),
under fluoroscopic guidance, to remove posterior osteophytes on one
side. A size-specific reamer (200) and rasp-reamer guide instrument
(10) were then removed from the disc space. The rasp-reamer guide
instrument (10) was then flipped about 180.degree. about the
longitudinal axis of reamer guide (80), and the previously
discussed steps were repeated for the contra-lateral side of the
spinal endplate.
[0029] After adequately preparing the endplates, the appropriately
sized implant was selected, packed with graft material and placed
in the prepared disc space.
* * * * *