U.S. patent application number 13/050388 was filed with the patent office on 2011-07-07 for method and apparatus for removing material from an intervertebral disc space, such as in performing a nucleotomy.
This patent application is currently assigned to MEDTRONIC XOMED, INC.. Invention is credited to Kenneth M. Adams, Tom J. Francis, Dana A. Oliver.
Application Number | 20110166576 13/050388 |
Document ID | / |
Family ID | 37806208 |
Filed Date | 2011-07-07 |
United States Patent
Application |
20110166576 |
Kind Code |
A1 |
Oliver; Dana A. ; et
al. |
July 7, 2011 |
METHOD AND APPARATUS FOR REMOVING MATERIAL FROM AN INTERVERTEBRAL
DISC SPACE, SUCH AS IN PERFORMING A NUCLEOTOMY
Abstract
Instrument and method for removing material from an
intervertebral disc. The instrument includes outer and inner
tubular members. The outer tubular member defines a passage and a
cutting window. The inner tubular member is coaxially disposed
within the passage, and defines a central lumen and a cutting tip.
The cutting tip forms an open mouth having a plurality of teeth.
Upon assembly, the cutting tip is exposed within the cutting window
combining to define a shaving head. A powered handpiece is coupled
to the inner tubular member, and the shaving head is inserted into
an intervertebral disc and positioned such that the cutting tip
contacts targeted material (e.g., nucleus, annulus and/or end
plate). The handpiece is activated to rotate the cutting tip
relative to the cutting window. Contacted material is sheared
between an edge of the cutting window and the teeth of the cutting
tip.
Inventors: |
Oliver; Dana A.;
(Jacksonville, FL) ; Adams; Kenneth M.; (Bonita
Springs, FL) ; Francis; Tom J.; (Cordova,
TN) |
Assignee: |
MEDTRONIC XOMED, INC.
Minneapolis
MN
|
Family ID: |
37806208 |
Appl. No.: |
13/050388 |
Filed: |
March 17, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11289266 |
Nov 29, 2005 |
7927361 |
|
|
13050388 |
|
|
|
|
Current U.S.
Class: |
606/84 |
Current CPC
Class: |
A61B 17/32002 20130101;
A61B 2017/2904 20130101; A61B 2017/00261 20130101 |
Class at
Publication: |
606/84 |
International
Class: |
A61B 17/16 20060101
A61B017/16 |
Claims
1. A surgical intervertebral disc material shaving instrument for
use with a powered handpiece, the instrument comprising: an
elongated outer tubular member defining a central passage and a
cutting window at a distal end thereof, the cutting window being
fluidly connected to the central passage and defined by a perimeter
edge forming at least four teeth on a first longitudinal side and
at least four teeth on a second longitudinal side thereof; and an
inner tubular member coaxially disposed within the central passage,
the inner tubular member defining a central lumen and a cutting tip
at a distal end thereof, the cutting tip including a plurality of
circumferentially-extending teeth formed about at least a portion
of a mouth otherwise fluidly connected to the lumen; wherein upon
final assembly, the cutting tip is exposed within the cutting
window, the cutting tip and cutting window combining to define a
shaving head configured to shear intervertebral disc material and
aspirate sheared material through the mouth and lumen.
2. The instrument of claim 1, wherein the cutting tip has a
diameter in the range of 3-8 mm.
3. The instrument of claim 2, wherein the cutting tip has an outer
diameter of 4.5 mm.
4. The instrument of claim 1, wherein the outer tubular member
includes a proximal segment and a distal segment, the distal
segment forming the cutting window and extending at an angle
relative to a longitudinal axis of the proximal segment in the
range of 0-90.degree..
5. The instrument of claim 4, wherein the distal segment extends at
an angle in the range of 20-45.degree. relative to the proximal
segment.
6. The instrument of claim 5, wherein the distal segment extends at
an angle of 45.degree. relative to the proximal segment.
7. The instrument of claim 1, wherein the distal segment extends
from the distal end to the bend, the distal segment having a length
in the range of 1-3.5 cm.
8. The instrument of claim 7, wherein the distal segment has a
length of 2.5 cm.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/289,266, filed Nov. 29, 2005, the contents
of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to removal of intervertebral
disc material. More particularly, it relates to a method and
powered device for removing some or all of the material (tissue,
cartilaginous bone, etc.) associated with an intervertebral disc,
for example in performing a nucleotomy.
[0003] The vertebral spine includes, amongst other structures, a
series of bony vertebrae, adjacent ones of which are supported and
separated by an intervertebral disc. In a healthy spine, the discs
maintain separation between the vertebrae, promoting fluid
circulation throughout the spine, and providing a cushioning effect
between the vertebral structures. An intervertebral disc generally
includes an annulus fibrosis (or "annulus"), a nucleus pulposus (or
"nucleus"), and opposing end plates. The end plates are akin to
cartilaginous bone and serve to attach adjacent vertebrae to the
disc. The nucleus is disposed between the end plates,
circumferentially constrained by the annulus.
[0004] Intervertebral discs are elastic in nature, and can be
damaged or displaced. For example, intervertebral discs can be
overtly stressed by excessive movement, excess body weight, injury,
disease, and/or gradual deterioration with age. Intervertebral disc
injuries or other abnormalities can result in serious back pain and
physical disability, and are often chronic and difficult to treat.
For example, the annulus may bulge or tear, with the distended
nucleus tissue compressing against a spinal nerve (e.g., disc
herniation). Similarly, the disc may degenerate over time, leading
to a collapse of the disc space.
[0005] Surgical procedures have been developed to repair damage or
displaced intervertebral discs. These procedures include
nucleotomies or discectomies in which a portion (e.g., the
nucleus), or an entirety of the intervertebral disc is excised.
Fusion is another accepted technique and entails the bony portions
of the spine being fused together to limit the relative motion
between adjacent vertebrae. Insertion/implantation of the
fusion-inducing device(s) again requires removal of certain discal
tissue. Similarly, disc decompression/fusion procedures require
forming a hole in the annulus possibly followed by removal of
nucleus tissue prior to backfilling with fusion material. More
recently, nucleus replacement implants have been developed; these
products also require removal of discal tissue (i.e., the nucleus
and/or portions of, or all of, the annulus) prior to
implantation.
[0006] Regardless of the exact procedure, various manual
instruments for the removal of intervertebral disc material(s) are
conventionally employed. These manual instruments include
osteotomes, surgical chisels, guillotine cutting devices, etc. The
highly confined nature of the surgical site associated with the
intervertebral disc, the delicate surrounding structures (e.g.,
nerves), and the wide-range of material to be cut (i.e., the
nucleus tissue is fairly soft, whereas the annulus tissue is quite
tough), have likely given rise to the reliance upon simple, manual
devices. While viable, use of manual instrumentation can render the
procedure overly time consuming. Often times, several different
manual instruments must be passed in and out of the surgical site
multiple times in order to remove the desired discal material. This
increases the chance of damage to sensitive structures adjacent to
the spine (vascular and nervous). The manual instruments also
require separate irrigation and suction device(s) to clean the
surgical site during and after the procedure. Further, for certain
procedures such as nucleotomies, manual surgical instruments
require a surgeon to rely upon tactile feel to ensure that the
annulus is not violated.
[0007] Injured and degenerated intervertebral discs pose serious
health problems to a large number of patients. Many current and
future treatments require the removal of nucleus and/or other
discal tissue. Manual intervertebral disc material-removing tools
are time-consuming to use, and require multiple other instruments.
Available powered instruments for cutting intervertebral disc
material do not afford the ability to deftly shave only targeted
bodily structures, an attribute essentially required by the anatomy
forming and surrounding the intervertebral disc. Further, available
powered instruments may not be able to adequately cut the disparate
bodily materials (in terms of hardness and toughness) typically
presented by an intervertebral disc. Any advancement in the tools
and related methods for performing this delicate material removal
within or at the disc space will be well-received.
SUMMARY OF THE INVENTION
[0008] Some aspects of the present invention relate to a method of
removing material from an intervertebral disc otherwise defined by
a nucleus surrounded by an annulus and opposing end plates. The
method includes providing a surgical shaving instrument including
an elongated outer tubular member and an elongated inner tubular
member. The outer tubular member defines a central passage and a
cutting window at a distal end thereof. The cutting window is
defined by a perimeter edge and is fluidly connected to the central
passage. The inner tubular member is coaxially disposed within the
central passage, and further defines a central lumen and a cutting
tip at a distal end thereof. The cutting tip forms a mouth that is
open to the lumen and has a plurality of teeth formed along a
perimeter. Upon final assembly, the cutting tip is exposed within
the cutting window, with the cutting tip and cutting window
combining to define a bodily material shaving head. A powered
handpiece is coupled to the inner tubular member such that the
powered handpiece can cause the inner tubular member to rotate
relative to the outer tubular member. The shaving head is inserted
into an intervertebral disc and positioned such that the cutting
tip contacts targeted material of the disc. The powered handpiece
is activated to rotate the cutting tip relative to the cutting
window. Contacted bodily material is, as a result, sheared between
the edge of the cutting window and the teeth of the cutting tip.
Finally, the sheared material is aspirated through the inner
tubular member's lumen via the mouth. In one embodiment, the
surgical instrument further includes an irrigation mechanism
fluidly connected to the bodily material shaving head, with the
method further including irrigating the material shaving head while
shearing tissue.
[0009] Other aspects of the present invention relate to a surgical
intervertebral disc material shaving instrument for use with a
powered handpiece. The instrument includes outer and inner tubular
members. The outer tubular member defines a central passage and a
cutting window. The cutting window is fluidly connected to the
central passage and is defined by a perimeter edge having opposing,
first and second longitudinal sides. At least four teeth are formed
on each of the opposing longitudinal sides. The inner tubular
member is coaxially disposed within the central passage, and
defines a central lumen and a cutting tip. The cutting tip forms a
plurality of circumferentially-extending teeth about a mouth that
is otherwise fluidly connected to the lumen. Upon final assembly,
the cutting tip is exposed within the cutting window, with the
cutting window and the cutting tip combining to define a material
shaving head adapted to shear intervertebral disc material, as well
as to aspirate sheared material through the mouth and lumen.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a perspective view of an intervertebral disc
material shaving instrument in accordance with aspects of the
present invention;
[0011] FIG. 2 is a cross-sectional, partial exploded view of the
instrument of FIG. 1;
[0012] FIG. 3A is an enlarged top plan view of a distal segment of
an outer tubular member portion of the instrument of FIG. 1;
[0013] FIG. 3B is a side view of the segment of FIG. 3A;
[0014] FIG. 3C is an enlarged, top plan view of a distal segment of
an inner tubular member portion of the instrument of FIG. 1;
[0015] FIG. 3D is a cross-sectional view of the assembled
instrument of FIG. 1;
[0016] FIG. 4 is an enlarged, top plan view of the material shaving
head formed by the instrument of FIG. 1
[0017] FIG. 5 is a simplified, top plan view of an intervertebral
disc in combination with the instrument of FIG. 1 upon initial
approach;
[0018] FIG. 6 is the view of FIG. 5 with the instrument fully
inserted; and
[0019] FIG. 7 is a simplified, side cross-sectional view of FIG.
6.
DETAILED DESCRIPTION OF THE INVENTION
[0020] One embodiment of an intervertebral disc shaving instrument
20 in accordance with the principles of the present invention is
shown in FIGS. 1 and 2. The instrument 20 includes an outer tubular
assembly 22 and an inner tubular assembly 24. The outer tubular
assembly 22 includes an outer tubular member 26 and a first hub
assembly 28. Similarly, the inner tubular assembly 24 includes an
inner tubular member 30 (best seen in FIG. 2) and a second hub
assembly 32. Details on the various components are provided below.
In general terms, however, the inner tubular member 30 is coaxially
disposed within the outer tubular member 26, with the tubular
members 26, 30 combining to define a bodily material shaving head
34 (FIG. 1). During use, the instrument 20 is coupled to a powered
handpiece (not shown) that rotates the second hub assembly 32, and
thus the inner tubular member 30, relative to the outer tubular
member 26 in an oscillating fashion, to effectuate shearing of
intervertebral disc material (not shown) at the shaving head
34.
[0021] The outer tubular member 26 is an elongated body defining a
proximal segment 40, an intermediate segment 42, and a distal
segment 44. Further, the outer tubular member 26 defines a central
passage 46 (FIG. 2) extending from the distal segment 44 to the
proximal segment 40.
[0022] With specific reference to FIG. 2, the proximal segment 40
is adapted for connection to the first hub assembly 28, and defines
a longitudinal axis A. For example, the proximal segment 40 forms a
proximal open end 47 and a radial aperture 48 both of which are
open to the central passage 46. As described below, the open end 47
facilitates placement of the inner tubular member 30 within the
central passage 46, whereas the aperture 48 establishes fluid
connection between the central passage 46 and a corresponding
component of the first hub assembly 28. Alternatively, the proximal
segment 40 can assume a variety of other forms.
[0023] The intermediate segment 42 extends from the proximal
segment 40 to the distal segment 44 and forms a bend 50. In one
embodiment, the distal segment 44 is linear in longitudinal
extension. Thus, due to the bend 50, the distal segment 44 extends
at or forms a bend angle .THETA. relative to the longitudinal axis
A of the proximal segment 40. The bend angle .THETA. is selected to
facilitate desired positioning of the distal segment 44 (and thus
of the tissue shaving head 34) within an intervertebral disc space
(not shown) using an expected surgical approach to the disc space
as described below. With this in mind, the bend angle .THETA. is in
the range of 0-90.degree.. For example, it has surprisingly been
found that for posterior disc approach applications, the bend angle
.THETA. is preferably in the range of 20-45.degree., more
preferably 45.degree.. It has further been surprisingly found that
for lateral disc approach procedures, the bend angle .THETA. is
preferably in the range of 0-12.5.degree., more preferably
12.5.degree.. Notably, however, principles of the present invention
are not limited to a particular value or range for the bend angle
.THETA.. Along these same lines, two or more bends can be provided
along a length of the outer tubular member 26 (e.g., along one,
two, or all of the segments 40-44). Further, the bend 50 can be
formed at a longitudinal position varying from that shown in FIGS.
1 and 2 (e.g., along the proximal segment 40). Preferably, however,
a length L of the distal segment 44 (i.e., linear distance from a
distal termination point of the bend 50 to a distal-most end 52 of
the distal segment 44) is in the range of 1.5-3.5 cm, more
preferably 2.5 cm. It has surprisingly been found that by forming a
"working end" of the instrument 20 to have a length of 2.5 cm is
highly conducive to cutting operation within an intervertebral disc
via a posterior lumbar approach (e.g., as part of a posterior
lumbar intervertebral fusion operation). Notably, the length L can
vary in other embodiments.
[0024] As mentioned above, the distal segment 44 terminates at the
distal end 52 that is preferably closed to the central passage 46.
Further, the distal segment 44 forms a cutting window 54 proximal
the closed distal end 52. As described in greater detail below, the
closed distal end 52 serves to distally shield a cutting surface of
the inner tubular member 30, whereas the cutting window 54 exposes
the surface. Thus, in one embodiment, an exterior surface of the
closed distal end 52 is curved.
[0025] With reference to FIGS. 3A and 3B, the cutting window 54 is
open or fluidly connected to the central passage 46, and is defined
by a perimeter edge 56. Relative to a longitudinal extension of the
outer tubular member 26, the perimeter edge 56 generally defines
opposing first and second longitudinal sides 58, 60, and opposing
lateral ends 62, 64. With these spatial designations in mind, in
one embodiment, the perimeter edge 56 forms a plurality of teeth 66
along each of the longitudinal sides 58, 60. The teeth 66 can
assume a variety of forms, but in one embodiment are symmetrically
arranged relative to the side 58, 60. In one embodiment, each of
the sides 58, 60 includes or forms at least four teeth 66 to
promote aggressive removal of intervertebral disc material. The
teeth 66 are formed to be highly sharpened (e.g., tip width or
thickness on the order of approximately 0.005 inch), and wrap or
curve in conformance with a curvature of the remainder of the outer
tubular member 26. In one embodiment, a tip-to-tip spacing between
adjacent ones of the teeth 66 (along a corresponding side 58 or 60)
is in the range of 0.04-0.06 inch, more preferably approximately
0.05 inch (.+-.0.002 inch). Further, in one embodiment, the lateral
ends 62, 64 are similarly sharp. While other dimensions and/or
configurations can be employed, it has surprisingly been found that
the above-described preferences are highly conducive to cutting the
disparate material structures associated with an intervertebral
disc.
[0026] Returning to FIG. 2, the outer tubular member 26 is
preferably formed of a hardened, surgically safe material, capable
of supporting the inner tubular member 30 at high
rotational/oscillation speeds (e.g., oscillation speed of 5,000
RPM), while maintaining the bent shape illustrated. Thus, for
example, the outer tubular member 26 is formed of 304 stainless
steel; although a multitude of other materials are equally
acceptable. Regardless, the central passage 46 is sized to
coaxially receive the inner tubular member 30 in a manner allowing
the inner tubular member 30 to rotate within the passage 46. In one
embodiment, and as described below, a diameter of the central
passage 46 is slightly greater than an outer diameter of the inner
tubular member 30 to establish an irrigation pathway.
[0027] The first hub assembly 28 is adapted to receive and retain
the proximal segment 40 of the outer tubular member 26, and in one
embodiment includes an irrigation collar 68, an outer hub 70, and
an inner hub 72. The irrigation collar 68 forms an irrigation port
74, and is configured to establish an irrigation fluid flow path to
and from the central passage 46 of the outer tubular member 26 upon
final assembly, as described below. The outer hub 70 and the inner
hub 72 are adopted to secure the irrigation collar 68 to the outer
tubular member 26, and thus can assume a variety of forms. In one
embodiment, however, the outer hub 70 is sized for securement over
the irrigation collar 68 as well as to the outer tubular member 26.
Conversely, the inner hub 72 is sized for securement between the
irrigation collar 68 and the outer tubular member 26, and in one
embodiment forms a longitudinal passageway 76 and a radial opening
77. The longitudinal passageway 76 extends through an entirety of
the inner hub 72, whereas the radial opening 77 is sized and
positioned for fluid connection to the port 74 (and the radial
aperture 48 of the outer tubular member 26) upon final assembly. To
further promote a complete, sealed final relationship, the first
hub assembly 28 further includes seals (e.g., O-rings) 78 and a
seal hub 79 in one embodiment. Regardless, the first hub assembly
28 establishes a mechanism for delivering irrigation liquid from an
irrigation source (not shown) to the shaving head 34 via the
irrigation port 74 and the passage 46. The irrigation fluid serves
to "clean" the surgical site, augment lubrication between the inner
and outer tubular members 30, 26, and facilitate
evacuation/aspiration of material from the surgical site (described
below) by clearing "clogs" at the shaving head 34. Alternatively,
the first hub assembly 28 can assume a variety of other forms.
[0028] The inner tubular member 30 is, similar to the outer tubular
member 26, an elongated tube defining a proximal region 80, an
intermediate region 82, and a distal region 84. Further, the inner
tubular member 30 defines a central lumen 86 extending from the
proximal region 80 to the distal region 84. Once again, the inner
tubular member 30 is sized to be coaxially received within the
outer tubular member 26, with the proximal region 80 adapted for
mounting to the second hub 32. In one embodiment, at least the
intermediate region 82 has a flexible construction such that the
inner tubular member 30 will assume the shape of the outer tubular
member 26 (and in particular the bend 50) upon insertion of the
inner tubular member 30 within the outer tubular member 26. For
example, the intermediate region 82 can be or includes a wound
coil(s) or reinforced tube(s) (e.g., inner and outer spiral wraps
assembled over a spiral cut formed in the outer tubular member 30),
series of laser cut dovetail sections, etc. (it being understood
that the intermediate region 82 is illustrated generally in FIG.
2). Regardless, while the regions 80-84 may have differing
constructions (e.g., the proximal and distal regions 80, 84 are
metal tubes, whereas the intermediate region 82 is a wound coil),
the inner tubular member 30 has an overall construction capable of
maintaining structural integrity when rotated at high speeds (e.g.,
oscillation speeds on the order of 5,000 RPM).
[0029] The distal region 84 forms a cutting tip 90. With additional
reference to FIG. 3C, the cutting tip 90 includes a plurality of
teeth 92 formed in a circumferentially-extending manner about a
mouth 94. The teeth 92 are highly similar to the teeth 66 (FIGS. 3A
and 3B) previously described, symmetrically arranged along opposite
sides of the mouth 94 (it being understood that only one set of the
teeth 92 are visible in FIG. 3C). Thus, in one embodiment, at least
four of the teeth 92 are formed along each side of the mouth 94,
and are highly sharpened. Further, in one embodiment, the teeth 92
are sized and positioned to be spatially aligned with the teeth 66
upon final assembly. Thus, in one embodiment, adjacent ones of the
teeth 92 have a tip-to-tip spacing on the order of 0.04-0.06 inch,
more preferably approximately 0.05 inch (.+-.0.002 inch).
[0030] The mouth 94 is open to, and thus fluidly connected with,
the lumen 86. As described in greater detail below, this
configuration establishes an aspiration pathway from the mouth 94
and through the lumen 86. In this regard, material aspirated via
the lumen 86/mouth 94 can be removed via an appropriate port
associated with the second assembly hub 32. In one embodiment, the
distal region 84 has a relatively large outer diameter, on the
order of 3-8 mm, more preferably 4.5 mm, to reduce clogging of the
lumen 86 during use. Alternatively, other dimensions can be
employed.
[0031] Regardless of the exact configuration, at least as a
majority of an inner diameter of the outer tubular member 26 is, in
one embodiment, slightly larger than an outer diameter of the inner
tubular member 30 so as to establish an annular gap 100 between the
two components 26, 30 upon final assembly as shown in FIG. 3D. It
will be understood that while FIG. 3D illustrates the inner tubular
member 30 as being approximately centered relative to the outer
tubular member 26, in actual practice, the inner tubular member 30
may contact the outer tubular member 26 at various radial
locations. Along these lines, in one embodiment, the cutting tip 90
(FIG. 3C) of the inner tubular member 30 may have a diameter larger
than a remainder thereof (such as by separately forming the cutting
tip 90 and assembling to a remainder of the inner tubular member
30) that more closely matches an inner diameter of the outer
tubular member 26. Regardless, a size of the gap 100 is exaggerated
in the view of FIG. 3D for purposes of explanation. With additional
reference to FIGS. 1 and 2, the annular gap 100 extends from the
irrigation port 74 to the cutting window 54 to establish an
interior irrigation pathway or mechanism by which an irrigation
fluid can be delivered from the irrigation port 74 to the cutting
window 54 (and thus the shaving head 34) via the annular gap 100.
Alternatively, a separate irrigation tube (not shown) can be
provided along (or formed with) an exterior of the outer tubular
member 26.
[0032] With specific reference to FIG. 2, the second hub assembly
32 is sized for mounting to the inner tubular member 30 and
includes, in one embodiment, a rotating hub 102 and a spring 104.
The rotating hub 102 is adapted for coupling to a powered handpiece
(not shown) as known in the art. The spring 104 facilitates
releasable engagement with the powered handpiece, and in
alternative embodiments, can be eliminated. To this end, the
powered handpiece can assume a variety of forms, and can be
electrically, or battery, or pneumatically powered.
[0033] Assembly of the instrument 20 includes securing the first
hub assembly 28 to the outer tubular member 26. In one embodiment,
the inner hub 72 is mounted over the proximal segment 40 such that
the radial opening 77 is aligned, or otherwise fluidly connected
to, the radial aperture 48. To ensure affixment of the inner hub 72
to the outer tubular member 26, an adhesive (e.g., Loctite
adhesive) can be employed. The irrigation collar 68 is mounted over
the inner hub 72 such that the port 74 is aligned with, or
otherwise fluidly connected to, the radial opening 77 (and thus the
radial aperture 48). The seals 78 are included at opposite sides of
the port 74/radial opening 77 interface to provide a fluid-sealed
relationship. The outer hub 70 is assembled or formed over the
outer tubular member 26 and the irrigation collar 68. Where
desired, an adhesive (e.g., Loctite adhesive) can be employed to
bond the outer hub 70 to the irrigation collar 68.
[0034] The second hub assembly 32 is mounted to the proximal region
80 of the inner tubular member 30. An adhesive can be employed to
bond the rotating hub 102 to the inner tubular member 30. The inner
tubular member 30 is distally slid or inserted into and through the
inner hub 72 and the outer tubular member 26 such that the cutting
tip 90 is at or within the cutting window 54. To this end, the seal
hub 79 sealingly engages an exterior of the inner tubular member 30
such that irrigation fluid within the outer tubular member 26
(e.g., within the gap 100 (FIG. 3D)) will not flow or leak proximal
the seal hub 79.
[0035] The shaving head 34 upon final assembly is shown in greater
detail in FIG. 4. In particular, the cutting tip 90 is exposed at
the cutting window 54. During use, as the inner tubular member 30
is rotatably oscillated relative to the outer tubular member 26, a
shearing action is created between the teeth 92 of the cutting tip
90 and the teeth 66 of the cutting window 54. By providing a large
number of sharp teeth, this shearing motion is able to aggressively
remove material, yet provides a user with the ability to perform a
controlled shaving or shearing operation, thus ensuring that only
desired bodily material is contacted and cut. To this end, the
closed distal end 52 of the outer tubular member 26 provides a
blunt surface for non-traumatically contacting anatomical
structures, thus providing instrument safety during "blind" cutting
procedures.
[0036] One method of removing material from an intervertebral disc
110 using the intervertebral disc material shaving instrument 20 in
accordance with principles of the present invention is illustrated
in FIGS. 5-7. By way of reference, the intervertebral disc 110
generally includes a nucleus 112 surrounded by an annulus 114 and
opposing ends plates 116, 118 (FIG. 7). The end plates 116, 118 in
turn, are formed as part of adjacent vertebrae 120, 122 (FIG. 7),
respectively, and thus are akin to cartilaginous bone. With these
general definitions in mind, the instrument 20 is employed to
surgically remove or shave some or all of the material (e.g.,
tissue, cartilaginous bone, etc.) associated with the
intervertebral disc 110. For example, one common procedure
associated with treatment of a diseased intervertebral disc 110 is
a nucleotomy in which a portion, or all, of the nucleus 112 is
removed. With this in mind, the instrument 20 is deployed to the
disc 110, for example via an posterior-lateral approach.
Alternative approaches to the disc 110 are also acceptable and
within the principles of the present invention, such as posterior
approach, transforaminal approach, anterior approach, left or right
lateral approach, etc. Regardless, as shown in FIG. 5, the shaving
head 34 is positioned at an exterior of the annulus 114, aligned
with an opening 124 formed therein. The opening 124 can be a
naturally-occurring tear or similar passage; alternatively, the
opening 124 can be surgically cut or otherwise created in the
annulus 114. The closed distal end 52 contacts the annulus 114 in a
non-traumatic manner, and protects the annulus 114 from potentially
damaging, undesired contact with the teeth 66 (FIG. 3A) and 92
(FIG. 3C).
[0037] The shaving head 34 is then distally advanced within the
annulus 114, with the bend 50 facilitating desired extension of the
shaving head 34 "across" the nucleus 112 region as shown in FIG. 6.
That is to say, the bend 50 is configured to anatomically "match"
the expected insertion site of the tissue shaving head 34 relative
to the opening 124 in the annulus 114 (that is otherwise offset
from a "center" of the disc 110 so as to avoid contact with other
bodily structures such as nerves). Thus, the bend angle .THETA.
(FIG. 2) is a function of the expected disc 110 approach location.
With the shaving head 34 properly positioned, the bend 50 generally
resides at the annulus 114.
[0038] Regardless of the exact positioning, the instrument 20 is
powered to effectuate removal of contacted material. More
particularly, and with additional reference to FIG. 7, the powered
handpiece (not shown) is activated, causing the cutting tip 90
(FIG. 3C) to rotationally oscillate relative to the cutting window
54. For example, the cutting tip 90 can be rotationally oscillated
at speeds at or in excess of 5,000 RPM. In one embodiment, the
powered handpiece is operated to rotate the inner tubular member 26
(FIG. 2) two revolutions in one direction, followed by two
revolutions in the opposite direction, etc., although other
operational formats are also acceptable. Nucleus tissue 112,
otherwise in contact with the cutting tip 90/cutting window 54, is
sheared between the two components, and aspirated from the surgical
site via the mouth 94/lumen 86 (FIG. 2). Further, irrigation fluid
is directly applied to the surgical site via the irrigation
mechanism previously described so as to minimize clogging of the
tissue shaving head 34, and in particular the mouth 94/lumen 86.
The irrigation fluid can also serve to lubricate the surgical site
as well as the inner tubular member 30/outer tubular member 26
interface.
[0039] While the instrument 20 has been described in connection
with performing a nucleotomy, other material of the intervertebral
disc 110 can also be aggressively shaved or sheared with the
instrument 20. For example, the annulus 114 tissue and/or end plate
116, 118 cartilaginous bone can also be shaved/sheared as
desired.
[0040] Although the present invention has been described with
reference to preferred embodiments, workers skilled in the art will
recognize that changes can be made in form and detail without
departing from the spirit and scope of the present invention.
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