Note: Descriptions are shown in the official language in which they were submitted.
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MET~OD AND APPARATUS FOR
MATERIAL REMOVAL
BACKGROUND OF THE INVENTION-
.
1. Field of the Invention
The invention relates generally to method and
apparatus for effecting the removal of material such as
5 organic materials from a wor]c surface. More
particularly, the invention relates to method and
apparatus for removing such material with a rotatably
driven cutting apparatus and the removal of the cut
material by way of negative pressure applied in the
vicinity of the work site in which the cutting apparatus
is operable.
2. Descri~tion o~ the Related Art
Cutting apparatus and methods which effect material
15 ~ removal from a work sur~ace and evacuation o~ the cut
material from the vicinity of cutter operation have
particular applicability in such diverse fields as
- carpentry, metal working, and a variety of surgical
procedures. In the latter inst~nce, such apparatus and
methods have particular applicability in the field of
endoscopic, and particularly arthroscopic, surgical
procedures. Such surgical procedures are generally
referred to as "closed" procedures, as the surgical site
is accessed by forming only one or several comparatively
small incisions in the body of the patient through which
various specialized instruments can be insertedi. These
"closed" procedures are to be contrasted with
conventional, "open" procedures, in which one or more
comparatively large incisions are formed in the
patient's body to providei maximum exposure of the
surgical site to the environment. Endoscopic
instruments and methods (hereinafter referred to
collectively as "instrumentation") have enjoyed
considerable success since the advent of this surgical
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technology, as surgeons, patients and insurance
providers alike have become increasingly receptive to
~he benefits such as their comparatively lesser degree
of invasiveness and remarkably shortened recuperation
periods that are afforded by these procedures.
Furthermore, operations which heretofore have required
open surgical procedures, during which a general
anaesthetic was generally used to sedate the patient,
can now be performed in a clo~.ed, endoscopic-type
procedure, in which a local anaesthetic agent can
oftentimes be employed. ~s a result of the foregoing
advantages, not only can patient recuperation be
expedited, but the risks attendant with general as
opposed to local anesthetics can be altogether avoided
in many instances. For all of the foregoing reasons,
endoscopic instrumentation has exhibited nearly
unprecedented growth since its inception.
A principal limitation in all endoscopic surgicaI
procedures involves not only access to the surgical site
to be treated, but also the removal of material that is
successfully cut or otherwise removed from the surgical
site. As -used throughout this disclosure, the terms
"cut", "cutting" and variations thereof are to be
regarded as encompassing any method of material removal,
including slicing, abrading and shaving, unless the
context clearly suggests otherwise. While
instrumentation for facilitating access to remote
surgical sites such as various joints in the human body
is the subject of our copending application, U.S. Serial
No. 611,278 filed on November 9, 1990, the current state
of the art of surgical instrumentation does not
adequately address the difficulties experienced by
surgeGns in removing fine shavings and other debris that
can arise from the various cutting processes that are
used to reduce the dimensions of, in particular, hard
materials such as bone and calcified cartilaginous
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materials. A problem exists in the removal of such
fine, particulate remnan~s of such materials as they are
susceptible to avoiding surgeon detection and/or
withdrawal by the suction apparatus typically associated
with such cutters. Instead, this material tends to be
radially displaced outwardly and away from the rotatable
cutting apparatus, thereby avoiding to an appreciable
extent the beneficial effects of the suction apparatus
and/or irrigati~g fluids such as saline solution
circulated through the surgical site. These
difficulties can become even more pronounced when
gaseous rather than liquid irrigation media are
utilized, as gaseous media, while improving
visualization of the surgical site, is generally not as
effective as liquid media in flushing debris from the
surgical site. The foregoing difficulties that have
been experienced in removing such fine, particulate
material from remote portions such as skeletal joints of
' the body of a patient have resulted in a hinderance to
expedient and complete patient recoveries.
Accordingly, it is an object of the subject
- invention to provide method and apparatus for removing
material from a work surface and effectively collecting
the removed material for withdrawal from the work site.
Another object of the subject invention i~ to
provide various cutter head configurations that can be
adapted to existing cutter apparatus to improve the
efficiency with which material can be separated and
withdrawn from a work surface such as an internal body
structure of a patient.
A further object of the subject invention is to
provide cutter methods which tend to collect rather than
radially discharge debris from material that is cut.
Yet a further obj~ct of the subject invention is to
provide surgical instrumentation which expedites
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surgical procedures and enhances the time and extent of
patient recovery.
BRIEF_DESCRIPTION OF T~:
5These and other objects and advantages will become
apparent from a reading of the following description in
conjunction with the accompanying drawings, in which:
Fig. 1 is a schematic sectional side view of
surgical instrumentation with which the cutting
10apparatus and methods of the subject invention are
applicable;
Fig. 2 is an exploded view of one aspect of a
cutter head constructed in accordance with the
principles of the subject invention;
15Fig. 3 is a frontal view of the cutter member head
depicted in Fig. 2;
Figs. 4-6 are simplified schematic sectional side
views of the cutter member head illustrating various
cutting edge arrangements;
20Fig. 7 is a perspective view of the sheath portion
of the apparatus depicted in Fig. 2;
Fig. 8 is a sectional side view of the apparatus
illustrated in Fig. 2 in combination with the distal end
of a surgical instrument of the type depicted in Fig. l;
25~ig. 9 is an exploded view of an alternative aspect
of a cutter head constructed in accordance with the
principles of the subject invention;
Fig. 10 is a frontal view of the cutter member head
depicted in Fig. 9;
30Fig. 11 is a side view of the cutter head depicted
in Fig. 9; and
Fig. 12 is a view along the line 12-12 of Fig. 10.
SUMMARY OF THE INVENTION:
35The invention relates generally to method and
apparatus for effecting the removal of material of
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various levels of density and hardness. The disclosed
method and apparatus have particular utility in closed
surgical applications, where difficLIlties are oftentimes
encountered in removing material that is cut by cutting
apparatus. Various angled blade configurations are
provided to effect differing characters of cutting such
as abrading and slicing. While the preferred
embodiments are particularly useful for rotatably driven
cutters, the principles of the disclosed invention are
equally applicable for reciprocc~bly-driven cutting
equipment as well as for disposable and reusable cutting
equipment.
In the apparatus of the invention, a cutter head
for use with a driveable material removal instrument
such as surgical shaver is provided, in which the cutter
head is provided with cutting means including a cutter
member having at least one cutting element formed along
an exterior surface thereof. An aperture extends from
, the cutting element and to receive material that is cut
or otherwise removed by the cutting element. The
cutting element is configured so as to direct the
removed material into the aperture as it is removed by
the cutting element. A passage in fluid communication
with the aperture provides for the removal from the
aperture of cut material for transport therefrom upon
the application of negative pressure to the passage.
Preferably, the cutting means is coupled to a source of
rotational drive input thereto; however, other forms of
drive input, such as reciprocable drive input, can be
provided in lieu thereof. The cutter member can be
provided with a plurality of cutting elements that are
symmetrically or asymmetrically spaced about the cutter
member. The cutting elements can be in the form of
slots which are defined by first and second edges, at
least one of which is provided with a sharpened surface.
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The sharpened surface of tQe cut~ing element can be
formed along the lateral exterior ~urface of the cutter
member or along a tab extending from a cutter member
distal end. The sharpened surface of the respective
edge mounting arrangements is provided with an angular
orientation which preferably falls within the range of
from about 5 to about 70 with respect to a tangent
line extending from an outer surface of the edge.
The method of the invention provides for the
removal of material from a work surface, in which a
cutting member having at least one cutting edgP is
advanced against the work surface so as to engage and
remove material therefrom. The material thus removed is
directed by the cutting edge into an aperture formed in
the cutting member and extending from the cutting edge.
Negative pressure is applied to draw the removed
material through the aperture and into a passage
extending through the cutti~g member and positioned in
, fluid communication with ths aperture, thereby providing
an evacuation path for the withdrawal of material
removed from the work surface. The foregoing method is
particularly useful for removing material such as bone,
calcifications such as bunions, and other materials from
the bodies of various organisms. In a preferred aspect
of the method, the cutter member is a rotatably driven
cutting member; however, the use of non-rotatably driven
cutting members is Pmbraced by the foregoing method.
The cutting member can be straight or angularly oriented
with respect to a supply of driving input thereto. The
cutting edge can be formed by a variety of metal working
processes, 6uch as electron discharge machining (EDM)
and rotary cutting.
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DETAILED DESCRIPTION O~ THE PREFERRED EMBODIME~TS:
With reference to the drawings, wherein like
reference characters represent corresponding parts
throughout the various views, and with particular
reference to Figs. 1 and 2, a rotatably drivable cutter
head 10 in accordance with the s~ject invention is
disclosed for use in conjunction wit:h cutting apparatus
such as surgical shavers, depicted generally by
reference character 12. Such surgical apparatus are
particularly advantageous for performing various closed
surgical procedures in remote locations such as skeletal
~oints such as the indicated knee cap 14. While the
instrument 12 illustrated in Fig. 1 is of the general
variety having a curved distal end configuration for
traversing curvalinear paths such as that indicated by
reference character 16, it is to be appreciated and
understood that the subject invention described
hereinbelow is applicable for use with both curved as
.~
I well as straight distal end cutting equipment. Such
equipment is generally provided with an elongated shaft
18 through which rotational driving input supplied from
a motor 20 can be transmitted to the cutter head 10.
Negative pressure is typically applied through one or
more apertures formed in the shaft 18 for facilitating
removal of material that is cut by operation of the
rotatably-driven cutter head 10.
With reference to Fig. Z, the cutter head 10 of the
subject invention is qenerally comprised of two
components: a cutter member 24 and a sheath 26 which at
least partially surrounds the cutter me~ber. The cutter
member 24 and sheath 26 are each provided with generally
cylindrical cross-sectional configurations, albeit of
different diameters. The cutter member, in turn, is
comprised of a head portion 28 which extends from a
shank 30. Preferably, the head and shank portions of
the cutter member 24 are formed as an integral member.
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A shoulder 32 is preferably provided to inhibit rearward
displacement of the cutter head 24 in the manner
described below. The position of the shoulder 32 can be
at the junction between the head 2~ and shank 30, as
shown, or can be along any other portion of the cutter
member 28. A proximal end of the shank 30 is provided
with means such as gear teeth 33 for receiving
rotational driving input that is transmitted thereto by
appropriate power transmitting means such as the shaft
18 (Fig. 1) andtor drive components contained therein.
The preferred power transmitting arrangement is that
which is the subject matter of our copending patent
application, Serial No. 611,278 that was filed on
November 9, 1990. However, other suitable arrangements
for transmitting rotational driving input to a cutter
head, such as that which can be provided by belts,
transmissions, biasing means or other means, is
encompassed by the subject invention, in which case an
, appropriately-configured engagement arrangement would be
substituted for the arrangement of gear teeth 33
provided at the proximal end of the shank 30.
The cutter member head 28 is provided with a
generally smooth, uniform exterior surface which tapers
inwardly toward a generally flat distal end 36 of
reduced diameter, as shown in Figs. 2 and 3. A
plurality of slots 38 extend generally radially inwardly
from the surface 39 of the cutter member head 28 so as
to define apertures 40 which extend from the cutter
member head surface 3g to a tubular lumen 42 which
3~ extends the length of the cutter member 24. The slots
38, which can be formed by rotary cutting, electron
discharge machining, or any other suitable process, are
defined by a compound edge surface 44 that is comprised
of a first edge 46 that is arranged generally parallel
to the longitudinal axis L of the cutter head 24 and a
second edge 48 which extends in a generally curvalinear
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fashion from the respective distal and proximal ends of
the first edge 46. As used throughout this description,
the term "proximal" refers to a direction or direction
of travel from the free end of the cutter member head
toward a isource of drive input thereto, and "distal"
refers to a direction or direction of travel toward the
free end of the cutter member head.
With continuing reference to Figs. 2 and 3, the
cooperation of the respective first and second slot
edges 46, 48 provides the cutter head 24 with a
generally semi-helically fluted configuration. It is to
be appreciated, however, that the overall configuration
of the cutter head will vary in accordance with both the
number and configuration of slots 38 provided therein.
In the illustrated embodiment, the first edge 46 is
provided with a sharpened edge surface for removing
material against which it is rotatably driven. While
the second edge ~8 can optionally be provided with a
' sharpened surface as well, it is to be appreciated that
rotation in the clockwise direction indicated by the
arrow is likely not to provide for an appreciable degree
- of positive (i.a., cutting) engagement of that edge wit~
material to be cut by the cutter head. Preferably, at
least the first cutting edge 46 is formed from surgical
grade stainless steel. The walls 50 and 52, which
extend radially inwardly from the respective slot edges
46 and 48, are preferably arranged such that at least
one of the walls is tapered inwardly along their
respective extensions toward the cutter head lumen 42 so
as to provide a work surface which, together with the
sharpened angled cutting edge provided along slot edge
46, facilitates removal of material such as mammalian
bone and tissue as the material is rotatably cut by the
cutting edge 46.
Figs. 4-6 illustrate in an exemplary fashion
various of the cutting angle configurations that are
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W092/1525~ -lO- PCT/US~2/01614
obtainable in accordance with ~ ~tl~ Qf the subject
invention. The cutting angle, designated by the
characters "~" in the various illustrations, is defined
herein as the angle which extends between the cutting
edge 46 and a tangent drawn to the cutting edge. It
will be appreciated that, as ~ approaches zero, the edge
46 exhibits a ~ore slender, razor-edged profile which is
optimal for cutting relatively soft materials such as
body tissues. As the angle ~ increases toward 90 , the
edge 46 exhibits a more square, block-like profile which
is best suited for abrading relatively hard materials
such as bone. In the preferred embodiment of the
invention, the included angle ~ for the slotted cutting
member of the subject invention can range between 0 and
90 , but is preferably in the range of from about 5 to
about 70 in accordance with the nature of the material
to be cut and user preference. With reference to Fig.
4, the first (cutting) edge 46 is provided with a very
, narrow included angle ~ so as to effect a materi~al
slicing rather than abrading-type of material cutting.
Slots of this type can be formed by, for example, use of
a saw blade-type cutter or wire EDM that is applied
along an acute angle with respect to a tangent of the
cutter head so as to provide a cutting edge 46 that
defines an included angle ~ that is comparatively small
to that of the cutting edges depicted in the
arrangements of Figs. 5 and 6. Such cutting edges are
well suited for the slicing of relatively soft materials
such as body tissue and cartilage. With reference to
Fig. 5, the angle ~ is on the order of approximately
90 , which can be advantageous for abrading relatively
dense, hard material such as bone. Such cutting edges
provide for a generally smooth, continuous level of
abrasion that can be relatively easily controlled by the
user. The arrangement depicted in Fig. 6 provides for
a more aggressive extent of abrasion from tha~ depicted
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in Fig. 5, as the edge 46 is formed with an angle ~ of
about 45 . This arrangement provides an intermediate
level of abrading which is suitable for use with hard
surfaces such as wood, bone and calcified areas of the
body such as bone spurs in the foot. As the body
material is cut and directed into the slot apertures 40
in the foregoing manner, the cut material is also drawn
by negative pressure applied to the cutter head lumen 42
so as to draw the cut material from the aperture 40 into ;
the lumen 42 for removal therethrough by appropriate
negative pressure-generating means as indicated by
reference number 22 (Fig. 1) from the body of the
patient.
Operability of the cutter member in the foregoing
manner affords a considerable advance in the art of
material cutting, and particularly abrading-type
processes, as hard material such as bone can be removed
and the debris resulting therefrom can be collected in
, the slots as the debris is produced. Material abrading
and debris collection proceeds in the cutter heads of
the subject invention without the necessity, of a
reactionary force produced by surfaces such as tubular,
structures surrounding the cutter apparatus against
which the debris is typically forced in prior art
apparatus. As a result of the configuration and
operational advantages of the foregoing cutter
instru~entation, material can be removed to provide for
much greater tolerances between elements such as
skeletal bones that are displaceable relative to one
another than has heretofore been capable.
Figs. 7 and 8 illustrate details of the
configuration of the sheath 26 which at least partially
surrounds the cutter member 24 described above. As is
indicated in the drawings, the sheath 26 is provided
with a generally cylindrical cross-sectional
configuration along its proximal segment 54 and an open-
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sided, semi-cylindrical configuration along its distal
segment 56. A proximal portion of the sheath distal
segment extending outwardly from the longitudinal
midline L 60 as to define a window 58 for receiving the
cutter head 28. The wall 60 defining the window 58 is
provided with a generally concave configuration along
its lower, lateral surface so as to increase the
exposure of the cutter member which is rotatably driYen
therein. The distal end 62 of the sheath is configured
complimentary to the distal end 36 of the cutter member
so as to receive the cutter member therein and inhibit
distal movement of the cutter member in a longitudinal
direction.
The nature of cooperation between the cutter member
head 28 and sheath 26 is best illustrated in Fig. 8,
which illustrates further in schematic form the
arrangement for providing rotational driving input to
the cutter member 24. As is shown in the drawing, the
' proximal end of the sheath 26 is coupled in a
conventional manner to a curved interconnector 64 which
serves generally to couple the cutter head lo to the
- instrument shaft 18. Further details of the curved
interconnector and the manner in which cutter head
rotational driving input is transmitted therethrough are
described in our copending U.S. patent application
Serial No. 611,278, the disclosure of which is
incorporated herein ~y reference. As is shown in the
drawing, the proximal end of the cutter shank 30 which
is provided with means such as gear teeth 33 for
receiving rotational driving input thereto extends into
the distal end of the interconnector 64 so as to engage
complimentary-configured means such as gear teeth 66
formed along a distal end of the drive shaft 68 received
within the shaft 18 and protruding distally therebeyond.
The interior surface of the interconnector 64 defines a
ledge 70 adjacent the interconnector distal end against
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which the cutter head shoulder 32 is positioned when the
entirety of the cutter head 10 is mounted to a cutting
instrument such as the surgical shaver device 12
depicted in Fig. 1. `
Figs. 9-12 illustrate an alternative aspect of the
invention, in which the cutter head 10 is comprised of
a cutter member 24 that is adapted to be received within
a cutter sheath 26 so as to be at least partially
surrounded thereby. The cutter member 24 is comprised
of a cutter head 28 from which extends at a proximal end
thereof a shank 30 having appropriate means such as gear
teeth 33 for receiving rotational driving input in the
manner described above. A shoulder 32 is provided along
the exterior surface 39 of the cutter member to inhibit
proximal displacement of the cutter head by cooperating
with means such as interconnector ledge 70 (Fig. 8).
The cutter member and sheath 24 and 26 are provided with
generally cylindrical cross-sectional configurations and
' are dimensioned such that the outer diameter "d" (Fig.
10) of the head 28 of the cutter member 24 is of a
lesser value than is the inner diameter "D" of the
sheath 26. The head of the cutter member 24 is
inhibited from longitudinal displacement in a distal
direction by an inwardly-extending flange 74 (Fig. 11)
formed at the distal end of the sheath 26.
A cutting edge 46 is formed along the free end 76
of a tab 78 which extends radially outwardly from a
portion of the periphery 80 of the cutter member head
distal end 36. The tab 78 can be configured so as to
preferably extend at an angle of from about 5 to about
70 from the plane defined by the cutter head member
distal end 36, thereby positioning the cutting edge at
the distal-most end of the instrument. An aperture 40
is preferably formed in the cutter head member distal
end 36 at a position adjacent the tab cutting edge 46.
Preferably, the tab 78 is formed from a section of the
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distal end 36 that is displaced outwardly therefrom, as
can be accomplished by forming a distal end cutout in
the form of a tab 78 and distally displacing the tab
therefrom so that the tab remains attached to the distal
end along the periphery thereof. The tab cutting edge
46 is formed in any of a variety of conventional
manners, such as by grinding or otherwise removing
material from the tab free end 76. Preferably, the tab
as initially formed from the distal end is oversized
with respect to its final dimensions, to permit for
formation of the cutting edge in a manner which reduces
the tab length of on the order of up to about 50~ or
more, thereby providing an aperture/tab relationship
which facilitates both the tab displacement of material
into the aperture as well as the ability of the aperture
to receive material of various dimensions that is cut by
the tab edge 46. The cutting edge can be provided with
a variety of contours in accordance with the nature of
1 the procedure to be performed and user preference. ~he
cutting edge is characterized by the angle ~ that is
illustrated in Fig. 12. ~ith reference to the drawing,
the cutting angle ~ is characterized as the angle which
extends from the plane of the distal end 36 to the
cutting edge surface 92. Preferably, this angle extends
in the range of from about 5 to about 70 . As can be
appreciated from the foregoing description and drawing
illustration, as the angle a is decreased, the rake or
angle of the cutting edge is diminished, resulting in a
cutting edge that is better adapted for material slicing
rather than abrading. Correspondingly, as the angle cr
is increased, the edge becomes more broad in profile,
rendering it better suited to abrading types of material
cutting.
The foregoing detailed description is illustrious
of various embodiments of cutter head arrangements of
the subject invention. It is to be appreciated from the
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foregoing detailed description and accompanying ~rawings
that variations an~ changes that can be made to the
invention as set forth hereinabove are expressly
intended to be encompassed by this description and the
accompanying claims.
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