Note: Descriptions are shown in the official language in which they were submitted.
WO 92/08416 PCT/US91/08348
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Title: SURGICAL INSTRUMENT FOR MATERIAL REMOVAL
BACKGROUND OF THE INVENTION
The invention relates to surgical instruments of
the type which have heretofore found principal us~ in
endoscopic, and especially rthroscopic, surgical
procedures. Such instruments, and speci~ically meniscus
cutters utilized in shoulder, knee and other sur~ical i-
procedures, have been considered less than completely
acceptable in large part because of technical problems
associated with the positioning of the meniscal tissue
within the mouth or wi~dow o~ the cutter. This problem
results principally from the space limitations
encountered in endoscopic-type surgical procedures and
the difficulty in angling and maneuvering the instrument
to the meniscal material to be removed. A~ such, it is
not unusual incident to the use of conventional
(straight) surgical instruments to require multiple skin
incisions and the use of a secondary instrument, such as
a knife blade, in conjunction with the meniscus cutter
to develop edges that can be brought in by suction to a ::
position where they can be cut or otherwise removed ~rom
the body of a patient. ~ .
U.S. Patent No~ 4,646l738 is illustrative o~ the ~:
prior art and the limitations of conventional
arthroscopic instruments and surgical procedures that
~5 are commonly practiced. This referenced patent
disclose~ a specific surgical instrument which is stated ~ .
to overcome the inadequacies of the prior art devices~ : -
at th~t time, principally by providing an instrument in
: which the cutting element is positioned at an angle
relative the body of the instrument. The instrument
includes a continuous outer tubular member which axtends
the length of~ the instrument and is bent during :~ :
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manufacture to achieve a predetermined angle. An
elaborate flexible transmission system which extends
through the outer tube comprises a composite, spirally-
wound tube consisting of an inner spiral, a middle
spiral and an outer spiral. The arrangement of multiple
spiral tubes, which are spot-welded, are each
alternately spiraled relative to adjac:ent spirals to
enable rotation of the transmission tube in opposite
directions. It can be appreciated that the mechanical
complexity of this device renders it unduly expensive to
manufacture and therefore procure, and subjects the
instrument to an increased likelihood of failure.
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SUMMARY OF THE INVENTION ~
It is an object of the invention to provide a ~ -
surgical instrument adapted for both arthroscopic and
more general (open) surgical procedures in which the
operating end portion or cutter head of the instrument
is disposed at an angle with respect to the shaft of the
instrument that is predetermined in accord with the
procedure involved and the speci~ic location of the
operating site to allow access thereto with minimal
~rauma to the surgical site. Such an instrument, to be
practical, should be structurally stable, incorporate a
positive drive for both clockwi~e and counterclockwise
rotational movement of a cutter de~ice, include minimal
suction channel disruption, be easily steriliæable, and
inexpensive in both material cost and assembly
procedures to thereby enable its use as an economically
feasible disposable item.
In the surgical instrument of the present -~
invention, the ansular orientation of the cutter head is
achieved by the provision of a hollow connector elbow
between a linear outer tube and a linear cutter head
sheath that are respectively mounted to the angularly
oriented legs of the elbow. Instruments of different
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angles are easily manufactured by the use of
appropriately angled and rigid prefo~ed elbows,~ with
the remainder of the components being standardized, that
are of the same or substantially similar constructio~
regardless of the angle of the elbow.
The cutter includes a hollow cutter shaft with a
generally laterally directed mouth at the distal end
thereof having blade edges which, upon rotation of the
cutter shaft, cooperate with blade edges in a window
laterally defined through the cutter sheath to provide
a compound cutting action that is applicable for use in
removing tissue or other material from the ~)ody of a
patient. As used herein, the terms "cutter" and
"cutting" and respective derivatives thereof encompass
various apparatus and proc~sses for effecting as
slicing, shaving and abrading by which body material is
to be separated from a material source upon progressive
advancement of khe cutter device of the subject
application thereagainst. The proximal end o~ the
cutter shaft is provided with a plurality of equally
spaced, rearwardly directed gear teeth that are
positioned peripherall~ about and within the end portion
of the shaft as a continuation of the inner and outer
peripheries of the shaft to define a driven gear 4 The
driven geax is located at the angle of the elbow and is
in meshed driving engagement with a similarly fo~ned
gear on the distal end of an elongate hcllow drive
shaft. It is pre~erred that the angle defined by the
connector elbow be between about 180 degrees (wher~in
the legs are in linear alignment) and approximately 90
degrees (where the legs are generally at right angles to
each other). The depth and shape of the drive and
driven gear teeth are such as to ensure a posi~ive
driving mesh at any of th~ desired angles within the
a~orementioned range. The preferred angle, that is the
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angle considered to be most practical for standard
arthroscopic surgery, is approximately 165 degrees.
The outer tube and elbow preferably present a
smooth, continuous inner bearing surface that cooperate
5with smooth exterior bearing surfaces defined by the
exterior surfaces of the drive shaft and cutter shaft
along the lengths thereof for rotational support of the
drive shaft and cutter shaft within the outer tube and
cutter sh~ath without separate bearing means. The gear-
l0joi~ed drive shaft and cutter shaft clefine a smooth
continuous interior material-withdrawing passage 1-
interrupted only at the meshing gears and adapted,
through the meshing gears, for positive rotation in both
clockwise and countercloekwise directions.
15The outer tube and cutter sheath respectively
telescopically engage the two legs of the connector
elbow and are permanently fixed thereto, pre~erably by
welding. However, other suitable securing means can be
provided. When assembled, both the drive shaft and the
20cutter shaft, while freely rotatable, can be supported
along substantially the full lengths thereof or by one
or more bearing sections and are precluded ~rom
longitudinal shifting within the outer tube and cutter
sheath.
25Other features and advantages of the invention will
be appreciated from the details of construction and
manner of use of the instrument as more fully
hereinafter presented.
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BRIEF DESCRIPTION OF THE_DRAWINGS
30Figure l is a schematic illustration of a prior art
instrument illustrating the dif~iculty in accessing
: posterior menisGus material with a straight shaft;
Figure 2 is a schematic illustration similar to
Figure 1 illus~rating the angled instrument of the
3 5present inveDtion;
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Figure 3 is an enlarged side elevational view of
the forward angled portion o~ the instrument;
Figure 4 is a longitudinal cross-sectional view
through the structure of Figure 3;
Figure 5 is a view of the cutter end of Figure 4
with the cutter shaft rotated 90 degrees and presented
partially in elevation;
Fi~ure 6 is an enlarg~d sectional detail
illustrating the positioning mPans for the drive shaft;
Figure 7 is a cross-sectional view similar to
Figure 4 with a connector elbow of a lesser angle;
Figure 8 is an exploded perspective vie~w o the
components of the instrument; and
Figures 9-12 are perspective views of various
alternative cutter head arrangements.
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DESCRIPTION OF PREFERRED~EMBODIMENTS
Referring now more specifically to the drawings,
wherein like reference characters represent
corresponding components throughout the various views,
and with particular reference to Figurs l, there is
illustrated a conventional arthroscopic instrument 10
wi~h the operating end portion thereof linearly aligned
with the straight sha~t. The problem o~ accessing
angularly ofPset areas is apparent Prom the schematic
cross section through the knee construction, as the
instrument 10 is unable to negotiate khe curvalinear
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channel lla between bone elements llb and llc.
Figure 2, in the same or substantially similar
surgical environment as sho~n in Figure 1, illustrates
the surgical instrument 12 of the present invention in
which provision is made for accessing angularly offset
areas such as the channel 11 a in a manner nok possible
with the conventional straight instrument lO of Figure
1.
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The instrument 12 comprises an elongate linear or
straight shank 14 with an angularly-directed cutter head
or operating end portion 16 at the distal end thereof.
The proximal end of the ~hank 14 is associated, in a
conventional manner, with a vacuum or suction source as
schematically shown at 18, and a drive motor 20, As an
alternative to the use of a drive motor, m2ans can be
provided for a manual d~iving of the cutter head 16.
The shank 14 comprises a hollow cy:lindrical outer
tube 22 having a smooth surfaced bore 24 therethrough
which, along substantially the full length thereof,
defines a continuous bearing surface. The distal or
forward end portion of the outer tube 22 is counterbored
to define an annular recess 26 terminating in an
annular, radially inwardly extending and forwardly
directed shoulder 28, as shown in Figure 6.
The angle of the instrument, or more particularly
the cutter head 16 with respect to the ~,ube 22, is
de~ined by a connector elbow 30, as shown more clearly
in Figure 3. The elbow 30 is of rigid hollow tubular
const~uction and, in accord with the specific area to be
accessed by the instrume~t, can be configured so as to
provide any of a range of angles "a" that are between
approximately 90 degrees and approximately 180 degrees.
As a practical matter, and as indicated in Figures 4 and
7, most surgical sites to which the subject invention is
concerned can be accessed by cutter heads oriented at
an~where from a range of about 105 degrees (Fig. 7) to
about 165 degrees (Fig. 4).
Referring now to Figure 4, the connect~r elbow 30,
with its angularly related elongate proximal and distal
}egs 32 and 34 thereof and the angle juncture
therebetween, is provided with smooth inner and outer
surfaces defining, when assembled to the outer tube 22,
smooth continuations of the inner and outer surfaces of
; the tube 22. The pFoximal leg 32 is exteriorly recessed
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about the proximal end thereof to define an elongated
exterior reces~ 36 which complements the counterbore 26
of the outer tube 22 for telescopic reception and
nesting therein. As noted in the detail of Figure 6,
S the proximal edge 38 of the proximal elbow leg 32
terminates slightly forward of the shoulder 28 of the
counterbore 26, defining therewith an annular recess or
groove 40. The forward adge of the outer tube 22, as
shown in Figures 4 and 7, abutts again~;t the exterior
annular shoulder 42 defined about the proximal leg 32 by
the recess 36. The engagement of the recessed proximal
end portion of the elbow leg 32 within the counterbored
distal end portion of the outer tube 22 is rigidified,
preferably by welding, and is such as to provide ~or
substantially continuous outer and inner surfaces, with
the exception of the annular recess 40, as described
above. .
The distal end portion of the distal leg 3 4 of the
connector elbow is similarly externally recessed to
define an elongated annular recess 44. An elongate
cutter sheath 46, of a thickness corresponding to the
depth of the reces~ 44, has the proximal end thexeof
received within the recess 44 along the length of the ~
recess to definP a smooth exterior sur~ace continuation :
o~ the distal leg 34. The sheath 46 projects beyond the
distal end of the distal elbow leg 34 and terminates in .
a retaining end 48 }aterally directed at least partially :
across the forward or distal end of the cutter sheath
4 6 . The cutter sheath includes at, or immediately
adjacen~ the distal end thereof, a cutter w.indow 50 with
blade edges. The window 50 opens either completely or
partially latexally along at least a portion of the
linear extent of the cutter sheath 46.
Mounted within the cutter sheath 464 (Figure 4~ is
an elongate hollow cutter shaft 52 with a proximal
portion coextensive with the distal leg 34 and having a :~
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smooth e.xterior surface 54 in bearing engagement with
the inner surface of leg 34 along the length thereof.
The distal end portion 56 of the cutter shaft 52 is
configured so as to be radially thicker than the
proximal portion thereof and defines an exterior,
rearwardly-directed annular shoulder 58 which bears
against the leading edge of the distal leg 34 of the
elbow 30. The exterior of the distal end portion 56 of
the cutter shaft 52 is, for the linear extent of the
sheath 46 forward of the leg 34 and to the retaining end
48, in bearing engagement with the inner surface of the
sheath 46. The boxe 60 which extends substantially
axially through the cutter shaft 52 is of a smooth
surface and exhibits a constant diameter that terminates
in an end wall 62 having an exterior surface bearing
against the retaining end 48 of the sheath 46.
With particular referenc~ to Fi~ures 4 and 5, there
is depicted ~ cutter, comprising a mouth 64 with
peripheral cutting edges, that is formed through the
cutter shaft 52 immediately rearward of the distal end
62 thereof and generally laterally directed to cooperate
with the sheath window 50, and more particularly the
cutting edges 65 d~fined thereabout. At least onel and
preferably both, of the cutter mouth and sheath window
edges is form~d from suitably sharpenedr and optionally
hardened surgical grade stainless steel~ The
cooperation provides for a shearing action as the cutter
shaft 52 is rotated, either clockwise or
counterclockwise, within the oper~ting end portion 16 of
the instrument. The preferred rotatioral rate of
operation is from about 100 rpm to about 7,000 rpm, in
accordance with such factors as surgeon preference,
cutter head configuration, the type of drive motor 20
used with the instrument 12, and the typ2 of surgery and
~ocation of the surgical site. Preferably, the
instrument 12 i~ used with a drive motor 20 that is
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controllable to provide a range of cutter blade
rotational rates that can be controlled by the user.
The cutter sheath 46 is preferably rigidly joined
at the telescopic overlap with the recessed distal end
portion cf the Plbow leg 34 by conventional securing
means such as welding. The cutter sha~t 52, while
~reely rotatable within the cutter sheath 46 and elbow
leg 34 and in stable bearing engagement along at least
substantially the full length thereo~, is retained
lo against longitudinal movement or shifting by and between
the retaining end 48 of the sheath 46 and the shoulder
58 on the cutter shaft 52 which engages the leading or
distal end of the elbow leg 34. ! :
The cutter shaft 52 is prefarably configured so as
to be gear driven with a driven gear 66 integrally
defined at the proximal end of the shaft 52, located at
the angle of the elbow connector 30, by a plurality of
gear teeth 68 cut or otherwise formed directly in the :.
proximal end portion of the cutter shaft 52, whereby the
formed teeth 68 are provided with inner and outer
surfaces which define smooth continuations of the .
respective inner and outer surfaces of the cutter shaft
52. :.
Rotatable driving of the cutter shaft 52 is
effected by an elongate hollow drive shaft 70 that is
longitudinally received within, and coextensive with,
the outer tube 22 and the linearly-aligned proximal leg .
32 of the connector 30. The outsr surface 72 of thP
drive shaft 70 defines a smooth ~earing surface in .
engagement with the inner surface 24 of the outer tube
22 and the inner surface of the proximal elbow leg 32 .
along the full length thereof. This outer surface 72
includas an annular groove 74 that is radially aligned ~.
with the groove 40 and forms therewith a closed channel
which encircles the drive shaft 70. This closed channel
: receives a steel wire retainer ring 76 which extends
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into both grooves 40 and 74, substantially completely
filling the annular channel defined thereby. The
retainer ring 76 retains the drive shaft 70 against
longitudinal movement relative to the outer tube 22,
while allowiny for rotation of the drive shaft 7~ within
the outer tuhe with the shaft supported and stabilized
during rotation by the substantially full length en~aged
bearing surfaces 24 and 72.
The distal.end portion of the drive shaft 70 has a
10 drive gear 78 formed thereat which complements the
driven gear 68 formed on the proximal end of the cutte~r
shaft 52 and similarly includes a series of equally
spaced peripheral gear teeth 80, the opposed surfaces of
which form smooth continuations of the inner surface or
15 bore of the drive shaft 70 and the outer bearing surface
72 thereof.
The gear teeth 68 and 80 mesh at the angle joinder
of the legs of the elbow 30 and are configured to
provide for a positive driving mesh regar~less of the
20 angle of the elbow within the contemplated range of the
invention. The adaptability of the meshing of the gear
teeth will be appreciated from a compar~.son of the
structur s depicted Figures 4 and 7.
: While not speciPically detailed, it will be
25 appreciated that the proximal end of the drive shaft 70
and the proximal end of the outer tube 22 are joined, in
the manner of a conventional surgical cutting
instrument, with both motor means 20 for effecting a
driving of the drive shaft 70 and appropriate suction
30 generating apparatus 18 for obtaininy vacuum positioning
of material to be cut by the surgical instrument 12 and
removal of cut material through the aligned ~ores in the
drive shaft and cutter shaft.
::: Constructed in the above manner, it: will be
: 35 : appreciated that a full range o~ an~ular instruments can
be ~anufactured wherein the components, other than for
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the elbows, are standardized, thus facilitating assembly
and through the use of preformed el~ows assuring a
consistent uniformity.
As described, the individual componen~s are rigid
elements which, with regard to the outer components
including the outer tube 22, elbow 30 andi cutter sheath
46, are rigidly fixed, as by welding, to rotatably
receive the drive components therein and therethrough.
The inner and outer components themselvles provide for
full length engaged bearing surfaces without additional
bearing means, and can be configured from a wide range
of surgical grade materials such as stainless steel,
plastics, or a combination of stainless steel and
plastic. Alternatively, one or more bearing ~;ections
can be provided along the respective inner an~i outer
components. Similarly, and again without additional
means such as separate gears or the like, the drive
shaft and cutter shaft are in direct driving engagement
through integral gear teeth formed at the adjacent ends
thereof. The engaged gear teeth are operable through a
range of fixed angular orientations and are equally
e~fective for both clockwise and counterclockwise
driving engagement.
With respect to Figures 9 through 12, it is
contemplated that th~ instrument of the invention can
utilize a variety of cutter heads in accord with the
particular cutting or material accommodating situation~
For example, rather than the flat ended mouth and window
arrangement suggested in Figure 5, both the sheath
window and cutter shaft mouth can be provided with a
generally oval con~iguration with continuously aurving
sur~aces as shown in Figure 9. Alternatively, the
sheath window, as shown in Figure 10, can ba configured
with a multitude of apertures 90 of reduced dimension
that are oval or circular in c~nfiguration and which
: ~boperate with an underlyin~ cutter shaft opening which,
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WO92/08416 PCT/US91/08348
upon rotation of the cutter shaft, sweeps by each of the
individual windows to achieve a shaving effect as
opposed to a broader cutting effect achieved by the
cutter head of Figures 5 and 9. With respect to the
cutter head arrangement depicted in Figure ll, the edge
surface 65 of the sheath window 50 is provided with a
serrated surface alony its opposed edges that are
aligned with the longitudinal axis of the cutter head so
as to provide a plurality of opposed teeth 92 which,
lO together with the rotary action of the cutter element,
facilitate a broader cutting effect that is generally
comparable, or even greater, than that providecl by the
arrangement depicted in Figure 9. As shown in Figure
12, the cutter head can be in the form o~ an abrader 64'
15 rotatably received within the cutter window 50. In the
depicted arrangement, the distal end 96 of the abrader
64' extends beyond the open, distal end 98 of the cutter
window 50 to permit for the abrading of body material
such as bone or cartilage upon axial or laterial
20 extension, or any combination thereof, of the abrader
64' against the material to be removed. It is to be
appreciated, however, that ~ variety of different
configurations for abraders and cutter windows,
including closed window con~iguration~, can be provided
25 in accordance with the teachings of the subject
application. In each instance, the angle of the cutter
head i5 determined by the ~ixed angle elbow with the
material to be acted on drawn into the cutter head as a
part o~ the cutting procedure, and upon being se~ered,
30 e~fectively evacuated through the smooth bores of the
aligned cutter and drive shafts.
While the surgical instrument of the in~ention has,
in Figure 2, been illustrated as used in the performance
o~ an arthroscopic procedure on a knee, the instrument
35 has substantially broader applications. For example,
the angled instrum~nt of the subject invention is
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particularly applicable for use in shoulcler surgery for,
among other of a wide variety of surgical applications,
abrading the scapula neck inferior. S:imilarly, it is
contemplated that the instrument will have practical
applications in a wide range of surg$cal procedures
other than arthroscopic procedures, such as conventional
(open) surgery as well as microsurgical procedures upon
appropriate scaling of the respective components of the
surgical instrument.
From the foregoing, it will be apprecia~ed that the
described instrument is unique in its solutic)n of the
vexing problem of obtaining access to areas normally
difficult to reach with conventional, i.e., straight~
instruments and doing so in a manner which minimizes
trauma to the surgical site as compared to that
experienced in conventional procedures requiring
multiple instruments or instruments of complex
construction. As will be recognized, the principals of
the invention, and in particular the rigid connector
elbow and full length rigid shafts with direct bearing
surfaces, can be utilized in conjunction with a variety
of different forms of cutters, drive means and suction
apparatus, all of which are to be regarded as ~alling
within the scope of the invention as set forth in the
foregoing detailed description and accompanying patent
claims.
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