Note: Descriptions are shown in the official language in which they were submitted.
~WO91/07gl5 1 PCT/US~0/06~1
. BIOPSY I~STRUMENT, ~ ;
STYLET AND CANNULA ASSEMBLY 2 0 7 2 9 7 4
REFER~NCE TO RELATED APPLICATIONS
This application is a continuation-in-part of United
States Patent Application Serial No. 521,259, filed on May
9, 1990, which is a continuation of United States Patent
Application Serial No. 441,776, filed on November 27, 1989
and now issued on July 10, 1990 as U.S. Patent No.
4,940,061, both by the same inventive entity, and entitled
BIOPSY INST~UMENT.
FIELD OF THE INVENTION
This invention relates to an instrument for extracting
samples of tissue from humans and other animals and more
particularly to an instrument for automatically performing a
biopsy of a tissue mass in an accurate, expeditious manner
with a minimum of discomfort to the patient.
BACKGROUND OF THE INVENTION
It is often desirable and frequently absolutely
necessary to sample or test a portion of tissue from humans
and even other animals, particularly in the diagnosis and
treatment of patients with cancerous tumors, pre-malignant
conditions and other diseases or disorders. Typically in
the case of cancer, when the physician establishes by means
of procedures such as palpitation, 2 ray or ultra sound
imaging that suspicious circumstances exist, a very
important process is to establish whether the cells are
cancerous by doing a biopsy. Biopsy may be done by an open
or closed technique. Open biopsy removes the entire mass
(excision biopsy) - a part of the mass (incision biopsy).
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Closed biopsy on the other hand is usually done with a
needle-like instrument and may be either an aspiration or a
core biopsy. In needle aspiration biopsy, individual cells
or clusters of cells are obtained for cytologic examination
and may be prepared such as in a Papanicolaou smear. In
core biopsy, as the term suggests, a core or fragment of
tissue is obtained for histologic examination which may be
done via a frozen section or paraffin section.
The type of biopsy depends in large part in
circumstances present with respect to the patient and no
single procedure is ideal for all cases. However, core
biopsy is e~tremely useful in a number of conditions and is
being used more frequently by the medical profession.
A variety o~ biopsy needles and devices have been
described and used for obtaining specimens of tissue. For
e~ample, re~erence is made to U.S. Patents 4,651,752;
4,702,260; and 4,243,048 which show biopsy needles of
varying types. Additionally, a number of very specialized
devices for extracting samples of tissue have been described
such as the biopsy device in U.S. Patent 4,461,305, which
device is designed specifically for removing a sample of
tissue from the female uterine cervix. Other devices have
been disclosed which relate to surgical cutting
instruments. For example, U.S. Patent 4,589,414 discloses
an instrument which is particularly designed to operate in
the area of the knee to withdraw tissue chips. Also
available are so-called biopsy guns for removing a core of
tissue which customarily are spring powered devices and must
be cocked with considerable force. When actuated such guns
produce a loud snapping noise, combined with a jerking
action. Such a biopsy gun may employ a needle set
consisting of an inner stylet and an outer tube called a
cannula. The stylet is a needle like device with a notched
cut-out at its distal end. The cannula in effect is a ~ -~
hollow needle with an angled cutting surface at its distal
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end which slides ove~ the stylet. When the stylet is forced
into tissue, the tissue is pierced and relaxes into the
notched cut-out of the stylet. When the cannula is then
slid forward, the tissue in the notch of the stylet is
sliced off and retained in the notch until the cannula is
withdrawn. Examples of such devices are shown in U.S.
patents 4,600,014 and 4,699,154. Although such spring
powered biopsy guns will remove a core or sample of tissue,
they have rather serious disadvantages. For one, they must
be manually cocked with a plunger bar. Such "cocking" of
the gun re~uires considerable force and the gun must be
cocked for each biopsy cut. ~ further disadvantage is that
the springs provi1ed in the gun accelerate the needles until
a mechanical stop position is reached, creating a loud
snapping noise and jerking motion which is a problem both to
the physician and the patient. This noise and jerking
action can cause the patient to jump and in some cases even
prevents the physician from striking the intended tissue
target. Another disadvantage is that the force and velocity
delivered to the stylet and cannula rapidly diminishes when
traveling from a retracted to a fully e~tended position
resulting in tissue samples of lower quality.
Accordingly it is a principal object of this invention
to provide an instrument for obtaining samples of tissue
from tissue masses.
It is a further object of this invention to provide a
biopsy instrument which is able to provide a substantially
constant force and velocity to that portion of the
instrument which penetrates the tissue mass and severs a
portion of tissue for further e~amination.
It is another object of this invention to provide an
instrument for automatically performing a biopsy of a tissue
mass in an accurate and expeditious manner with a maximum of
accuracy and a minimum amount of discomfort to the patient.
It is a still further object of this invention to ;
provide an instrument for performing tisæue mass biopsies by
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removing a core or sample of tissue, which instrument
eliminates the need for springs and mechanical stops, which
is silent in operation and has the ability to effectively
penetrate even small tissue masses.
It is another object of this invention to provide an
instrument for obtaining tissue samples from tissue masses
which instrument requires no manual setting or cocking ana
which may be "fired" multiple times without any abrupt
starts or sto~s.
It is still another object of this invention to provide
a biopsy instrument which includes means to convert rotary
motion to sequential, linear motion of substantially
constant force and velocity to the means for penetrating and
severing a tissue sample from a tissue mass.
These and other objects of the invention will be
apparent from the following description and claims.
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SUMMARY OF THE INVENTION
~ ased on the prior art instruments for biopsy samples
from tissue masses, and the actual present state of this
art, there then exists a need for an instrument which is
capable of automatically removing a tlssue sample or core
sample of pre-determined si~e where the process is done very
rapidly, is easily repeated if required, is accurate, is
relatively simple for the physician to use, is virtually
noiseless, and in use results in minimal discomfort to the
10 patient.
Accordingly, we have invented an instrument for removing
tissue samples from a tissue mass which instrument
automatically penetrates, severs, and removes the tissue ~-
portion for examination. The instrument is motor powered,
preferably by self-contained rechargeable batteries, and
employs electrically actuated stops instead o~ mechanical
stops to control the action of penetration and retraction
from the tissue mass. The portion of the instrument which
penetrates the tissue mass and severs a portion thereof, the
tissue penetrating and severing means, includes an inner
stylet which penetrates the tissue mass and a hollow outer
tube or cannula which surrounds the stylet and serves to
sever a sample of tissue. In a preferred form the tissue
penetrating end of the stylet is notched so that when the
stylet penetrates the tissue mass, a portion o the tissue
relaxes in the notched area. After tissue penetration by
the stylet, the cannula, having a cutting surface at its
distal end, penetrates the tissue and cuts off the tissue
portion residing in the notched area of the stylet. The
tissue penetrating and severing means are operably connected
to a special motor powered rotary cam assembly by means of
cam followers and it is a feature of this invention that the
rotary motion of the cam is converted to sequential, linear
motion in the tissue penetrating and severing means, the
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linear motion being of substantially constant force and
velocity.
In operation, the physician or technician actuates the
instrument by pressing a button causing the stylet to move
forward in a rapid, precise manner and penetrate the tissue
mass followed with penetration of the mass by the cannula,
resulting in a portion or core of tissue being severed and
retained in the notched portion of the stylet. Further
actuation by the physician causes the cannula to retract
exposing the tissue sample in the stylet for easy removal.
An additional actuation causes retraction of the stylet and
a resetting of the cannula/stylet assembly for further use.
In a preferred embodiment, the instrument has two
actuators or buttons which cycle the action of the
15 stylet/cannula assembly as described above. Actuation of .~ -
one button, called a fire button, causes penetration of the ~ ~
stylet and cannula into the tissue mass. An initial
actuation of the other button, called a retraction button,
causes retraction of the cannula to e~pose a sample of the
tissue. A second actuation of the retract button retracts
the stylet and the instrument is ready for further use.
Special electrical circuitry allows the stylet/cannula
assembly to move in a forward or reverse direction via the
rotary motion of a special function cam assembly with a cam
travel of approximately 360 degrees. Motion ~ithin a single
revolution of the cam is controlled via a limit switch
assembly, stopping the motion at pre-defined stylet/cannula
assembly locations of, for ~xample: (1) where both the
stylet and cannula are forward; (2) where the stylet is
forward but the cannula has been moved back; and (3) where
both the stylet and cannula are back. The limit switch
assembly includes two principal components, a stationary
limit switch wiper plate and a rotary limit switch board.
The stationary limit switch wiper is provided with spring
finger contacts which are electrically connected to the
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actuation buttons and other circuit components. The rotary
limit switch board is a circuit board which is fixed to a
rotatable drive shaft and rotates therewith. An
electrically conductive circuit pattern is present on one
face and the wiper plate and rotary limit switch board are
mounted in line in the instrument and in contact with each
other concentrically about the drive shaft. As the drive
shaft rotates either clockwise or counterclockwise, the
circuit pattern on the rotary limit switch board creates
particular circuit paths by contacting specific spring
finger contacts on the stationary limit switch plate during
the rotational motion. The purpose of these specific
circuit paths on the rotary limit switch board allows the
stylet/cannula assembly to stop at prescribed positions.
The instrument is also provided with what is called a
toggle assembly which includes a stationary wiper plate, a
toggle board and a toggle piate. ~he stationary wiper plate
is similar to the stationary limit switch wiper plate in the
limit switch assembly and is provided with spring finger
contacts which are electrically conn~cted to the actuation
buttons and other circuit comp~onents. The toggle board has
an electrically conductiYe circuit pattern present on one
face. The wiper plate and toggle board are mounted in line
and in contact with each other concentrically about the
drive shaft. As the drive shaft rotates either clockwise or
counterclockwise, a key on the drive shaft encounters a
protrusion in the central opening of the toggle board. When
the key and the protrusion meet the toggle board is forced
to rotate a slight distance in a clockwise or
counterclockwise direction and the circuit pattern on the
toggle board creates again a specific electrical circuit by
contacting specific spring finger contacts on the stationary
wiper plate. The purpose of the specific circuit paths of
the toggle board is to allow the stylet/cannula assembly to
travel in prescribed directions either forward or backward
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via depression of the retract button. This particular
construction and circuitry allows the retract button to
serve as a dual function switch in the retraction phase of
the action of the biopsy instrument. Thus after the forward
motion of the stylet/cannula assembly is completed, the
retract button can be depressed and the stylet of the
stylet/cannula assem~ly moves backward through approximately
one-half a revolution of the special function cam. The
limit switch assembly stops the motion at appro~imately the ~'
mid-point of reverse travel of the cam and the toggle board
is again mechanically,rotated either clockwise or
counterclockwise as previously described. The shift in the '~
position of the toggle board changes the electrical
circuitry to allow a second actuation of the retract button
whi~h permits the continuation of the reverse motion until
the limit switch assembly stops rotation of the cam and the
cannula is fully retracted.
The present invention further provides a biopsy stylet
and cannula assembly suitable for use with a biopsy
instrument having a first drive rod and a second drive rod,
comprising a cannula mount with a cannula secured thereto
and having a recess on the backside of the cannula mount to
receive the first drive rod of the biopsy instrument; and, a
stylet mount having a stylet secured thereto, wherein the
stylet mount also has a recess in a backside thereof for
receiving the second drive rod of the biopsy instrument. A
locking mechanism may be provided to secure the stylet mount
and/or the cannula mount to the drive rods. The stylet and
cannula assembly preferably has a generally rectangular
frontal profile.
The present invention also provides a biopsy instrument,
stylet and cannula assembly including a biopsy instrument
with two drive rods, a cannula mount with a cannula disposed
on one drive rod, a stylet mount having a stylet secured
thereto disposed on the other drive rod, and a mechanism for
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urging the cannula mount and stylet mount forwardly off of
the drive rods for removal. The urging mechanism may
comprise a pivoting lever.
The use of the recesses and of the locking mechanisms
for securing to the drive rods conceivably could be utilized
in biopsy instruments having more conventional spring loaded
or other such compression drive mechanisms to power the
drive rods.
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WO9l/079l5 PCT/US90/~6891
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BRIEF DESCRIPTION OF THE DRAWINGS
The above noted advantages and other characteristic
features of the present invention will be in part apparent
from the accompanying drawings, and in part pointed out in
the following detailed description of the preferred
embodiment of the invention in which reference will be made
to the accompanying drawings wherein like reference numerals
designate corresponding parts and wherein:
Fig. l is a perspective view of the biopsy instrument of
this invention;
Fig. 2 is a side elevational view taken on the line 2-2
of Fig. l;
Fig~ 3A is a side elevational view taken on the line 3A
of Fig. 3;
Fig. 4A-4D are part side elevational views showing the
action involved in penetration of a tissue mass by the
stylet and cannula and retraction of the cannula fro~ the
tissue mass;
Fig. 5 is a cross section of the stylet/cannula assembly
taken on the line 5-5 of Fig. 4D;
Fig. 6 is an exploded perspective view of the biopsy
instrument illustrating the major component parts thereof;
Fig. 6A and 6B are sectional views of the instrument
ta~en on the lines 6A-6A and 6B-6B respectively of Fig. 6;
Fig. 7 is a plan view of the rotary cam showing the cam
grooves; ~ ,
Fig. 8 is an elevational view of one side of the wiper
assembly;
Fig. 9A is an elevational view of one side of the toggle
printed circuit board;
Fig. 9B is an elevational view of one side of the wiper
assembly of the limit switch assembly;
Fig. lOA-lOG are schematic drawings showing the
electrical circuitry involved in the various actions of the
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biopsy instrument;
Fig. llA and llB are part side sectional views of the
biopsy instrument showing the action and construction of the
cannula and stylet blocks;
Fig. 12 is a section taken on the line 12-12 of Fig. llA;
Fig. 13 is a section taken on the line 13-13 of Fig. llA;
Figs. 14A and 14B are graphs comparing the force and
velocity delivered by the tissue penetrating and severing
means of a typical spring powered biopsy gun and the
instrument of the present invention;
Fig. 15A is a side view of an alternative embodiment of
the biopsy instrument of this invention showing a stylet and
cannula assembly being inserted in a front end thereof;
Fig. 15B is a front view of the device of Fig. 15A;
Fig. 15C is a partially cut away top view of the front
end of the alternative embodiment of the biopsy instrument
showing lever 286 pivoted outwardly;
Fig. 15D is an inside side view of the lever used in the
device of Fig. 15C;
Fig. 15E is a front view of the lever of Fig~ 15D;
Fig. 15F is a bottom view of the lever of Fig. 15D;
Figs. 16A, 16B, 16C, 16D and 16E are a side view, a
bottom view, a top view, a front view, and a rear view of a
cannula mount and cannula according to the present
invention; and, the right side view and let side view are
mirror images of one another;
Figs. 17A, 17B, 17C, 17D and 17E are a side view, a
bottom view, a top view, a front view, and a rear view of a
stylet mount and stylet according to the present invention;
and, the right side view and left side view are mirror
images of one another;
Figs. 18A, 18B, 18C, 18D and 18E are a side view, a
bottom view, a top view, a front view, and a rear view of a
stylet and cannula assembly according to the present
invention; and, the right side view and left side view are
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WO~1/07915 PCT/US90/06891
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mirror images of one another;
Fig. l9A is a side view in full section of the stylet
and cannula assembly according to the present invention
shown mounted on two drive pins; and
Fig. l9B is a rear cross section view, taken along the
line l9B-19B of Fig. 18A.
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WO91/07915 PCT/~S90/06891
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DESCRIPTION OF THE P~EFERRED EMBODIMENT
For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to
the embodiment illustrated in the drawings and specific
language will be used to describe the same. It will
nevertheless be understood that no limitation of the scope
of the invention is thereby intended, such alterations and
further modifications in the illustrated device, and such
further applications of the principles of the invention as
illustrated therein being contemplated as would normally
occur to one skilled in the art to which the invention
relates.
Considering now the drawings in detail, Fig. l
illustrates a perspective view of one embodiment of the
15 inventive biopsy instrument which is shown generally at l0 ~ -
with the tissue piercing and removing means shown generally
at 12. The tissue piercing and removing means comprises a
stylet 14 and cannula 13. Referring to Fig. 2 which is a
sectional view through the instrument shown in FigO l, and
Fig. 6, which is an exploded view of a number of the
components of the instrument, the instrument l0 is shown as
having an outer housing 15 provided with a motor 18 mounted
in one end thereof. Motor 18 is reversible and preferably
of the DC type and prefera~ly powered by rechargeable
batteries 16 contained within the housing. Suitable
contacts 17 are provided to recharge the batteries. Motor
18 is operably engaged with planetary gear assembly 20 by
means of shaft l9 which shaft engages central gear 21.
Central gear 21 in turn meshes with planetary gears 22 which
in turn engage with annulus gear 23. In a preferred
embodiment the DC motor operat0s at about l0,000 rpm with
the gearing being ahout a 6:l ratio. One end of the
planetary gear set 20 is mounted in bearing 24 which in turn
is secured within the housing by bracket 39. Drive shaft 25
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WO91/0791~ P~T/US90/0S~91
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is secured at its end 26 in the D-shaped opening 35 of the
planetary gear set by means of a set screw or other suitable
fastening means.
Positioned adjacent to the gear assembly are the means
for controlling the movement of the stylet/cannula assembly
12 in a forward (piercing) direction or in a reverse
direction with respect to the tissue mass. Such means
includes a toggle assembly comprising stationary wiper plate
28, a toggle boa~d 34 and a toggle plate 40. Positioned
adjacent to the toggle assembly is a limit switch assembly
comprising a limit switch wiper plate 45 and a limit switch
board 50, all as bes't shown in Fig. 6. Stationary wiper
plate 28 is provided with a central opening 32 for passage
of drive shaft 25. On one side of wiper plate 28 is a
series of vertically positioned contact pins 29. Along the
base of the wiper plate are a series of wire contact posts
31. As shown there are si~ spring contact pins and six
contact posts. As shown in Fig. 8, the reverse side of
stationary wiper plate 28 is provided with a series of
electrically conductive circuit paths 33 with one end of
each circuit path connected to a wire contact post 31 and
the other end connected to a contact pin 29. Immediately
adjacent to the stationary wiper plate 28 is circular shaped
toggle board 34 having a central opening 36 for passage of
drive shaft 25 with a protrusion 37. Positioned toward the
outer edge of toggle circuit board 34 and on one side
thereof is pin 38. As shown in Fig. 9A, the reverse side of
the toggle circuit board 34 is provided with a series of
electrically conductive circuit paths 30. Certain of the
spring contact pins 29 make contact with circuit paths 30.
The toggle assembly is completed by the toggle path 40
mounted and positioned within the instrument by bracket 41.
Again as shown in Fig. 6, the toggle plate is provided with
a central rectangular opening 40a, V-shaped opening 43 and
spring 42 which is secured to an inner wall of housing 15.
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WO 91/07915 PCI/lJS90/06891
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In the assembled instrument, pin 38 of toggle board 34 rides
within V-shaped opening 43 and this combination serves to
control the amount of rotary movement of the toggle board.
The toggle board can rotate a distance in either a clockwise
or counterclockwise direction and the amount of rotation is
controlled by pin 38 in V-groove 43.
Adjacent to the toggle assembly is the limit switch
assembly made up of stationary limit switch wiper plate 45
and limit switch board 50. Wiper plate 45 is similar in
construction to the stationary wiper plate 28 of the toggle
assembly having a central opening 46 and being provided on
one side thereof with a series of vertically positioned
contact pins 47 and a series oE wire contact posts 48 along
the base of the wiper plate 45. The contact pins 47 make
direct contact with a side of the limit switch board 50 and
this side of the limit switch hoard is shown in Fig. 9B. As
with the stationary wiper plate ~8 and the toggle board 34,
board 50 has a central opening 54 and electrically
conductive circuit paths 49. Limit switch board 50 rotates
with drive shaft 25 and is therefore provided with a split
collar 51 for passage of the shaft 25. Clamp 52 surrounds
the collar 51 and when tightened by screw 53 insures that
the limit switch board will rotate with shaft 25.
The components of the instrument which guide the
stylet/cannula assembly 12 will now be detailed. As
previously described, the physician or technician actuates
the instrument causing the stylet 14 to move forward in a :
rapid and precise manner to penetrate the tissue mass
followed by penetration of the mass by the cannula 13,
resulting in a portion or core of tissue being severed and
recained in the notched portion of the stylet. Further
actuation causes the cannula to retract exposing the tissue
sample in the notched portion at the distal end of the
stylet for easy removal. An additional actuation causes
retraction of the stylet and a resetting of the
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WO9l/07915 PCT/US90/06~91
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cannula/stylet assembly for further use. The penetration
and retraction of the stylet and cannula assembly is
controlled in part by hollow rotary cam 55 which is best
illustrated in Figs. 6 and 7. Cam 55 is provided with a
5 continuous groove 56 and a preferred groove pattern is shown
in even greater detail in Fig. 7. As shown, continuous
groove 56 is made up of three sections. A first groove
section 56a is positioned substantially parallel to one end
of cam 55 and extends about a portion of the circumference
of the cam. A second groove section 56b is positioned
substantially parallel;~to the other end of the cam and also
extends about a portion of the circumference of the cam.
Section 56c conne~s section 56a and 56b in a generally
diagonal manner. Cam 55 is rotated by means of drive shaft
~5 and, as partly shown in Figs. 4A-4D, this is accomplished
by securing shaft end 26 into the opening 63 of the end wall
53 of cam 55. Thus rotation of shaft 25 in a clockwise or
counterclockwise direction causes identical rotation of the
cam. Housing 58 surrounds cam 55 and serves to properly
position the cam within the instrument.
As previously described, stylet 1~ moves within and is
surrounded by cannula 13. The non-penetrating end of stylet
14 is mounted in stylet block 74. Correspondingly, the
non-penetrating end of cannula 13 is mounted into cannula
25 block 75. As shown in Fig. 6, stylet block 74 is provided
with extension 76 which is in alignment with and moves
through opening 77 of the cannula block 75 to aid in proper
alignment of the stylet and cannula blocks and therefore the
stylet/cannula assembly.
Mounted in the ends of each of the cannula and stylet
blocks are drive rods 62 which rods are in turn secured to
drive arms 61. Each o~ drive arms 61 is provided with cam
follower 60, which ride in the continuous groove 56 of cam
55. Thus, rotation of cam 55 will result in sequential
linear movement of the stylet and cannula.
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This sequential linear movement is well illustrated in
Figs. 4A-4D. In Fig. 4A, each of the stylet 14 and cannula
13 are in a retracted position and immediately adjacent the
tissue mass ll. Initial rotation of cam 55, as shown in
Fig. 4B, results in lateral movement of stylet block 74 and
its attached stylet to penetrate the tissue mass where a
portion of the tissue is caught in notch 14a. Continued
rotation of the cam, as shown in Fig. 4C, results in
movement of the cannula block 75 and its attached cannula
into the tissue mass severing the portion of the tissue
within notch 14 from the tissue mass. As shown in Fig. 4D,
rotation of cam 55 has been reversed thus causing retraction
of the cannula exposing the tissue sample in notch l~a for
easy removal by the technician. Further rotation of cam 55 ;
will result in retraction of the stylet and the instrument
is again ready for use as shown in Fig. 4A.
Because of the need for precise movement of stylet and
cannula, guide means shown generally at 64 are used to
further aid in proper alignment of the stylet/cannula
assembly. As shown in Figs. 6, 6A and 6B, guide means 64
includes a generally cylindrical shaped housing 68 having a
rectangular opening 69 appro~imately sized to accommodate
the stylet and cannula blocks 74 and 75. Thus the stylet
and cannula blocks move laterally within the interior of
housing 68 and bear on the interior walls of the housing
aiding proper alignment. In addition, guide means 64 also
includes a cylindrical shaped guide 65 and bulkhead 70, the
latter separating guide 65 and housing 68. Guide 65, as
best shown in Fig. 6B, is a solid cylinder provided with
vertical channels 66 through which drive rods 62 operate.
Guide 65 is so constructed that separator 71 is provided
between channels 66 to assist in maintaining proper spacing
and alignment of the drive rods. ;~
In a preferred embodiment, the instrument has two
actuators or buttons which set as to motion the action of
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WO91/07915 PCT/US9OJ06891
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2072~74
the stylet/cannula assembly. Actuation of the fire button,
causes initial penetration of the stylet into the tissue
mass followed by penetration of the cannula. The initial
actuation of the retract button, causes retraction o~ the
cannula exposing the sample of tissue. A second actuation
of the retract button retracts the stylet and the instrument
is ready for further use.
Thus, as shown in Figs. 2, 3 and 3A, the instrument -
includes retract button 80 and a fire button 83, both of
which are preferably provided with a rubber seal. As shown
in Fig. 2, the retract button is located on the underside of
the instrument.~ Depression of the retract button engaqes
contacts 81 c~mpieting the circuit and allowing current to
flow into wire 82. As illustrated in Fig. 3, fire button 83
is located away from the retract button and on one side of
the instrument. The depression of fire button 83 actuates
micro switch 85 by means of lever 84 mounted on pivot pin B6.
The biopsy instrument is provided with an assembly and
circuitry which permits the stylet/cannula assembly to move
in a ~orward or reverse direction via the rotary motion of
the special function cam assembly with a rotation of
approximately 360 degrees. Rotation of cam 55 is controlled
via the limit switch assembly, stopping the rotation at -
pre-defined stylet/cannula assembly locations of, for
example: (1) both the stylet/cannula are forward; (2) the
stylet is forward but the cannula has been moved back; and
(3) where both the stylet and cannula are back. Such limit
swi.tch assembly is composed of two principal components,
stationary limit switch wiper plate 45 and rotatable limit
switch board 50. Stationary wiper plate 45 is provided with
six spring finger contacts 47 which are electrically
connected to the actuation buttons 80 and 83 and other
circuit components. The limit switch board 50 is a circuit
board which is fixed to the drive shaft 25. An electrically
conductive circuit pattern is present on one face thereof
~WO91/07915 PCT/US90/06891
2~
and the wiper plate 45 and rotatable limit switch board are
mounted in line in the instrument and in contact with each
other concentrically about the drive shaft. As the drive
shaft rotates clockwise or counterclockwise, the circuit
pattern on the rotatable limit switch board creates
particular circuit paths by connecting specific spring
finger contacts during the rotational action. The purpose
of these specific circuit paths on the rotatable limit
switch board allows the stylet/cannula assembly to stop at
prescribed positions.
The instrument is also provided with a toggle assembly
which includes a stationary wiper plate 28, toggle board 34
and toggle plate 40. The stationary wiper plate is very
similar to the stationary limit switch wiper plate 45 in the
limit switch assembly and is also provided with si~ spring
finger contacts 29 which are an electrical contact with the
actuation buttons and other circuit components. Toggle
board 34 has electrically conductive circuit pattern 30
deposited on one face. Wiper plate 28 and toggle board 34
are mounted in line and in contact with each other
concentrically about the drive shaft 25. As the drive shaft
rotates either clockwise or counterclockwise, key 27 on ~
shaft 25 contacts protrusion 37 on the toggle board. When -
the key and protrusion meet the toggle board is forced to
rotate a slight distance in clockwise or counterclockwise
direction and the circuit pattern on the toggle board
creates a particular circuit path by being in contact with
specific spring fingers 29. The amount of rotation of the
toggle board is controlled by pin 38 riding in V-shaped
opening 43. The purpose of the specific circuit paths of
the toggle board is to allow the stylet/cannula assembly to
travel in prescribed directions of motion via depression of
the retract button 80. This particular construction allows
the retract button 80 to serve as a dual function switch in
the retraction phase of the biopsy instrument. After the
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W091/0791~ PCT/VS90/06891
20729-~4 -20- ~
forward motion of the stylet/cannula assembly is completed,
retract button 80 can be pressed and the stylet of the
stylet/cannula assembly moves back or retracts resulting
from approximately one-half a revolution of the special
function cam. The llmit switch assembly stops the rotation
at approximately the mid-point of reverse travel nd the
toggle hoard is mechanically rotated as previously
described. Th~ shift in the position of the toggle board 34
changes the electrical circuitry to allow a second actuation
of the retract button which continues the cam rotation until
the limit switch assembly stops rotation at the end of
travel and the cannula is fully retracted.
Figs. lOA-lOG illustrate schematically the basic
circuitry involved in various actions of the biopsy
instrument. In these figures, the circuitry and activity of
the toggle assembly is shown generally at 90, and the
circuitry and activity of the limit switch assembly is shown
generally at lOO. Connectors 31 of the stationary wiper
plate 28 of the toggle assembly are designated "t", "B",
~C", "~ D~ and ~A~. Connectors 48 of the limit switch
wiper plate 45 are designated "K", "G", "H", "E", "I", and
'~J". In the limit switch assembly schematic lOO, the arm
limit switch is designated 102 and the sample limit switch
is designated 104. In the toggle assembly schematic 90, the
positions of the rotatable toggle board 34 are designated
either 92 or 94. Closing the arm limit swit~h 102 initiates
the sequential, linear forward motion of both the stylet and
cannula. The arm limit switch 102 thus controls the
sequential forward movement of the stylet/cannula assembly.
The sample limit switch 104 controls the retraction of the
cannula. The path of current flow of all figures lOA - lOG
is shown with bold lines.
Fig. lOA illustrates a ready to fire situation; that is,
both the stylet and cannula are fully retracted. The toggle
~oard 34 has rotated with an imaginary point on the shaft 25
~ W09l/079l5 -21- PCT/US90/06891
i 2 b 7~ 7 4
or cam 55 being at 0 degrees. As shown in Fig. lOA, the
position of the toggle board is at 94 which allows current
to flow only to fire button 83. Both the arm limit switch
102 and the sample limit switch 104 are open and the retract
button is therefore not in the circuit and even if
depressed, no action would occur.
Fig. lOB illustrates what happens when the fire button
is depressed. Depression of the fire button sends current
to the motor "M" causing rotation of the cam "C" 55 and
forward movement of the stylet and cannula. As shown in the
limit switch assembly 100 of Fig. lOB, both the arm limit
switch 102 and sample limit switch 104 are open and no
current is flowing through the limit switch assembly.
Fig. lOC illustrates the situation at the end of the
fire cycle shown in Fig. lOB. At this point, shaft 25 and
cam 55 have rotated appro~imately 320 degrees from an
initial 0 degree position and each of the stylet and cannula
have moved sequentially to a fully extended position. Key
27 on shaft 25 has made contact with protrusion 37 of toggle
board 34 to rotate toggle board 34 which in turn causes the
toggle switches to move from position 94 to position 92.
This mo~ement of the toggle switches results in a break in
the circuit path to motor M. In the limit switch assembly
100, the arm limit switch 102 ls open, and the sample limit
switch 104 is closed. Both the stylet and cannula are
forward.
In Fig. lOD, the circuit at fire button 83 is now open
and the toggle switches of the rotatable toggle board 34 are
at the position designated 92, as they were at the end of
the fire cycle shown ;n Fig. lOC. The toggle board in this
position allows current to flow to the retract button 80 via
the limit switch assembly circuit. As shown in the limit
switch assembly circuit 100, the sample limit switch 104 is
closed and the arm limit switch 102 i5 open. Thus,
depression of retract button 80 causes the motor M to
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WO~1/07915 PCT/~S90/06891
`20~97~ -22-
reverse, causing rotation of the cam to reverse, resulting
in retraction of the cannula.
In Fig. lOE, the toggle switches of the toggle board are
at position 92 and in this position actuation of the fire
button would have no effect. In the limit switch assembly
circuit l00, arm limit switch 102 is closed and the sample
limit switch is open. The retract button circuit 80 is open
preventing any further cam motion. In this situation, the
cannula is back and the stylet is forward.
Fig. l0F, shows the activity upon a second depres~ion of
the retract button 80. In the toggle assembly 90, the
toggle board swi~tches are in the position designated 92
which allows cùrrent to flow to the retract button via the
limit switch assembly circuit l00. The arm limit switch 102
is closed. When the retract button is depressed motor M
operates retracting the stylet and thus both the stylet and
cannula are in a ready to fire position. ;
Fig. lOG illustrates the situation at the end of the
retraction of both the stylet and cannula. At the end of
the retraction cycle, the drive shaft key moves the toggle
board to a 20 degree rotation point. In the limit switch
assembly l00, the arm limit switch 102 is open and the
sample limit switch 104 is closed. Thus the retract button
is not in the circuit at this point, and no action will
occur even if depressed.
One of the features of the instrument of this invention
is its ability to deliver a substantially constant force and
velocity to the tissue penetrating and severing means, that
is the stylet and cannula, thereby obtaining a higher
quality tissue sample. This is graphically illustrated in
Figs. 14A and 14B where the force and velocity of a typical
spring powered instrument (indicated by a dashed line) is
compared with the biopsy instrument of this invention
~indicated by a solid line). Assuming that the stylet and
cannula travel a distance of about l inch from a retracted
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WO9l/079~5 PCT/US~0/06~91
-23- 2 ~7;2-97~4
to a fully extended position, as shown in Fig. 14A it will
be seen that the instrument of this invention delivers a
virtually constant force to the stylet and cannula from a
retracted to fully extended position. On the other hand,
the spring powered instrument, although initially delivering
a considerably greater force, this force diminishes very
rapidly due to tissue resistance and spring
characteristics. Substantially the same is true with
respect to the velocity of the stylet and cannula of the two
instruments. As shown in Fig. 14B, although the initial
velocity of each instrument is about the same, the
instrument of this invention delivers a constant velocity
over almost all of the travel of the stylet and cannula
whereas in the spring powered instrument the velocity again
diminishes very rapidly throughout the required travel.
Referring to FIGS. 15A-15F, a second embodiment of the
invention is shown generally is biopsy instrument 210 having
a second embodiment of a stylet/cannula assembly shown as -~
212. The stylet and cannula assembly 212 and its component
20 parts are illustrated in FIGS. 16A-16E, 17A-17E, 18A-18E,
l9A and l9B.
Biopsy instrument 210 is substantially the same as
biopsy instrument 10 previously descrlbed with certain
modifications and refinements. One such improvement is the
25 presence of lever 2B6 at front end 271 of the biopsy ~ -
instrument. As illustrated in FIGS. 15A-15F, lever 286 has
pivot 288 located between handle end 289 and cam end 287.
Pivot 288 (shown in phantom lines in FIG. 15A) is pivotably
attached to front end 271 alongside of rectangular opening
30 269 which receives stylet mount 274 and cannula mount 275
therein. As described with instrument 10, biopsy instrument
210 has two drive rods in the front end 271 for successively
moving the mounts for cannula 213 and stylet 214. Lever 286
enables the operator to more easily remove stylet mount 274
35 and cannula mount 275 from opening 269.
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WO91/0~91~ PCT/US90/06891
~ -24-
~07297~` ~
As shown in FIG. 15C, lever 286 may be swung outwardly
in the direction of arrow "S" by the operator pulling
outwardly on handle end 289. This causes lever 286 to pivot
about pivot 288, causing cam end 287 to apply force "F"
along the back side of stylet mount 274. Note that
optionally mount 274 has a rounded back surface to more
smoothly engage with cam end 287. The force against mount
274 correspondingly e~erts force on mount 275, urging both
of the mounts 274 and 275 forwardly off of drive rod 262a
and 262b. Of course, lever 286 may be made to engage mount
275 as well. Furthermore, other mechanisms may be provided
to forwardly urge the~mounts off the drive rods, such as a
wedging mechanism, a threaded screw mechanism, or the like.
Thus, this mec~anism for urging the mounting blocks off
the drive rods is especially useful in conjunction with
another feature of the present invention, described below,
which provides a locking mechanism to lock the cannula mount
and stylet mount on the drive rods.
Another optional feature (not illustrated) is lever 286
may have a stop member projecting laterally inward from end
289 across opening 269 when lever 286 is in a closed or
loaded position. Such stop member acts to block the stylet
and cannula mounts from being projected out of opening 269
upon firing of the biopsy device, and yet swings out of the
way during removal of the mounts such as illustrated
generally in FIG. l5C.
Biopsy instrument 210 includes firing button 283. Also,
instrument 210 may optionally have a modified cam, like cam
55, with section 56c of the cam groove modified so its slope
is not constant, but instead varies.somewhat near sections
56a and 56b. In this way, the velocity of the stylet and
cannula are not necessarily constant, but it is believed
improved performance can be achieved.
Stylet and cannula assembly 212 include cannula mount
35 275 having a tubular cannula 213 secured thereto and
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WO91/07915 P~T/US90/06891
~ -25~ ` 20`7~ 74
projecting forwardly therefrom. Cannula mount 275 has drive
rod recess 223 in backside 225 of the cannula mount. This
recess is sized and positioned for receiving drive rod 262a
(see FIG. l9A) of the biopsy instrument therein. Similarly,
stylet mount 274 has drive rod recess 222 therein in
backside 224 of the stylet mount for receiving drive rod
262b therein. Stylet mount 274 has stylet 214 secured
thereto, projecting forwardly and located within tubular
cannula 213. Stylet 214 is slidable through cannula 213 as
described above with cannula 13 and stylet 14. Stylet mount
274 slides along a top side 240 of a bottom portion 238 of
cannula mount 275. Cannula mount 275 also includes a
forward portion 239 which projects above top side 240 of
bottom portion 238 of the cannula mount. In this way, front
portion 239 is in front of stylet mount 274, providing
forward confinement for stylet mount 274.
As illustrated in FIGS. 16D, lBD and l9B, the stylet and
cannula assembly 212 has a generally rectangular frontal
profile which is receivable in rectangular opening 269 in
the front end of the biopsy instrument. This is similar to
the previously described rectangular opening 69 sized to
accommodate the stylet and cannula mounts 74 and 75 to
provide a guide way for the stylet and cannula assembly.
Similarly, assembly 212 has a generally rectangular shape
having a height "H" and a width "W" as illustrated. In the
preferred embo~iment, height H is appro~imately Q.8 inches
and width W is approximately 0.4 inches. Note that this
generally rectangular shape may vary somewhat, such as with
a slightly rounded top profile 218 along the top side of
assembly 212 and with truncated corners, such as truncated
corner 217 along the bottom side of assembly 212. Opening
269 acts as a guideway in the front end of the biopsy
instrument surrounding drive pin 262a and drive pin 262b and
keeping the forward and reward movement of assembly 212 in
proper alignment.
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W091/079l5 PCT/U~90/06891
`,,2~7,a~,7~ -26- ~
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Mount 274 and mount 275 may have a variety of
configurations, such as the use of lateral ribs like rib 249
and rib 245 as illustrated. In the preferred embodiment,
mounts 274 and 275 are made of molded plastic, although
other materials may be used including metal.
Referring to FIGS. l9A and l9B, a preferred version of a
locking mechanism to hold mount 275 and mount 274 on to
drive rod 262a and drive rod 262b, respectively, is shown.
Drive rod 262a includes annular groove 231 therein near its
forward end. Rod 262a is disposed in recess 223. One or
more locking projections, such as projection 228, projection
229 and projection 230 engage annular groove 231. These
projections are deformable to allow the projections to snap
in and out of the annular groove upon insertion or removal
of rod 262a from recess 223. Preferably, these projections
are positioned in recess 223 at distance D of at least 0.2
inches behind front wall 243 within recess 223. Distance D
may be greater than 0.2 inches if necessary, but should be
sufficient to accommodate the tapered forward end of the
drive rod. Similarly, in recess 222 of the stylet mount
274, the locking mechanism 232 should be spaced a distance
from front wall 242 of at least 0.2 inches. Likewise, drive
rod 262b has annular groove 235 therein which receives
snap-in locking projections 232, 233 and 234. The locking
action caused by the interaction of these projections in the
recesses and annular grooves on the drive rods prevent
assembly 212 from being shot out of opening 269 like a
projectile upon actuation of the drive mechanism in biopsy
instrument 210. This allows for a safer instrument while
allowing removal by actuation of lever 286, as described
above, to overcome the locking action of the projection and
grooves. The locking mechanisms also allow for rearward
movement of the stylet and cannula in response to rearward
movement of the drive rods. It is to be understood that
other such locking mechanisms may be utilized including
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~ WO91/07915 -27- PCT/US90/06891
0~7-2 9`7 ~
substitution of things such as divots or recesses in the
drive rod, rather than annular grooves. Another approach
n~ay be the utilization of a recess or groove in the stylet
and/or cannula mount with a radially outward projection on
the drive rod. Likewise, although a friction fit, such as
by utilizing an elastomeric liner may also be used, a
positive locking mechanism, as illustrated is preferred.
The present invention also provides the ornamental
design for cannula mount 275 and cannula 213, stylet mount
274 and stylet 214, and stylet and cannula assembly 212, as
shown and described.
While the invention has heen illustrated and described
in detail in the drawings and foregoing description, the
same is to be considered as illustrative and not restrictive
in character, it being understood that only the preferred
embodiment has been shown and described and that all changes
and modifications that come within the spirit of the
invention are desired to be protected.
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