Abstract:
Soft tissue biopsy apparatus for obtaining a tissue specimen comprises a compact handle functioning as a housing having an opening at a front end thereof through which a tubular cannula is arranged to pass. Disposed in the lumen of the cannula is a stylet having a notch formed near its distal end in which a tissue sample is to be captured. First and second springs are operatively coupled individually to the cannula and stylet and a cocking slide incorporating a force reducing mechanism is used to compress the springs while establishing the size of the specimen to be collected in the notch. A trigger mounted on the cocking slide can be used to release the compressed springs in close succession to first advance the end of the stylet beyond the end of the cannula whereby tissue to be extracted flows into the notch and then the spring driving the cannula is released forcing the cannula forward and severing the piece of tissue contained in the notch from surrounding tissue.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application is a continuation-in-part of U.S. patent application Ser. No. 10/391,737, filed Mar. 19, 2003 now abandoned, and entitled “Soft Tissue Biopsy Instrument”. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates generally to a biopsy instrument, and more particularly to an improved apparatus for performing soft tissue biopsy. 
   2. Discussion of the Prior Art 
   In the “Background of the Invention” section of U.S. Pat. No. 5,036,860, there is set forth a discussion of prior art soft tissue biopsy devices and the shortcomings of those devices. The contents of U.S. Pat. No. 5,036,860 are hereby incorporated by reference as if set forth in full herein. 
   The preferred embodiment of the invention described in the &#39;860 patent comprises an elongated housing having somewhat the shape of a ballpoint pin and with a small opening at one end. A first and hollow cannula is positioned within the housing and is reciprocally moveable. One end of the first cannula extends through the opening in the elongate housing and has a sharpened tip for insertion into tissue from which a biopsy specimen is to be taken. A needle-like stylet is positioned within the first cannula and is reciprocally moveable within the lumen of the first cannula. The needle has a sharpened tip for facilitating insertion into tissue and proximate the sharpened tip is a notch or recess into which the tissue specimen projects when the needle is inserted into soft tissue. 
   The needle stylet is mounted in a slide, allowing it to move independently of the first, outer cannula. A spring and latch mechanism is provided that allows the needle and cannula combination to be placed in a cocked position. Once the device is cocked, it is inserted into the soft tissue from which a specimen is to be withdrawn and the device is “fired”. In a two-step sequence, the needle stylet is first returned to its uncocked position and then the outer cannula also is advanced to slide over and sever the biopsy sample from surrounding tissue and to capture the specimen contained in the stylet&#39;s notch as the needle and first cannula are simultaneously withdrawn from the target tissue. 
   During a soft tissue biopsy procedure, it is often desirable to collect multiple samples proximate a suspected tumor or the like. In the prior art devices described in the &#39;860 patent, only a single sample can be taken for any one penetration of tissue by the outer cannula. This is because the outer cannula and the stylet housed therein must be removed from the patient before a first sample can be released for microscopic examination. Thus, it would be advantageous to have a soft tissue biopsy device that would allow multiple samples to be extracted from the patient without having to create multiple puncture wounds, thereby reducing patient trauma. 
   PCT International Publication WO 96/04851 describes a biopsy instrument that is designed to be fired twice to collect two biopsy specimens in a notched stylet without removing the instrument from the patient&#39;s body. However, it has no provision for adjusting the length of the multiple specimens. They are each necessarily of the same length. 
   While prior art biopsy devices of the type described have permitted adjustment of the sample size to be excised, none, so far as is known, has allowed multiple samples of different sizes to be extracted without having to make multiple punctures with the cannula. 
   In the prior art arrangement described in the &#39;860 patent, the release of a spring force for driving the sampling stylet results in the triggering of the outer cannula as the stylet reaches its end of travel point. It would be advantageous in an instrument of the type described if the outer cannula movement can be made independent of stylet firing if so desired in a fully automated device. 
   Then, too, it is important that the soft tissue biopsy instrument provide for one-handed operation and that it be safe to use, having suitable interlocks for preventing premature, unintended firing of the stylet and/or outer cannula. 
   SUMMARY OF THE INVENTION 
   The foregoing objects and advantages are achieved by providing a soft tissue biopsy instrument that comprises a housing member having a generally hollow handle that is partitioned into first and second compartments. The housing member has closed distal and proximal ends but with a small aperture formed through the distal end. A tubular cannula of a predetermined inside diameter has a tubular hub affixed to its proximal end. The distal end of the tubular cannula is beveled to a sharp, tissue piercing point and the outside diameter of the cannula allows it to freely pass through the aperture in the distal end of the housing. 
   The instrument further comprises a stylet that is adapted to be slidably inserted into and removed from the lumen of the cannula. The stylet has a slide member affixed to a proximal thereof and a sharpened distal end. Formed a predetermined distance proximal of the distal end of the stylet is a notch of a predetermined length and depth in which multiple tissue specimens are to be collected. The slide member on the distal end of the stylet is reciprocally moveable in a guideway formed in the housing member. First and second compression springs are individually disposed in the first and second compartments formed in the housing. The first spring is operatively disposed between the housing and the slide member on the proximal end of the stylet and the second spring is operatively disposed between the housing and the tubular hub on the proximal end of the cannula. In order to compress and store energy in the springs, a cocking assembly is slidably mounted on the housing and is operatively coupled to the first and second springs for compressing both springs, while simultaneously retracting the cannula and the stylet in a proximal direction in discrete steps where the number of steps establishes the length of the specimen(s). The cocking assembly further supports a release button which, when depressed, sequentially releases energy stored in the first and second springs to first drive the stylet in the distal direction and then drive the cannula in a distal direction whereby a single tissue sample is cut free of surrounding tissue and retained in the stylet&#39;s notch. The device can be recocked to collect a further specimen or the stylet can be withdrawn from the lumen of the cannula without a need to also remove the cannula from its position within the body of the patient. As such, the specimen(s) collected in the stylet&#39;s notch can be removed and the stylet replaced within the cannula without having to reinsert the cannula. 

   
     DESCRIPTION OF THE DRAWINGS 
     The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of a preferred embodiment, especially when considered in conjunction with the accompanying drawings in which like numerals in the several views refer to corresponding parts. 
       FIG. 1  is a perspective view of the biopsy instrument; 
       FIG. 2  is a perspective drawing of the stylet used in the biopsy device of  FIG. 1 ; 
       FIG. 3  is a perspective drawing of a piece part comprising the instrument&#39;s handle; 
       FIG. 4  is a perspective view of the stylet spring retention sleeve; 
       FIG. 5  is a perspective view of the cannula spring retention sleeve; 
       FIG. 6  is a perspective view of the handle&#39;s rear cover member; 
       FIG. 7  is a bottom perspective view of the device of  FIG. 1  with the cocking and trigger assembly removed; 
       FIG. 8  is a perspective view of the handle&#39;s front cover; 
       FIG. 9  is a perspective view of the sequence actuating shutter forming part of the assembly of  FIG. 1 ; and 
       FIG. 10  is an exploded view of the biopsy instrument of  FIG. 1  showing the internal components in their appropriate orientation. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The preferred embodiment of the invention illustrated in the drawings constitutes a new and improved automated tissue biopsy device that permits unique operating features and ease of operation, not available in other commercially available automated needle biopsy devices. Included as features of the invention and described in detail hereinbelow are:
         Following insertion of the needle into soft tissue and the firing of the device, a stylet containing the tissue sample can be removed from the device without extracting the biopsy needle from the patient;   The stylet can be replaced in the device and the device can be cocked and refired while it remains in the patient;   Multiple samples of the same or differing length can be collected by multiple cocking and firing sequences without removing the stylet from the cutting cannula.   A single button/slide assembly on the device is used to control all of the functions of the device, namely, the cocking, setting of tissue sample size, sequential or closely simultaneous firing of the stylet and cannula and allows the removal of the stylet from the cannula; a unique firing mechanism built into spring retention sleeves permits automatic firing of both the needle and the cannula either individually or sequentially;   A unique force divider substantially reduces the cocking force, thereby permitting simultaneous cocking of the stylet and cannula drive springs and selective adjustment of the tissue sample size to be extracted. Reduction of the cocking force tends to insure that the cannula will not be moved during the cocking operation;   A unique mechanism prevents the device from being fired before cocking is completed;   A unique sequencing actuator controls the firing sequence whereby the stylet is fired first and the cannula second and also controls the latching sequence whereby needle orientation is properly managed.       

   The way in which the foregoing features are realized will now be explained. Certain terminology will be used in the following description for convenience in reference only and will not be limiting. The words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the device and associated parts thereof. Said terminology will include the words above specifically mentioned, derivatives thereof and words of similar import. 
   Referring to  FIG. 1 , there is indicated generally by numeral  10  a somewhat enlarged perspective view of a soft tissue biopsy device. It is seen to comprise a molded plastic handle member  12  having an outer needle or cannula  14  projecting through an opening formed in a front face  16  of the device. The needle or cannula  14  is preferably formed from stainless steel and may comprise hypodermic stock of a predetermined length and a diameter in a range of from about 14 ga. to about 20 ga. Its distal end  18  is beveled to a sharp point to facilitate its ability to pass through soft tissue. 
   The cannula  14  has a lumen for receiving a tissue sampling stylet  20  therethrough. The stylet  20  is affixed to a molded plastic grip member  22  having dove-tail side edges  24  and  26  that ride in a slot  28  provided in the handle  12 . The grip member includes an outwardly projecting ear  30  having serrated side surfaces to facilitate its being gripped between a thumb and forefinger to facilitate its being pulled rearward beyond the end  32  of the guideway  28  so that the stylet  20  can be fully extracted from the confines of the outer tubular cannula  14 . 
   Referring momentarily to  FIG. 2 , it will be seen that the stylet  20  includes an elongated notch  34  in which one or multiple sample(s) can be captured and retained following the firing of the device, all as will be further explained. The distal end of the stylet  20  is beveled to a sharp cutting edge  36 . Its proximal end  38  extends through a tubular bore  40  formed in a downwardly projecting rib  42  that is integrally formed with the grip member  22 . The grip member  22  also includes a transversely extending slot  44  for receiving a latch member  46  ( FIG. 1 ) therein. When the latch member is in the position illustrated in  FIG. 1 , the grip member  22  is effectively connected to an internal spring-driven ferrule which will be further described when the exploded view of  FIG. 4  is explained. 
   Also slidable mounted to the handle member  12  is a combination cocking slide  48  and firing trigger  50 . As the cocking slide  48  is pulled rearward by the user&#39;s finger, springs associated with the cannula  14  and stylet  20  are simultaneously compressed to store energy. Also, sliding the cocking lever  48  rearward displaces the grip member  22  rearward to establish how much of the notch  34  will become exposed out the end of the tubular needle  14  during a first phase of the firing sequence of the device. This establishes the size of the specimen that will be collected. To aid the user, a numeric scale  52  is mounted alongside the guideway  28  and a fiducial mark (arrow) on the grip member  22  points to the scale to indicate the size of the sample to be extracted. A further indicator  53  is visible through a hole  55  in the handle  12 . When the device has been cocked and is ready to fire, the indicator  53  shows red. Once the trigger  50  has been depressed to fire, both the stylet  20  and the cannula  14 , the indicator  53  shows green. 
   A molded piece part comprising the housing  12  is illustrated in perspective in  FIG. 3 . Molded from a suitable medical grade plastic in an injection molding operation, the housing  12  includes a generally flat base  54  having a slot  56  formed longitudinally through it. Supported on the base are first and second generally tubular portions  58  and  60  with a common wall  62  extending between them. Formed through the thickness dimension of the tubular member  60  is a longitudinally extending slot  64  leading away from a generally rectangular aperture  66 . Likewise, the tubular member  58  also includes a longitudinally extending slot  68 . The wall  62  where the tubular members  58  and  60  merge with one another define a V-shaped groove  70 . Integrally formed with and projecting upwardly from the top surface of the tubular members  58  and  60  are wedge-shaped wings  72  and  74  whose vertical walls  76  and  78  define a guideway for the stylet gripper member  22 . That is, the stylet gripper member  22  is dimensioned to fit between the vertical walls  76  and  78  and with the fin  42  resting in the V-shaped groove  70 . 
   Referring next to  FIG. 4 , there is shown a stylet spring retention sleeve  47  which is generally cylindrical and which has the latch member  46  integrally molded therewith. The sleeve  80  has a generally open rearward end  82  and a closed forward end  84 . The closed end  84  includes a rectangular aperture  86 . The outside diameter of the sleeve  82  is sized so as to allow it to freely slip into the second tubular portion  60  of the handle member  12  with the latch member  46  projecting upward through the slot  64 . 
     FIG. 5  is a perspective view of the cannula spring retention sleeve, which is indicated generally by numeral  88 . It, too, is cylindrical and hollow with an open rearward end  90  and a closed forward end  92 . A rectangular aperture  94  extends through the otherwise closed end  92 . Extending radially outward from the exterior surface of the cannula spring retention sleeve  88  is a protuberance  96  that has a bore  98  formed through it for receiving a proximal end portion of the cannula  14  therein. When the sleeve  88  is inserted into the housing member  12 , the protuberance  96  extends out through the longitudinal slot  68  when the sleeve  88  is contained within the first tubular portion  58  of the handle  12 . Also one or the other of colored areas  99  or  101  will be visible through the aperture  55  depending on whether the device is cocked or not. 
   Turning next to  FIG. 6 , it shows a perspective view of a rear cover  100  for the housing  12 . Projecting outward from the inner face of the cover plate  100  are barb latches  102  and  104  that are adapted to mate with rectangular apertures  106  and  108  formed through the wall of the housing member  12 . The barb members  102  and  104  are sufficiently resilient to allow them to deflect as the cover plate  100  is pushed against the rear edge of the housing. Upon reaching the apertures  106  and  108 , the barbs spring through those openings to latch the cover in place. 
   Also projecting perpendicularly from the rear face of the cover plate  100  are longitudinally extending posts  110  and  112  each having a plurality of ratchet teeth  114  and  116  formed thereon. As can be seen in the exploded view of  FIG. 10 , helically wound compression springs  118  and  120  surround the posts  110  and  112  and fit into the sleeves  80  and  88  that are held within the housing  12  when assembled. The end portions  122  and  124  of the posts  110  and  112  extend through the rectangular openings  86  and  94  formed in the closed ends of the sleeves  80  and  88 . The spacing between adjacent ratchet teeth establishes the resolution in specimen size that can be collected. 
   Referring again to the cover member  100 , a further cylindrical post  126  projects perpendicularly from the rear face of the cover  100  and a further compression return spring  128  ( FIG. 7 ) is disposed on the post  126  for a purpose that will be further explained hereinbelow. 
   The front cover for the housing  12  is shown in  FIG. 8  and is indicated generally by numeral  130 . A stepped rib  134  having a first portion  136  of a predetermined height dimension and a second portion  138  of approximately twice the height of the portion of the rib  136 , thereby defining a stop or shoulder  140  is centrally disposed on the inner surface of the front cover  130  and acts as a glide for a shutter  144 . 
   Integrally molded with the front cover is a top member  142  that fits between the vertical edges  76  and  78  of the wedge-shaped wings  72  and  74  of the handle  12 . 
     FIG. 9  is a perspective view of a sequence actuating shutter  144  which is adapted to cooperate with the stepped rib  134  that is formed on the inner face of the front cover  130 . Formed inwardly from the side edge  146  is a notch  150  having a first reference surface  152  at a first predetermined distance from a reference end  154  of the shutter member. In a like way, a notch  156  having a reference surface  158  extends inward from the side edge  148  of the shutter. The reference surface  158  is at a slightly greater displacement from the reference edge  154  than is the reference surface  152 . The shutter  144  further includes the central groove  160  formed partially through the thickness dimension of the shutter  144  and leading to a slot  162  that extends completely through the thickness dimension of the shutter. The shutter  144  is juxtaposed to the rear face of the front cover  130  so that the portion  136  of the rib  134  fits within the groove  160  of the shutter while the portion  138  of double thickness extends into the slot  162 . The shutter is dimensioned and the groove  160  is sized to allow the shutter  144  to slide relative to the inside surface of the front cover until a point is reached where the shoulder  140  engages the bottom  164  of the slot  162  thereby providing a stop mechanism preventing the posts  110  and  112  from becoming hyper extended. The trigger  50  is likewise protected from over extension. 
   Turning now to the exploded assembly drawing of  FIG. 10 , with the spring retaining sleeves  80  and  88  inserted into the respective first and second tubular portions  58  and  60  ( FIG. 3 ) of the handle  12  and the rear cover plate  100  also affixed to the handle, the inner ends of the springs  118  and  120  abut the closed ends of the sleeves  80  and  88  while the ends  122  and  124  of the posts  110  and  112  extend through the rectangular apertures  86  and  94  of the sleeves. Front cushions  166  and  168  are adhesively affixed to the closed ends of the sleeves  80  and  88  and these cushions or pads have rectangular openings that align with the rectangular openings in the ends of the sleeves  80  and  88 . 
   When the front cover  16  is assembled onto the handle  12 , the ends  122  and  124  ( FIG. 6 ) of the posts  110  and  112  fit into the slots  150  and  156  of the sequence actuating shutter  144 . 
   A slide member  170  ( FIG. 10 ) is dimensioned to fit in sliding relation to the housing  12 . More particularly, the slide member  170  includes a pair of flanges  172  and  174  adapted to ride in channels  176  and  178  of the housing  12 . The cocking lever  48  has a pair of lateral edge channels  171  and  173  designed to fit into guideways  177  and  179  of housing  12  ( FIG. 3 ). A gear rack  175  is molded into the base of the cocking lever  48 . Formed through the raised center portion of the slide plate  170  is a rectangular opening  182  and fitted into that opening is a pinion gear  184  that is journaled for rotation on a pin  186  that passes through a transverse bore  188  formed in the raised center portion  180 . With reference to  FIG. 7 , it can be seen that a similar gear rack  190  is formed along the length of the handle  12  in alignment with the pinion gear  184 . The slide  170  further includes an outwardly projecting rib  192  at a front edge thereof that is adapted to cooperate with the closed front ends of the sleeves  80  and  88 . 
   In operation, as the cocking lever  48  is pulled rearward by the user&#39;s index finger, the projection  192  on slide  70  is in engagement with the spring retaining sleeves  80  and  88  and pulls those sleeves rearward, compressing the springs  118  and  120  as they move. An edge of the rectangular openings in the spring retention sleeves  80  and  88  engage the teeth  114  and  116  on the posts  110  and  112  to hold the sleeves  80  and  88  in place when finger pressure is removed. 
   In that the cannula  14  is attached to the protuberance  96  on the sleeve  88  and the stylet moves with the sleeve  80  by virtue of the engagement of the latch member  46  with the transverse slot  44  in the grip member  22 , it moves rearward with the displacement of the spring retaining sleeve  80 . Once the cocking slide has been drawn rearward a desired measured amount as reflected by the arrow on the stylet grip  22  and the numerical indicia  52 , the soft tissue biopsy device is ready for use in collecting a first specimen of a pre-set length. 
   Using appropriate imaging, the physician advances the cannula  14  and the stylet  20  projecting from the front end  16  of the handle into the area of the body where a tissue sample is to be taken. As the trigger button  50  is depressed, the front edge  51  thereof is brought into engagement with the bottom edge of the sequence actuating shutter  144 , displacing it along the guide  136  of the front cover  130  and first elevating the post supporting the spring  120 . When that post is elevated to the point where its teeth no longer engage the mating edge of the rectangular aperture  86  of the spring retaining sleeve  80 , the spring drives the sleeve  80  forward until its cushioned front end hits the closed end of housing  12 . In that the latch member  46  is engaged with the notch  44  of the stylet grip  22 , the stylet will be driven into the tissue where the sample is to be taken. The tissue fills the portion of the notch  34  extending beyond the end of the cannula  14 . When the release button  50  is further depressed, it elevates the shutter member  144  to the point where the teeth  116  on the post  112  supporting the spring  118  no longer engages the edge of the rectangular opening on the front end of the sleeve  88 , thus allowing the spring  118  to drive the sleeve  88  forward against the closed end of the housing  12 . This drives the cannula affixed to the protuberance  96  forward to slice the tissue sample contained within the notch of the stylet free of surrounding tissue. 
   At this point, the cocking lever  48  can again be pulled proximally a desired measured distance while the cannula  18  remains in place within the tissue to again cock the biopsy device in preparation of collecting a further specimen. The distal end of the cannula can be advanced, if desired, and when the trigger  50  is again depressed and the stylet driven distally, the friction between the earlier collected specimen and the inner wall of the cannula will cause the specimen to move to the proximal end of the notch  34 , making room for the further specimen to prolapse into the notch before the cannula again is driven distally to sever the specimen from surrounding tissue. This process can be repeated until the notch  34  in the stylet becomes filled. 
   Now, with the device of the present invention, the tissue sample(s) can be removed from the device without displacing the cannula from its current position within the body. This is done by rotating the latch member  46  out from the notch  44  in the stylet grip  22  and then pulling back on the ear  30  on the grip member to slide the stylet out from the lumen of the cannula  14 . Once the tissue sample(s) is removed from the notch in the stylet, the stylet can be replaced by sliding its distal end into the proximal end of the cannula and guiding the grip member  22  to its frontmost position, at which point the latch member  46  can again be rotated into the groove  44 , latching the stylet and its grip to the spring retaining sleeve  80 . With the instrument still in its position within the body of the patient, it can be recocked by again drawing back on the cocking slide member  48  preparatory to again firing the instrument. 
   By providing a gear rack on the undersurface of the cocking slide  48  as well as the undersurface of the housing  12 , and by providing the pinion gear  184 , a mechanical advantage is achieved lessening the finger force required to compress the springs  118  and  120 . The arrangement of the pinion gear  184  with the racks reduces the distance traveled by the slide member  170  by a 2:1 ratio, allowing a shorter return spring  128  to be used. 
   By depressing the firing trigger  50  down firmly in a single stroke, the stylet and the cannula will be advanced in rapid succession determined by the offset in the height of surfaces  158  and  152  relative to the reference surface  154  of the sequence actuating shutter  144 . When desired, by slowly depressing the firing trigger  50 , the stylet can be advanced without automatically releasing the cannula. By further depressing the firing trigger  50  at a later time, the cannula will be advanced. The surface  151  on shutter  144  ( FIG. 9 ) is arranged to cooperate with the end portion  125  of the post  112  ( FIG. 6 ) to prevent the stylet sleeve  80  from latching until after the cannula sleeve  88  ( FIG. 5 ) becomes latched, thereby synchronizing the latching sequence. 
   It should be noted that the biopsy device  10  cannot be fired while the cocking action is taking place. Until the cocking lever  48  has been returned to its forwardmost position by the return spring  128 , the edge  51  of the trigger button  50  cannot engage the edge  154  of the shutter  144  to lift the posts  110  and  112  so that their teeth no longer engage the bottom edge of the rectangular openings in the two spring retention sleeves. 
   This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the invention itself.