Abstract:
Medical instruments and methods of using the instruments are described. In some embodiments, a medical instrument includes a housing, a stylet having a portion in the housing, a movable first member in the housing, the movable member being connected to the stylet, and a second member located in the housing to reduce movement of the first member. The second member is configured to change movement of the first member from a first direction to a second direction different than the first direction.

Description:
TECHNICAL FIELD  
       [0001]     The invention relates to medical instruments, such as a biopsy needle instrument.  
       BACKGROUND  
       [0002]     A biopsy needle instrument can be used to obtain a tissue specimen for microscopic examination, e.g., to determine malignancy, while preferably subjecting the patient to the least trauma. In some embodiments, such instruments can have of a long, thin probe, called a stylet, within a close-fitting hollow needle, called a cannula. The stylet has a notch into which tissue can prolapse when the stylet enters the tissue.  
         [0003]     During use, a firing device first projects the stylet into tissue, followed immediately by the cannula. As the cannula slides over the stylet, the cannula severs tissue that has prolapsed into the notch of the stylet from the surrounding mass, and captures the prolapsed tissue as a specimen within the notch. The instrument can then be withdrawn and the piece of tissue removed from the stylet.  
       SUMMARY  
       [0004]     The invention relates to medical instruments, such as a biopsy needle instrument.  
         [0005]     In some circumstances, when a biopsy needle instrument is fired to propel a stylet, the stylet can rebound or kick back at the end of its travel. This kick back can reduce the accuracy of the instrument. In one aspect, the invention features a medical instrument having reduced kick back of the stylet.  
         [0006]     In another aspect, the invention features a medical instrument, including a housing, a stylet having a portion in the housing, a movable first member in the housing, the movable member being connected to the stylet, and a second member located in the housing to reduce movement of the first member, the second member configured to change movement of the first member from a first direction to a second direction different than the first direction.  
         [0007]     Embodiments may include one or more of the following features. The second member includes a raised portion configured to contact the movable first member. The raised portion is off-centered relative to a longitudinal axis of the instrument. The housing includes a recessed portion capable of accommodating a portion of the movable first member. The relief portion is on a side wall of the housing. The instrument further includes a cannula having a portion in the housing, and a movable third member connected to the cannula, wherein the second member is between the first member and the third member. The instrument further includes a pivotable latch capable of holding and releasing the movable third member. The instrument further includes a pivotable latch capable of holding and releasing the movable first member. The instrument further includes a first trigger capable of engaging the pivotable latch to release the movable first member. The instrument further includes a second trigger capable of engaging the pivotable latch to release the movable first member. The first trigger is located at a distal end of the housing. The first trigger is located between a distal end and a proximal end of the housing.  
         [0008]     In another aspect, the invention features a medical instrument, including a housing, a movable stylet block in the housing, a stylet connected to the stylet block, a movable cannula block in the housing, a cannula connected to the cannula block, and a stop between the stylet block and the cannula block, the stop configured to contact the stylet block off-centered relative to a center longitudinal axis of the medical instrument.  
         [0009]     Embodiments may include one or more of the following features. The stop includes a raised portion configured to contact the stylet block off-centered. The housing includes a recessed portion configured to accommodate a portion of the stylet block. The instrument further includes a pivotable latch capable of holding and releasing the cannula block. The instrument further includes a pivotable latch capable of holding and releasing the stylet block. The instrument further includes two triggers, either trigger capable of pivoting the latch to release the stylet block.  
         [0010]     In another aspect, the invention features a method of operating a medical instrument. The method can include moving a first member connected to a stylet from a retracted position to an extended position, and changing the direction of movement of the first member from a first direction to a second direction.  
         [0011]     Embodiments may include one or more of the following features. Changing the direction of movement of the first member includes rotating the first member. The method includes rotating the first member relative to an axial axis of the medical instrument. Changing the movement of the first member includes contacting the first member against a portion of the medical instrument off-centered relative to a longitudinal axis of the medical instrument. The method further includes stopping the movement of the first member. Movement of the first member is stopped and changed substantially simultaneously. The method further includes moving a portion of the first member towards a recessed portion of the medical instrument. The method further includes pivoting a latch holding a cannula in a retracted position to release the cannula. The method further includes activating a trigger at a distal end of the medical instrument to move the first member. Activating the trigger pivotally releases a latch holding the first member in the retracted position. The method further includes activating a trigger between the distal end and the proximal end of the medical instrument to move the first member. Activating the trigger pivotally releases a latch holding the first member in the retracted position.  
         [0012]     In another aspect, the invention features a method of operating a medical instrument, including moving a first member connected to a stylet, and contacting the first member against a second member located off-centered relative to a longitudinal axis of the instrument. The method can further include moving a portion of the first member into a recessed portion of the instrument. The method can further include rotating the first member.  
         [0013]     Other aspects, features, and advantages of the invention will be apparent from the description of the preferred embodiments thereof and from the claims. 
     
    
     DESCRIPTION OF DRAWINGS  
       [0014]      FIG. 1  is a perspective view of a biopsy needle instrument.  
         [0015]      FIGS. 2A, 2B ,  2 C,  2 D, and  2 E are exploded, perspective views of the instrument of  FIG. 1 , at various stages of assembly.  
         [0016]      FIG. 3  is a perspective view of a portion of a housing of the instrument of  FIG. 1 .  
         [0017]      FIG. 4  is a perspective top view of a stylet block of the instrument of  FIG. 1 .  
         [0018]      FIG. 5  is a perspective view of a portion of the stylet block and the housing of the instrument of  FIG. 1 .  
     
    
     DETAILED DESCRIPTION  
       [0019]     Referring to  FIG. 1 , a needle biopsy device  10  includes a housing  12 , a stylet  14 , and a cannula  16  coaxially receiving the stylet. Housing  12  includes a top shell  18  and a bottom shell  20  configured to mate together to form the housing. At its distal end  22 , stylet  14  is configured to penetrate tissue and includes a cupped notch  24  configured to collect a tissue sample. At its distal end  26 , cannula  16  is configured to sever tissue that has prolapsed into notch  24 . Both stylet  14  and cannula  16  extend proximally toward housing  12  and have portions inside the housing  12 . Stylet  14  and cannula  16  can be moved between retracted positions and extended positions. During use, stylet  14  and cannula  16  are loaded or cocked to their retracted positions, ready to be triggered, by moving a load button  28  proximally. When stylet  14  and cannula  16  are fired, they rapidly move distally to their extended positions, e.g., to collect a tissue specimen that has prolapsed into notch  24  of the stylet.  
         [0020]     Referring to  FIGS. 2A-2E , particularly to  FIG. 2E , at their proximal ends, stylet  14  and cannula  16  are connected to a movable stylet block  30  and a movable cannula block  32 , respectively. Stylet block  30  is configured to be movable to a retracted position, where the stylet block can be held, and subsequently, selectively released. Stylet block  30  includes a post  34  configured to engage with a loading mechanism  36 . Loading mechanism  36  includes a slidable member  38  slidably received on a platform  40  that rests on stylet block  30  and cannula block  32  ( FIG. 2B ). Slidable member  38  includes a projection  42  configured to attach to (e.g., snap in with) load button  28 , and a notch  44  configured to engage with post  34  of stylet block  30 . Thus, as load button  28  is moved proximally, notch  44  engages with post  34  to move stylet block  30  (and connected stylet  14 ) proximally to their retracted positions where they can be held by a stylet latch  46 .  
         [0021]     Stylet latch  46  is configured to hold stylet block  30  in a retracted position, and to release the stylet block selectively. Stylet latch  46  includes a distal component  48  and a proximal component  50 . Distal component  48  includes a side trigger  52 , a pivot  54 , and a wedge-shaped portion  56 . At its proximal end, distal component  48  has an angled surface  57  that engages with the distal end of proximal component  50 , as described below. Portion  56  is configured to allow stylet block  30  to slide to its retracted position, and thereafter, to engage with the stylet block (at the proximal face of the stylet block) to hold the stylet block in its retracted position. Side trigger  52  is located on the outside of housing  12  when device  10  is fully assembled. When side trigger  52  is pushed toward housing  12 , distal component  48  pivots about pivot  54  (arrow A), which moves wedge-shaped portion  56  out of engagement with stylet block  30 . When released from portion  56 , stylet block  56  is capable of moving distally under the spring force of a stylet spring  58 . Alternatively, stylet block  30  can be moved out of engagement with wedge-shaped portion  56  by operating proximal component  50  of stylet latch  46 . As shown, the area of distal component  48  near pivot  54  is formed relatively thick to provide good stiffness, and the area of the distal component at side trigger  52  is formed relatively thin to allow the distal component to flex as well as to provide clearance with other components in device  10  as the side is pushed in. The angled portion between pivot  54  and side trigger  52  provides a quick transition from the thick area to the thin area. The angled distal end of distal component  48  helps to keep side trigger  52  positioned outside of housing  12 .  
         [0022]     Proximal component  50  includes a rear trigger  60 , and an angled surface  62  at the distal end of the proximal component. When rear trigger  60  is pushed proximally, angled surface  62  engages with (e.g., rides on) angled surface  57  of distal component  48 , thereby causing distal component  48  to pivot about pivot  54  (arrow A) and moving wedge-shaped portion  56  out of engagement with stylet block  30  (arrow E,  FIG. 2D ). Thus, stylet block  30  can be fired by pushing either side trigger  52  or rear trigger  60 .  
         [0023]     After stylet block  30  is fired, device  10  is configured to stop and to deflect the movement of the stylet block. Referring further to  FIGS. 3, 4 , and  5 , bottom shell  20  of housing  12  includes a stop member  64  located between stylet block  30  and cannula block  32 . On the proximal side of stop member  64 , bottom shell  20  includes a rib or a raised portion  66  located off-center relative to the center longitudinal axis (L) of device  10 . As shown, rib  66  is formed at a lower corner of stop member  64  (e.g., by molding), but in other embodiments, the rib can be formed anywhere off-center of longitudinal axis L. Rib  66  is high enough for stylet block  30  to contact when the stylet block reaches its end point of travel. Referring particularly to  FIG. 5 , bottom shell  20  further includes a recessed portion or a relief  68  configured to accommodate a portion  70  of stylet block  30  (as shown, a rear corner).  
         [0024]     During use, after side trigger  52  or rear trigger  60  is activated, stylet block  30  is propelled distally toward stop member  64 . Stylet block  30  then strikes rib  66 , which causes the stylet block to rotate or to deflect (arrow B,  FIG. 4 ). In other words, when stylet block  30  strikes rib  66 , the movement of the stylet block is changed from a first direction (e.g., generally linearly and distally) to a second direction (e.g., sideways). It is believed that the deflection can also slightly misalign cannula  16  and stylet  14  to create friction to dissipate energy that may otherwise create kickback. No kinetic energy is believed to be dissipated until the end of the travel of stylet block  30 , such that the speed of stylet  14  during travel is enhanced (e.g., maximized) and the energy that is dissipated at the end of travel is excess energy. Rotation of stylet block  30  also moves portion  70  of the stylet block into recessed portion  68 . As a result, stylet block  30  is prevented from hitting stop member  64  and rebounding or kicking back, which can cause inaccurate sampling of tissue.  
         [0025]     Referring particularly to  FIG. 2E , cannula block  32  is configured to be movable to a retracted position, where the cannula block can be held, and subsequently, selectively released. Cannula block  32  includes a cannula post  72  configured to engage with slidable member  38  of loading mechanism  36  ( FIG. 2B ). As load button  28  is moved proximally, slidable member  38  engages with cannula post  72  to move cannula block  32  (and connected cannula  16 ) proximally to their retracted positions, where they can be held by a cannula latch  74 .  
         [0026]     Cannula latch  74  is configured to hold cannula block  32  in a retracted position, and to selectively release the cannula block. Cannula latch  74  includes two identical wedge-shaped portions  76  (only one of which is visible in  FIG. 2E ) and a pivot  78 . Wedge-shaped portions  76  are configured to allow cannula block  32  to slide to its retracted position, and thereafter, to engage with cannula block (at the proximal face of the cannula block) to hold the cannula block in its retracted position. Pivot  78  allows cannula latch  74  to seesaw (arrow C) so that cannula block  32  can be moved to and locked in its retracted position, and subsequently released. During use, when stylet block  30  is released from its retracted position and moves distally, the stylet block engages cannula latch  74  and pivots the cannula latch (arrow D). As a result, wedge-shaped portions  76  pivot out of engagement with and release cannula block  32 . Cannula block  32  is then capable of moving distally under the spring force of a cannula spring  80 .  
         [0027]     Examples of suitable stylet  14  and cannula  16  configurations are exemplified by the ASAP™ Automated Biopsy System having a Delta Cut® needle or a Channel Cut® needle (available from Boston Scientific Corp., Natick, Mass.), and described in Chu, U.S. Pat. No. 5,989,196, and commonly assigned U.S. Ser. No. 10/728,248, filed Dec. 4, 2003, hereby incorporated by reference.  
         [0028]     The components of device  10  (e.g., housing  12 , latches  46  and  72 , stylet block  30 , or cannula block  32 ) described above can be formed by injection molding techniques, e.g., of polycarbonate and/or ABS. Stylet  14 , cannula  6 , and springs  58  and  80  can be formed of stainless steel.  
         [0029]     In operation, cannula  16  and stylet  14  are loaded (e.g., moved proximally and retained in their retracted positions) and subsequently fired (e.g., released and propelled distally). More specifically, device  10  is loaded by moving load button  28  proximally, which moves cannula block  32  proximally via slidable member  38  and cannula post  72 . Cannula block  32  is moved proximally past wedge-shaped portions  76 , where the cannula block is held in its retracted position by portions  76 . Cannula spring  80  is compressed between stop member  64  and cannula block  32 . Moving load button  28  further proximally moves stylet block  30  proximally via notch  44  of slidable member  38  and post  34 . Stylet block  30  is moved proximally past wedge-shaped portion  56 , where the stylet block is held in its retracted position by portion  56 . Stylet spring  58  is compressed between a portion of bottom shell  20  and stylet block  30 . Device  10  is loaded and ready to be fired.  
         [0030]     To fire device  10 , distal end  22  of stylet  14  is placed adjacent to a target area, and either side trigger  52  or rear trigger  60  is actuated. For example, actuating side trigger  52  causes stylet latch  46  to pivot about pivot  54  (arrow E), thereby moving wedge-shaped portion  56  out of engagement with stylet block  30  and releasing the stylet block. Upon disengagement, stylet block  30  and stylet  14  are propelled distally by the spring force of stylet spring  58 , which allows the stylet to penetrate the targeted area, e.g., tissue. Stylet block  30  then strikes rib  66  and rotates (arrow B,  FIG. 4 ), which causes portion  70  of the stylet block to enter into recessed portion  68  of bottom shell  20 . As discussed above, this deflection of stylet block  30  dissipates energy from stylet spring  58 , reduces rebound of the stylet block and enhances accuracy of the device.  
         [0031]     Substantially simultaneously with striking rib  66 , stylet block  30  also engages and pivots cannula latch  74  about pivot  78  (arrow D,  FIG. 2E ). Pivoting cannula latch  74  disengages wedge-shaped portions  76  from cannula block  32 . Upon disengagement or release, cannula block  32  and cannula  16  are propelled distally by the spring force of cannula spring  80 , which allows the cannula to slide over stylet  14  and to sever a specimen that has prolapsed into notch  24  of the stylet.  
         [0032]     Device  10  can then be withdrawn from the targeted area. The specimen can be removed from notch  24  by first retracting cannula  16  and cannula block  32  proximally. The specimen can be placed on a slide or in a preservative solution. If desired, stylet  14  can be retracted to load device  10  and to collect another specimen.  
         [0033]     In other embodiments, the features described above, such as rib  66  and/or recessed portion  68 , can be incorporated into other embodiments of needle biopsy devices. Other embodiments of needle biopsy devices are described in commonly assigned U.S. Ser. No. 10/300,249, filed Nov. 20, 2002; U.S. Ser. No. 10/300,512, filed Nov. 20, 2002; and U.S. Ser. No. 10/728,248, filed Dec. 4, 2003, hereby incorporated by reference.  
         [0034]     In some embodiments, housing  12  can be made of different materials, e.g., to enhance the grip or “feel” of device  10 . For example, housing  12  can be formed of materials with different hardness, e.g., a core of relatively hard material and an outer layer of relatively soft material. The outer layer can be a foamy material, such as a urethane, to enhance the grip and/or to absorb vibrations from the firing of device  10 . Housing  12  can be formed with two or more different materials. For example, as shown in  FIG. 1 , device  10  includes side portions  100  formed of different materials to enhance grip and comfort.  
         [0035]     In other embodiments, referring to  FIG. 1 , housing  12  includes an opening  102  that, together with stylet block  30 , can provide a visual indication that device  10  is loaded. More specifically, when stylet block  30  is loaded to its retracted position, the stylet block can be seen through opening  102 . In some embodiments, stylet block  30  is formed of a bright color, e.g., red, to enhance its visibility.  
         [0036]     Terms such as “side”, “top” and “bottom” are used to describe embodiments as shown in the orientation of the figures and not intended to be limiting.  
         [0037]     Other embodiments are within the claims.