Medical instrument

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.

TECHNICAL FIELD

The invention relates to medical instruments, such as a biopsy needle instrument.

BACKGROUND

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.

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 The instrument can then be withdrawn and the piece of tissue removed from the stylet.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

The invention relates to medical instruments, such as a biopsy needle instrument.

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.

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.

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.

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.

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.

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.

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.

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.

Other aspects, features, and advantages of the invention will be apparent from the description of the preferred embodiments thereof and from the claims.

DETAILED DESCRIPTION

Referring toFIG. 1, a needle biopsy device10includes a housing12, a stylet14, and a cannula16coaxially receiving the stylet. Housing12includes a top shell18and a bottom shell20configured to mate together to form the housing. At its distal end22, stylet14is configured to penetrate tissue and includes a cupped notch24configured to collect a tissue sample. At its distal end26, cannula16is configured to sever tissue that has prolapsed into notch24. Both stylet14and cannula16extend proximally toward housing12and have portions inside the housing12. Stylet14and cannula16can be moved between retracted positions and extended positions. During use, stylet14and cannula16are loaded or cocked to their retracted positions, ready to be triggered, by moving a load button28proximally. When stylet14and cannula16are fired, they rapidly move distally to their extended positions, e.g., to collect a tissue specimen that has prolapsed into notch24of the stylet.

Referring toFIGS. 2A-2E, particularly toFIG. 2E, at their proximal ends, stylet14and cannula16are connected to a movable stylet block30and a movable cannula block32, respectively. Stylet block30is configured to be movable to a retracted position, where the stylet block can be held, and subsequently, selectively released. Stylet block30includes a post34configured to engage with a loading mechanism36. Loading mechanism36includes a slidable member38slidably received on a platform40that rests on stylet block30and cannula block32(FIG. 2B). Slidable member38includes a projection42configured to attach to (e.g., snap in with) load button28, and a notch44configured to engage with post34of stylet block30. Thus, as load button28is moved proximally, notch44engages with post34to move stylet block30(and connected stylet14) proximally to their retracted positions where they can be held by a stylet latch46.

Stylet latch46is configured to hold stylet block30in a retracted position, and to release the stylet block selectively. Stylet latch46includes a distal component48and a proximal component50. Distal component48includes a side trigger52, a pivot54, and a wedge-shaped portion56. At its proximal end, distal component48has an angled surface57that engages with the distal end of proximal component50, as described below. Portion56is configured to allow stylet block30to 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 trigger52is located on the outside of housing12when device10is fully assembled. When side trigger52is pushed toward housing12, distal component48pivots about pivot54(arrow A), which moves wedge-shaped portion56out of engagement with stylet block30. When released from portion56, stylet block30is capable of moving distally under the spring force of a stylet spring58. Alternatively, stylet block30can be moved out of engagement with wedge-shaped portion56by operating proximal component50of stylet latch46. As shown, the area of distal component48near pivot54is formed relatively thick to provide good stiffness, and the area of the distal component at side trigger52is formed relatively thin to allow the distal component to flex as well as to provide clearance with other components in device10as the side is pushed in. The angled portion between pivot54and side trigger52provides a quick transition from the thick area to the thin area. The angled distal end of distal component48helps to keep side trigger52positioned outside of housing12.

Proximal component50includes a rear trigger60, and an angled surface62at the distal end of the proximal component. When rear trigger60is pushed proximally, angled surface62engages with (e.g., rides on) angled surface57of distal component48, thereby causing distal component48to pivot about pivot54(arrow A) and moving wedge-shaped portion56out of engagement with stylet block30(arrow E,FIG. 2D). Thus, stylet block30can be fired by pushing either side trigger52or rear trigger60.

After stylet block30is fired, device10is configured to stop and to deflect the movement of the stylet block. Referring further toFIGS. 3,4, and5, bottom shell20of housing12includes a stop member64located between stylet block30and cannula block32. On the proximal side of stop member64, bottom shell20includes a rib or a raised portion66located off-center relative to the center longitudinal axis (L) of device10. As shown, rib66is formed at a lower corner of stop member64(e.g., by molding), but in other embodiments, the rib can be formed anywhere off-center of longitudinal axis L. Rib66is high enough for stylet block30to contact when the stylet block reaches its end point of travel. Referring particularly toFIG. 5, bottom shell20further includes a recessed portion or a relief68configured to accommodate a portion70of stylet block30(as shown, a rear corner).

During use, after side trigger52or rear trigger60is activated, stylet block30is propelled distally toward stop member64. Stylet block30then strikes rib66, which causes the stylet block to rotate or to deflect (arrow B,FIG. 4). In other words, when stylet block30strikes rib66, 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 cannula16and stylet14to 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 block30, such that the speed of stylet14during travel is enhanced (e.g., maximized) and the energy that is dissipated at the end of travel is excess energy. Rotation of stylet block30also moves portion70of the stylet block into recessed portion68. As a result, stylet block30is prevented from hitting stop member64and rebounding or kicking back, which can cause inaccurate sampling of tissue.

Referring particularly toFIG. 2E, cannula block32is configured to be movable to a retracted position, where the cannula block can be held, and subsequently, selectively released. Cannula block32includes a cannula post72configured to engage with slidable member38of loading mechanism36(FIG. 2B). As load button28is moved proximally, slidable member38engages with cannula post72to move cannula block32(and connected cannula16) proximally to their retracted positions, where they can be held by a cannula latch74.

Cannula latch74is configured to hold cannula block32in a retracted position, and to selectively release the cannula block. Cannula latch74includes two identical wedge-shaped portions76(only one of which is visible inFIG. 2E) and a pivot78. Wedge-shaped portions76are configured to allow cannula block32to 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. Pivot78allows cannula latch74to seesaw (arrow C) so that cannula block32can be moved to and locked in its retracted position, and subsequently released. During use, when stylet block30is released from its retracted position and moves distally, the stylet block engages cannula latch74and pivots the cannula latch (arrow D). As a result, wedge-shaped portions76pivot out of engagement with and release cannula block32. Cannula block32is then capable of moving distally under the spring force of a cannula spring80.

Examples of suitable stylet14and cannula16configurations 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.

The components of device10(e.g., housing12, latches46and74, stylet block30, or cannula block32) described above can be formed by injection molding techniques, e.g., of polycarbonate and/or ABS. Stylet14, cannula16, and springs58and80can be formed of stainless steel.

In operation, cannula16and stylet14are loaded (e.g., moved proximally and retained in their retracted positions) and subsequently fired (e.g., released and propelled distally). More specifically, device10is loaded by moving load button28proximally, which moves cannula block32proximally via slidable member38and cannula post72. Cannula block32is moved proximally past wedge-shaped portions76, where the cannula block is held in its retracted position by portions76. Cannula spring80is compressed between stop member64and cannula block32. Moving load button28further proximally moves stylet block30proximally via notch44of slidable member38and post34. Stylet block30is moved proximally past wedge-shaped portion56, where the stylet block is held in its retracted position by portion56. Stylet spring58is compressed between a portion of bottom shell20and stylet block30. Device10is loaded and ready to be fired.

To fire device10, distal end22of stylet14is placed adjacent to a target area, and either side trigger52or rear trigger60is actuated. For example, actuating side trigger52causes stylet latch46to pivot about pivot54(arrow E,FIG. 2D), thereby moving wedge-shaped portion56out of engagement with stylet block30and releasing the stylet block. Upon disengagement, stylet block30and stylet14are propelled distally by the spring force of stylet spring58, which allows the stylet to penetrate the targeted area, e.g., tissue. Stylet block30then strikes rib66and rotates (arrow B,FIG. 4), which causes portion70of the stylet block to enter into recessed portion68of bottom shell20. As discussed above, this deflection of stylet block30dissipates energy from stylet spring58, reduces rebound of the stylet block and enhances accuracy of the device.

Substantially simultaneously with striking rib66, stylet block30also engages and pivots cannula latch74about pivot78(arrow D,FIG. 2E). Pivoting cannula latch74disengages wedge-shaped portions76from cannula block32. Upon disengagement or release, cannula block32and cannula16are propelled distally by the spring force of cannula spring80, which allows the cannula to slide over stylet14and to sever a specimen that has prolapsed into notch24of the stylet.

Device10can then be withdrawn from the targeted area. The specimen can be removed from notch24by first retracting cannula16and cannula block32proximally. The specimen can be placed on a slide or in a preservative solution. If desired, stylet14can be retracted to load device10and to collect another specimen.

In other embodiments, the features described above, such as rib66and/or recessed portion68, 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.

In some embodiments, housing12can be made of different materials, e.g., to enhance the grip or “feel” of device10. For example, housing12can 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 device10. Housing12can be formed with two or more different materials. For example, as shown inFIG. 1, device10includes side portions100formed of different materials to enhance grip and comfort.

In other embodiments, referring toFIG. 1, housing12includes an opening102that, together with stylet block30, can provide a visual indication that device10is loaded. More specifically, when stylet block30is loaded to its retracted position, the stylet block can be seen through opening102. In some embodiments, stylet block30is formed of a bright color, e.g., red, to enhance its visibility.

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.

Other embodiments are within the claims.