Stapler with auto-matic lockout mechanism

A surgical stapling device (10) is provided that includes a handle assembly (12), a movable trigger (26) and an elongated body portion (14). A staple containing shell assembly (22) is mounted on a distal end of the elongated body portion (14) and an anvil assembly (20) is movably mounted relative to the staple containing shell assembly (22). An auto-lock safety mechanism (40) is provided to prevent secondary actuation of the surgical stapling device after initial actuation. The auto-lock safety mechanism (40) includes a primary lock or slider assembly (42) for blocking movement of the trigger (26) and a secondary lock or stopper (44) for blocking movement of the slider assembly (42) prior to approximation of the anvil assembly (20) relative to the staple containing shell assembly (22). A slider (70) is urged to a locked or blocking position by a biasing member (72).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage Application of PCT/CN2014/093575 under 35USC § 371 (a), the disclosure of the above-identified application is hereby incorporated by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a surgical stapling device. More particularly, the present disclosure relates to a surgical stapling device having an automatic internal lock out mechanism to prevent re-firing of the surgical stapling device.

2. Background of Related Art

Surgical stapling devices and, in particular, circular surgical stapling devices, are often used to treat and remove hemorrhoids from within the rectum of a patient. Typically, an anvil assembly of the surgical stapling device is positioned in the rectum beyond the hemorrhoid and is connected to a staple containing shell of the surgical stapling device which is located forwardly of the hemorrhoid. Next, the hemorrhoidal and/or mucosal tissue is tied off to a center rod of the anvil assembly using purse string sutures and the anvil assembly is approximated to a position adjacent the staple containing shell to clamp the hemorrhoidal or mucosal tissue. Thereafter, the surgical stapling device is actuated by depressing a firing trigger of the surgical stapling device to eject staples from the staple containing shell and create a circular line of staples through tissue adjacent the hemorrhoid. Simultaneously, a circular knife excises the hemorrhoidal and/or mucosal tissue positioned within the staple containing shell inwardly of the staple line. The surgical stapling device containing the excised portion of the hemorrhoidal and/or mucosal tissue captured between the anvil assembly and the staple containing shell is then removed from the patient.

Various external lock out devices have been provided on surgical stapling devices to prevent inadvertent actuation of a firing trigger of a stapling device prior to use. These lockout devices include movable latches positioned between the firing trigger and a handle housing of the surgical stapling device which engage the firing trigger and prevent actuation of the firing trigger until the latch is manually moved to an unlocked position. While useful, these latches not only require manual manipulation to unlock the firing trigger but, more importantly, require manual operation to relock the firing trigger after the surgical stapling device has been fired.

In use, an operator may inadvertently reactuate the surgical stapling device prior to or during removal of the surgical stapling device from the patient or prior to resetting the manual external latch. Such an action could cause tissue damage and jeopardize the success of the surgical procedure.

Thus, there is a need for a surgical stapling device for use in the treatment of hemorrhoids as well as a variety of other procedures which includes lockout device to prevent premature actuation of the surgical stapling device. There is also a need for a surgical stapling device containing an internal automatic lock out mechanism which automatically prevents a second actuation of the surgical stapling device after initial firing.

SUMMARY

In one aspect of the present disclosure, a surgical stapling device is provided that includes a handle assembly having a stationary handle housing and a movable trigger mounted to the handle housing. An elongated body portion extends from the handle housing. A staple containing shell assembly is mounted on a distal end of the elongated body portion and an anvil assembly is movably mounted relative to the staple containing shell assembly. An approximation mechanism includes a rotatable approximation knob mounted on the stationary handle housing and a screw shaft assembly extending from the approximation knob to the anvil assembly. The approximation mechanism is configured such that rotation of the approximation knob effects translation of the screw shaft assembly within the handle assembly to move the anvil assembly from a first position spaced from the staple containing shell assembly to a second approximated position adjacent the staple containing shell assembly. A pusher extends through the elongated body portion from the handle housing to the staple containing shell assembly. The movable trigger is movable into engagement with the pusher such that movement of the movable trigger toward the stationary handle housing drives the pusher distally to drive staples out of the staple containing shell assembly and into the anvil assembly. A slider assembly is positioned within the handle housing and includes a slider and a biasing member. The slider is movable between a first position blocking the movable trigger from movement and a second position spaced from the movable trigger. The biasing member is positioned to urge the slider towards the first position.

In embodiments, the slider is longitudinally movable within the handle housing and includes at least one trigger block positioned to engage the movable trigger.

In certain embodiments, the biasing member includes a coil spring.

In some embodiments, the slider assembly includes a switch that is fixedly attached to the slider and extends through a window formed through the handle housing.

In embodiments, the slider includes a mount having an upright bar and a proximally extending arm and the switch is fixedly attached to a proximal end of the proximally extending arm. The coil spring is mounted around the proximally extending arm and engages the upright bar at a first end of the coil spring and the handle housing at a second end of the coil spring.

In certain embodiments, the switch includes at least one flexible latch that is configured to be received within a notch formed in an edge of the window in the handle housing when the slider assembly is in the second position to retain the slider assembly in the second position.

In embodiments, the slider includes a longitudinal slot and the pusher includes a protrusion movable within the longitudinal slot such that distal movement of the protrusion into engagement with one end of the longitudinal slot disengages the at least one flexible latch of the switch from the notch in the handle housing.

In some embodiments, the switch defines a notch. The switch covers an indicator of the handle housing when the slider is in the first position and reveals the indicator of the handle housing when the switch is moved towards the second position.

In another aspect of the disclosure, a surgical stapling device includes a handle assembly having a stationary handle housing and a movable trigger mounted to the handle housing. An elongated body portion extends from the handle housing. A staple containing shell assembly is mounted on a distal end of the elongated body portion and an anvil assembly is movably mounted relative to the staple containing shell assembly. A rotatable approximation knob is mounted on the stationary handle housing and a screw shaft assembly extends from the approximation knob to the anvil assembly such that rotation of the approximation knob moves screw shaft assembly from an advanced position to a retracted position to move the anvil assembly from a first position spaced from the staple containing shell assembly to a second approximated position adjacent the staple containing shell assembly. A pusher extends through the elongated body portion from the handle housing to the staple containing shell assembly and is engagable with the movable trigger such that movement of the movable trigger toward the stationary handle housing drives the pusher distally to drive staples out of the staple containing shell assembly and into the anvil assembly. A slider assembly includes a slider having a tab at a proximal end of the slider. The slider is positioned within the handle housing and is movable between a first position blocking the movable trigger from movement and a second position spaced from the movable trigger. A flexible stopper is positioned within the handle housing and is releasably engagable with the tab of the slider. A block is affixed to the screw shaft assembly and is movable longitudinally within the handle housing in response to rotation of the approximation knob. The block is engagable with the flexible stopper as the screw shaft assembly moves from the advanced position towards the retracted position to move the flexible stopper out of engagement with the tab of the slider to facilitate movement of the slider from the first position to the second position.

In embodiments, the stopper includes a first longitudinal bar mounted to the handle housing, a cross bar connected to the first longitudinal bar and a second longitudinal bar having a distal end connected to the cross bar. The second longitudinal bar includes a catch configured to releasably engage the tab of the slider.

In some embodiments, the block includes a projection having a cam edge that is engagable with the catch to move the catch out of engagement with the tab of the slider.

In certain embodiments, the catch includes an inwardly directed portion formed on the proximal end of the second longitudinal bar and a cam on the second longitudinal bar located distally of the inwardly directed portion. The cam and the inwardly directed portion define a gap configured to receive the tab of the slider.

In some embodiments, the cam includes an angled cam face which is positioned to engage the cam edge of the projection on the block.

In embodiments, the projection on the block is positioned to engage the tab on the slider such that proximal movement of the block moves the slider proximally. The slider assembly includes a switch which is positioned within a window of the handle housing over an indicator, wherein proximal movement of the slider effects movement of the switch to reveal the indicator through the window in the handle housing.

DETAILED DESCRIPTION OF EMBODIMENTS

An embodiment of the presently disclosed surgical stapling device will now be described in detail with reference to the drawings wherein like numerals designate identical or corresponding elements in each of the several views. As is common in the art, the term “proximal” refers to that part or component closer to the user or operator, i.e. surgeon or physician, while the term “distal” refers to that part or component further away from the user.

Referring initially toFIG. 1, there is disclosed a surgical stapling device10for use in hemorrhoidal surgery. Surgical stapling device10generally includes a handle assembly12and an elongated body portion14having an elongated outer tube16and a distal head portion18.

Distal head portion18includes an anvil assembly20and a shell assembly22which are provided to approximate and staple tissues captured therebetween. While not specifically shown, anvil assembly20includes an anvil head containing staple clinching pockets and an anvil shaft for removable connection to elongated body portion14. Likewise, while not specifically shown, shell assembly22includes a plurality of staples and pushers designed to drive the staples out of shell assembly22, through tissue and into the staple clinching pockets of anvil assembly20in a manner commonly known in the art.

Handle assembly12generally includes a stationary handle housing24extending proximally from elongated body portion14, a movable or firing trigger26pivotally mounted to handle housing24and a rotatable approximation knob28positioned on a proximal end30of handle housing24. Actuation of rotatable approximation knob28functions to move anvil assembly20relative to shell assembly22to capture tissue therebetween as is known in the art. See, e.g., U.S. Pat. No. 7,303,106 to Milliman et al. (“the '106 patent”) which is incorporated herein by reference in its entirety. In embodiments, an external, manually actuated trigger latch32is pivotally mounted on handle housing24and engagable with firing trigger26to block movement of firing trigger26. Handle housing24is formed as two joined handle housing halves24aand24b. In the presently disclosed stapling device10, the trigger latch32is optional and can be discarded.

Surgical stapling device10additionally includes an indicator34that is, visible through a window36formed in handle housing24, and provides a visual indication of the degree of approximation of the anvil assembly20relative to shell assembly22. A safety button or switch38is movable within window36and is associated with an auto-lock safety mechanism40described in more detail hereinbelow.

Referring now toFIGS. 2-7, and initially with regard toFIGS. 2-3A, the auto-lock safety mechanism40includes switch38, a primary lock or slider assembly42movably mounted within handle housing24, a secondary lock or stopper44(FIG. 4) mounted in handle housing24and a cam member or block46which is affixed to a screw shaft assembly48. The screw shaft assembly48is operably engaged with the approximation knob28at its proximal end (FIG. 1) and to the anvil assembly20at its distal such that the approximation knob28is actuable to move the anvil assembly20in relation to the shall assembly22as described below.

With specific reference toFIG. 2, screw shaft assembly48extends through an extension knob tube50. The extension knob tube50supports a collar52that is rotatably mounted within the handle housing24and is connected to the approximation knob28. As is known in the art (see the '106 patent), a proximal end of screw shaft assembly48includes a helical groove which receives a pin or projection (not shown) provided in the collar52. Rotation of approximation knob28, and thus extension knob tube50and collar52, moves the pin within the helical groove in screw shaft assembly48to move screw shaft assembly48within the housing24proximally and distally relative to shell assembly22.

Firing trigger26includes a lever54and an upright arm56that extends into the handle housing24. Upright arm56may be formed as a pair of spaced upright arms56aand56b. A pivot pin58extends through upright arm56and is mounted to the handle housing24to allow firing trigger26to pivot relative to handle housing24. An elongate, cylindrical pusher60extends through outer tube16(FIG. 1) from firing trigger26to shell assembly22. Movement of firing trigger26toward handle housing24causes a distal edge62of each upright arm56a,56bto engage and drive a flange64, located at a proximal end66of cylindrical pusher60, distally to drive pusher60distally. As pusher60is driven distally within outer tube16, a distal end (not shown) of pusher60drives the staples out of shell assembly22and into the staple clinching pockets of anvil assembly20to staple tissue captured between the shell assembly22and the anvil assembly20. A coil spring68is provided around cylindrical pusher60between an inner wall of housing24and a surface of pusher60to bias the pusher60proximally within handle housing24and elongated outer tube16. Biasing pusher60proximally, via engagement of flange64with arms56a,56b, urges firing trigger26towards the unfired position away from handle housing24.

Referring now toFIGS. 3 and 3A, slider assembly42of auto-lock safety mechanism40is provided to initially block movement of firing trigger26until manually released and thereafter, automatically re-block firing trigger26after firing of the stapling device10. This provides a higher degree of safety as compared to a manually actuated latch32which requires manual operation to reengage safety latch32after actuating the firing trigger26. In addition to switch38, slider assembly42includes a slider70and a spring72mounted on slider70which biases the slider70distally within handle housing24as will be discussed in further detail below. Slider70can be formed of sheet metal and includes a central body portion74, a distal body portion76extending distally from central body portion74and a proximal body portion78extending proximally from central body portion74. A downwardly depending arm or tab80extends from a proximal end of proximal body portion78and is received within secondary lock or stopper44(FIG. 2) as discussed in detail below to prevent movement of slider70within handle housing24.

Central body portion74includes a pair laterally extending arms or trigger blocks82,84at a distal end86of central body portion74. Trigger blocks82,84are positioned to engage flat surfaces172aformed on upright arms56aand56b, respectively of firing trigger26to prevent movement of firing trigger26as described in more detail hereinbelow (seeFIG. 14). Central body portion74additionally includes a proximally extending L-shaped mount88for fixedly supporting the switch38and a coil spring72. The switch38can be fixedly secured to the slider70using any known fastening technique including gluing, welding, overmolding, etc. Mount88extends proximally along a centerline of central body portion74and includes an upright bar90and a longitudinal, proximally extending arm92extending from upright bar90. Coil spring72is movably mounted over arm92and switch38is affixed to a proximal end94of arm92. The coil spring72abuts a proximal side98of upright bar90and an inner surface (not shown) of the handle housing24to bias slider70and switch38distally within handle housing24.

An elongate slot100extends longitudinally through distal body portion76from distal end86of central body portion74to a distal end102of distal body portion76. Elongate slot100receives a protrusion178formed on pusher60such that when the pusher60is moved distally by the firing trigger26, the slider70is pulled distally to disengage switch38from handle housing24in a manner described in detail below.

Switch38is affixed to mount88of slider70and includes a body portion104having an upwardly projecting distal finger tab106and a pair of distally extending latches108,110extending from body portion104beneath finger tab106. A notch112is formed in body portion106. The switch38is movable to reposition the notch112to cover or uncover the indicator34(FIG. 1).

With specific reference toFIGS. 3-3B, latch108of switch38includes a flexible arm114that extends from body portion104and terminates in an outwardly extending tab116(FIGS. 3 and 3A). Similarly, latch110also includes a flexible arm118that extends from body portion104and terminates in an outwardly extending tab120(FIG. 3B). Tabs116and118releasably engage handle housing24and temporarily hold switch38, and thus slider70, in a proximal position to free up firing trigger26for actuation as will be described in further detail below.

Referring toFIG. 4, stopper44is provided to prevent movement of slider70prior to the approximation of anvil assembly20with shell assembly22. Stopper44is generally U-shaped and includes a first longitudinal bar122, a second longitudinal bar124and a cross bar126flexibly connecting first longitudinal bar122to second longitudinal bar124. Specifically, a distal end128of first longitudinal bar122is connected to a first end130of cross bar126and a distal end132of second longitudinal bar124is connected to a second end134of cross bar126. In embodiments, first longitudinal bar122, second longitudinal bar124and cross bar126may be formed integrally from a flexible material such as, for example, spring steel, polymeric materials, etc.

As shown, a proximal end136of first longitudinal bar122has an inwardly directed portion138. Second longitudinal bar124is shorter than first longitudinal bar122and has a catch140formed at its proximal end142. Catch140includes an inwardly directed portion144formed at proximal end142and a cam146formed on second longitudinal bar124distally of inwardly directed portion142. Cam146has a distally facing, angled cam face148. Catch140defines a gap150between inwardly directed portion144and cam146for receipt of tab80of slider70.

As best shown inFIG. 5, stopper44is supported within proximal and distal supports152and154formed within handle housing24. The proximal and distal supports152and154extend inwardly from an inner surface156of handle housing half24b. Specifically, inwardly directed portion138of first longitudinal bar122is located and frictionally retained within proximal support152while distal end128of first longitudinal bar122and first end130of cross bar126are frictionally retained within distal support154. This leaves second longitudinal bar124free to flex downwardly relative to first longitudinal bar122to facilitate movement of catch140into and out of engagement with tab80of slider70as described in detail below.

Referring now toFIGS. 6-8, in order to move or cam catch140out of engagement with tab80of slider70, a block158having a projection160mounted on a first or upper surface162thereof is affixed to screw shaft assembly48. Specifically, screw shaft assembly48passes through a bore164(FIG. 8) formed through block158and is fixedly secured to block158using, for example, a set screw (not shown). Thus, when the screw shaft assembly48is translated within the handle housing24via actuation of the approximation knob, block158translates within handle housing24along with screw shaft assembly48. Block158additionally includes a pair of wings166and168which ride in corresponding channels (not shown) formed within handle housing halves24aand24bto guide movement of block158within the handle housing24. As best shown inFIG. 8, projection160is generally L-shaped and has a proximal cam edge170which is positioned to engage the angled cam face148of cam146of stopper44to urge catch140outwardly to disengage tab80on slider70from the catch40.

Referring now toFIGS. 1 and 6-15, the operation of auto-lock safety mechanism40, including slider assembly42and stopper44, will now be described. Referring toFIG. 1, trigger26is initially retained in a locked position by the trigger latch32which must be manually pivoted to an unlocked position. As noted hereinabove, trigger latch32is an optional feature of surgical stapling device10and is pivoted away from trigger26prior to use.

With reference also toFIG. 6, prior to approximation of the anvil assembly20in relation to the cartridge assembly22, tab80of slider70is received within catch140of stopper44and block158is in a distal or advanced position with projection160of block158spaced distally of cam146of catch140of stopper44. Engagement of tab80within the catch140prevents slider70from longitudinal movement within handle housing24. Coil spring72(FIG. 11) is under compression and urges the slider70in the distal direction.

Referring briefly toFIG. 11, in the initial locked out position, trigger blocks82and84of slider70, rest on upper flat surfaces172aof upright arms56aand56bof trigger26to prevent pivotal movement of trigger26. This internally “locks out” trigger26from actuation and firing of surgical stapling device10.

Referring again toFIG. 1, when the anvil assembly20is approximated or moved proximally toward shell assembly22by rotating approximation knob28screw shaft assembly48is moved proximally within the handle housing24. As the screw shaft assembly48is moved proximally, the block158is moved proximally within the handle housing24.

Referring again toFIGS. 6-8, block158moves from its initial advanced position positioned distally of cam146of catch140, wherein catch140of stopper44is engaged with tab80of slider70(FIG. 6), to a second position wherein proximal cam edge170of projection160on block158engages the angled cam face148of cam146. As block158moves proximally, angled cam face148is moved laterally by proximal cam edge170to cam catch140of stopper44out of engagement with tab80on slider70(FIGS. 7 and 8). The release of tab80of slider70from catch140of stopper44frees up slider assembly42to facilitate manual movement of the switch38and, thus, slider assembly42along handle housing24.

Referring for the moment toFIGS. 7, and 9-11, as screw shaft assembly48including block158is drawn proximally, projection160of block158engages tab80of slider70and pulls the slider assembly42proximally a short distance against the bias of the spring72. As slider assembly42is moved proximally, firing trigger26is still locked out from movement by trigger blocks82and84of slider70which still partially engage flats172aof upright arms56aand56bof the trigger26. Switch38, which is affixed to slider70, also moves proximally a short distance. Switch38moves from an initial position wherein switch38covers indicator34(FIG. 9) to second position wherein indicator34is visible through notch112in switch38(FIG. 10). This gives a visual indication to a clinician that the anvil assembly20and shell assembly22are approximated and confirms that the slider assembly42has been released from stopper44. Surgical stapling device10is now properly positioned about the tissues to be stapled.

Referring now toFIGS. 12-13, to release trigger26for actuation and firing of surgical stapling device10, the operator pushes against finger tab106of switch38to move switch38, and thus slider70, proximally within handle housing24(FIG. 13). As slider70is drawn proximally, coil spring72is compressed and trigger blocks82and84are moved away from upper flat surfaces172aof upright aims56aand56bof trigger26to unlock the trigger26for pivotal movement (FIG. 12).

As best shown inFIG. 13, when switch38is moved to its proximal-most position, the switch38and, thus, the slider70are retained in this position by tabs116,120. More specifically, switch38of slider assembly42is locked in a proximal most position by the outwardly extending tabs116,120on flexible arms114,118of switch38which snap into, notches174and176, respectively, formed in handle housing24(FIG. 13) adjacent window36. Receipt of tabs116,120in notches174,176maintains switch38, and thus slider assembly42, in the proximal position to maintain trigger blocks82,84spaced from flat surfaces172aof aims56a,56b, respectively of trigger26to maintain trigger26in the unlocked position.

As best shown inFIG. 14, in the unlocked position, the firing trigger26can be pivoted toward handle housing24to advance pusher60, against the bias of coil spring68, to fire staples from the shell assembly22through tissue and into anvil assembly20.

Referring toFIG. 14, upon full actuation of trigger26, primary slider lock assembly42is released to automatically re-lock out trigger26from a second actuation. More specifically, as pusher60is driven to a distal most position by trigger26, a protrusion178formed on pusher60rides within elongated slot100in slider70. As the distal most position of pusher60is reached and the staples have been formed against the anvil assembly20, block178engages the portion of slider70defining a distal end180of elongated slot100to thereby pull slider70distally within handle housing24. As slider70is pulled or forced distally, switch38is also forced distally such that the tabs116and120on flexible arms114and118of the switch38are released from locking notches174and176adjacent window36of handle housing24. This frees up slider assembly42to move distally under the bias of coil spring72. As the tabs116and120of switch38of slider assembly42are released from notches174and176, the slider70snaps distally and makes a “click” sound giving an audible indication to the clinician that actuation of the trigger26is complete and that the auto-lock safety mechanism40of surgical stapling device10has been automatically reactivated. It is noted that movement of the switch38distally also provides a visual indication to the clinician that actuation of the trigger26is complete. Upon release of trigger26, slider70returns to the initial position (FIG. 11) wherein slider70once again blocks trigger26from pivotal movement to prevent a second actuation of surgical stapling device10.

It should be noted that, upon rotation of approximation knob28to separate anvil assembly20from shell assembly22and release the now stapled tissues, block158is moved distally to draw projection160out of engagement with catch140of stopper44. Catch140flexes back into engagement with tab80on slider70to thereby again relock slider assembly42from further movement (FIG. 6).

Thus, in this manner, auto-lock safety mechanism40of surgical stapling10positively re-locks out trigger26from a second actuation after firing of surgical stapling device10.

It will be understood that various modifications may be made to the embodiments disclosed herein. For example, the disclosed coil springs may be replaced with other types of springs, such as, for example, leaf springs, etc. Further, as noted above, the external trigger latch may be omitted. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.