Abstract: A staple cartridge for use with a stapling device that has an actuator that is selectively actuatable in an axial direction and an anvil portion that is selectively movable between open and closed positions is disclosed. Various embodiments of the present invention include a cartridge body that movably supports first and second staple drivers. The staple drivers each support a staple thereon and serve to drive the staples into forming contact with the anvil upon actuation by the actuator. The various embodiments of the present invention enable the final formed heights of the staples to be varied without the need to use different sizes of staples.

Abstract: A tool actuating assembly for a multi-function surgical instrument is disclosed. The tool actuating assembly of the present invention can be utilized in a variety of differently configured multi-function surgical instruments and can be embodied in various physical configurations. The tool actuating assembly of the present invention provides for more efficient use of the tools of the instrument by the surgeon who is utilizing the instrument.

Abstract: A surgical cutting and fastening instrument is disclosed. The surgical cutting and fastening instrument comprises a pair of jaws comprising a distal end, a motor-powered firing member configured to move longitudinally along the pair of jaws toward the distal end, and a sensor configured to sense a fully-closed state of the pair of jaws. The surgical cutting and fastening instrument further comprises, one, a control circuit electrically coupled to the sensor, wherein the control circuit is configured to prevent a longitudinal movement of the firing member toward the distal end if the pair of jaws is not in the fully-closed state and, two, a remote user-controlled console.

Abstract: An exemplary surgical apparatus may include an end effector including a staple holder, an anvil movable relative to the staple holder, and staples held within the staple holder; a shaft extending from the end effector; a handle attached to the shaft, the handle including a single trigger; wherein actuation of the single trigger in a clamping mode clamps the end effector; and wherein actuation of the single trigger in a stapling mode deploys the staples.

Abstract: A surgical instrument includes a drive member movable by a drive motor between a home position and an end of stroke. A mechanical stop is disposed at or near the end of stroke and is structured to increase resistance to movement of the drive member from a first position to a second position. A control system detects a current spike associated with the increased resistance and interrupts power to the drive motor.

Abstract: A tiltable and repositionable anvil assembly for a stapler and a stapler comprising the same are provided. The tiltable and repositionable anvil assembly comprises: an anvil body having a connection portion for pivotable connection; a limitator; and a compression spring disposed between the anvil body and the limitator, in which in an operation of the stapler, the limitator is clamped at a clamping position between the connection portion of the anvil body and a connection portion of the stapler so as to keep the anvil body in a vertical state, and after the operation of the stapler, the limitator is moved away from the clamping position between the connection portion of the anvil body and the connection portion of the stapler, so that the anvil body is tiltable to a tilted state and the compression spring is compressed.

Abstract: A surgical fastener applying apparatus includes an end effector assembly having an anvil assembly and a cartridge assembly. The anvil assembly and/or the cartridge assembly is movable relative to the other between open and closed positions. The cartridge assembly is configured to retain a plurality of surgical fasteners therein. A fluid-actuated drive assembly including a distal piston member is configured to oscillate between proximal and distal positions. The distal piston member includes a base and a rack extending distally from the base and slidably disposed within the cartridge assembly. A drive beam is configured for translation through the cartridge assembly to eject the surgical fasteners from the cartridge assembly. A pawl assembly couples the drive beam to the rack such that the drive beam is incrementally advanced along the rack and through the cartridge assembly as the distal piston member oscillates between the proximal position and the distal position.

Abstract: A fastener cartridge can comprise a support portion, a tissue thickness compensator positioned relative to the support portion, and a plurality of fasteners positioned within the support portion and/or the tissue thickness compensator which can be utilized to fasten tissue. In use, the fastener cartridge can be positioned in a first jaw of a surgical fastening device, wherein a second jaw, or anvil, can be positioned opposite the first jaw. To deploy the fasteners, a staple-deploying member is advanced through the fastener cartridge to move the fasteners toward the anvil. As the fasteners are deployed, the fasteners can capture at least a portion of the tissue thickness compensator therein along with at least a portion of the tissue being fastened.

Abstract: A surgical including a handle assembly, an elongated portion, an end effector, and a stop member is disclosed. The elongated portion extends distally from the handle assembly. The end effector is disposed adjacent a distal portion of the elongated portion and includes a first jaw member and a second jaw member. At least one jaw member is movable with respect to the other jaw member between spaced and approximated positions. The stop member is disposed adjacent a distal portion of the first jaw member and is pivotable with respect to the first jaw member between a first position, a significant portion of the stop member being positioned external to the first jaw member, and a second position capturing the tissue between the first jaw member and second jaw member.

Abstract: A surgical stapling device having a rotating knob locking mechanism, and a method of using the surgical stapling device is disclosed. The surgical stapling device includes a housing, an actuation member, an elongated body portion rotatably supported on the housing, and a locking mechanism for preventing the rotation of the elongate body portion, the locking mechanism being automatically engaged upon actuation of the actuation member. The stapling device further includes a knob for rotating the elongated body portion. The locking mechanism includes a pivotably mounted member configured to engage the knob. The stapling device may further include an articulating tool assembly and an articulation lever for articulating the tool assembly. The articulation lever may be disposed on the knob for rotating the elongated body portion.

Abstract: An exemplary surgical apparatus may include a flexible articulation insert and at least one feeder belt extending through the articulation insert, where at least some of the staples are frangibly connected to the feeder belt. Another exemplary surgical apparatus may include at least one movable feeder belt; staples fixed to the feeder belt; and a flexible articulation insert having at least one feeder belt passage defined therein, the flexible articulation insert configured to bend through a range of motion; where each feeder belt extends through a corresponding feeder belt passage, and where each feeder belt passage is shaped such that the corresponding feeder belt and staples fixed thereto are slidable along the passage throughout the entire range of motion of the flexible articulation insert.

Abstract: A surgical device for clipping tissue can include a replaceable cartridge comprising a stack of clips contained therein and a firing drive configured to reciprocatingly eject, or deploy, the clips from the cartridge. After the clips have been deployed from the cartridge, a blocking member can be positioned to impede or block the firing drive. In at least one embodiment, the cartridge can include a biasing member configured to bias the blocking member into a firing chamber defined in the cartridge and/or surgical device. The surgical device can also include a crimping drive configured to deform a clip after it has been ejected from the cartridge. The blocking member can also be configured to impede or block the crimping drive after all of the clips from the cartridge have been used.

Abstract: An interactive display. The interactive display can include a first layer of information and a second layer of information. The first layer of information can include video feedback of a surgical instrument as viewed by an endoscope. The second layer of information can include a control panel, feedback measured and/or sensed by the surgical instrument, and/or controls for controlling the surgical instrument. A user can interface with the interactive display via a touch screen.

Abstract: A surgical instrument is provided including an outer housing shell defining a cavity, the outer housing shell defining an upper outer housing half and a lower outer housing half, wherein the upper outer housing half defines a longitudinal axis and an instrument module selectively insertable into the cavity of the outer housing shell. The instrument module includes an inner housing shell, at least one motor disposed within the inner housing shell, a control board being in electrical communication with the at least one motor and an energy source being in electrical communication with the at least one motor and the control board. The instrument module is inserted into the cavity of the outer housing shell in such a manner that the operative axis of the at least one motor is substantially parallel to the longitudinal axis of the upper outer housing half.

Abstract: A surgical fastener applying apparatus including an anvil half-section having a distal end and a longitudinal axis; a cartridge receiving half-section having a distal end and operatively couplable with the anvil half-section such that the distal ends of the half-sections are in juxtaposed relation; and a deflection control system operatively engaged with and reinforcing the distal end of the anvil half-section when a force is applied to the distal end of the anvil half-section in a direction transverse to the longitudinal axis.

Abstract: A surgical stapler includes an anvil assembly and a cartridge assembly. The anvil assembly defines staple forming depressions. One or both of the anvil assembly and the cartridge assembly are pivotable relative to the other between an open position and a clamped position. The cartridge assembly includes a first plurality of staples and a second plurality of staples. The first plurality of staples is initially positioned in alignment with the staple forming depressions of the anvil assembly for ejection from the cartridge assembly. The second plurality of staples is movably supported in the cartridge assembly from a first position misaligned with the staple forming depressions of the anvil assembly to a second position aligned with the staple forming depressions for subsequent ejection from the cartridge assembly.

Abstract: A surgical stapling device that comprises an end effector that is configured to receive various control motions from a robotic system.

Abstract: A shaft assembly is provided for interconnecting at least one rotatable drive shaft of a hand-held electromechanical surgical device, and an end effector actuatable by an axial drive force. The shaft assembly includes a flexible drive cable rotatably supported in an outer tube, the flexible drive cable includes a proximal end operatively connected to a respective rotatable drive shaft of the hand-held surgical device. The flexible drive cable being off set a radial distance from a central longitudinal axis of the outer tube. The shaft assembly includes an articulation rod at least partially slidably supported in the outer tube, and an articulation link having a proximal end pivotally connected to the distal end of the articulation rod and a distal end pivotally connected to a distal neck housing. The articulation rod being off set a radial distance from the central longitudinal axis of the outer tube.

Abstract: An apparatus for joining two hollow organ sections with an annular array of staples includes a staple cartridge assembly, an anvil assembly, and a buttress assembly. The staple cartridge assembly includes a plurality of surgical staples in an annular array. The anvil assembly includes an anvil member and a shaft extending therefrom. The anvil member defines a plurality of staple pockets for deforming the staples. The anvil assembly is movable relative to the staple cartridge assembly between spaced apart and approximated positions to adjustably clamp tissue between the staple cartridge and the anvil assemblies. The buttress assembly includes a cut ring secured with the anvil member, a buttress member disposed in a superposed relation with the plurality of staple pockets defined in the anvil member, and a retaining member having an attaching member configured to be secured with the cut ring to secure the buttress member with the anvil assembly.

Abstract: A surgical device is provided that includes a jaw portion, having a first jaw in opposed correspondence with a second jaw, the second jaw including a surgical member. The surgical device may include a shaft portion coupled to a proximal end of the jaw portion and at least one motor configured to rotate the jaw portion relative to the shaft portion, to move the jaw portion relative to the shaft portion, move the first jaw relative to the second jaw and move the surgical member within the second jaw. The surgical member may be prevented from moving within the second jaw unless the first jaw is in a closed position relative to the second jaw. Advantageously, the surgical member may include one or both a cutting element or a stapling element, disposed within one of the jaws.

Abstract: A surgical instrument having a handle portion, an elongated portion defining a longitudinal axis therethrough, an end effector, and a pin. The elongated portion extends distally from the handle portion. The end effector is disposed adjacent the elongated portion and includes a first jaw member and a second jaw member. The pin is disposed in mechanical cooperation with the first jaw member and includes an engaging section. In operation, the pin moves between a first position and a second position. While in the first position, the engaging portion of the pin is spaced from the second jaw member. In the second position, the engaging portion of the pin engages the second jaw member. The second jaw member includes a locking structure configured to maintain the position of the second jaw member with respect to the first jaw member during actuation of the end effector.

Abstract: A surgical instrument includes a handle portion, a shaft housing a firing bar, an end effector comprising an anvil, a lower jaw, and a stapling and severing assembly responsive to a longitudinal closing motion produced by the handle portion and the shaft. The lower jaw is configured to receive a removable cartridge. The cartridge includes a housing, a plurality of staples disposed in the housing, and a deck disposed over the plurality of staples. The deck defines apertures, with each aperture being substantially disposed over each staple. The instrument includes an anvil cartridge removably received in an anvil frame. The anvil cartridge is severed by the firing bar when the firing bar is advanced through tissue such that material from the anvil cartridge is released onto the severed tissue.

Abstract: The surgical stapling apparatus includes a handle assembly, an elongated body extending distally from the handle assembly, and an articulation mechanism for articulating a tool assembly. The articulation mechanism includes a first gear rotatably mounted on a transmission shaft and configured to engage a second gear, a clutch interconnecting the second gear and a main shaft; and a yoke shaft coupled to the main shaft and adapted to linearly advance a J-channel, the J-channel operatively connected to an articulation link. A motor assembly may rotate the transmission shaft of the articulation mechanism. Alternatively, the articulation mechanism may include an articulation knob. Users may manually rotate the articulation knob to articulate the tool assembly of the surgical stapling apparatus.

Abstract: An apparatus comprises a body and a shaft assembly. The shaft assembly is in communication with the body and comprises an end effector, first cam gear, second cam gear, and a lock bar. The end effector has an articulation joint. The first cam gear is rotatably positioned within the shaft assembly. The second cam gear is in communication with the end effector at the articulation joint. The lock bar is distally biased to lock against the second cam gear. The first cam gear is rotatable through a first range of motion to unlock the lock bar relative to the second cam gear. The first cam gear is rotatable through a second range of motion to rotate the end effector at the articulation joint.

Abstract: An end effector comprising a first jaw, a second jaw, and a firing member is disclose. The firing member, in various embodiments, further comprises a first portion configured to contact one of the first jaw and the second jaw, and a second portion configured to contact one of the first jaw and the second jaw. The first portion can be comprised of a first material. The firing member can further comprise an annex engaged with the first portion comprised of an annex material which is different than the first material. In various instances, the first portion and the second portion are configured to co-operatively set a tissue gap distance between the first jaw and the second jaw.

Abstract: A stapling apparatus has a buttress material removably attached to a staple cartridge of the stapling apparatus by at least one anchor releasable retained within a notch defined in the staple cartridge. The stapling apparatus has a staple pusher including a plurality of fingers for ejecting staples out of the staple cartridge, and at least one of the fingers includes a protrusion for pushing the at least one anchor out from the notch and releasing the buttress material.

Abstract: A surgical instrument includes an outer housing shell defining a cavity. The outer housing shell defines an upper outer housing half and a lower outer housing half. The upper outer housing half defines a longitudinal axis. An instrument module is selectively insertable into the cavity of the outer housing shell. The instrument module includes an inner housing shell, at least one motor disposed within the inner housing shell, a control board being in electrical communication with the at least one motor, and an energy source being in electrical communication with the at least one motor and the control board. The instrument module is inserted into the cavity of the outer housing shell in such a manner that the operative axis of the at least one motor is substantially parallel to the longitudinal axis of the upper outer housing half.

Abstract: A surgical fastener applying apparatus for applying fasteners to body tissue. The apparatus includes a cartridge receiving half-section defining an elongated channel member configured to releasably receive a stationary housing of a firing assembly. The stationary housing is dimensioned to releasably receive a single use loading unit therein, and includes a lockout structure that prevents insertion of the single use loading unit into the stationary housing after the stationary housing is mounted to the cartridge receiving half-section.

Abstract: Width of a space for receiving staples of a magazine is greater than length of the staples and is less than the sum of the length of the staples to ½ of the diameter of the staples, preferably ? thereof or less. The magazine is formed as half split bodies on either side of a rail along the length thereof, a convex positioning part is provided on one of the half split bodies, a concavity for engaging with the positioning convexity is formed on the other half split body, support holes for engaging with positioning parts are formed in the half split bodies, a locking part for holding engagement with the other half split body is provided on said one of the half split bodies, and a to-be-locked part for engaging with the locking part is formed on the other half split body.

Abstract: An improved apparatus and method of securing body tissue may be performed with a robotic mechanism. The robotic mechanism may be utilized to tension a suture with a predetermined force and urge a suture retainer toward body tissue with a predetermined force. Ultrasonic vibratory energy may be transmitted to the suture retainer to effect a gripping of the suture by the suture retainer. The body tissue may be secured with a staple. Legs of the staple may be bonded together to secure the staple. The legs of the staple may be bonded together by transmitting ultrasonic vibratory energy to the legs of the staple. A tissue positioning assembly may be used to hold the body tissue in a desired position. Images of the body tissue being secured may be obtained using various known devices including one or more endoscopes, a fluoroscope, a magnetic resonance imaging device, and/or other known imaging devices.

Abstract: A device and method for treatment of hemorrhoids, in which the devices includes: a housing insertable into the rectum; a tissue port configured to receive a tissue segment containing at least a portion of a hemorrhoidal blood vessel; opposing needle chambers including at least one pair of corresponding needles coupled by a suture in which the pair of corresponding needles are substantially opposite to one another and in an active position substantially aligned with the tissue segment; a needle driver that advances the pair of corresponding needles through the tissue segment to encircle a portion of the hemorrhoidal blood vessel with the suture, thereby ligating the hemorrhoidal blood vessel; and an actuator coupled to at least one of the needle chambers that actuates the needle chambers such that another pair of corresponding needles is in the active position.

Abstract: An exemplary surgical method of treating tissue within the body of a patient may include having an endocutter having an end effector; inserting the end effector into the body of a patient through an opening; engaging tissue with the end effector; stapling tissue along two staple lines with the end effector; cutting tissue between the staple lines with the end effector; releasing the tissue from the end effector; and repeating the engaging, stapling, cutting and releasing within the body of the patient on tissue at a different location within the body of the patient while maintaining the end effector within the body of the patient.

Abstract: A staple cartridge assembly comprising a cartridge housing, a plurality of staples, a plurality of staple pushers, and an actuation sled is disclosed. Each staple pusher includes a first base portion, and a second base portion laterally and longitudinally spaced from one another. The actuation sled disposed in the cartridge housing and is longitudinally translatable therethrough to move the staple pushers. The actuation sled includes at least a first cam wedge and a second cam wedge arranged to engage the first base portion and the second base portion of the pushers. The first cam wedge is laterally and longitudinally spaced apart from the second cam wedge.

Abstract: A surgical instrument includes a handle portion and a body portion extending distally from the handle portion and defining a first longitudinal axis. The surgical instrument includes an articulating tool assembly defining a second longitudinal axis and having a proximal end. The articulating tool assembly is disposed at a distal end of the body portion and is configured to be articulated with respect to the body portion, namely, the articulating tool assembly is movable from a first position in which the second longitudinal axis is substantially aligned with the first longitudinal axis to at least a second position in which the second longitudinal axis is disposed at an angle with respect to the first longitudinal axis. The surgical instrument also includes an articulation mechanism configured to articulate the articulating tool assembly.

Abstract: A tilt anvil assembly is disclosed which includes a center rod, a head assembly, and a torsion spring configured to pivot the head assembly relative to the center rod. The head assembly has a locking collar defining a locked position preventing pivotal movement of the head assembly, and an unlocked position allowing pivotal movement of the head assembly. The torsion spring selectively engages the locking collar to maintain the locking collar at either the locked or unlocked position.

Abstract: A surgical stapling device an elongated body portion having proximal and distal portions, and a head portion positioned adjacent the distal portion of the elongated body portion. The head portion includes a shell assembly and an anvil assembly movable relative to the shell assembly between un-approximated and approximated positions. The anvil assembly includes a center rod and an anvil head connected to the center rod. The center rod includes at least one aperture extending transversely therethrough and configured and dimensioned to receive a flexible member such that the flexible member extends transversely through the center rod.

Abstract: A surgical instrument system is disclosed including a surgical instrument and a remote user-controlled actuation console for controlling the surgical instrument.

Abstract: A surgical instrument including a handle assembly, an elongated portion, an end effector, and a stop member is disclosed. The end effector is disposed adjacent a distal portion of the elongated portion and includes a first jaw member and a second jaw member. At least one jaw member is movable with respect to the other jaw member between spaced and approximated positions. The first jaw member includes an upper tissue-contacting surface and a lower shelf portion. The shelf portion includes a groove disposed therein. The stop member is disposed adjacent a distal portion of the first jaw member and is pivotable with respect to the first jaw member between a first position, a significant portion of the stop member being positioned external to the first jaw member, and a second position where a lower portion of the stop member being positioned at least partially within the groove.

Abstract: A medical apparatus (100; 200; 300) is provided, comprising a closure device (21; 102; 202; 302) comprising a first or distal member or portion adapted to be placed on one side of an opening in a wall of a bodily organ, and a second or proximal member or portion adapted to be placed on the opposite side of the opening in the wall of the bodily organ, an insertion assembly (101; 201; 301) comprising at least one actuator operatively connected to at least one of said first or second members, wherein the insertion assembly further comprises at least one motor (105; 106; 205; 306) adapted to maneuver said at least one actuator.

Abstract: A staple inserter (12) for use with a surgical staple (10) during a surgical procedure, the surgical staple (10) including a middle section (14) and two side sections (16) that cantilever away from the middle section (14), the surgical staple (10) being selectively movable between a relaxed configuration and an opened configuration, the staple inserter (12) comprising a staple holder assembly (20) that is rotatable in a first direction relative to the surgical staple (10) to selectively engage and retain the surgical staple (10). The staple holder assembly (20) includes (i) a first engagement member (32) that is rotatable in the first direction relative to the surgical staple (10) to selectively engage and retain the surgical staple (10), and (ii) a second engagement member (32) that is rotatable in the first direction relative to the surgical staple (10) to selectively engage and retain the surgical staple (10).

Abstract: A surgical stapler comprises an anvil assembly, an anvil shaft, a driver, an actuating arm, a safety switch, and a safety feature. The anvil assembly couples with the anvil shaft. The driver drives a plurality of staples into tissue. The actuating arm is in communication with the surgical stapler and is configured to actuate the driver to drive the plurality of staples into tissue. The safety switch is moveable between a locked and an unlocked position. The safety switch prevents operation of the actuating arm when the safety switch is in the locked position. The safety switch enables operation of the actuating arm when the safety switch is in the unlocked position. The safety feature may prevent operation of the driver even when the safety switch is in the unlocked position or prevent operation of the safety switch.

Abstract: An exemplary surgical stapler may include a staple holder; an anvil movably connected to the staple holder; staple forming pockets defined in a surface of the anvil; and a staple trap movable within the anvil relative to the staple forming pockets. Another exemplary surgical stapler for may include a feeder belt; staples frangibly affixed to said feeder belt; an anvil against which the staples are bent in a controlled manner by engagement with staple forming pockets defined in that anvil; and at least one finger that presses a corresponding staple within a corresponding staple forming pocket laterally with a force sufficient to hold the staple in the staple forming pocket where said staple does not engage tissue after that staple is bent.

Abstract: Surgical stapling instruments surgical stapling cartridges are disclosed. At least one embodiment includes an end effector that has an elongate channel that is configured to operably support a surgical staple cartridge therein and an anvil that is movably supported on the elongate channel between an open position and closed positions in response to an application of opening and closing motions applied thereto. An anvil lock member cooperates with the anvil to retain the anvil in an open position when a staple cartridge has not been installed in the elongate channel and prevent the anvil from moving to a closed position until the staple cartridge has been seated within the elongate channel. Surgical staple cartridges are configured to move the anvil from an open position to an actuatable position when the cartridge has been installed in the end effector.

Abstract: A surgical severing and stapling instrument, suitable for laparoscopic and endoscopic clinical procedures, clamps tissue within an end effector of an elongate channel pivotally opposed by an anvil. Various embodiments are configured to be operably attached to a robotic system to receive actuation/control motions therefrom.

Abstract: A surgical stapler instrument has surgical stapler jaws, at least one staple line reinforcement material, and a fastener including a hook and a loop. The hook can be disposed on one of the surgical stapler jaws and the loop can be disposed on the staple line reinforcement material. Alternatively, the hook can be disposed on the staple line reinforcement material and the look on one of the surgical stapler jaws.

Abstract: A staple cartridge for use with a surgical stapler can comprise a cartridge deck and a plurality of staples at least partially positioned within the cartridge deck. In use, the staples can be supported by a first jaw of the surgical stapler and deformed by a second jaw. As the staples are being deformed, the cartridge deck can be pushed, or slid, downwardly relative to the staples.

Abstract: Sensor arrangements for determining the position of a firing element in an end effector of a surgical instrument. In various forms, the sensor arrangement comprises a resistive element supported in the end effector. As the firing element translates within the end effector, it movingly contacts the resistive element to generate signals indicative of the firing element position. In other arrangements, the sensor can detect the status or presence of a staple cartridge in the end effector. The sensor arrangement can communicate with a memory device, processor and indicator.

Abstract: A surgical stapling apparatus. Various embodiments include a rotatable elongated body that extends from a rotatable shroud on handle assembly and has a distal end configured for attachment to a disposable loading unit. The apparatus further includes a lockable rotation system for selectively locking the rotatable shroud to prevent rotation thereof about a longitudinal axis.

Abstract: An exemplary surgical apparatus may include a shaft defining a lumen therein; articulation bands extending through and slidable generally longitudinally within the lumen of the shaft; an end effector affixed to the articulation bands; and generally annular segments positioned about the articulation bands along at least a portion of the length of the articulation bands to define an articulated region, where the segments laterally constrain the articulation bands.

Abstract: A device for attaching a sheet-like implant to a target tissue. The device includes a fastener push rod including a first portion, a second portion and a force limiting mechanism operably coupled between the first portion and the second portion. A fastener is carried by the second portion of the fastener push rod. The force limiting mechanism transmits longitudinal movement of the first portion to the second portion while the forces applied to the fastener by the fastener push rod are less than a predetermined value such that longitudinal movement of the first portion of the fastener push rod causes substantially equivalent longitudinal movement of the second portion. The force limiting mechanism allows relative longitudinal motion between the first and second portions while the forces applied to the fastener are equal to or greater than the predetermined value such that the application of undue forces to the fastener is prevented.