WO2016192037A1

WO2016192037A1 - Surgical stapling instrument with self-locking screw

Info

Publication number: WO2016192037A1
Application number: PCT/CN2015/080568
Authority: WO
Inventors: Qianhong Yang; Hui Zhan
Original assignee: Covidien China Medical Devices Technology Co Ltd; Covidien LP
Current assignee: Covidien China Medical Devices Technology Co Ltd; Covidien LP
Priority date: 2015-06-02
Filing date: 2015-06-02
Publication date: 2016-12-08
Anticipated expiration: 2017-12-02

Abstract

The present disclosure provides a surgical stapling instrument including an approximation assembly including an approximation knob, an anvil retainer, and a drive screw having a proximal end and a distal end and defining a helical channel. The distal end of the drive screw is operatively connected to the anvil retainer which supports an anvil assembly. The approximation knob is operatively connected to the drive screw such that actuation of the approximation knob effects movement of the drive screw between retracted and advanced positions to move the anvil assembly between a spaced position and an approximated position in relation to a cartridge assembly. The helical channel includes a proximal portion having a first pitch, a distal portion having a second pitch and a central portion having a third pitch. The third pitch is greater than the first pitch and the second pitch. The first pitch is selected to minimize the likelihood of inadvertent proximal movement of the anvil retainer.

Description

SURGICAL STAPLING INSTRUMENT WITH SELF-LOCKING SCREW

BACKGROUND

1.Technical Field

The present disclosure relates generally to a surgical stapling instrument for applying surgical fasteners to body tissue. More particularly, the present disclosure relates to a circular surgical stapling instrument for treating hollow tissue organs having a drive screw including a self-locking helical channel design.

2.Background of Related Art

Circular stapling instruments are known in the medical arts for facilitating performance of a variety of surgical procedures including circular anastomis procedures and hemorrhoid treatment procedures. In a circular anastomis procedure two hollow organ end sections are joined together by driving a circular array of staples through the organ end sections to join the organ end sections together while simultaneously coring any tissue interior of the driven circular array of staples to open a tubular passage within the joined organ end sections. Examples of instruments for performing circular anastomosis of hollow organs are described in U.S. Patent Nos. 7, 303, 106, 6, 053, 390, 5, 588, 579, 5, 119, 983, 5, 005, 749, 4, 646, 745, 4, 576, 167, and 4, 473, 077, each of which is incorporated herein in its entirety by reference. In a hemorrhoid treatment procedure, hemorrhoid tissue or mucosal tissue adjacent the hemorrhoid tissue is dissected and sutured to remove the hemorrhoid and/or treat hemorrhoid prolapses.

Known circular stapling instruments include an elongated shaft having an anvil holding component disposed at a distal end of the elongated shaft. An anvil assembly including an anvil rod and anvil head is releasably mounted to the distal end of the anvil holding component. The anvil holding component is operably connected to a drive screw and is retractable within the elongated shaft of the stapling instrument to move the anvil assembly in relation to a cartridge assembly supported on a distal end of the elongated shaft between advanced and retracted positions.

Typically, the drive screw defines a helical channel and is supported for longitudinal movement within a handle assembly of the stapling instrument. The helical channel is configured to receive a pin which is axially fixed to the handle assembly but rotatable about the drive screw such that rotation of the pin in relation to the drive screw effects longitudinal movement of the drive screw and corresponding longitudinal movement of the anvil assembly in relation to the cartridge assembly.

During use of a circular stapling instrument, the force applied to the anvil holding component by the anvil assembly during attachment of the anvil assembly to the anvil holding component is translated through the instrument to the drive screw and onto the pin. This action can cause rotation of the drive screw and inadvertent proximal movement of the anvil holding component. Such inadvertent proximal movement of the anvil holding component may prevent the anvil assembly from being properly attached to the anvil holding component.

It would be advantageous to provide a circular stapling instrument having a drive screw that is configured to minimize the likelihood of inadvertent proximal movement of the anvil holding component during attachment of the anvil assembly to the anvil holding component.

SUMMARY

The present disclosure provides in one aspect a surgical stapling instrument including a handle assembly having a housing supporting an approximation knob and a central body portion extending distally from the handle assembly. A distal head portion is supported on a distal end of the central body portion and includes an anvil assembly and a cartridge assembly. The anvil assembly includes an anvil shaft and an anvil head supported on a distal end of the anvil shaft. The anvil assembly is movable in relation to the cartridge assembly between a spaced position and an approximated position. A drive screw has a proximal end and a distal end and defines a helical channel. The drive screw is operatively connected to the anvil assembly and movable within the handle housing between an advanced position and a retracted position. The approximation knob is operatively connected to the proximal end of the drive screw such that actuation of the approximation knob effects movement of the drive screw between retracted and advanced positions to move the anvil assembly between the spaced position and the approximated position. The helical channel includes a first proximal portion having a first pitch and a second portion positioned immediately distal of the first proximal portion having a second pitch, wherein the first pitch is less than the second pitch.

In embodiments, the first pitch is less than. 160 cm [Is this centimeters or inches？ ]

In some embodiments, the surgical stapling instrument includes a firing mechanism having a firing trigger that is actuable to eject staples from the cartridge assembly.

In certain embodiments, the firing mechanism includes a pusher link.

In embodiments, the surgical stapling instrument includes a rotatable sleeve having a proximal end coupled to the approximation knob and a distal end positioned about the proximal end of the drive screw. The distal end of the sleeve supports a pin that is received in the helical channel. The pin engages the drive screw in the proximal portion of the helical channel when the drive screw is in the advanced position.

In some embodiments, a collar fixedly supported on the distal end of the sleeve and rotatably supported within the housing of the handle assembly supports the pin.

In certain embodiments, the collar is axially fixed within the housing.

The present disclosure provides in another aspect a surgical stapling instrument including a handle assembly having a housing supporting an approximation knob. A central body portion extends distally from the handle assembly and supports a distal head portion including an anvil assembly and a cartridge assembly. The anvil assembly includes an anvil shaft and an anvil head supported on a distal end of the anvil shaft. The anvil assembly is movable in relation to the cartridge assembly between a spaced position and an approximated position. A drive screw has a proximal end and a distal end and defines a helical channel. The distal end of the drive screw is operatively connected to the anvil assembly and the drive screw is movable within the handle housing between an advanced position and a retracted position. The approximation knob is operatively connected to the drive screw such that actuation of the approximation knob effects movement of the drive screw between the retracted and advanced positions to move the anvil assembly between the spaced position and the approximated position. The helical channel includes a proximal-most portion having a first pitch, a distal-most portion having a second pitch and a central portion having a third pitch, the third pitch being greater than the first pitch and the second pitch.

In embodiments, the first pitch is less than. 160 cm. In certain embodiments, the second pitch is between. 160 cm and. 90 cm. In some embodiments, the third pitch is between. 520 cm and. 900 cm.

In embodiments, the central portion defines the third pitch and a fourth pitch, wherein the third and fourth pitches are greater than the first and second pitches.

In some embodiments, the third pitch is positioned proximally of the fourth pitch and is greater than the fourth pitch.

In certain embodiments, the surgical stapling instrument includes a firing mechanism having a firing trigger that is actuable to eject staples from the cartridge assembly.

In embodiments, the firing mechanism includes a pusher link.

In embodiments, the surgical stapling instrument further includes a rotatable sleeve having a proximal end coupled to the approximation knob and a distal end positioned about the proximal end of the drive screw.

In some embodiments, the distal end of the sleeve supports a pin that is received in the helical channel such that the pin engages the drive screw in the proximal-most portion of the helical channel when the drive screw is in the advanced position.

In embodiments, the surgical stapling instrument further includes a collar fixedly supported on the distal end of the sleeve. The collar is rotatably supported within the housing of the handle assembly and supports the pin.

In embodiments, the collar is axially fixed within the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the presently disclosed surgical stapling instrument with self-locking helical channel are described herein with reference to the drawings, wherein:

Fig. 1 is a side, perspective view of one embodiment of the surgical stapling instrument of the present disclosure with the anvil assembly separated from the anvil assembly holding component；

Fig. 2 is an enlarged view of the indicated area of detail shown in Fig. 1；

Fig. 3 is a side, perspective view of the surgical stapling instrument of the present disclosure with the anvil assembly supported on the anvil assembly holding component；

Fig. 4 is an enlarged view of the indicated area of detail shown in Fig. 3；

Fig. 5 is a side, perspective view of the surgical stapling instrument shown in Fig. 3 with a handle housing half-section removed；

Fig. 6 is an enlarged view of the indicated area of detail shown in Fig. 5；

Fig. 7 is a cross-sectional view taken along line 7-7 of Fig. 5；

Fig. 7A is an enlarged view of the indicated area of detail shown in Fig. 7；

Fig. 8 is an enlarged view of the indicated area of detail shown in Fig. 7；

Fig. 9 is a perspective view from one side of the drive screw of the surgical stapling instrument shown in Fig. 7； and

Fig. 10 is a side view of the drive screw of the surgical stapling instrument shown in Fig. 7.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure are now described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. As used herein, the term “clinician” refers to a doctor, a nurse, or any other care provider and may include support personnel. Throughout this description, the term “proximal” refers to the portion of the device or component thereof that is closest to the clinician and the term “distal” refers to the portion of the device or component thereof that is farthest from the clinician.

The presently disclosed surgical stapling instrument includes an anvil assembly and an anvil holding component. The anvil holding component releasably supports the anvil assembly and is connected to a drive screw of an approximation assembly of the surgical stapling instrument. The drive screw defines a helical channel that is configured to receive a pin that is supported on an approximation knob and is rotatable about the drive screw to effect longitudinal movement of the drive screw and the anvil holding component. The helical channel of the drive screw is configured to minimize inadvertent proximal movement of the anvil holding component caused by application of a force to the anvil holding component, such as during attachment of the anvil assembly to the anvil holding component.

Figs. 1-4 illustrate the presently disclosed surgical stapling instrument 10. Briefly, surgical stapling instrument 10 includes a handle assembly 12, a central body portion 14 and a distal head portion 16. Although the central body portion 14 is shown as being substantially straight, it is envisioned that the central body portion could be curved as is known in the art. The distal head portion 16 includes an anvil assembly 18 and a cartridge assembly 20. The cartridge assembly 20 is supported on a distal end of the central body portion 14 and includes a cartridge body 20a that has a circular configuration and supports an annular array of staples (not shown) . The anvil assembly 18 includes an anvil head 18a and an anvil shaft 18b. The anvil head 18a is supported on the distal end of the anvil shaft 18b and defines an annular array of staple pockets (not shown) that are positioned to receive the staples.

The handle assembly 12 includes a housing 12a, a firing mechanism including a firing trigger 24, an approximation knob 26, an indicator assembly 28, and a lockout mechanism 30. The approximation knob 26 forms part of an approximation mechanism that functions to retract and advance the anvil assembly 18 in relation to the cartridge assembly 20 as will be discussed in further detail below. The firing mechanism functions to advance a pusher link 31 (Fig. 7) to eject staples from cartridge 20a of the cartridge assembly 20. Operation of the various components of the handle assembly 12 including the firing mechanism, the indicator assembly 28 and the lockout mechanism 30 are described in U.S. Patent No. 7, 303, 106, the contents of which are incorporated herein by reference in their entirety. Accordingly, these components and assemblies will not be described in further detail herein.

Referring to Figs. 5 and 6, the approximation mechanism of the surgical stapling instrument 10 includes the approximation knob 26, a rotatable sleeve 34, a drive screw 36, and an anvil holding component or anvil retainer 38. The rotatable sleeve 34 includes a substantially cylindrical hollow body portion 40 and a substantially cylindrical collar 42 which together define a central bore 42a (FIG. 6) . The collar 42 defines an annular groove 44 (FIG. 6) that is dimensioned to receive an inwardly extending flange 46 formed on an inner wall of handle housing 12a of the handle assembly 12. The receipt of the flange 46 within the groove 44 axially fixes sleeve 34 within handle housing 12a while permitting rotation of the sleeve 34 in relation to the housing 12a. The proximal end of the body portion 40 of the rotatable sleeve 34 extends through an opening 47 (FIG. 7) in the proximal end of the housing 12a and is secured to the approximation knob 26 to rotatably fix the sleeve 34 to the approximation knob 26, such that rotation of the approximation knob 26 causes concurrent rotation of sleeve 34.

The drive screw 36 defines a helical channel 50 and is dimensioned to be slidably received within the central bore 42a (Fig. 8) of rotatable sleeve 34. A pin 52 extends radially through the collar 42 on the distal end of the sleeve 34 into helical channel 50 of the drive screw 36. Since the sleeve 34 is axially fixed with respect to the housing 12a of the handle assembly 12, rotation of the sleeve 34 about the screw 36 causes the pin 52 to move along the channel 50 of the drive screw 36 to effect axial movement of the drive screw 36 within the housing 12a of the handle assembly 12.

Referring to Figs. 7-10, the distal end 36a of the drive screw 36 defines a cylindrical recess 54 that is configured to receive a proximal end 38a of the anvil retainer 38. Both the distal end 36a of the drive screw 36 and the proximal end 38a of the anvil retainer 38 define bores 56 (Fig. 9) that receive a pin 58 to fixedly secure the anvil retainer 38 to the drive screw 36. It is envisioned that the drive screw 36 and the anvil retainer 38 can be secured together using other known fastening techniques, e.g., welding, crimping, screw threads, etc. As will be discussed in further detail below, longitudinal movement of the drive screw 36 is translated into longitudinal movement of the anvil retainer 38.

The distal end 38b (Fig. 7A) of the anvil retainer 38 includes a plurality of flexible, resilient fingers 60 (See, also, Fig. 4) that define a substantially cylindrical bore 62 that is dimensioned to receive the proximal end of the anvil shaft 18b of the anvil assembly 18. As best seen in Fig. 7A, each of the flexible fingers 60 defines a recess 64 having a proximally facing shoulder 66. The recesses 64 are dimensioned to receive an annular abutment 68 formed on the anvil shaft 18b to releasably secure the anvil assembly 18 to the anvil retainer 38. The annular abutment 68 has a diameter that is larger than the distal end of the bore 62 defined by the flexible fingers 60.

During attachment of the anvil assembly 18 to the anvil retainer 38, the anvil shaft 18b is inserted into the cylindrical bore 62 of the anvil retainer 38. When the annular abutment 68 of the anvil shaft 18b engages the distal end of the flexible fingers 60, the flexible fingers 60 are deformed or flex outwardly to allow the annular abutment 68 to pass into the cylindrical bore 62 and into the recesses 64 of the fingers 60. In this position, the shoulder 66 defining each recess 64 engages the annular abutment 68 to secure the anvil assembly 18 to the anvil retainer 38.

As shown in Figs. 7 and 7A, when the anvil assembly 18 is in an advanced position spaced from the cartridge assembly 20, the flexible fingers 60 are positioned distally of a cylindrical bearing 70 that is fixedly secured within the cartridge assembly 20 and defines a pathway for the anvil retainer 38 and the anvil shaft 18b as the anvil head 18a is moved from a position spaced from the cartridge assembly 20 to a position in approximation with the cartridge assembly 20. The bearing 70 is dimensioned to limit outward deflection of the flexible fingers 60 as the anvil retainer 38 is withdrawn into the bearing 70 after the anvil assembly 18 has been secured to the anvil retainer 38 to lock the anvil assembly 18 to the anvil retainer 38. As such, the bearing 70 more securely couples the anvil assembly 18 to the anvil retainer 38 to prevent separation of the anvil assembly 18 from the anvil retainer 38 when a force is applied to the anvil assembly 18 in a direction to disengage the anvil assembly 18 from the anvil retainer 38, such as during firing of the stapling instrument 10.

When the anvil assembly 18 is attached to the anvil retainer 38, a proximally directed force is applied to the anvil retainer 38 by the anvil assembly 18. This force is translated proximally along the anvil retainer 38 to the drive screw 36 and to the pin 52. As discussed above, the pin 52 is received in the helical channel 50 of the drive screw 36. In known devices, the pitch, i.e., the distance between two corresponding points on a helix, at the proximal end of the helical channel 50, where the pin 52 engages the drive screw 36 when the drive screw is in an advanced position, is such that the force of the drive screw 36 on the pin 52 has a lateral component that may cause the drive screw 36 to inadvertently rotate as the anvil assembly 18 is attached to the anvil retainer 38 or when another force is applied to the anvil retainer 38. If the drive screw 36 rotates during attachment of the anvil assembly 18 to the anvil retainer 38, the anvil retainer 38 may retract into the bearing 70. If this occurs, the flexible fingers 60 of the anvil retainer 38 may be prevented from flexing outwardly by engagement with the bearing 70 to prevent full insertion of the anvil shaft 18b into the bore 62 of the anvil retainer 38. If full insertion of the anvil shaft 18b into the anvil retainer 38 is prevented, the annular abutment 68 will not be received within the recesses 64 of the flexible fingers 60 and the anvil assembly 18 will not be securely attached to the anvil retainer 38.

Referring to Figs. 9 and 10, in order to minimize the likelihood that application of a proximally directed force on the anvil retainer 38, such as during the process of attaching the anvil shaft 18b to the anvil retainer 38, will cause inadvertent proximal movement of the anvil retainer 38 into the bearing 70, the pitch at the proximal end of the channel 50 of the drive screw 36 is reduced as compared to the pitch of the channel 50 immediately distally thereof. By reducing the pitch at the proximal end of the channel 50 where the pin 52 engages the drive screw 36 when the drive screw 36 is in its advanced position, the lateral component of any force generated by the drive screw 36 engaging the pin 52 can be minimized to prevent inadvertent rotation of the drive screw 36.

Typically, the pitch of the channel 50 is higher at the proximal end of the channel 50 and decreases distally along the drive screw 36. The greater pitch at the proximal end of the channel 50 allows the anvil assembly 18 to be approximated more quickly per turn of the approximation knob 26 when the anvil assembly 18 is spaced a large distance from the cartridge assembly 20. The pitch decreases towards the distal end of the channel 50 to allow for fine approximation of the anvil assembly 18 and cartridge assembly 20 as tissue positioned between the anvil assembly 18 and the cartridge assembly 20 is being compressed. For manufacturing reasons, the pitch “A” of the proximal end of the channel decreases towards pitch portion “B” . However, the pin 52 engages the channel 50 of the drive screw 36 in pitch portion “B” when the drive screw 36 is fully advanced. Thus, pitch portion “A” does not engage the pin 52 and thus, does not affect advancement of the drive screw 36. In the presently disclosed stapling instrument, the pitch of portion “B” at the proximal end of the helical channel 50 of the drive screw 36 is selected to minimize the lateral component of any force generated by contact between the pin 52 and the drive screw 36 such as during attachment of the anvil assembly 18 to the anvil retainer 38. In embodiments, the pitch of portion “B” of the helical channel 50 of the drive screw 36 is less than about. 160 cm in the area where the pin 52 engages the drive screw 36 when the drive screw 36 is in its advanced position. In other embodiments, the pitch of portion “B” can be less than about. 250 cm.

Referring to Fig. 10, in one embodiment of the presently disclosed surgical instrument 10, the pitch of the helical channel 50 of the drive screw 36 varies along the length of the drive screw 36. For example, the pitch of portion “B” of the helical channel 50 immediately distal of the proximal portion “A” of the helical channel 50 may increase in the distal direction from about. 160 cm to about. 900 cm. This pitch allows the anvil assembly 18 to be retracted towards the cartridge assembly 20 at an advanced rate as the approximation knob 26 is rotated by a clinician. In some embodiments, the pitch of portion “C” of the helical channel 50 may decrease from the pitch in portion “B” from about. 900 cm to about. 520 cm. This pitch allows for a first stage of finer approximation of the anvil assembly 18 and the cartridge assembly 20 as the anvil and

cartridge assemblies

18 and 20, respectively, draw nearer to each other. In some embodiments, the pitch of portion “D” of the helical channel 50 may remain constant at about. 520 cm. In some embodiments, the pitch of portion “E” of the helical channel 50 may be decrease even further at the distal end of the helical channel 50 from about. 520 cm to about. 160 cm to provide even finer approximation of the anvil assembly 18 and the cartridge assembly 20 as the anvil assembly 18 moves towards its fully approximated position. Further, in some embodiments, the pitch of portion “F” of the helical channel 50 may be reduced even further at the distal-most end of the helical channel 50 from about. 160 cm to about. 090 cm to provide even finer control of approximation.

It is noted that the pitch of the channel 50 need not continuously change along the length of the helical channel 50. More specifically, in some embodiments, the channel 50 of the drive screw 36 may have a pitch in portion “B” of less than about. 160 cm that increases to about. 520 cm, and the remaining portion of the channel 50 may have a pitch that remains constant for the remainder of the length of the channel 50. In other embodiments, the channel 50 of the drive screw 36 may have a pitch in portion “B” of less than about. 250 cm that increases to about. 520 cm and the remaining portion of the channel 50 may have a pitch that remains constant for the remainder of the length of the channel 50. Alternately, the remainder of the channel 50 may have a pitch that increases from, e.g., . 160 cm to between about. 520 cm and about. 900 cm and then decreases to about. 160 cm to provide for fine approximation. Thus, the pitch of the portion of channel 50 distally of portion “A” may be selected as desired to achieve any desired result, e.g., accelerated approximation or fine approximation.

While several embodiments of the disclosure have been described, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Any combination of the above embodiments is also envisioned and is within the scope of the appended claims. 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 of the claims appended hereto.

Claims

A surgical stapling instrument comprising:

a handle assembly including a housing supporting an approximation knob；

a central body portion extending distally from the handle assembly；

a distal head portion including an anvil assembly and a cartridge assembly, the anvil assembly including an anvil shaft and an anvil head supported on a distal end of the anvil shaft, the anvil assembly being movable in relation to the cartridge assembly between a spaced position and an approximated position； and

a drive screw having a proximal end and a distal end and defining a helical channel, the drive screw being operatively connected to the anvil assembly and movable within the housing of the handle assembly between an advanced position and a retracted position, the approximation knob being operatively connected to the proximal end of the drive screw such that actuation of the approximation knob effects movement of the drive screw between retracted and advanced positions to move the anvil assembly between the spaced position and an approximated position；

wherein the helical channel includes a first proximal portion having a first pitch and a second portion positioned immediately distal of the first proximal portion having a second pitch, wherein the first pitch is less than the second pitch.
The surgical stapling instrument of claim 1, wherein the first pitch is less than . 160 cm.
The surgical stapling instrument of claim 1, further including a firing mechanism including a firing trigger, the firing trigger being actuable to eject staples from the cartridge assembly.
The surgical stapling instrument of claim 3, wherein the firing mechanism includes a pusher link connecting the firing trigger with the cartridge assembly.
The surgical stapling instrument of claim 1, further including a rotatable sleeve, the rotatable sleeve having a proximal end coupled to the approximation knob and a distal end positioned about the proximal end of the drive screw.
The surgical stapling instrument of claim 5, wherein the distal end of the sleeve supports a pin that is received in the helical channel, the pin engaging the drive screw in the first proximal portion of the helical channel when the drive screw is in the advanced position.
The surgical stapling instrument of claim 6, further including a collar fixedly supported on the distal end of the sleeve, the collar being rotatably supported within the housing of the handle assembly and supporting the pin.
The surgical stapling instrument of claim 7, wherein the collar is axially fixed within the housing.
A surgical stapling instrument comprising:

a handle assembly including a housing supporting an approximation knob；

a central body portion extending distally from the handle assembly；

a distal head portion including an anvil assembly and a cartridge assembly, the anvil assembly including an anvil shaft and an anvil head supported on a distal end of the anvil shaft, the anvil assembly being movable in relation to the cartridge assembly between a spaced position and an approximated position； and

a drive screw having a proximal end and a distal end and defining a helical channel, the drive screw being operatively connected to the anvil assembly and movable within the handle housing between an advanced position and a retracted position, the approximation knob being operatively connected to the proximal end of the drive screw such that actuation of the approximation knob effects movement of the drive screw such that actuation of the approximation knob effects movement of the drive screw between the retracted and advanced positions to move the anvil assembly between the spaced position and the approximated position；

wherein the helical channel includes a proximal portion having a first pitch, a distal portion having a second pitch and a central portion having a third pitch, the third pitch being greater than the first pitch and the second pitch.
The surgical stapling instrument of claim 9, wherein the first pitch is less than . 160 cm.
The surgical stapling instrument of claim 10, wherein the second pitch decreases from . 160 cm to . 90 cm from a proximal end of the distal portion to a distal end of the distal portion.
The surgical stapling instrument of claim 11, wherein the third pitch decreases from . 520 cm and . 900 cm from a proximal end of the central portion to a distal end of the central portion.
The surgical stapling instrument of claim 9, wherein the central portion defines the third pitch and a fourth pitch, wherein the third and fourth pitches are greater than the first and second pitches.
The surgical stapling instrument of claim 13, wherein the third pitch is positioned proximally of the fourth pitch and is greater than the fourth pitch.
The surgical stapling instrument of claim 9, further including a firing mechanism including a firing trigger, the firing trigger being actuable to eject staples from the cartridge assembly.
The surgical stapling instrument of claim 15, wherein the firing mechanism includes a pusher link connecting the firing trigger with the cartridge assembly.
The surgical stapling instrument of claim 9, further including a rotatable sleeve, the rotatable sleeve having a proximal end coupled to the approximation knob and a distal end positioned about the proximal end of the drive screw.
The surgical stapling instrument of claim 7, wherein the distal end of the sleeve supports a pin that is received in the helical channel, the pin engaging the drive screw in the proximal-most portion of the helical channel when the drive screw is in the advanced position.
The surgical stapling instrument of claim 18, further including a collar fixedly supported on the distal end of the sleeve, the collar being rotatably supported within the housing of the handle assembly and supporting the pin.
The surgical stapling instrument of claim 19, wherein the collar is axially fixed within the housing.