Surgical instrument comprising an adapter assembly and an articulating surgical loading unit

Abstract

The present invention relates to surgical instruments comprising an adapter assembly and an articulating surgical loading unit, and provides an adapter assembly for a surgical instrument comprising a cam member defining a proximal cam slot and a distal cam slot, a first articulation shaft and a second articulation shaft. The first articulation shaft has a proximal portion received in the proximal cam slot, and a distal portion configured to be coupled to a surgical loading unit. The second articulation shaft has a proximal portion received in the distal cam slot, and a distal portion configured to be coupled to the surgical loading unit. The first and second articulation shafts are configured to move in opposite longitudinal directions in response to rotation of the cam member, thereby articulating the surgical loading unit.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to surgical instruments for endoscopic use, and more particularly to surgical instruments including an adapter assembly that articulately attaches a surgical loading unit. BACKGROUND

[0002] Various types of surgical instruments for treating tissue under endoscopic vision are known in the art and are commonly used, for example, to close tissue or organs in transection, resection, stapling, for closing organs in thoracic and abdominal surgery, and for electrosurgically fusing or sealing tissue.

[0003] One example of such a surgical instrument is a surgical stapling instrument. Generally, a surgical stapling instrument includes an end effector having an anvil assembly and a cartridge assembly for supporting an array of surgical staples, an access mechanism for accessing the cartridge assembly and anvil assembly, and a firing mechanism for ejecting surgical staples from the cartridge assembly.

[0004] During laparoscopic or endoscopic surgery, the surgical site is accessed through a small incision or through a narrow cannula inserted through a small access wound in the patient. Because of the limited area available for accessing the surgical site, many endoscopic instruments include a mechanism for articulating the end effector of the instrument relative to the main body portion of the instrument to better access the tissue to be treated. SUMMARY

[0005] In one aspect of the present disclosure, an adapter assembly includes a cam member defining a first cam slot and a second cam slot, an outer conduit extending distally from the cam member and having a distal portion configured to be coupled to a distal portion of a surgical loading unit, and first and second articulation shafts each having a proximal portion and a distal portion. The proximal portion of the first articulation shaft is operably coupled to the proximal cam slot of the cam member, and the proximal portion of the second articulation shaft is operably coupled to the distal cam slot of the cam member. The distal portion of each of the first and second articulation shafts is configured to be coupled to the surgical loading unit. The first and second articulation shafts are configured to translate in opposite directions in response to rotation of the cam member, thereby articulating the surgical loading unit relative to the outer conduit.

[0006] In aspects, the adapter assembly can further include a proximal ring member and a distal ring member disposed about the cam member, respectively. The proximal ring member can have a protrusion received in the first cam slot, and the distal ring member can have a protrusion received in the second cam slot. The proximal and distal ring members can be configured to move axially in opposite longitudinal directions in response to the rotation of the cam member.

[0007] In aspects, the proximal portion of the first articulation shaft can be axially constrained to the proximal ring member, and the proximal portion of the second articulation shaft can be axially constrained to the distal ring member. The first and second articulation shafts can be configured to move axially with the respective proximal and distal ring members.

[0008] In aspects, the first and second articulation shafts can rotate relative to and about the respective proximal and distal ring members.

[0009] In aspects, the proximal ring member can define an outer annular groove therein, and the proximal portion of the first articulation shaft can have an annular protrusion slidably received in the annular groove. The distal ring member can define an outer annular groove therein, and the proximal portion of the second articulation shaft can have an annular protrusion slidably received in the annular groove of the distal ring member.

[0010] In aspects, the adapter assembly can further include a knob housing disposed about a proximal portion of the outer catheter. The proximal portion of each of the first and second articulation shafts can be non-rotatably coupled to the knob housing and axially movable relative to the knob housing.

[0011] In aspects, the knob housing can include an inner surface defining a pair of longitudinally extending slots, and the proximal portion of each of the first and second articulation shafts can have a longitudinally extending ridge received in the respective pair of longitudinally extending slots of the knob housing.

[0012] In aspects, the proximal portion of the first articulation shaft can have an inwardly extending protrusion, and the distal portion of the outer catheter can define a longitudinally extending slot in which the protrusion of the first articulation shaft is received such that the distal portion of the outer catheter rotates about a longitudinal axis with the first articulation shaft in response to rotation of the knob housing.

[0013] In aspects, the proximal portion of each of the first and second articulation shafts can be disposed about the outer catheter and the cam member.

[0014] According to another aspect of the present disclosure, a surgical instrument is provided that includes a surgical loading unit and an adapter assembly. The adapter assembly includes a coupling mechanism having a drive shaft, a cam member operably coupled to the drive shaft and defining a proximal cam slot and a distal cam slot, an outer conduit extending distally from the cam member and having a distal portion configured to couple a distal portion of the surgical loading unit, and first and second articulating shafts each having a proximal portion and a distal portion. The proximal portion of the first articulating shaft is operably coupled to the proximal cam slot of the cam member, and the proximal portion of the second articulating shaft is operably coupled to the distal cam slot of the cam member. The distal portion of each of the first and second articulating shafts is configured to couple to the surgical loading unit. The first and second articulating shafts are configured to translate in opposite directions in response to rotation of the cam member, thereby articulating the surgical loading unit relative to the outer conduit.

[0015] In aspects, the adapter assembly can further include a knob housing rotatably coupled to the coupling mechanism and disposed about a proximal portion of the outer conduit. The proximal portion of each of the first and second articulating shafts can be non-rotatably coupled to the knob housing and axially movable relative to the knob housing.

[0016] In aspects, the proximal portion of each of the first and second articulating shafts can be curved and disposed about the outer conduit and the cam member. BRIEF DESCRIPTION OF DRAWINGS

[0017] An exemplary aspect of a surgical instrument including the disclosed adapter assembly is disclosed below with reference to the drawings, in which:

[0018] Figure 1 is a perspective view of a surgical instrument including a handle assembly, an adapter assembly, and a surgical loading unit;

[0019] Figure 2 is Figure 1 is a perspective view of the adapter assembly and surgical loading unit of

[0020] Figure 3 is a perspective view of internal components of the adapter assembly of Figure 2 including a coupling mechanism, an outer conduit, a pair of ring members, and a pair of articulating shafts;

[0021] Figure 4 is a perspective view of the adapter assembly of Figure 3 with components separated;

[0022] Figure 5 is a perspective view showing Figure 3a side perspective view of the adapter assembly of

[0023] Figure 6 is a side perspective view of the adapter assembly of Figure 3 a side perspective view of the adapter assembly of

[0024] Figure 7 is a side perspective view of the adapter assembly of Figure 3 a side perspective view of the adapter assembly of

[0025] Figure 8 is a longitudinal cross-sectional view of the surgical loading unit in an articulated position of Figure 1

[0026] Figure 9 is a side perspective view of the surgical loading unit in an articulated position of Figure 1

[0027] Figure 10 is a longitudinal cross-sectional view of the adapter assembly of Figure 3

[0028] Figure 11 is a longitudinal cross-sectional view of the adapter assembly of Figure 3 DETAILED DESCRIPTION

[0029] As used herein, the term "distal" refers to the portion of the surgical instrument furthest from the clinician, while the term "proximal" refers to the portion of the surgical instrument closest to the clinician. Additionally, as used herein, the term clinician refers to medical personnel including doctors, nurses, and support staff.

[0030] The present disclosure is directed to a surgical instrument including an adapter assembly configured to be actuated by a hand-held actuator or a surgical robotic system and a surgical loading unit coupled to the adapter assembly. The adapter assembly includes an articulation mechanism that drives articulation of the surgical loading unit relative to the adapter assembly. The articulation mechanism includes a rotatable cam member defining a pair of cam slots, each of the cam slots receiving a pin of a corresponding pair of ring members. When the cam member is rotated, the cam slots drive opposite longitudinal movement of the pair of ring members, which causes first and second articulation shafts to translate in opposite longitudinal directions. Translation of the articulation shafts in opposite longitudinal directions causes the surgical loading unit to articulate relative to an outer conduit of the adapter assembly. Other advantages of the disclosed surgical instrument and its components are described below.

[0031] Figure 1 and Figure 2 ​​​​A surgical instrument 10 including a handle assembly 12, an adapter assembly 20 configured to be coupled to the handle assembly 12, and a surgical loading unit 30 pivotably coupled to the adapter assembly 20 is shown. Although the surgical instrument 10 shown can be configured to fire an anastomosis device, it is contemplated that the surgical instrument 10 can be adapted to fire any other suitable fastener, such as a clip and a two-piece fastener. Moreover, although the figures show a linear surgical anastomosis instrument 10, it is contemplated that certain components described herein can be adapted for use in other types of endoscopic surgical instruments, including non-linear surgical anastomosis instrument loading units, endoscopic forceps, graspers, dissectors, other types of surgical anastomosis instruments, and powered vascular sealing and / or cutting devices, among others.

[0032] As shown, Figures 2 to 4 the adapter assembly 20 of the surgical instrument 10 includes a coupling mechanism 14, an outer conduit 24 extending distally from the coupling assembly 14, and an outer housing, such as a rotatable knob housing 21 for manually rotating a distal portion 24b of the outer conduit 24 and an attached surgical loading unit 30. The coupling mechanism 14 is configured to be operably coupled to the handle assembly 12 or a surgical robotic system (not shown) responsible for actuating the surgical instrument 10. The coupling mechanism 14 has a proximal housing 14a Figure 1 ) configured to be coupled to a distal half 13 Figure 3 ) of the handle assembly 12, a distal cap 14b attached to the proximal housing, and a plurality of drive assemblies supported by the proximal housing 14a for transmitting actuation forces from motors (not explicitly shown) of the handle assembly 12 to the surgical loading unit 30. For example, one of the drive assemblies is an articulation drive assembly 100 Figure 4 ) including a drive shaft 102 and a rotary gear 104. The drive shaft 102 is rotatably supported by the proximal housing 14a and is configured to receive actuation forces from one of the drive motors of the handle assembly 12. The drive shaft 102 supports a gear 106, such as a pinion gear, that is in meshing engagement with the rotary gear 104, such as a spur gear. The rotary gear 104 is disposed about and fixed to a cam 108 of the adapter assembly 20. In aspects, various alternative types of gears and / or drive transmission mechanisms can be provided, such as a belt drive, a helical gear, a bevel gear, a helical gear, or a screw gear, among others.

[0033] The outer conduit 24 Figure 2 ) of the adapter assembly 20 can be an assembly including a proximal conduit 24a Figure 3 ) disposed within the knob housing 21 and a distal conduit 24b connected to the proximal conduit 24a. The proximal conduit 24a is rotatably and axially fixed to the coupling mechanism 14, and the distal conduit 24b is configured to rotate relative to the proximal conduit 24a and with the knob housing 21 about a longitudinal axis “X” Figure 2 ) defined by the outer conduit 24.

[0034] Figures 3 to 5 A cam member 108 is shown, which can be a tubular shaft or a housing extending through and rotatably supported in the proximal catheter 14a of the outer catheter assembly 24. The cam member 108 can be fixed or non-rotatably coupled to the rotating gear 104 of the coupling mechanism 14 such that the cam member 108 rotates with rotation of the rotating gear 104. The cam member 108 has a tubular outer surface defining a proximal cam groove 108a and a distal cam groove 108b therein. The proximal and distal cam grooves 108a, 108b are longitudinally spaced apart from each other and encircle a central longitudinal axis defined by the cam member 108. The proximal and distal cam grooves 108a, 108b have opposite helical configurations, respectively. For example, the proximal cam groove 108a can have a left-handed helical configuration, while the distal cam groove 108b can have a right-handed helical configuration, or vice versa. In aspects, the proximal and distal cam grooves 108a, 108b can each have the same handedness, e.g., left- or right-handed.

[0035] Referring to Figure 3 , 4 , 6 and 7, the adapter assembly 20 further includes a pair of proximal and distal ring members 110, 112 operably coupled to the cam member 108, a pair of articulation shafts 120, 122 operably coupled to the ring members 110, 112, and a pair of articulation links 150, 152 operably coupling the articulation shafts 120, 122 to the surgical loading unit 30. Figure 8 The proximal and distal ring members 110, 112 are disposed around the proximal catheter 24a, respectively, which have ring bodies 110a, 112a and protrusions 110b, 112b, e.g., pins extending radially inward from the ring bodies 110a, 112a, respectively. The ring bodies 110a, 112a of each of the ring members 110, 112 define annular grooves 114, 116 in their outer surfaces. Flexible annular snap retainers 118, 124 can be received in the annular grooves 114, 116, thereby retaining the protrusions 110b, 112b fixed to the ring bodies 110a, 112a.

[0036] The protrusions 110b of the proximal ring member 110 extend through a first longitudinally extending guide slot 126 in the proximal catheter 24a Figure 7) and received in a proximal cam slot 108a of the cam member 108. The protrusion 112b of the distal ring member 112 extends through a second longitudinally extending guide slot (not explicitly shown) in the proximal catheter 24a and is received in a distal cam slot 108b of the cam member 108. First and second guide slots 126 are provided on opposite sides of the proximal catheter 24a and ensure that the proximal and distal ring members 110, 112 do not rotate during rotation of the cam member 108. Rotation of the cam member 108 causes the proximal and distal ring members 110, 112 to translate in opposite directions along the longitudinal axis "X" of the outer catheter 24 due to the protrusions 110b, 112b of the proximal and distal ring members 110, 112 being received in the respective proximal and distal cam slots 108a, 108b of the cam member 108.

[0037] As shown in FIGS. 1 and 2, the left articulation shaft 120 includes a proximal portion, e.g., a left half shell 120a having a semi-cylindrical configuration, and a distal portion, e.g., an elongated rod 120b extending distally from the left half shell 120a. Similarly, the right articulation shaft 122 includes a proximal portion, e.g., a right half shell 122a having a semi-cylindrical configuration, and a distal portion, e.g., an elongated rod 122b extending distally from the right half shell 122a. As described below, the right half shell 122a can be longer than the left half shell 120a. Figure 3 Figure 4 As shown in FIGS. 1 and 2, the left articulation shaft 120 includes a proximal portion, e.g., a left half shell 120a having a semi-cylindrical configuration, and a distal portion, e.g., an elongated rod 120b extending distally from the left half shell 120a. Similarly, the right articulation shaft 122 includes a proximal portion, e.g., a right half shell 122a having a semi-cylindrical configuration, and a distal portion, e.g., an elongated rod 122b extending distally from the right half shell 122a. As described below, the right half shell 122a can be longer than the left half shell 120a.

[0038] Each of the half shells 120a, 122a of the left and right articulation shafts 120, 122 has an annular protrusion 134, 136 extending inwardly proximally therefrom. Since the left half shell 120a is shorter than the right half shell 122a, the annular protrusion 134 of the left half shell 120a is slidably received in the annular slot 114 of the distal ring member 112. The annular protrusion 136 of the right half shell 122a is slidably received in the annular slot 116 of the proximal ring member 110. This allows the right and left articulation shafts 122, 120 to rotate with the knob housing 21 Figure 4 ) about the proximal and distal ring members 110, 112, the longitudinal movement of the proximal and distal ring members 110a, 112a is transmitted to the respective right and left articulation shafts 122, 120.

[0039] ​The outer surface of each of the left and right half-shells 120a, 122a has a longitudinally extending ridge 128 extending outwardly (the ridge of the right side half-shell 122a is not explicitly shown). Each of the ridges 128 is slidably received in a corresponding longitudinally extending channel or slot 130 defined in the inner surface 132 of the knob housing 21. The engagement of the ridges 128 of the left and right half-shells 120a, 122a with the channels 130 defined in the opposite sides of the knob housing 21 effects the translation of the left and right articulating shafts 120, 122 relative to and within the knob housing 21 while also forming a non-rotatable engagement with the knob housing 21 such that the articulating shafts 120, 122 can rotate with the knob housing 21.

[0040] The left and right half-shells 120a, 122a of the left and right articulating shafts 120, 122 further include inwardly extending tabs or lugs 138, 140, respectively, Figure 3 extending through corresponding left and right longitudinally extending guide slots 144a, 144b defined in the distal conduit 24b. The guide slots 144a, 144b in the distal conduit 24b allow the left and right half-shells 120a, 122a to translate relative to the distal conduit 24b while non-rotatably coupling the left and right half-shells 120a, 122a to the distal conduit 24b.

[0041] Referring to Figure 4 , 8 and 9, each of the elongated shafts 120b, 122b of the left and right articulating shafts 120, 122 has a proximal portion 146a, 148a and a distal portion 146b, 148b. The proximal portion 146a, 148a of each of the elongated shafts 120b, 122b defines an opening that has received therein the respective lug 138, 140 of the left and right half-shells 120a, 122a to axially secure the left half-shell 120a to the left elongated shaft 120b and the right half-shell 122a to the right elongated shaft 122b. The left and right elongated shafts 120b, 122b of the respective left and right articulating shafts 120, 122 extend distally through the distal conduit 24b and terminate distally at the tip of the distal conduit 24b.

[0042] The first articulating link 150( Figure 8) has a proximal end portion 150a pivotably coupled to a distal end portion 146b of the left elongated rod 120b, and the second articulation link 152 has a proximal end portion 152a pivotably coupled to a distal end portion 148b of the right elongated rod 122b. In aspects, the first and second articulation links 150, 152 can be coupled to the first and second elongated rods 120b, 122b via an intermediate shaft (not explicitly shown). The first and second links 150, 152 each have a distal end portion 150b, 152b pivotably coupled to opposite sides of the sleeve 32 of the surgical loading unit 30. As such, the opposite longitudinal motions of the first and second articulation shafts 120, 122 caused by rotation of the cam member 108 push and pull the corresponding first and second links 150, 152 relative to the adapter assembly 20 to articulate the surgical loading unit 30.

[0043] The surgical loading unit 30 is adapted to be attached to the distal conduit 24b of the adapter assembly 20, and can be configured for single use or multiple uses. The pivot joint 26 Figure 9 ) is pivotably coupled to and axially constrained on the distal conduit 24b. The pivot joint 26 is configured to pivotably support the sleeve 32 of the surgical loading unit 30 thereon. The surgical loading unit 30 includes an end effector 34 supported on the sleeve 32. The end effector 34 includes an anvil 36 non-rotatably coupled to the sleeve 32, and a stapler cartridge assembly 37 disposed opposite the anvil 36. The stapler cartridge assembly 37 has a chassis 38 pivotably coupled to the sleeve 32 and a stapler cartridge body 40 configured for movable receipt in a channel of the chassis 38. A knife bar (not explicitly shown) is translatable through the end effector 34 to cut tissue positioned therebetween. The knife bar is further configured to selectively open and close the end effector 34 and fire a stapler from the end effector 34 as it translates therethrough.

[0044] In operation, with reference to Figure 10 and Figure 11 , to articulate the surgical loading unit 30, the drive shaft 102 of the articulation drive assembly 100 is rotated via actuation of the handle assembly 12 Figure 1 ). As the cam member 108 is fixed to the rotating gear 104 Figure 5 ), the cam member 108 rotates with the rotating gear 104 about the central longitudinal axis "X" of the outer conduit 24. As the cam member 108 rotates, the proximal cam slot 108a of the cam member 108 drives the pin 110a of the proximal ring member 110 through the proximal cam slot 108a in a proximal direction, and the distal cam slot 108b of the cam member 108 drives the pin 112b of the distal ring member 112 through the distal cam slot 108b in a distal direction.

[0045] The proximal movement of the proximal ring member 110 is in Figure 10 The arrow "A" indicates the direction that drives the proximal movement of the right hinge shaft 122, because the right half of the housing 122a of the right hinge shaft 122 engages with the proximal ring member 110. Similarly, the distal movement of the distal ring member 112... Figure 10 The arrow "B" indicates the direction that drives the distal end of the left hinge shaft 120 to move, because the left half-shell 120a of the left hinge shaft 120 engages with the distal ring member 112. Thus, the right and left hinge shafts 122, 120 move from a first position corresponding to the non-hinged orientation of the surgical loading unit 30 (…). Figure 10 (That is, the surgical loading unit 30 is coaxial with the external catheter 24,) and moves to the second position corresponding to the hinge orientation of the surgical loading unit 30. Figure 11 (That is, the surgical loading unit 30 pivots relative to the external catheter 24 at a non-parallel angle.) Figure 9 ).

[0046] Specifically, since the first articulated link 150 acts as a pivotal coupling between the left articulation shaft 120 of the adapter assembly 20 and the left side of the surgical loading unit 30, and the second articulated link 152 acts as a pivotal coupling between the right articulation shaft 122 of the adapter assembly 20 and the right side of the surgical loading unit 30, the proximal movement of the right articulation shaft 122 and the distal movement of the left articulation shaft 120 are... Figure 9 The arrow "C" indicates the hinge that drives the surgical loading unit 30 in the right direction. It is anticipated that rotation of the cam member 108 in the opposite direction would cause the surgical loading unit 30 to hinge in the left direction.

[0047] To allow the surgical loading unit 30 to rotate about the longitudinal axis "X" of the external catheter 24, the knob housing 21 can be manually rotated about the longitudinal axis "X". This is due to the ridge 128 of the left half-housing 120a... Figure 3 The ridge of the right half-shell 122a (not shown) is captured in the left channel (not shown) of the knob housing 21, and the ridge of the right half-shell 122a is captured in the right channel 130 of the knob housing 21. Figure 4) so the left and right articulation shafts 120, 122 rotate with rotation of the knob housing 21. The arcuate recesses 114, 116 in the proximal and distal ring members 110, 112 allow the left and right articulation shafts 120, 122 to rotate relative to and around the proximal and distal ring gears 110, 112 during rotation of the knob housing 21. Moreover, since the protrusion 138 of the left half housing 120a is received in the left slot 144a of the distal catheter 24b and the protrusion 140 of the right half housing 122a is received in the right slot 144b of the distal catheter 24b, rotation of the left and right articulation shafts 120, 122 causes a corresponding rotation of the distal catheter 24b relative to the proximal catheter 24a, thereby also rotating the attached surgical loading unit 30 about the longitudinal axis "X".

[0048] Those skilled in the art will appreciate that the adapter assemblies and methods specifically described herein and shown in the drawings are non-limiting exemplary aspects of the present disclosure. It is contemplated that elements and features shown or described in connection with one exemplary aspect of the present disclosure can be combined with elements and features of another aspect without departing from the scope of the present disclosure. Likewise, other features and advantages of the present disclosure will be appreciated based on the foregoing description. Accordingly, the present disclosure is not to be limited, except as by the appended claims.

Claims

1. An adapter assembly comprising: a cam member defining a first cam slot and a second cam slot; an outer catheter extending distally from the cam member and having a distal portion configured to be coupled to a surgical loading unit; a first articulation shaft having a proximal portion operably coupled to the first cam slot of the cam member, and a distal portion configured to be coupled to the surgical loading unit; and a second articulation shaft having a proximal portion operably coupled to the second cam slot of the cam member, and a distal portion configured to be coupled to the surgical loading unit, wherein the first and second articulation shafts are configured to translate in opposite directions in response to rotation of the cam member, thereby articulating the surgical loading unit relative to the outer catheter, the adapter assembly further comprising: a proximal ring member disposed about the cam member and having a protrusion received in the first cam slot; and a distal ring member disposed about the cam member and having a protrusion received in the second cam slot, wherein the proximal and distal ring members are configured to move axially in opposite longitudinal directions in response to the rotation of the cam member, wherein the proximal portion of the first articulation shaft is axially constrained to the proximal ring member, and the proximal portion of the second articulation shaft is axially constrained to the distal ring member, such that the first and second articulation shafts are configured to move axially with the respective proximal and distal ring members, wherein the first and second articulation shafts are rotatable relative to and about the respective proximal and distal ring members.

2. The adapter assembly of claim 1, wherein the proximal ring member defines an outer annular slot therein, and the proximal portion of the first articulation shaft has an annular protrusion slidably received in the outer annular slot.

3. The adapter assembly of claim 2, wherein the distal ring member defines an outer annular slot therein, and the proximal portion of the second articulation shaft has an annular protrusion slidably received in the outer annular slot of the distal ring member.

4. The adapter assembly of claim 1, further comprising a knob housing disposed about a proximal portion of the outer catheter, wherein the proximal portion of each of the first and second articulation shafts is non-rotatably coupled to the knob housing and axially moveable relative to the knob housing.

5. The adapter assembly of claim 4, wherein the knob housing includes an inner surface defining a pair of longitudinally extending slots, and the proximal portion of each of the first and second articulation shafts has a longitudinally extending ridge received in a respective pair of longitudinally extending slots of the knob housing. ​ ​ 6. The adapter assembly of claim 4, wherein the proximal portion of the first articulation shaft has a protrusion extending inwardly, and the distal portion of the outer conduit defines a longitudinally extending slot in which the protrusion of the first articulation shaft is received, such that the distal portion of the outer conduit rotates about a longitudinal axis with the first articulation shaft in response to rotation of the knob housing.

7. The adapter assembly of claim 1, wherein the proximal portion of each of the first and second articulation shafts is disposed about the outer conduit and the cam member.

8. A surgical instrument comprising: a surgical loading unit; and an adapter assembly comprising: a coupling mechanism having a drive shaft; a cam member operably coupled to the drive shaft and defining a proximal cam slot and a distal cam slot; an outer conduit extending distally from the cam member and having a distal portion configured to be coupled to the surgical loading unit; a first articulation shaft having a proximal portion operably coupled to the proximal cam slot of the cam member, and a distal portion configured to be coupled to the surgical loading unit; and a second articulation shaft having a proximal portion operably coupled to the distal cam slot of the cam member, and a distal portion configured to be coupled to the surgical loading unit, wherein the first and second articulation shafts are configured to translate in opposite directions in response to rotation of the cam member, thereby articulating the surgical loading unit relative to the outer conduit, wherein the adapter assembly further comprises: a proximal ring member disposed about the cam member and having a protrusion received in the proximal cam slot; and a distal ring member disposed about the cam member and having a protrusion received in the distal cam slot, wherein the proximal and distal ring members are configured to move axially in opposite longitudinal directions in response to the rotation of the cam member, wherein the proximal portion of the first articulation shaft is axially constrained to the proximal ring member, and the proximal portion of the second articulation shaft is axially constrained to the distal ring member, such that the first and second articulation shafts are configured to move axially with the respective proximal and distal ring members, wherein the first and second articulation shafts are rotatable relative to and about the respective proximal and distal ring members.

9. The surgical instrument of claim 8, wherein the proximal ring member defines an outer annular slot therein, and the proximal portion of the first articulation shaft has an annular protrusion slidably received in the outer annular slot.

10. The surgical instrument of claim 9, wherein the distal ring member defines an outer annular slot therein, and the proximal portion of the second articulation shaft has an annular protrusion slidably received in the outer annular slot of the distal ring member.

11. The surgical instrument of claim 8, wherein the adapter assembly further comprises a knob housing rotatably coupled to the coupling mechanism and disposed about a proximal end portion of the outer catheter, wherein the proximal end portion of each of the first and second articulation shafts is non-rotatably coupled to the knob housing and is axially movable relative to the knob housing.

12. The surgical instrument of claim 11, wherein the knob housing comprises an inner surface defining a pair of longitudinally extending slots, and the proximal end portion of each of the first and second articulation shafts has a longitudinally extending ridge received in a respective pair of longitudinally extending slots of the knob housing.

13. The surgical instrument of claim 11, wherein the proximal end portion of the first articulation shaft has an inwardly extending protrusion, and the distal end portion of the outer catheter defines a longitudinally extending slot in which the protrusion of the first articulation shaft is received such that the distal end portion of the outer catheter rotates about a longitudinal axis with the first articulation shaft in response to rotation of the knob housing.

14. The surgical instrument of claim 8, wherein the proximal end portion of each of the first and second articulation shafts is curved and disposed about the outer catheter and the cam member.

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