Abstract:
A surgical instrument particularly suited to endoscopic use articulates an end effector by including a fluid transfer articulation mechanism that is proximally controlled. A fluid control, which is attached to a proximal portion, transfers fluid through the elongate shaft through a first fluid passage to a first fluid actuator that responds by articulating an articulation joint. Two opposing fluid actuators may respond to differential fluid transfer to effect articulation. Thereby, design flexibility is achieved by avoiding the design constraints of transferring a mechanical motion through the tight confines of the elongate shaft sufficient to effect articulation.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is related to and claims the benefit of commonly owned U.S. patent application Ser. No. 11/061,908 entitled “SURGICAL INSTRUMENT INCORPORATING A FLUID TRANSFER CONTROLLED ARTICULATION MECHANISM” to Kenneth Wales and Chad Boudreaux filed on 18 Feb. 2005, the disclosure of which is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates in general to surgical instruments that are suitable for endoscopically inserting an end effector (e.g., endocutter, grasper, cutter, staplers, clip applier, access device, drug/gene therapy delivery device, and an energy device using ultrasound, RF, laser, etc.) to a surgical site, and more particularly to such surgical instruments with an articulating shaft.  
       BACKGROUND OF THE INVENTION  
       [0003]     Endoscopic surgical instruments are often preferred over traditional open surgical devices since a smaller incision tends to reduce the post-operative recovery time and complications. Consequently, significant development has gone into a range of endoscopic surgical instruments that are suitable for precise placement of a distal end effector at a desired surgical site through a cannula of a trocar. These distal end effectors engage the tissue in a number of ways to achieve a diagnostic or therapeutic effect (e.g., endocutter, grasper, cutter, staplers, clip applier, access device, drug/gene therapy delivery device, and energy device using ultrasound, RF, laser, etc.).  
         [0004]     The positioning of the end effector is constrained by the trocar. Generally, these endoscopic surgical instruments include a long shaft between the end effector and a handle portion manipulated by the clinician. This long shaft enables insertion to a desired depth and rotation about the longitudinal axis of the shaft, thereby positioning the end effector to a degree. With judicious placement of the trocar and use of graspers, for instance, through another trocar, often this amount of positioning is sufficient. Surgical stapling and severing instruments, such as described in U.S. Pat. No. 5,465,895, are an example of an endoscopic surgical instrument that successfully positions an end effector by insertion and rotation.  
         [0005]     More recently, U.S. patent application Ser. No. 10/443,617, “SURGICAL STAPLING INSTRUMENT INCORPORATING AN E-BEAM FIRING MECHANISM” to Shelton IV et al., filed on 20 May 2003, which is hereby incorporated by reference in its entirety, describes an improved “E-beam” firing bar for severing tissue and actuating staples. Some of the additional advantages include affirmatively spacing the jaws of the end effector, or more specifically a staple applying assembly, even if slightly too much or too little tissue is clamped for optimal staple formation. Moreover, the E-beam firing bar engages the end effector and staple cartridge in a way that enables several beneficial lockouts to be incorporated.  
         [0006]     Depending upon the nature of the operation, it may be desirable to further adjust the positioning of the end effector of an endoscopic surgical instrument. In particular, it is often desirable to orient the end effector at an axis transverse to the longitudinal axis of the shaft of the instrument. The transverse movement of the end effector relative to the instrument shaft is conventionally referred to as “articulation”. This is typically accomplished by a pivot (or articulation) joint being placed in the extended shaft just proximal to the staple applying assembly. This allows the surgeon to articulate the staple applying assembly remotely to either side for better surgical placement of the staple lines and easier tissue manipulation and orientation. This articulated positioning permits the clinician to more easily engage tissue in some instances, such as behind an organ. In addition, articulated positioning advantageously allows an endoscope to be positioned behind the end effector without being blocked by the instrument shaft.  
         [0007]     Approaches to articulating a surgical stapling and severing instrument tend to be complicated by integrating control of the articulation along with the control of closing the end effector to clamp tissue and fire the end effector (i.e., stapling and severing) within the small diameter constraints of an endoscopic instrument. Generally, the three control motions are all transferred through the shaft as longitudinal translations. For instance, U.S. Pat. No. 5,673,840 discloses an accordion-like articulation mechanism (“flex-neck”) that is articulated by selectively drawing back one of two connecting rods through the implement shaft, each rod offset respectively on opposite sides of the shaft centerline. The connecting rods ratchet through a series of discrete positions.  
         [0008]     Another example of longitudinal control of an articulation mechanism is U.S. Pat. No. 5,865,361 that includes an articulation link offset from a camming pivot such that pushing or pulling longitudinal translation of the articulation link effects articulation to a respective side. Similarly, U.S. Pat. No. 5,797,537 discloses a similar rod passing through the shaft to effect articulation.  
         [0009]     In co-pending and commonly owned U.S. patent application Ser. No. 10/615,973 “SURGICAL INSTRUMENT INCORPORATING AN ARTICULATION MECHANISM HAVING ROTATION ABOUT THE LONGITUDINAL AXIS” to Frederick E. Shelton IV et al, the disclosure of which is hereby incorporated by reference in its entirety, a rotational motion is used to transfer articulation motion as an alternative to a longitudinal motion.  
         [0010]     While these mechanically communicated articulation motions have successfully enabled an endoscopic surgical stapling and severing instrument to articulate, development trends pose numerous challenges and barriers to entry into the market. Conflicting design objects include a shaft of as small a diameter as possible to reduce the size of the surgical opening yet with sufficient strength to perform the several motions (e.g., closing, firing, articulation, rotation, etc.). In addition, transferring sufficient force without binding and other frictional problems imposes design constraints that limit desirable features and reliability.  
         [0011]     In U.S. Pat. No. 6,755,338, a medical instrument has a shaft that is manually deformable to a desired curved shape. To accommodate longitudinal clamping and firing motions down the deformable shaft, a pair of hydraulic lines pass down the shaft that are each part of a respective closed hydraulic system. Each hydraulic line communicates between a proximal piston moved by a trigger and a distal activator. The distal activator for clamping is a linearly moving piston that is proximally biased by a spring and mechanically connected to an end effector. The distal activator for firing is an actuation balloon that expands linearly in the distal direction. While linearly moving activators provide one way to cause actuation at a distal end of an implement portion of a medical portion, it may be desirable to produce another type of actuating motion.  
         [0012]     Consequently, a significant need exists for a surgical instrument that incorporates an actuating mechanism that that may be incorporated within the close confines of an implement portion.  
       BRIEF SUMMARY OF THE INVENTION  
       [0013]     The invention overcomes the above-noted and other deficiencies of the prior art by providing a surgical instrument having an implement portion that incorporates fluid bladders in the implement portion that reliably expand and contract in response to fluid transfer from a handle.  
         [0014]     In one aspect of the invention, a surgical instrument has a handle having a control positionable to vary an internal volume of a reservoir with fluid transfer in relation to this volume change occurring through an elongate implement portion having a longitudinal axis sized for insertion through a cannula to reach internal tissue. An actuator changes in volume in relation to the fluid transfer and is positioned within a cavity in the implement portion to laterally actuate an actuating member. The actuator and/or the reservoir are advantageously formed of a bladder shaped for lateral actuation Thereby, fluid transfer control may be flexibly integrated into an elongate implement portion, avoiding various constraints on mechanical linkages that would otherwise be generally used.  
         [0015]     In another aspect of the invention, a surgical instrument includes a compression surface movably attached to a handle to vary an internal volume of a reservoir bladder that performs fluid transfer in relation thereto to cause the actuation of the actuating bladder in the implement portion. Thereby, a closed fluid control system may be incorporated into a surgical instrument with desirable performance characteristics.  
         [0016]     In yet another aspect of the invention, a surgical instrument includes a differential control in a handle to differentially vary fluid transfer from the fluid source to first and second conduits that respectively control first and second actuating bladders that work differentially in opposition against a motive surface of an actuated member attached to an elongate implement portion. Thereby, the advantages of selectively forcing the motive surface with similar force in either of two directions achieves responsive actuation of the implement portion as desired.  
         [0017]     These and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0018]     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and, together with the general description of the invention given above and the detailed description of the embodiments given below, serve to explain the principles of the present invention.  
         [0019]      FIG. 1  is a front top perspective view of a surgical stapling and severing instrument shown with an open end effector, or staple applying assembly, with an articulation mechanism actuated by a fluidic actuation control, and with the staple cartridge removed.  
         [0020]      FIG. 2  is a front perspective view of an implement portion of the surgical instrument of  FIG. 1  with a double pivot closure sleeve assembly and end effector removed to expose a single pivot frame ground articulated by a fluidic articulation mechanism.  
         [0021]      FIG. 3  is a perspective disassembled view of an elongate shaft and articulation mechanism of the surgical stapling and severing instrument of  FIG. 1 .  
         [0022]      FIG. 4  is a diagram of a laterally moving fluidic articulation mechanism with the rack and gear segment pivoting depicted in a nonarticulated state for the surgical instrument of  FIG. 1 .  
         [0023]      FIG. 5  is cross-section, back view in elevation of the fluidic articulation mechanism of  FIG. 11  taken along lines  5 - 5 .  
         [0024]      FIG. 6  is a diagram of the laterally moving fluidic articulation mechanism of  FIG. 4  with the rack and gear segment pivoting depicted in an articulated state.  
         [0025]      FIG. 7  is cross-section, back view in elevation of the fluidic articulation mechanism of  FIG. 6  taken along lines  7 - 7 .  
         [0026]      FIG. 8  is a back, cross-section view in elevation of a tubular shaft of the surgical instrument of  FIG. 1  taken along lines  8 - 8  alternatively incorporating a pair of collapsible bellows for bladders and showing the T-bar in an articulated position with a right bellows expanded and a left bellows collapsed.  
         [0027]      FIG. 9  is a longitudinal cross section view of a communicating combination of a reservoir bladder and an actuating bladder for the surgical instrument of  FIG. 1  with one bladder expansively biased by containing a lateral compression spring.  
         [0028]      FIG. 10  is a longitudinal cross section view of a communicating combination of a reservoir bladder and an actuating bladder for the surgical instrument of  FIG. 1  with one bladder expansively biased by having open cell foam.  
         [0029]      FIG. 11  is a longitudinal cross section view of a bladder for the surgical instrument of  FIG. 1  formed from a plugged, heated and blown metal tube.  
         [0030]      FIG. 12  is a longitudinal cross section view of a communicating combination of a reservoir bladder and actuated bladder assembled from different materials for the surgical instrument of  FIG. 1 .  
         [0031]      FIG. 13  is a longitudinal cross section view of a bladder formed from expanded tubing material having a communicating end and a heat or glue sealed end for the surgical instrument of  FIG. 1 .  
         [0032]      FIG. 14  is a longitudinal cross section view of a bladder formed from laminated materials including an inner blow molded plastic layer, intermediate resilient layer, and a lubrication layer for the surgical instrument of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0033]     Overview of articulating shaft. Turning to the Drawings, wherein like numerals denote like components throughout the several views,  FIG. 1  depicts a surgical instrument, which in the illustrative versions is more particularly a surgical stapling and severing instrument  10 , that is capable of practicing the unique benefits of the present invention. In particular, the surgical stapling and severing instrument  10  is sized for insertion, in a nonarticulated state as depicted in  FIG. 1 , through a trocar cannula passageway to a surgical site in a patient (not shown) for performing a surgical procedure. Once an implement portion  12  is inserted through a cannula passageway, an articulation mechanism  14  incorporated into a distal portion of an elongate shaft  16  of the implement portion  12  may be remotely articulated, as depicted in  FIG. 1 , by an articulation control  18 . An end effector, depicted in the illustrative version as a staple applying assembly  20 , is distally attached to the articulation mechanism  14 . Thus, remotely articulating the articulation mechanism  14  thereby articulates the staple applying assembly  20  from a longitudinal axis of the elongate shaft  16 . Such an angled position may have advantages in approaching tissue from a desired angle for severing and stapling, approaching tissue otherwise obstructed by other organs and tissue, and/or allowing an endoscope to be positioned behind and aligned with the staple applying assembly  20  for confirming placement.  
         [0034]     Handle. The surgical and stapling and severing instrument  10  includes a handle portion  22  proximally connected to the implement portion  12  for providing positioning, articulation, closure and firing motions thereto. The handle portion  22  includes a pistol grip  24  toward which a closure trigger  26  is pivotally and proximally drawn by the clinician to cause clamping, or closing, of the staple applying assembly  20 . A firing trigger  28  is farther outboard of the closure trigger  26  and is pivotally drawn by the clinician to cause the stapling and severing of clamped tissue clamped in the staple applying assembly  20 . Thereafter, a closure release button  30  is depressed to release the clamped closure trigger  26 , and thus the severed and stapled ends of the clamped tissue. The handle portion  22  also includes a rotation knob  32  coupled for movement with the elongate shaft  16  to rotate the shaft  16  and the articulated staple applying assembly  20  about the longitudinal axis of the shaft  16 . The handle portion  22  also includes a firing refraction handle  34  to assist in retracting a firing mechanism (not depicted in  FIG. 1 ) should binding occur, so that opening of the staple applying assembly  20  may occur thereafter.  
         [0035]     It will be appreciated that the terms “proximal” and “distal” are used herein with reference to a clinician gripping a handle of an instrument. Thus, the surgical stapling assembly  20  is distal with respect to the more proximal handle portion  22 . It will be further appreciated that, for convenience and clarity, spatial terms such as “vertical” and “horizontal” are used herein with respect to the drawings. However, surgical instruments are used in many orientations and positions, and these terms are not intended to be limiting and absolute.  
         [0036]     An illustrative multi-stroke handle portion  22  for the surgical stapling and severing instrument  10  of  FIG. 1  is described in greater detail in the co-pending and commonly-owned U.S. patent application entitled “SURGICAL STAPLING INSTRUMENT INCORPORATING A MULTISTROKE FIRING POSITION INDICATOR AND RETRACTION MECHANISM” to Swayze and Shelton IV, Ser. No. 10/374,026, the disclosure of which is hereby incorporated by reference in its entirety, with additional features and variation as described herein. While a multi-stroke handle portion  22  advantageously supports applications with high firing forces over a long distance, applications consistent with the present invention may incorporate a single firing stroke, such as described in co-pending and commonly owned U.S. patent application “SURGICAL STAPLING INSTRUMENT HAVING SEPARATE DISTINCT CLOSING AND FIRING SYSTEMS” to Frederick E. Shelton IV, Michael E. Setser, and Brian J. Hemmelgarn, Ser. No. 10/441,632, the disclosure of which is hereby incorporated by reference in its entirety.  
         [0037]     Implement portion (articulating elongate shaft and staple applying assembly). In  FIGS. 1-3 , the implement portion  12  advantageously incorporates the multiple actuation motions of longitudinal rotation, articulation, closure and firing within a small diameter suitable for endoscopic and laparoscopic procedures. The staple applying assembly  20  (“end effector”) has a pair of pivotally opposed jaws, depicted as an elongate channel  40  with a pivotally attached anvil  42  ( FIG. 1 ). Closure and clamping of the anvil  42  to the elongate channel  40  is achieved by longitudinally supporting the elongate channel  40  with a frame assembly  44  ( FIG. 3 ) rotatingly attached to the handle portion  22  over which a double pivot closure sleeve assembly  46  longitudinally moves to impart a closing and opening respectively to a distal and proximal motion to the anvil  42 , even with the staple applying assembly  20  articulated as in  FIG. 2 .  
         [0038]     The staple applying assembly  20  is described in greater detail in co-pending and commonly-owned U.S. patent application Ser. No. 10/955,042, “ARTICULATING SURGICAL STAPLING INSTRUMENT INCORPORATING A TWO-PIECE E-BEAM FIRING MECHANISM” to Frederick E. Shelton IV, et al., filed 30 Sep. 2004, the disclosure of which is hereby incorporated by reference in its entirety.  
         [0039]     With particular reference to  FIG. 3 , the frame assembly  44  includes a single pivot frame ground  48  whose proximal end is engaged to the rotation knob  32 , with a right half shell  50  thereon shown in  FIG. 3 . It should be appreciated that a proximal end of the closure sleeve assembly  46 , specifically of a closure straight tube  52 , encompasses the proximal end of the frame ground  48 , passing further internally to the handle portion  22  to engage closure components (not shown) that longitudinally translate the closure sleeve assembly  46 . A circular lip  54  at the proximal end of the closure straight tube  52  provides a rotating engagement to such components. Engaging components of the rotation knob  32  pass through a longitudinal slot  56  on a proximal portion of the straight closure tube  52  to engage an aperture  58  proximally positioned on the frame ground  48 . The longitudinal slot  56  is of sufficient length to allow the closure longitudinal translation of the closure sleeve assembly  46  at various rotational angles set by the rotation knob  32  to the closure sleeve assembly  46  and the frame ground  48 .  
         [0040]     The elongate shaft  16  supports the firing motion by receiving a firing rod  60  that rotatingly engages firing components of the handle portion  22  (not shown). The firing rod  60  enters a proximal opening  62  along the longitudinal centerline of the frame ground  48 . The distal portion of the frame ground  48  includes a firing bar slot  64  along its bottom that communicates with the proximal opening  62 . A firing bar  66  longitudinally translates in the firing bar slot  64  and includes an upwardly projecting proximal pin  68  that engages a distal end  70  of the firing rod  60  to form a firing member.  
         [0041]     The handle portion  22  supports articulation by incorporating a rectangular reservoir cavity  72 , one lateral portion depicted in a distal portion of the rotation knob  32 . A bottom compartment  74  that resides within the rectangular reservoir cavity  72  has laterally spaced apart left and right baffles  76 ,  78 . An articulation actuator  80  slides laterally overtop of the bottom compartment  74 , its downward laterally spaced left and right flanges  82 ,  84 , which are outboard of the baffles  76 ,  78 , each communicating laterally to left and right push buttons  86 ,  88  that extend outwardly from the respective shell halves of the rotation knob  32 . The lateral movement of the articulation actuator  80  draws left and right flanges  82 ,  84  nearer and farther respectively to the left and right baffles  76 ,  78 , operating against left and right reservoir bladders  90 ,  92  of a fluidic articulation system  94 , each bladder  90 ,  92  communicating respectively and distally to left and right fluid conduits or passageways  96 ,  98  that in turn communicate respectively with left and right actuating bladders  100 ,  102 . The latter oppose and laterally pivot a T-bar  104  of the articulation mechanism  14 .  
         [0042]     The frame assembly  44  constrains these fluidic actuations by including a top and distal recessed table  106  of the frame ground  48  upon which resides the fluid passages  96 ,  98  and actuating bladders  100 ,  102 . The T-bar  104  also slidingly resides upon the recessed table  106  between the actuating bladders  100 ,  102 . Proximal to the T-Bar  104 , a raised barrier rib  108  is aligned thereto, serving to prevent inward expansion of the fluid passages  96 ,  98 . The frame assembly  44  has a rounded top frame cover (spacer)  110  that slides overtop of the frame ground  48 , preventing vertical expansion of the fluid passages  96 ,  98  and actuating bladders  100 ,  102 , as well as constraining any vertical movement of the T-bar  104 . In particular, the frame cover  110  includes features that enable it to also provide an articulation locking member  111 .  
         [0043]     A distal end (“rack”)  112  of the T-bar  104  engages to pivot a proximally directed gear segment  115  of an articulated distal frame member  114  of the articulation mechanism  14 . An articulating closure tube  116  encompasses the distal frame member  114  and includes a horseshoe aperture  118  that engages the anvil  42 . A double pivoting attachment is formed between the closure straight tube  52  and articulating closure ring  116  over the articulating mechanism  14 , allowing longitudinal closure motion even when the articulation mechanism  14  is articulated. In particular, top and bottom distally projecting pivot tabs  119 ,  120  on the closure straight tube  52  having pin holes  122 ,  124  respectively are longitudinally spaced away from corresponding top and bottom proximally projecting pivot tabs  126 ,  128  on the articulating closure ring  116  having pin holes  130 ,  132  respectively. An upper double pivot link  134  has longitudinally spaced upwardly directed distal and aft pins  136 ,  138  that engage pin holes  130 ,  122  respectively and a lower double pivot link  140  has longitudinally spaced downwardly projecting distal and aft pins  142 ,  144  that engage pin holes  132 ,  124  respectively.  
         [0044]     In  FIGS. 2-3 , an articulation lock mechanism  200  is advantageously incorporated to maintain the staple applying assembly  20  at a desired articulation angle. The articulation lock mechanism  200  reduces loads on the left and right actuating bladders  100 ,  102 . In particular, a compression spring  202  is proximally positioned between a proximal end  204  of the articulation locking member  111  and the handle portion  22 , biasing the articulation locking member  111  distally. Selective abutting engagement of a distal frictional surface distally projecting from the articulation locking member  111  engages a corresponding locking gear segment in a brake plate (not shown) received into a top proximal recess  220  of the articulating frame member  114 .  
         [0045]     The articulation lock mechanism  200  is described in greater detail in the commonly-owned U.S. patent application Ser. No. 11/194,437, “Surgical Instrument with an Articulation Shaft Locking Mechanism” to Wales et al., filed 1 Aug. 2005, the disclosure of which is hereby incorporated by reference in its entirety.  
         [0046]     The elongate shaft  16  is depicted in an articulated position with the closure sleeve assembly  46  removed from around the frame assembly  44  and without the elongate channel  40  and anvil  42 . Articulation actuator  80  is shown moved laterally to the left to compress right proximal reservoir bladder  90  and expanded distal right actuation bladder  100  moving T-bar  104  to the position shown. Thus, lateral movement of the articulation actuator  80  articulates the distal frame  114  clockwise about the single pivot frame ground  48  as shown. The articulation actuator  80  advantageously also automatically engages and disengages the articulation lock mechanism  200 . In particular, a toothed detent surface  225  along a proximal top surface of the articulation actuator  80  receives an upwardly projecting locking pin  226  from the proximal end  204  of the articulation locking member  111 . The engagement of the locking pin  226  within the root of the toothed detent surface  225  provides sufficient distal movement of the articulation locking member  111  for locking engagement. Lateral movement by an operator of the articulation actuator  80  proximally urges the locking pin  226  proximally, and thus disengages the articulation locking member  111  from the distal frame member  114 . When the operator releases the articulation actuator  80 , the locking pin  226  is urged by the compression spring  202  into the adjacent detent in detent surface  225  to lock the locking mechanism  111 , and thereby the staple applying assembly  20 , and to constrain the articulation mechanism  14  at a desired articulation position by constraining and expanding the inflated shape of the proximal left and right reservoir bladders  90 ,  92 .  
         [0047]     In use, a laterally moving articulation mechanism  230  is shown schematically in  FIGS. 4-7  and includes a fluid control system  235  having fluid filled parallel left and right fluid bladders  236 ,  238  extending longitudinally therein that move a lateral member or T-bar  240  laterally by the movement of fluids  242 . All directions are in reference to the longitudinal axis. Referring to the unarticulated view of  FIGS. 4 and 5 , the distally located end effector  232  pivots about pin  244  and has a gear segment  246  at a proximal end. Pivot pin  244  is attached to a frame (not shown). A rack  248  at a distal end of the T-bar  240  operably engages gear segment  246 . T-bar  240  and rack  248  are laterally moveable along axis A-A. A distal portion of the long left and right fluid bladders  236 ,  238  lies laterally to the laterally moveable T-bar  240  and are laterally constrained within a closure sleeve  250  and vertically constrained by a frame  252  below and a spacer  254  above. Left actuating fluid bladder  236  is filled with fluid  242  and has left distal actuating bladder  256 , left fluid passageway  258 , and a left proximal reservoir bladder  260 . Right fluid bladder  238  contains fluid  242  and has a right distal actuating bladder  262 , right fluid passageway  264 , and right proximal reservoir bladder  266 . A fixed divider  270  extends from the frame  252  and separates the bladders  260 ,  266  and the fluid passageways  258 ,  264 . The fixed divider  270  and the closure sleeve  250  constrain the fluid passageways  258 ,  264  and prevent expansion in the fluid passage sections  258 ,  264  of the bladders  236 ,  238 . A laterally moveable “C”-shaped compression member  272  is included in articulation control mechanism  230  for the compression of one of the proximal reservoir bladders  260 ,  266  and the articulation of the end effector  232 . In addition, other components such as a firing bar  274  passing through a firing bar slot  276  in the frame  252  may be incorporated ( FIGS. 5, 7 ).  
         [0048]     Rather than a rounded rectangular shape, the cross sectional shape of a bladder may be modified to be any shape. For example it could be advantageous to construct the distal and/or proximal bladders as a pleated bellows. In  FIG. 8 , a tubular shaft  278  for the surgical instrument  10  is as described above for  FIGS. 4-7  with the exception that a left actuating bladder  256   a  and a right actuating bladder  262   a  are both of a rectangular pleated design with the former shown in a compressed state and the latter shown in an expanded state in a lateral cavity  280 . Pleated right actuating bellows  262   a  collapse easily into the confined area of the right portion of the lateral cavity  280  as depicted. Similarly, pleated left actuating bellows  256   a  expand easily to fill the area of left portion of the lateral cavity  280 . While not shown, pleated bladders may also be used for the proximal reservoir bladders. It should be appreciated that actuating bladders and distal bladders may be formed into other cross sectional shapes such as rounds, squares, triangles, hexagons, octagons, or any other shape that meets the needs of the mechanism.  
         [0049]     Fluid Bladders. It should be appreciated with the benefit of the present disclosure that such bladders may be constructed in various ways from various combinations of materials. While shown as a unified part above, these bladders may be assembled from multiple parts or constructed as a single unitary fluid bladder. For multiple part construction, at least one of the bladders may be attached to any of the other elements. Many leak proof attachment methods are available for assembly such as welding, glue, press fit, heat staking, crimp fittings, clamps fittings, joints and the like. Two basic types of fluid bladders may be constructed. One is a high pressure, non-elastic rigid bladder from either rigid or elastomeric materials, and the other is a lower pressure elastomeric balloon.  
         [0050]     Rigid balloon materials are known in the medical arts and are used for dilation or angioplasty or the expansion of stents within blood vessel walls. Rigid balloons are made from non-compliant or low compliant materials that retain their designed size and shape under high-pressure loading. Typically, these balloons are thin walled and are formed from high tensile materials with low elongation. Typical materials for these balloons are polyvinyl chloride (PVC), cross linked polyethylene, and polyester (PET) polyethylene terrapthalate, nylon and others. For angioplasty balloons, thin walled sections of PET tubing may be blow molded into a balloon shape. Each of the left and right fluid bladders may be formed from a continuous piece of thin walled tubing with both the proximal and distal bladders formed by expanding local sections of the thin walled tubing. Expansion of the proximal and distal bladder areas may be accomplished by locally heating the tubing and blow molding the bladder shapes therein. One of the open ends of the formed fluid bladders may then be sealed, and the other open end of the bladders may act as a fill port for fluids. After filling, the open fill port is sealed. Alternately, the fluid bladders may be assembled from multiple pieces rather than a single piece. Non-bladder portions of the fluid bladders, such as fluid passageways, may be formed from rigid or semi-rigid tubing or other materials.  
         [0051]     Alternately, elastomeric balloons may also be used to construct fluid bladders. These elastomeric materials are formed into a first shape and, with the application of pressure, may expand to a larger shape. Elastomeric materials may expand and return to the original shape a number of times without degradation of the elastomeric properties. While not able to handle pressures as high as rigid materials, elastomeric bladders may be used to articulate. Confining or constraining the elastomeric fluid bladders between walls or constraints prevents bulging of bladder material into unwanted areas and increases the forces that may be applied. Elastomeric bladders may be constructed by various processes including dip molding or, like IV bags, formed from two sheets that are welded or glued together. Elastomeric bladders may be formed from latex, rubber, silicone, polyurethane, polyethelene, polypropelene, Teflon, or any one of a number of elastic or semi-elastic engineering materials.  
         [0052]     Additionally, conventional blow molding techniques may be used to form bladders. Unlike the thin walled PET shrink tubing used in angioplasty balloons, conventional blow molding techniques use a hollow tube or molded hollow preform that is heated and moved to an injection station where low pressure air is typically used to initially inflate the rod or preform. A burst of high-pressure gas is then applied to force the expanded hot tube or preform into contact with the walls of the mold to cool the blown material in the net shape. While producing thin walls, the preform blow molding process produces thin walls that are much thicker than the less than 4 mil angioplasty balloons. This process forms many current products such as soda bottles, disposable pipettes with a rigid tube and expanded bladder, and containers. For the formation of bladders, a preform shape is first injection molded with the appropriate material thickness at the expandable bladder areas to provide the desired wall thickness when the bladders are expanded in the blow molding process. Once the bladders are blow molded into net shape, they may be filled with fluid and sealed. Appropriate blow molding materials include nylon, polyester (PET), polyethelene, polyprolelene, high density polyethelene (HDPE) and any one of a number of known blow molding materials.  
         [0053]     In addition to rigid and elastomeric bladders, bladder construction may be springy or flaccid. That is, at least one of the proximal bladders or at least one of the distal bladders may be constructed from a spring material that wants to resume its original shape after compression and release. Alternately, at least one of the proximal bladders or at least one of the distal bladders may be constructed from a generally flaccid material. Such materials have a weak spring rate, if any, and do not tend to expand back to the original pre-deformed shape. Flaccid bladders or springy bladders may advantageously include the internal compression spring that forces the walls of the bladder outward. The internal compression spring may be formed from a variety of materials including metallic springs, plastic springs, foams, squeezable elastomerics and the like. A sealed assembly of a full flaccid bladder with a partially filled spring bladder (on a passageway) results in the spring bladder expanding and drawing fluid from the flaccid bladder. Assembly of a pair of partially compressed spring bladders (of equal spring rate walls and size) results in both spring bladders being in the partial compressed position. Compression of one of the partially filled spring bladders results in full expansion of the uncompressed spring bladder and reduction of the compressed spring bladder. Release of the compressed spring bladder enables the compressed spring bladder to expand and draw fluid back into the compressed spring bladder. This process is spring rate controlled and if both bladders have the same spring rate, the fluid will be drawn back into the released compressed spring bladder until both spring bladders are equally filled. If desired, mismatched spring rates for the spring bladders may be used to draw and store fluids into one of the bladders as desired.  
         [0054]     In  FIG. 9 , as an example of an added resilient structure, a bladder  800  is depicted to include an actuating bladder  802  in fluid communication through a fluid passage or conduit  804  to a reservoir bladder  806 . In this illustrative version, a compression spring  808  laterally biases the actuating bladder  802  to an expanded state. Advantageous features of the compression spring  808  includes providing a restoring force to expand bladder  802  or to center an end effector (not shown), as well as other advantages. If desired, springs may be placed in either one of both bladders  802 ,  806  or in both bladders  802 ,  806 .  
         [0055]     In  FIG. 10 , an alternate resilient structure, depicted as an open cell foam  810 , fills the actuating bladder  802  rather than using a compression spring. Thus, fluid may be forced into and out of the open cell foam  810  as desired for expansion with the open cell foam  810  providing a degree of resilience.  
         [0056]     In  FIG. 11 , a metal-walled bladder  900  may be formed from metal tubing  902  that is heated and pressure blown with a plugged end  904  either closed by a plug  906  before or after forming of an enlarged portion  908 . The dimensions of the enlarged portion  908  may be controlled by selecting the temperature of heating, the amount of the metal tubing  902  that is heated, and/or surrounding the metal tubing  902  with a fixture (not shown) that constrains expansion to desired outer diameters for a neck portion  910 , the enlarged portion  908 , and the plugged end  904 . Resulting thinner walls  912  of the enlarged portion  908  provides a desired degree of flexibility as a trade-off with burst strength deemed suitable for a fluid reservoir or actuator.  
         [0057]     In  FIG. 12 , a fluid control assembly  1000  may be assembled from a flaccid bladder  1002  that communicates via a rigid conduit  1004  to a deformable bladder  1006 . The deformable bladder  1006  may be advantageously formed of a shape memory alloy (SMA) which are metals, such as NiTi (Nickel-Titanium), CuZnAl, and CuAlNi. SMAs exhibit two very unique properties: shape memory effect and pseudo-elasticity, made possible through a solid state phase change, that is a molecular rearrangement, which occurs in the shape memory alloy. In most SMAs, a temperature change of only about 10° C. is necessary to initiate a phase change between Martensite and Austenite.  
         [0058]     Martensite, the relatively soft and easily deformed phase of SMAs, exists at lower temperatures. Austenite, the stronger phase of shape memory alloys, occurs at higher temperatures. The shape of the Austenite structure is cubic. The un-deformed Martensite phase is the same size and shape as the cubic Austenite phase on a macroscopic scale, so that no change in size or shape is visible in shape memory alloys until the Martensite is deformed. The temperatures at which each of these phases begin and finish forming are represented by the following variables: M s , for the temperature at which Marsenite starts to form; M f , for the temperature at which Marsenite finishes forming; and A f , for the temperature at which Arsenite finishes forming. The shape memory effect is observed when the temperature of a piece of shape memory alloy is cooled to below the temperature M f . At this stage, the alloy is completely composed of Martensite which can be easily deformed. After distorting the SMA, the original shape can be recovered simply by heating the wire above the temperature A f . The heat transferred to the wire is the power driving the molecular rearrangement of the SMA, similar to heat melting ice into water, but the SMA remains solid. The deformed Martensite is now transformed to the cubic Austenite phase, which is configured in the original shape of the wire.  
         [0059]     Pseudo-elasticity occurs in SMAs when the SMA is completely composed of Austenite (temperature is greater than A f ). Unlike the shape memory effect, pseudo-elasticity occurs without a change in temperature. The load on the SMA is increased until the Austenite becomes transformed into Martensite simply due to the loading. The loading is absorbed by the softer Martensite, but as soon as the loading is decreased, the Martensite begins to transform back to Austenite since the temperature of the wire is still above A f , and the wire springs back to its original shape.  
         [0060]     Thus, the deformable bladder  1006  may be deformed by fluid pressure and/or mechanical pressure with the shape memory effect or pseudo-elasticity relied upon to restore the deformable bladder  1006  to a desired shape (e.g., compressed or expanded). The flaccid bladder  1002  transfers a corresponding amount of fluid through the rigid conduit  1004  in proportion to the change in volume of the deformable bladder  1006 . Either the flaccid bladder  1002  or the deformable bladder  1006  may serve as an actuating bladder with the other serving as a reservoir bladder having a controlled volume. For example, a deformable bladder  1006  (i.e., actuating bladder) may be formed to have a pleated, compressed state that is then heat treated to remember that shape. Alternatively, the deformable bladder  1006  may formed to have an expanded shape and then be deformed to a compressed state.  
         [0061]     In  FIG. 13 , an alternative flaccid or resilient bladder  1100  is formed from longitudinally continuous tubing material  1102  by heat sealing or internally gluing an inner diameter  1104  of one end  1106  that is held closed and flattened until cooled and/or set to form a non-communicating seal. An expanded portion  1108  of the tubing material  1102  communicates through a neck portion  1110 .  
         [0062]     In  FIG. 14 , a further alternative laminate bladder  1200  that may be advantageously used in the surgical instrument of  FIG. 1  is formed from a blow molded inner plastic layer  1202  with sufficient strength to define an expanded shape of the bladder  1200 . A resilient layer  1204 , such as Latex rubber, encompasses the inner plastic layer  1202  to provide additional strength and perhaps a compression force to bias the bladder  1200  toward a smaller volume. An outer lubricant layer  1206  (e.g., silicone, Teflon) assists in assembling the bladder  1200  into a surgical instrument (not shown) and is used to avoid binding/adhesion to walls of a bladder cavity that could cause improper expansion or contraction.  
         [0063]     Alternately, whereas a three-layer laminated bladder is described above with the layers in a selected order, laminated bladders can be made from any two or more layers and the order of the layers and layer materials can be varied to suit the needs of the surgical instrument. For example, it can be advantageous to add an additional lubricated layer as the innermost layer to the three layers  1202 ,  1204 , and  1206  listed above for a dry fluid such as microparticles (described below), or to use an inner protective layer on an outer metal layer to act as a barrier between the metal and fluid.  
         [0064]     While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications may readily appear to those skilled in the art.  
         [0065]     For example, a single reservoir bladder may serve as both a left and right actuating bladder as described in the aforementioned and incorporated U.S. patent application Ser. No. 11/061,908 entitled “SURGICAL INSTRUMENT INCORPORATING A FLUID TRANSFER CONTROLLED ARTICULATION MECHANISM” to Kenneth Wales and Chad Boudreaux filed on 18 Feb. 2005.  
         [0066]     For another example, reservoir and/or actuating bladders may be incorporated into a surgical instrument for purposes other than articulation, such as for opening and/or closing an anvil of a stapling and severing end effector as described in commonly owned and co-pending U.S. patent application Ser. No. 11/165,094, entitled “SURGICAL INSTRUMENT HAVING FLUID ACTUATED OPPOSING JAWS” to Wales et al., filed 23 Jun. 2005, the disclosure of which is hereby incorporated by reference in its entirety.  
         [0067]     As yet another example, a single fluid transfer approach may be incorporated wherein a single fluid actuator expands and compresses to effect articulation, perhaps assisted by a resilient opposing member that is not in fluid or pneumatic communication with the handle. An application consistent with such a design, for instance, could include just one bladder attached to a T-bar so that when compressed by the withdrawal of fluid, it pulls the T-bar with it.  
         [0068]     As yet a further example, fluids used in a laterally moving device may be either compressible or incompressible. As used herein, the term “fluid” comprises liquids, gases, gels, microparticles, and any other material which may be made to flow between a pressure gradient. While any fluid may be used, sterilized solutions such as saline, mineral oil or silicone are illustrative flowable materials.