Abstract:
The invention provides surgical or diagnostic tools and associated methods that offer improved user control for operating remotely within regions of the body. These tools include a proximally-located actuator for the operation of a distal end effector, as well as proximally-located actuators for articulational and rotational movements of the end effector. Control mechanisms and methods refine operator control of end effector actuation and of these articulational and rotational movements. A multi-state ratchet for end effector actuation provides enablement-disablement options with tactile feedback. The tool may also include other features. A force limiter mechanism protects the end effector and manipulated objects from the harm of potentially excessive force applied by the operator. An articulation lock allows the fixing and releasing of both neutral and articulated configurations of the tool and of consequent placement of the end effector. A rotation lock provides for enablement and disablement of rotatability of the end effector.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to the following concurrently filed U.S. patent applications: “Tool with articulation lock” of Hegeman, Danitz, Hinman, and Alvord, “Tool with force limiter” of Hinman and Bertsch, “Tool with rotation lock” of Hinman and Danitz, and “Articulating tool with improved tension member system” of Hegeman, Danitz, Bertsch, and Alvord. 
     
    
     INCORPORATION BY REFERENCE 
       [0002]    All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. 
       FIELD OF THE INVENTION 
       [0003]    This invention relates to tools with end effectors whose actuators may be operated in multiple different operation states. 
       BACKGROUND OF THE INVENTION 
       [0004]    The popularity of minimally invasive surgery has been growing rapidly due to its association with decreased complication rates and post-surgical recovery times. The instruments employed are generally hand-operable and typically include a handle, a shaft that may or may not be rotatably attached to the handle, a rotation knob rigidly fixed to the proximal end of the shaft near the handle in instances where the shaft is rotatably attached to the handle, and a tool or end effector attached to the distal end of the shaft. To manipulate the instruments, they are held at the handle and typically pivoted about a pivot point defined by the entry incision, i.e., the incision made in the abdominal wall for laparoscopic procedures. The end effector may also be rotated about the shaft axis, as for example, by rotating a rotation knob, if present. In use, these instruments have limited control and range of motion and become physically taxing as the length of the procedure increases. 
         [0005]    Surgical procedures such as endoscopy and laparoscopy typically employ instruments that are steered within or towards a target organ or tissue from a position outside the body. Examples of endoscopic procedures include sigmoidoscopy, colonoscopy, esophagogastroduodenoscopy, and bronchoscopy, as well as newer procedures in natural orifice transluminal endoscopic surgery (“NOTES”). Traditionally, the insertion tube of an endoscope is advanced by pushing it forward, and retracted by pulling it back. The tip of the tube may be directed by twisting and general up/down and left/right movements. Oftentimes, this limited range of motion makes it difficult to negotiate acute angles (e.g., in the rectosigmoid colon), creating patient discomfort and increasing the risk of trauma to surrounding tissues. 
         [0006]    Laparoscopy involves the placement of trocar ports according to anatomical landmarks. The number of ports usually varies with the intended procedure and number of instruments required to obtain satisfactory tissue mobilization and exposure of the operative field. Although there are many benefits of laparoscopic surgery, e.g., less postoperative pain, early mobilization, and decreased adhesion formation, it is often difficult to achieve optimal retraction of organs and maneuverability of conventional instruments through laparoscopic ports. In some cases, these deficiencies may lead to increased operative time or imprecise placement of components such as staples and sutures. 
         [0007]    Recently, surgical instruments, including minimally invasive surgical instruments, have been developed that are more ergonomic and which have a wider range of motion and more precise control of movement. These instruments may include mechanisms that articulate using a series of links coupled with one or more sets of tension bearing members, such as cable. As with conventional instruments used in minimally invasive surgery, rotation of the shaft and end effector with respect to the handle is an important feature of cable and link type instruments to aid with dissecting, suturing, retracting, knot tying, etc. Ergonomic, flexible, and intuitive mechanisms that facilitate manual control of the end effectors of such instruments are also important factors as medical procedures become more advanced, and as surgeons become more sophisticated in operating abilities. Further improvements in the features and design of surgical instruments are desirable. 
       SUMMARY OF THE INVENTION 
       [0008]    Embodiments of the invention include a shaft having a proximal end and a distal end, an end effector at the distal end of the shaft, a movable end effector actuator at the proximal end of the shaft and operably connected to the end effector, and an actuator movement controller operably connectable to the end effector actuator. The actuator movement controller includes a user-activated state changer that is changeable among several states. These states include ones in which the movement controller is (1) enabled and engaged with the end effector actuator to prevent movement of the end effector actuator in at least one of two opposing directions, (2) enabled and disengaged from the end effector actuator to permit movement of the end effector actuator in a first direction and a second direction opposite to the first direction in response to continuous user input via the state changer, and (3) disabled to permit movement of the end effector actuator in a first direction and a second direction opposite to the first direction in the absence of user input via the state changer. In some embodiments, the first state (enabled and engaged) may prevent movement of the end effector actuator in both directions. 
         [0009]    In some embodiments the end effector includes jaws. In some embodiments the actuator movement controller includes a ratchet. In some embodiments the state changer includes a movable trigger. In some embodiments with a trigger, the state changer further includes a toggle operatively connected to the trigger so as to be movable with the trigger and to be rotatable with respect to the trigger. In some of the embodiments with a toggle, the toggle is operatively connected to the trigger so as to move with the trigger without rotating with respect to the trigger when the movement controller is enabled. 
         [0010]    In some embodiments where the toggle is so-connected to the trigger, surgical instrument further includes a handle at the proximal end of the shaft, and the trigger is supported by the handle, and is movable with respect to the handle. The toggle is disposed within the handle, and the trigger may include a toggle-camming surface and the toggle may include trigger-camming surface complementary-to and engagable with the trigger surface. The handle of some embodiments may include a toggle guide, operatively connected to the toggle, to guide movement of the toggle. Engagement of the complementary camming surfaces of the trigger and toggle respectively, due to movement of the trigger creates a rotational force between the trigger and toggle. 
         [0011]    Embodiments summarized immediately above may further include a wing extending radially from a toggle body, the handle toggle guide comprising a slot in which the toggle wing is disposed to prevent rotation of the toggle as the toggle moves with the trigger. The handle&#39;s toggle guide may include a handle canning surface complementary-to, and engagable with the toggle wing&#39;s camming surface such that engagement of the handle camming surface with the toggle wing&#39;s camming surface creates a rotational force between the handle and the toggle. In such embodiments, the toggle may have a range of motion, and the handle toggle guide may be adapted to prevent rotation of the toggle in a first portion of the toggle&#39;s range of motion and to permit rotation of the toggle with respect to the trigger in a second portion of the toggle&#39;s range of motion. The toggle may further include a wing extending radially from a toggle body, the handle toggle guide include a slot in which the toggle wing is disposed when the toggle is in the first portion of its range of motion, the toggle wing being outside the slot when the toggle is in the second portion of its range of motion 
         [0012]    Returning to the movable trigger, in some embodiments the trigger is movable from a first position in which the movement controller is enabled and engaged to a second position in which the movement controller is enabled and disengaged. The trigger may be further movable to a third position in which the movement controller is disabled. In such embodiments with the third position, the trigger may be further movable so as to enable and engage a disabled movement controller. The movement controller may further include a state change notifier that is operatively connected to the trigger and adapted to provide notice of an impending change in movement controller state that will be caused by further movement of the trigger. The state change notifier is adapted to provide tactile feedback to a user through the trigger of an impending change in movement controller state that will be caused by further movement of the trigger; such tactile feedback may include an increased level of resistance to movement of the trigger. 
         [0013]    Embodiments of the invention include a shaft having a proximal end and a distal end, an end effector at the distal end of the shaft, a movable end effector actuator at the proximal end of the shaft and operably connected to the end effector, and an actuator movement controller operably connectable to the end effector actuator. The actuator movement controller may include a state changer and a biasing member. The state changer may be movable against the biasing member in response to a user input from a first state in which the movement controller is enabled and engaged with the end effector actuator to permit movement of the end effector actuator in one direction and prevent movement of the end effector actuator in an opposite direction to a second state in which the movement controller is enabled and disengaged from the end effector actuator to permit movement of the end effector actuator in a first direction and a second direction opposite to the first direction. The biasing member may be operably connected with the state changer to move the state changer from the second state to the first state when the user input ceases or diminishes. 
         [0014]    In some embodiments, as summarized above, the state changer may be movable against the biasing member in response to a user input from the second state to a third state in which the movement controller is disabled to permit movement of the end effector actuator in a first direction and a second direction opposite to the first direction in the absence of user input via the state changer. 
         [0015]    In some embodiments the end effector includes jaws. In some embodiments the actuator movement controller includes a ratchet. In some embodiments the state changer includes a movable trigger. In some embodiments, the controller may further include a state change notifier adapted to provide notice of an impending change in movement controller state that will be caused by further movement of the state changer. In some embodiments, the state changer has a range of motion and the biasing member includes a first spring, the state change notifier includes a second spring. In typical embodiments, the second spring has a spring constant greater than the spring constant of the first spring. The state changer may be disposed with respect to the first and second spring so as to deform the first spring during a first portion of its range of motion in the second state without deforming the second spring and to deform the second spring in a second portion of its range of motion in the second state, the second spring applying a greater force on the state changer in the second portion of its range of motion than the first spring applies on the state changer in the second portion of its range of motion. 
         [0016]    Embodiments of the invention include a method for operating a medical instrument, the instrument including, as summarized above, an end effector at the distal end of a shaft, an end effector actuator at a proximal end of the shaft, and an actuator movement controller. The method includes, without limitation regarding order, (1) actuating the end effector by moving the end effector actuator in a first direction while engaging the actuator movement controller with the end effector actuator to prevent movement of the end effector actuator in a second direction opposite to the first direction, (2) providing a first user input to disengage the actuator movement controller from the end effector actuator to permit movement of the end effector actuator in the first and second directions during the user input, and (3) providing a further user input to disable the actuator movement controller to permit movement of the end effector actuator in the first and second directions in the absence of user input via the state changer. 
         [0017]    In some embodiments, providing the first user input includes moving a trigger. More specifically, moving the trigger may include moving the trigger a first distance and providing the further user input may include moving the trigger to a second distance beyond the first distance. 
         [0018]    The step of providing user input may further include providing notice that further user input will disable the actuator movement controller. In some embodiments, prior to the step of providing a further user input, the method further may include providing notice that further user input will disable the actuator movement controller, and such providing notice may include providing a tactile sensation to the user. 
         [0019]    Providing the first user input may also include moving the trigger a first distance, providing the further user input may include moving the trigger to a second distance beyond the first distance, the step of providing notice comprising providing increased resistance to trigger movement after moving the trigger the first distance but prior to moving the trigger the second distance. 
         [0020]    Before providing the further user input, the method further may include removing the first user input to re-engage the actuator movement controller with the end effector actuator to prevent movement of the end effector actuator in the second direction. Providing the first user input may include moving a trigger and removing the first user input may include releasing the trigger. 
         [0021]    In some embodiments, the method operating a medical instrument may further include providing a subsequent user input after the further user input to re-enable the actuator movement controller. Some embodiments of the method further include ceasing the further uset input prior to providing the subsequent user input. Finally, providing the first user input may include moving the trigger a first distance, providing the further user input may include moving the trigger to a second distance beyond the first distance, ceasing the further user input may include releasing the trigger, and providing the subsequent user input may include moving the trigger. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The novel features of the invention are set forth with particularity in the claims that follow. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings which are briefly described below. 
           [0023]      FIG. 1  is a front perspective view of an articulatable surgical tool. 
           [0024]      FIG. 2  is perspective view of a surgical tool in an articulated position. 
           [0025]      FIG. 3  is an exposed side view of a surgical tool with an end effector actuator and an end effector both in an open position. 
           [0026]      FIG. 4  is an exposed side view of a surgical tool with an end effector actuator and an end effector both in a closed position. 
           [0027]      FIG. 5  is a side view of the proximal portion of a tool, showing the handle and proximal end of the shaft, with an articulation locking sleeve in a distal and unlocked position. 
           [0028]      FIG. 6  is a side view of the proximal portion of a tool, showing the handle and proximal end of the shaft, with an articulation locking sleeve in a proximal and locked position. 
           [0029]      FIG. 7  is an exposed view of a portion of a tool from an overhead distal-looking perspective, the portion including the handle, locking rotation knob, and a proximal link. 
           [0030]      FIG. 8  is an exposed view of a handle from a distal-looking perspective. 
           [0031]      FIG. 9  is an exposed view of a handle from a proximal-looking perspective. 
           [0032]      FIG. 10  is an exposed side view of a surgical tool with an end effector actuator and an end effector both in an open position, the end effector jaws embracing an object. 
           [0033]      FIG. 11  is an exposed side view of a surgical tool with an end effector actuator in a closed position and the end effector in an open position, the end effect or jaws embracing an object, the force applied by the closed end effector actuator having been absorbed by a force limiter. 
           [0034]      FIG. 12  is an exposed view of the multi-state ratchet mechanism within the handle, showing from right (distal) to left (proximal), a trigger, toggle, pawl, and rack; in this view, the ratchet is in its enabled and engaged state. 
           [0035]      FIG. 13  is an exposed view of the multi-state ratchet mechanism within the handle as in  FIG. 12 ; in this view, the ratchet is in its enabled but disengaged state. 
           [0036]      FIG. 14  is an exposed view of the multi-state ratchet mechanism within the handle as in  FIG. 12 ; in this view, the ratchet is still engaged and disabled, but increased resistance provides the user with an indication that further depression of the trigger will change the state of the ratchet from enabled to disabled. 
           [0037]      FIG. 15  is an exposed view of the multi-state ratchet mechanism within the handle as in  FIG. 12 ; in this view, the ratchet is in a disabled state. 
           [0038]      FIG. 16  is an exposed view of the multi-state ratchet mechanism within the handle as in  FIG. 12 ; in this view, the ratchet is still in a disabled state, but the trigger has been fully released. 
           [0039]      FIG. 17  is an exposed view of the multi-state ratchet mechanism within the handle as in  FIG. 12 ; in this view, the ratchet is still in a disabled state with the trigger depressed such that when it is released the ratchet will return to the enabled and engaged state depicted in  FIG. 12 . 
           [0040]      FIG. 18  is a simplified side view of the handle showing a trigger; the toggle is located immediately proximal to the trigger (not seen); the position labeled with letters “A” identifies the position of a cross-section detail shown in  FIG. 17 . 
           [0041]      FIG. 19  is a cross-sectional detail, as indicated in  FIG. 18 , showing the proximal portion of the toggle within a compartment of the handle, with toggle wings in handle slots. 
           [0042]      FIG. 20  is a side view of a toggle in a vertical orientation, the distal- and trigger engaging portion at the top, and the pawl-engaging portion below. 
           [0043]      FIG. 21  is a side view of a trigger from a slightly distal-looking perspective, showing camming surfaces that engage the toggle and stems that engage the handle. 
           [0044]      FIG. 22  shows a trigger (right) and toggle (left) aligned but in an exploded view, exposing a small trigger spring. 
           [0045]      FIG. 23  shows a view of a trigger and toggle with their camming surfaces partially engaged, when the toggle is held in slots of the handle. 
           [0046]      FIG. 24  shows a view of a trigger and toggle with their camming surfaces rotated out of the handle slots such that their camming surfaces are fully engaged. 
           [0047]      FIG. 25  is a perspective view of a pawl. 
           [0048]      FIG. 26  is a side view of a pawl. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0049]    Steerable articulating instruments are described in U.S. Pat. No. 7,090,637; US 2005/0107667; US 2005/0273084; US 2005/0273085; and US 2006/0111209, US 2006/0111210. The articulating mechanisms of the tools described in those publications use multiple pairs of segments or links controlled, e.g., by multiple sets of cables. Depending upon the specific design of the device, the links can be discrete segments (as described, e.g., in U.S. Pat. No. 7,090,637) or discrete portions of a flexible segment (as described, e.g., in US 2005/0173085). The instrument may also include steerable or controllable links separated by bushings, e.g., as described in US 2005/0273084 US 2006/0111209 and US 2006/0111210, or any by any other type of link. 
         [0050]    When using such articulating instruments, a user may manipulate the proximal end of the instrument, thereby moving one or more proximal links of the articulation mechanism. This movement results in relative movement of the distal link(s) corresponding to the proximal link(s). It may at times be desirable to lock or otherwise maintain the straight or bent shape of the instrument, as provided by the ability to articulate. In certain embodiments of this invention, the shape of the instrument is maintained by preventing movement of at least one of the proximal links with respect to the rest of the instrument. 
         [0051]    Many instruments, including articulating instruments, have distally-located end effectors (e.g., a set of jaws) that are controlled by proximally-located movable end effector actuators (e.g., a moveable portion of the handle, or a thumbpiece). In typical embodiments of the moveable actuator, movement is possible in two directions, typically opposing or reciprocal. In some embodiments, the end effector actuator has various operation states in which movement is permitted or prevented by a movement controller, such as a ratchet mechanism that has various operating states. The operating states of the end effector actuator are, of course, reflected in the operating state of the end effector. 
         [0052]    Accordingly, certain embodiments of this invention provide methods and devices for changing the operational state of an end effector actuator between a first state (1) in which movement of the actuator is prevented in at least one of two opposite directions; a second state (2) in which the actuator is permitted to move in two directions in response to continuous user input to a state changer; and a third state (3) in which the actuator is permitted to in two directions in the absence of user input to a state changer. Regarding state 1, wherein the ratchet mechanism is engaged, in some embodiments, the movement is disallowed in both directions, in other embodiments, movement is permitted in one direction, and prevented in one. The determinant of whether movement is prevented in one or both directions may be related to the steepness of the angle of mutually engaging teeth of the rack and pawl. The desirability of such variations is associated with the specific use to which the end effector is being applied. 
         [0053]      FIGS. 1-26  show an articulatable tool  100  with an end effector  102  at its distal end and an end effector actuator  104  within a handle  106  at its proximal end. The end effector actuator  104  in typical embodiments of the tool is a movable portion of the handle, typically operated by the thumb of a user, and therefore may be referred to as a thumbpiece. Instrument  100  may be used in various contexts, including medical procedures such as a laparoscopic procedure that requires grasping or cutting within a patient. 
         [0054]    The tool embodiments depicted herein include an ability to articulate, although some embodiments may not articulate. Articulation mechanism components include proximal articulation links  108  and  110  which extend distally from handle  106 , and distal articulation links  112  and  114  extend proximally from end effector  102 . Proximal link  108  is connected to and moves with handle  106 . Likewise, distal link  112  is connected-to and moves with end effector  102 . Further details of ball and socket links suitable for use with this invention may be found in US 2005/0273084, US 2006/0111209, and US 2006/0111210. Embodiments of the presently described invention may make use of any type of link known in the art, the aforementioned specific links are merely offered as examples. An elongated shaft  116  is typically disposed between the proximal links and the distal links. Although the shaft depicted in figures herein is represented as a rigid embodiment, other shaft embodiments may be flexible. 
         [0055]    Further with regard to features that support articulation in the depicted embodiments ( FIGS. 3 and 4 ), a set of tension bearing members  118  is attached to proximal link  108 , extends through proximal link  110 , shaft  116  and distal link  114  and is attached to distal link  112 . (Although not limited to cables, a typical embodiment of a tension bearing member is a cable, and cables will be commonly referred to herein, as exemplary tension bearing members.) A second set of control cables  120  is attached to proximal link  110 , extends through shaft  116  and is attached to distal link  114 . In this embodiment, there are three control cables  118  in the first set and three control cables  120  in the second set. It should be appreciated, however, that other numbers of control cables may be used to connect corresponding proximal and distal links. In addition, mechanisms or tension bearing members other than cables may be used to operably connect corresponding links. 
         [0056]    As shown in  FIG. 2 , movement of handle  106  and proximal link  108  with respect to proximal link  110  moves end effector  102  and distal link  112  in a relative and corresponding manner. Likewise, movement of proximal link  110  with respect to shaft link  116  moves distal link  114  with respect to shaft link  116  in a relative and corresponding manner, also as shown in  FIG. 2 . This relative articulation movement provides a way for a user to remotely manipulate the end effector through movement of the handle. 
         [0057]    In the shown exemplary embodiments ( FIGS. 1-4 ,  10 , and  11 ) the end effector  102  is a pair of jaws. Other end effectors for any surgical or diagnostic application, or for other applications, including non-medical applications, may be used with the articulating tool of this invention. Actuation force is transmitted from end effector actuator  104  through a transmission that includes a linearly movable tension bearing member or rod  125  and a rotatable rod actuator  122 , as shown in  FIGS. 3 ,  4 , and  7 . In some embodiments, the tension bearing member or rod  125  is also capable of bearing a compressive load, such that an end effector can receive a compressive force transmitted by the end effector actuator. 
         [0058]    In order to maintain a particular position of the end effector with respect to the shaft, whether the position is a straight or neutral position, or an articulated position, the articulating tool of this invention may include an articulation lock. The articulation lock embodiment described below is merely one example, numerous other embodiments are provided in the concurrently filed application of Hegemen et al., entitled “Tool with Articulation Lock”, which is hereby incorporated into this application by this reference. 
         [0059]    In the embodiment shown in  FIGS. 1-6 , the articulation lock includes a movable rigid sleeve  130 . In the unlocked position shown in  FIGS. 1-5 , sleeve  130  is distal to proximal links  108  and  110 . In the locked position shown in  FIG. 6 , however, sleeve  130  has been moved proximally to a position adjacent to and covering links  108  and  110  as well as the proximal end of shaft  116 , thereby blocking relative movement between links  108  and  110  and between link  110  and shaft  116 . In this locked position, relative movement between distal links  112  and  114  and between link  114  and shaft  116  is prevented as well. 
         [0060]    As shown in  FIG. 6 , a sleeve support mechanism  132  extends proximally from shaft  116  to provide sliding support for sleeve  130 . A distal stop  134  provides a limit of distal movement of sleeve  130 ; a similar stop (not shown) is provided on or within handle  106  to limit proximal movement of sleeve  130 . Detents, ridges or other mechanisms may be provided to maintain the sleeve in its proximal or distal positions and to provide tactile feedback to the user regarding the position of the sleeve. 
         [0061]    Some embodiments of the inventive tool with a multi-state ratchet mechanism include features that provide rotatability of end effectors, and some of these embodiments further include a rotation lock that allows or disallows such rotation. A rotation lock may comprise a locking knob  101 , as can be seen in  FIGS. 1-7 . Other components of the depicted rotation lock include teeth  103  within the knob  101  that are visible in  FIG. 7 ; these teeth engage the complementary teeth  105  within the handle  106  that are visible in  FIG. 9 . These embodiments are described in detail in concurrently filed application of Hinman and Danitz entitled “Tool with Rotation Lock”, which is hereby incorporated into this application by this reference. 
         [0062]    Some embodiments of the inventive tool with a multi-state ratchet mechanism include a force limiter that establishes an upper limit on the actuation force that may be delivered to the end effector by the end effector actuator. An embodiment of a force limiter  200  may be seen in  FIGS. 3 ,  4 ,  7 ,  10 , and  11 . These embodiments are described in detail in concurrently filed application of Hinman and Bertsch entitled “Tool with End Effector Force Limiter”, which is hereby incorporated into this application by this reference. 
         [0063]    The instrument of this invention has an actuator movement controller, comprising a ratchet mechanism that controls the way that an end effector actuator (a thumbpiece, for example) and an end effector can be moved by a user. A state changer, such as a trigger  224  may be used to change among the end effector actuation states. In the embodiment shown in  FIGS. 1-26 , but particularly in  FIGS. 12-18 , and as laid out in Table 1, the instrument has three end effector actuation states: (1) a state in which the movement controller is enabled and engaged with the end effector actuator to prevent movement of the end effector actuator in at least one direction—in some embodiments movement is prevented in one direction and permitted in the other while in some embodiments movement in both directions is locked; (2) a state in which the movement controller is enabled and disengaged from the end effector actuator to permit movement of the end effector actuator in a first direction and a second direction opposite to the first direction, the disengagement by virtue of continuous user input via a state changer associated with the movement controller; and (3) a state in which the movement controller is disabled, even without user input via the state changer, to permit movement of the end effector actuator in a first direction and a second direction opposite to the first direction in the absence of user input via the state changer. 
         [0064]    The numbering scheme of these described states (1, 2, and 3) is provided as an aid to understand the invention and its various operational states, and is in merely one of various numbering schemes that could be used. Movement through the states is cyclical, and in some sense, the cycle could be described with any state as a starting point or a “first state”. As will be described further below, movement between states 1 and 2 is “reversible”, and can go in either direction, from state 1 to state 2, and from state 2 to state 1. Movement from state 2 to state 3, however, has a unidirectionality (2 to 3), and is not reversible. Similarly, movement from state 3 (back) to state 1 is not reversible. The “reversibility” of the change between states 1 and 2 provides benefit to the user for the combination of subtlety and precision that it brings to the operation of the tool. Subtlety comes from the intuitiveness of the physical maneuver and for the minimal burden on attention and physical effort that the maneuver requires; precision comes from the on/off nature of the operational impact of the ratcheting lock. 
         [0000]    
       
         
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Overview of Operational States of the Movement Controller (Multi-state Ratchet) of One Embodiment 
               
               
                 and Associated Aspects 
               
             
          
           
               
                   
                 end effector 
                 state changer 
                   
                 toggle 
                 movement controller 
               
               
                 state 
                 (jaws) status* 
                 (trigger) status 
                 springs&#39; status 
                 rotation 
                 (ratchet) state 
               
               
                   
               
             
          
           
               
                 1 
                 jaws movement is 
                 trigger is released 
                 both springs expanded 
                  0° 
                 enabled 
                 engaged 
               
               
                   
                 prevented in at least 
               
               
                   
                 one direction** 
               
               
                 2 
                 jaws can be closed 
                 trigger is partially 
                 light spring compressing 
                   
                 enabled 
                 disengaged 
               
               
                   
                 and opened 
                 depressed 
                   
                   
                   
                 “temporarily” or 
               
               
                   
                   
                 further trigger 
                 light spring compressed 
                   
                   
                 “reversibly”, i.e., can 
               
               
                   
                   
                 depression meets 
                 heavy spring compressing (i.e., state 
                   
                   
                 be re-engaged by 
               
               
                   
                   
                 greater resistance 
                 change notifier is providing tactile 
                   
                   
                 trigger release 
               
               
                   
                   
                   
                 feedback of imminent change) 
               
               
                 3 
                 jaws can be closed 
                 trigger is fully 
                 both springs fully compressed 
                  45° 
                 disabled 
                 disengaged stably 
               
               
                   
                 and opened 
                 depressed 
               
               
                   
                   
                 trigger is released 
                 both springs expanded 
                  90° 
               
               
                   
                   
                 trigger is fully 
                 both springs fully compressed 
                 135° 
               
               
                   
                   
                 depressed 
               
               
                 back 
                 See State 1, above 
                 see State 1 
                 see State 1 
                 180° 
                 see State 1 
                 see State 1 
               
               
                 to 1 
               
               
                   
               
               
                 *The moveability status of the end effector (i.e., jaws) also applies to the moveability of an end effector actuator, such as a thumbpiece operated by the user. 
               
               
                 **The movement prevention may either be one-way (i.e., closing allowed, opening prevented) or two-way (opening and closing both prevented), depending on the nature of the engagement between the ratchet&#39;s rack and the pawl. 
               
             
          
         
       
     
         [0065]    Some embodiments provide a movement controller using a ratchet mechanism that, when engaged, permits the end effector actuator to be moved in one direction (e.g., to close a pair of jaws) while preventing the end effector actuator to move in the other direction (to, e.g., maintain the jaws in their closed state). As shown in  FIGS. 3 ,  4 ,  10 , and  11 , for example, the ratchet is formed from a rack of teeth  220  extending from end effector actuator  104 . A movable pawl is rotatably mounted in handle  106 . In other embodiments, the teeth of the rack  220  may be configured with a steepness of angle (not shown) such that the engaged state prevents movement of the pawl with respect to the rack in either direction. In other embodiments, prevention of movement in either direction by the engaged ratchet is provided by other engagement features well known in the art, such as pins or friction surfaces. A user may change the operation state of the ratchet by operating a state changer or trigger  224  which connects to pawl  222  through a toggle  226 . 
         [0066]    Details of the ratchet mechanism and ratchet state changer (e.g., a trigger and a toggle) are shown in  FIGS. 12-26 . Toggle-located features and trigger-located features may also be seen more clearly in  FIGS. 21 and 22 , respectively.  FIGS. 22-24  provide detail on both the trigger  224  and toggle  226  in the context of their mutual alignment and interaction.  FIGS. 18 and 19  provide some detail on the state changer (comprising toggle  226 ) and its location within—and interaction with the handle  106 .  FIGS. 25 and 26  provide detail on an embodiment of a pawl  222  that is engaged by the toggle  226 .  FIGS. 12-18  depict a cycling of an embodiment of a multi-state ratchet or movement controller through its various operational states. These operational states along with the status of various of its components are also shown in Table 1. 
         [0067]    In  FIG. 12 , the ratchet is in its enabled and engaged state, with the trigger fully extended distally, or outwardly from the handle. In this state, there is little or no actuation force being applied to trigger  224  by a user, and a trigger spring  228  disposed in an internal channel  225  formed in trigger  224  (only visible in cut-away portion of  FIG. 16 ) biases trigger  224  distally away from a distal extension  229  of toggle  226 . In some embodiments, the dimensions of the trigger  224  and toggle  226  are such that in this state an optional gap occurs in channel  225  (not shown) between trigger  224  and toggle  226  simply for the purpose of reducing occurrence of the trigger vibrating in response to movements of the pawl. 
         [0068]    Toggle  226  has a pair of wings  230 . In the enabled and engaged state, shown in  FIG. 12 , wings  230  are disposed in a pair of corresponding slots  232  formed in handle  106 . (A cross-section of the toggle and handle in this state is shown in  FIG. 19 .) The proximal end  227  of toggle  226  engages pawl  222 . 
         [0069]    As shown in  FIG. 13 , the ratchet is still enabled, but it has become temporarily or reversibly disengaged by the trigger being partially depressed, per the second of three states as described above. As the trigger  224  is depressed and moved proximally by a user, trigger  224  engages toggle  226 , and both elements move proximally against the operation or bias of a first toggle spring  234 . A pair of stems  236  extend laterally and about midway from trigger  224 , and ride in corresponding channels  240  formed in handle  106  (see  FIGS. 8 and 9 ) to guide the linear motion and to prevent rotation of trigger  224 . In the position shown in  FIG. 13 , the ratchet is in the enabled-but-disengaged state in which the user may freely move end effector actuator in both directions so long as the user continues to hold the trigger  224  depressed. The toggle&#39;s wings  230  are still in their handle slots  232 , and if the user releases trigger  224 , the toggle (and trigger) will move distally under the operation of spring  234  to re-engage the ratchet and return to the enabled and engaged state shown in  FIG. 12 . 
         [0070]    By way of reviewing the operational status of the ratchet mechanism in this second state, several aspects are notable. The ratchet is temporarily disengaged by virtue of the teeth of the rack and the teeth of the pawl not being engaged. The disengagement is maintained as long as the user provides an input force that maintains the trigger in a partially depressed position. The disengagement is temporary (or provisional or reversible) inasmuch as the user can release the trigger to its biased outward position, whereupon the ratchet returns to its first state, as described above, of being engaged. Finally, the releasing and partially depressing of the trigger to go back and forth between the first state ( FIG. 12 ) and second state ( FIG. 13 ) is repeatable. 
         [0071]    In  FIG. 13 , a second toggle spring  246  biases a ring  244  distally against a shoulder  248  formed in handle  106 . If instead of releasing the trigger, the user continues to push trigger  224  proximally from the position shown in  FIG. 13 , a proximally-facing shoulder  242  on toggle  226  engages ring  244  and moves it against the bias provided by spring  246 . In this embodiment, spring  246  is stiffer (i.e., it has a greater spring constant) than spring  234 ; the user will therefore receive tactile feedback in the form of increased resistance to further trigger pushing as soon as toggle shoulder  242  pushes ring  244  proximally, as shown in  FIG. 14 . 
         [0072]    While the ratchet state in  FIG. 14  is still enabled but disengaged (the second state as described above) the increased resistance provides the user with an indication that depressing the trigger further will change the state of the ratchet from enabled to disabled, as further described below. The ratchet mechanism in  FIG. 14 , by being in the second state (enabled and disengaged, as in  FIG. 13 ), will still return to the first state (enabled and engaged) upon release of the trigger to its biased distal position. The new aspects of the state depicted in  FIG. 14  (vs.  FIG. 13 ) involve the trigger being yet further depressed, and the greater resistance thereby encountered by the user, which is perceived as a tactile feedback. The greater resistance is a manifestation of a state change notice provided by the state change notifier comprising spring  246 . In this embodiment, the information provided by the state change notice is that the mechanism is nearly ready to move into a disabled state (the third state, as described above), wherein the ratchet is stably disengaged, and unable to passively revert to the first state. 
         [0073]      FIGS. 15 and 16  depict the ratchet mechanism at different points in the third state, wherein the ratchet is disabled, and ultimately stably disengaged.  FIG. 15  shows the toggle transitioning to the stably disengaged state as shown in  FIG. 16 . In  FIG. 15 , toggle  226  has been pulled proximally sufficiently to enable wings  230  to leave slots  232 . Trigger  224  has four identical helical camming surfaces  250  on its proximal end which engage with four corresponding camming surfaces on the distal end of toggle  226 . The four camming surfaces are of two kinds, though identical in slope: two camming surfaces  252  on wings  230 , and two camming surfaces  254  on the enlarged shaft portion of toggle  226 . Camming surfaces of the toggle  226  and trigger  224  are most easily seen in  FIGS. 20 and 21 , respectively. In the enabled and engaged state, shown in  FIG. 12 , and the enabled and disengaged state, shown in  FIGS. 13 and 14 , the longitudinal shoulder  256  or  257  at the end of each toggle camming surface is offset from the longitudinal shoulders  258  at the end of each trigger camming surface. Once wings  230  leave slots  232 , however, toggle  226  is free to rotate under the camming interaction of surfaces  250  against surfaces  252  and  254 . Toggle  226  will rotate 45° until the toggle longitudinal surfaces  256  and  257  meet the trigger longitudinal surfaces  258 , as shown in  FIG. 15 . 
         [0074]    When the user releases trigger  224  from the position shown in  FIG. 15 , the toggle and trigger move distally together until camming surfaces  252  on toggle  226  engage two camming surfaces  260  formed on the inside of handle  106  (seen best in  FIGS. 8 and 9 ) that cause the toggle to rotate another 45° (to reach a point of 90° rotation from the reference point of the first state) until longitudinal surfaces  257  meet corresponding handle longitudinal surfaces  262 . The handle camming surfaces hold toggle  226  and prevent further distal movement from this position; trigger  224  continues to move distally under the action of spring  228 , as shown in  FIG. 16 . In this state, the ratchet is disengaged, the trigger  224  is fully released and distal, and the user may freely move end effector actuator  104  (and consequently the end effector or jaws  102 ) in either direction. 
         [0075]    To return the ratchet to the enabled states, the user depresses trigger  224  again to move trigger camming surfaces  250  against toggle camming surfaces  252  and  254 . When proximal movement of trigger  224  moves toggle  226  sufficiently proximal for the toggle&#39;s longitudinal surfaces  257  to clear the handle longitudinal surfaces  262 , the camming action between the trigger and toggle once again rotates the toggle 45° to the state shown in  FIG. 17 . When the user releases trigger  224 , engagement of toggle camming surfaces  252  with two other camming surfaces  264  formed in handle  106  causes another 45° rotation of toggle  226  until wings  230  reach slots  232 , thereby enabling toggle  226  to move distally under the action of spring  234  to the enabled and engaged ratchet state shown in  FIG. 12 . At this point, the toggle has rotated 180° from its reference position of the initial first state. Two cycles of moving through the first to third state take the toggle through a complete 360° rotation. 
         [0076]    While the inventive surgical instruments and devices have been described in some detail by way of illustration, such illustration is for purposes of clarity of understanding only. It will be readily apparent to those of ordinary skill and in the art in light of the teachings herein that certain changes and modifications may be made thereto without departing from the spirit and scope of the appended claims. For example, while the multi-state ratchet mechanism described in here has typically been in the context of tools with an articulating mechanism comprising at least two links, the mechanisms may be used in an instrument comprising only a single link, a multiplicity of links, and with any number of cables or cable sets operably connecting the links. Further, while the context of the invention is considered to be surgical or medical diagnostic procedures, embodiments of the multi-sate ratchet mechanism or tools having such a mechanism may have utility in other non-medical contexts as well.