Abstract:
A forceps includes a first jaw member, a second jaw member, a drive rod assembly and a moveable handle attached to a fixed handle. The first jaw member and the second jaw member are in opposing relation relative to one another, and at least one of the first jaw member and the second jaw member is relatively movable from a first open position to a second clamping position when the first jaw member and the second jaw member cooperate to grasp tissue therebetween. Moving the moveable handle relative to the fixed handle moves the drive rod assembly for imparting movement of at least one of the first jaw member and the second jaw member from the first position and the second position. The moveable handle has an actuator with a lost motion connection between the first and second jaw members and the actuator.

Description:
FIELD 
       [0001]    The present disclosure relates to a forceps. More specifically, the present disclosure relates to a forceps with jaw force limiter. 
       BACKGROUND 
       [0002]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
         [0003]    Generally forceps may be utilized for laparoscopic surgery. The forceps may be employed to control delicate movements inside a patient and may include an end effector assembly with a pair of opposed resilient jaws that are closed against each other to grip tissue. Further, the forceps may utilize electrical energy that is delivered to the pair of opposed resilient jaws to coagulate or gut the tissue. Such devices, however, may produce high jaw forces to compress the tissue and, in some circumstances, high jaw forces to open the jaws. These high jaw forces can result in breakage of the end effector assembly. 
         [0004]    Accordingly, there is a need in the art for forceps with a force limiting mechanism that prevents clamping forces imparted by the forceps&#39; end effector from exceeding a predetermined amount of force to prevent breakage of the end effector. 
       SUMMARY 
       [0005]    The present invention provides a forceps with a jaw force limiter. Accordingly, pursuant to one aspect of the present invention, a forceps includes a first jaw member, a second jaw member, a drive rod assembly and a moveable handle attached to a fixed handle. The first jaw member and the second jaw member are in opposing relation relative to one another, and at least one of the first jaw member and the second jaw member is relatively movable from a first open position when the first jaw member and the second jaw member are disposed in spaced relation relative to one another to a second clamping position when the first jaw member and the second jaw member cooperate to grasp tissue therebetween. Moving the moveable handle relative to the fixed handle moves the drive rod assembly for imparting movement of at least one of the first jaw member and the second jaw member from the first position and the second position. The moveable handle has an actuator with a lost motion connection between the first and second jaw members and the actuator. The lost motion connection includes a yoke on the end of the moveable handle and a drive shuttle. The yoke includes flanges and the drive shuttle is configured so that if a force imparted on the drive rod assembly exceeds a predetermined amount of force, the flanges of the yoke deflect outwardly to allow relative axial motion between the yoke and the shuttle, which allows relative movement between the moveable handle and the fixed handle without the first jaw member moving relative to the second jaw member. 
         [0006]    The foregoing aspect of the present invention can be further characterized by one or any combination of the features described herein, such as: at least one of the yoke and the shuttle has a tapered surface that enables the at least one of the yoke and the shuttle to disengage from the other of the yoke and the shuttle; the at least one of the yoke and the shuttle has tapered surfaces on the front and the back of the at least one of the yoke and the shuttle that enables the at least one of the yoke and the shuttle to disengage from the other of the yoke and the shuttle; the drive rod assembly moves at least one of the first jaw member and the second jaw member towards the second clamping position as the moveable handle is moved towards the fixed handle; the lost motion connection allows the moveable handle to move away from the fixed handle without the first jaw member moving relative to the second jaw member so that the first jaw member and the second jaw member do not move towards the first open position when the moveable handle moves away from the fixed handle; the lost motion connection allows the moveable handle to move towards the fixed handle without the first jaw member moving relative to the second jaw member so that the first jaw member and the second jaw member do not move towards the second clamping position when the moveable handle moves towards the fixed handle; the first jaw member and the second jaw member each includes a sealing surfaces, each sealing surface being configured to connect to a source of electrosurgical energy; and the source generates electrosurgical energy to coagulate tissue grasped between the first jaw member and the second jaw member. 
         [0007]    Accordingly, pursuant to another aspect of the present invention, a forceps includes a first jaw member, a second jaw member, a driver rod assembly, a moveable handle attached to a fixed handle, and a restorative member that provides a biasing force that biases the moveable handle away from the fixed handle. The first jaw member and the second jaw member are in opposing relation relative to one another, and the first jaw member and the second jaw member are relatively movable from a first open position when the first jaw member and the second jaw member are disposed in spaced relation relative to one another to a second clamping position when the first jaw member and the second jaw member cooperate to grasp tissue therebetween. Moving the moveable handle relative to the fixed handle moves the drive rod assembly for imparting movement of the first jaw member and the second jaw member between a first position and the second position. The moveable handle has an actuator with a lost motion connection between the first and second jaw members and the actuator. The lost motion connection transfers the biasing force to the movable handle to return the movable handle away from the fixed handle to maintain the first jaw member and the second jaw member in the second clamped position. 
         [0008]    The foregoing aspect of the present invention can be further characterized by one or any combination of the features described herein, such as: the lost motion connection includes a yoke on the end of the moveable handle and a drive shuttle, the yoke including flanges and the drive shuttle being configured so that if a force imparted on the drive rod assembly exceeds a predetermined amount of force, the flanges of the yoke deflect outwardly to allow relative axial motion between the yoke and the shuttle, which allows relative movement between the moveable handle and the fixed handle without the first jaw member moving relative to the second jaw member; at least one of the yoke and the shuttle has a tapered surface that enables the at least one of the yoke and the shuttle to disengage from the other of the yoke and the shuttle; the at least one of the yoke and the shuttle has tapered surfaces on the front and the back of the at least one of the yoke and the shuttle that enables the at least one of the yoke and the shuttle to disengage from the other of the yoke and the shuttle; the drive rod assembly moves at least one of the first jaw member and the second jaw member towards the second clamping position as the moveable handle is moved towards the fixed handle; the lost motion connection allows the moveable handle to move away from the fixed handle without the first jaw member moving relative to the second jaw member so that the first jaw member and the second jaw member do not move towards the first open position when the moveable handle moves away from the fixed handle; the lost motion connection allows the moveable handle to move towards the fixed handle without the first jaw member moving relative to the second jaw member so that the first jaw member and the second jaw member do not move towards the second clamping position when the moveable handle moves towards the fixed handle; the first jaw member and the second jaw member each includes a sealing surfaces, each sealing surface being configured to connect to a source of electrosurgical energy; and the source generates electrosurgical energy to coagulate tissue grasped between the first jaw member and the second jaw member. 
         [0009]    Accordingly, pursuant to yet another aspect of the present invention, a method of using forceps includes one or more of the following steps: moving a moveable handle relative to a fixed handle of the forceps to grasp tissue between a first jaw member and a second jaw member of the forceps, the first jaw member and the second jaw member being in opposing relation relative to one another, the first jaw member and the second jaw member being relatively movable from a first open position when the first jaw member and the second jaw member are disposed in spaced relation relative to one another to a second clamping position when the first jaw member and the second jaw member cooperate to grasp tissue therebetween, and moving the moveable handle relative to the fixed handle to release the tissue. Moving the moveable handle relative to the fixed handle moves a drive rod assembly for imparting movement of the first jaw member and the second jaw member between the first position and the second position. The moveable handle has an actuator with a lost motion connection between the first and second jaw members and the actuator. The lost motion connection includes a yoke on the end of the moveable handle and a drive shuttle. The yoke includes flanges and the drive shuttle is configured so that if a force imparted on the drive rod assembly exceeds a predetermined amount of force, the flanges of the yoke deflect outwardly to allow relative axial motion between the yoke and the shuttle, which allows relative movement between the moveable handle and the fixed handle without the first jaw member moving relative to the second jaw member. 
         [0010]    The method of using the forceps may be further characterized by one or any combination of the following features: at least one of the yoke and the shuttle has a tapered surface that enables the at least one of the yoke and the shuttle to disengage from the other of the yoke and the shuttle; the at least one of the yoke and the shuttle has tapered surfaces on the front and the back of the at least one of the yoke and the shuttle that enables the at least one of the yoke and the shuttle to disengage from the other of the yoke and the shuttle; the drive rod assembly moves the first jaw member towards the second jaw member as the moveable handle is moved towards the fixed handle; the lost motion connection allows the moveable handle to move away from the fixed handle without the first jaw member moving relative to the second jaw member so that the first jaw member and the second jaw member do not move towards the first open position when the moveable handle moves away from the fixed handle; the lost motion connection allows the moveable handle to move towards the fixed handle without the first jaw member moving relative to the second jaw member so that the first jaw member and the second jaw member do not move towards the second clamping position when the moveable handle moves towards the fixed handle; the first jaw member and the second jaw member each includes a sealing surfaces, each sealing surface being configured to connect to a source of electrosurgical energy; and the source generates energy to coagulate tissue grasped between the first jaw member and the second jaw member. 
         [0011]    Further features, advantages, and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0012]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the drawings: 
           [0013]      FIG. 1  is a perspective view of a forceps in accordance with the principles of the present invention; 
           [0014]      FIG. 2  is an interior view of the forceps shown in  FIG. 1 ; 
           [0015]      FIG. 3  is an expanded view of the forceps shown in  FIG. 1 ; 
           [0016]      FIG. 4  is an expanded view of an upper jaw and slider sub-assembly for the forceps shown in  FIG. 1 ; 
           [0017]      FIG. 4A  is a close-up view of the region  4 A shown in  FIG. 4 ; 
           [0018]      FIG. 5  is a side view of the upper jaw shown in  FIG. 4 ; 
           [0019]      FIG. 6  is cross-sectional view of the upper shown in  FIG. 5 ; 
           [0020]      FIG. 7  is a side view of a probe sub-assembly; 
           [0021]      FIG. 8A  is an expanded view of the probe sub-assembly shown in  FIG. 7  combined with a connector sub-assembly; 
           [0022]      FIG. 8B  is a side view of the probe sub-assembly and connector sub-assembly shown in  FIG. 8A ; 
           [0023]      FIG. 8C  is close-up side view of the upper jaw and the probe; and 
           [0024]      FIG. 9  is a cross-sectional view of a handpiece for the forceps shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0026]    With reference to  FIG. 1 , an instrument embodying the principles of the present invention is illustrated therein and designated at  10 . In certain configurations, the instrument  10  is a bipolar forceps used to seal, coagulate, or cut the tissue. The instrument  10  may be employed during surgery to grip a feature of interest including a part of a body, an anatomical feature, tissue, veins, arteries, or a combination thereof. 
         [0027]    Current may be passed through the forceps  10  so that the forceps are used for electrosurgery. For example, a therapy current may be passed from one jaw to a second jaw when tissue is located within the jaw and the therapy current may coagulate blood, cauterize, cut, or a combination thereof. The forceps  10  may generally include one or more working assemblies and sufficient controls to work the one or more assemblies. The forceps  2  may include parts employed to perform the recited functions and may include generally, a stylet (e.g., a tubular member, a hollow tube, or an assembly of tubes), a hand piece, one or more operable mechanisms used to actuate the stylet, or a combination thereof. The hand piece may be an assembly of parts or housing structures capable of forming a hand piece structure with a cavity. Note that the present invention is not limited to laparoscopic procedures. That is, the below described jaws can be employed with any type of medical device that clamps onto tissue. 
         [0028]    Turning now to  FIG. 1 , the forceps  10  includes a handpiece  12  and a sheath member  18  with a proximal portion connected to the handpiece  12  with a connector knob  22 . In various arrangements, the sheath member  18  can be an outer pipe with a heat shrink. An end effector unit  28  extends from a distal portion  26  of the sheath member  18 . The handpiece  12  includes a moveable handle  16  configured to move relative to a fixed handle  14 . The handpiece  12  also includes a first switch button  32  and a second switch button  30 . 
         [0029]    Referring further to  FIGS. 2 and 3 , the forceps  10  includes a flexible circuit  50  that electrically communicates with the first and second switch buttons  30  and  32 . The flexible circuit  50 , in turn, electrically communicates with a contact switch circuit  52  that is electrically connected to an electrosurgical energy source  13 . When the second switch button  30  is depressed, the energy source  13  is activated to supply energy to the end effector  28  to coagulate tissue grasped by the end effector  28 . And when depressed, the first switch button  32  activates the electrosurgical energy source  13  to supply sufficient energy, electrosurgical or ultrasonic, to the end effector  28  to cut and seal tissue grasped by the end effector  28 . 
         [0030]    The forceps  10  includes an actuator  34  associated with the moveable handle  16 . The actuator  34  includes a slider  48 , a biasing member such as a spring  44  positioned about the slider  48 , and a shuttle  42  also positioned about the slider  48 . The moveable handle  16  includes an extension  56  with a yoke  58 . The yoke  58  is engaged with the shuttle  42 , and together the yoke  58  and the shuttle  42  form a lost motion connection, described in more detail below, between the actuator  34  and the end effector  28 . Squeezing the moveable handle  16  towards the fixed handle  14  moves the shuttle  42  distally, that is, towards the end effector  28 . Such movement of the shuttle  42  compresses the spring member  44  against an enlarged flange  60  (see, for example,  FIG. 4 ), so that the slider  48  moves distally as well. 
         [0031]    Referring also to  FIGS. 4, 4A, 5 and 6 , the slider  48  is connected to a tubular member or inner pipe  19  that is disposed inside the sheath member  18  and is configured to enable the tubular member  19  to reciprocate within the sheath member  18 , and, hence, operates as a drive rod assembly to open the end effector  28  and to close the end effector  28  to a clamping position. The drive rod can be a hollow shaft; hence, the drive rod assembly can operate as a push tube assembly or driver tube assembly. The sheath member  18  includes a connector  61 , and a holder  62  resides within the connector  61 . The end effector  28  includes a first jaw member such as the upper jaw member  68  attached to the connector  61  with a set of pins  70  and  72 . More specifically, the set of pins  70  and  72  extend through a pair of holes  73  in the connector  61  and through pair of holes  71  of the upper jaw member  68 . The inner ends of the pins  70  engage with respective slots  63  of the holder  62 . A pin  76  engages the end of the tubular member  19  to the upper jaw member  68 . Accordingly, movement of the tubular member  19  distally causes the tubular member  19  to push against the pin  76 , which, in turn, pushes against the upper jaw member  68  to pivot the upper jaw member  68  downwards about the pins  70  and  72  to the clamping position. The holder  62  remains stationary within the sheath  18  and helps keep a distal member  86  ( FIG. 7 ) centered in the tubular member  19 . The holder  62  is made of an insulating material, such as, for example, a plastic, to ensure that the distal member  86  and the tubular member  19  are electrically isolated from each other. An electrode  64  is attached to the bottom of the upper jaw member  68  with a pine or shaft  74  and is electrically connected to the energy source  13  such that the electrode  64  functions as a sealing surface. 
         [0032]    Turning now to  FIG. 7 , the forceps  10  further includes a sub-assembly member  80  with an inner shaft  83  housed within an inner sheath  84 . The inner shaft  83  is connected to an enlarged proximal end  82  and to the distal member  86  at the distal end of the shaft  83 . The distal member  86  can be a probe, a second jaw member, or both a probe and a second jaw member. The distal member  86 , in various arrangements, receives ultrasonic energy delivered by the source  13 , such that the distal member functions as a cutting element. The distal member  86  can function as an electrode with a sealing surface. Hence, if both the upper jaw member  68  includes an electrode  64  and the distal member  86  includes an electrode, the end effector  28  operates as opposed electrodes of a bipolar forceps. 
         [0033]    As shown in  FIG. 8A , the enlarged proximal end  82  is housed in a two piece probe holder  90 A and  90 B. Elongated electrical contacts  92 A and  92 B are positioned on the outside of the probe holders  90 A and  90 B and are electrically connected to the electrical source  13 . As further shown in  FIG. 8A , the inner shaft  83  and the inner sheath  84  are positioned within the tubular member  19  and are configure to allow the tubular member  19  to reciprocate over the inner sheath  84 . 
         [0034]    Referring also to  FIG. 8B , the two-piece probe holder  90 A and  90 B includes an enlarged flange  96  that engages with one of a set of ribs  46  (see, for example,  FIG. 2 ) inside the handpiece  12 . Accordingly, the probe sub-assembly member  80  remains stationary within the handpiece  12  while the slider  48 , the spring  44  and the shuttle  42  are able to translate relative to the sub-assembly  80 . 
         [0035]    Referring now to  FIG. 9 , the slider  48  includes a flange  60 . A second biasing member such as a spring  45  is positioned between the flange  60  and a surface  104  of a reduced diameter region of the connector knob  22 . Thus, movement of the moveable handle  16  towards the fixed handle  14  causes the yoke  58  to move distally. Since the yoke  58  is engaged with the shuttle  42 , distal movement of the yoke  58  pushes the shuttle  42 , which compresses the spring  44  against the slider flange  60 , which, in turn, moves the slider  48  distally. Distal movement of the slider  48  compresses the spring  45  between the surface  104  and the flange  60 . Since the tubular member  19  is connected to the slider  48 , movement of the slider  48  results in movement of the tubular member  19  within the sheath  18  and over the inner sheath  84 . And, as described earlier, since the tubular member  19  is engaged with the pin  76 , distal movement of the tubular member  19  results in distal movement of the pin  76 , which causes the upper jaw member  68  to pivot downwards to the closed clamping position. To open the end effector  28 , the moveable handle  16  is moved away from the fixed handle  14 . More specifically, movement of the handle  16  away from the fixed handle  14  results in the shuttle  42  to move proximally, which allows the spring  44  to expand to lessen the compressive forces on the flange  60  of the slider  48 . As a result, the spring  45  is able to expand as well to push against the flange  60 , which results in proximal movement of the slider  48 . Since, as discussed above, the slider  48  is connected to the end effector  28 , proximal movement of the slider  48  results in the upper jaw member to pivot upwards to the open position. Further note that in certain arrangements of the forceps  10 , the spring  45  acts as a restorative member that provides a biasing force on the moveable handle  16  away from the fixed handle  14 . Specifically, the lost motion connection, that is, the yoke  58  and the shuttle  42 , transfers the biasing force to the moveable handle  16  to return the moveable handle  16  away from the fixed handle  14  to maintain the upper jaw member  68  and the distal member  86  in the closed clamping position. 
         [0036]    During use of the forceps  10 , excessive clamping forces imparted on the end effector  28  may result in breakage of the end effector  28 . In particular, such forces can cause the pins  70  and  72  or  74  and  76  to break away or disengage from the upper clamping member  68 . The lost motion connection described previously prevents such breakage from happening. The shuttle  42  includes a distal flange  100  and a proximal flange  102 . The distal flange  100  allows the yoke  58  to snap over the shuttle  42 , as indicated by the arrows  110 , before the clamping forces of the end effector  28  become excessive as the moveable handle  16  is squeezed towards the fixed handle  14 . That is, if the clamping force imparted by the drive rod assembly exceeds a predetermined amount of force, the distal flange  100  of the yoke  58  deflects outwardly to allow enable relative axial movement between the yoke  58  and the shuttle  42 , which allows relative movement between the moveable handle  16  and the fixed handle  14  without the upper jaw member  68  moving relative to the distal member  86 . 
         [0037]    Similarly, excessive forces may occur while opening the end effector  28  as the moveable handle  16  is moved away from the fixed handle  14 . Hence, if the opening force imparted by the drive rod assembly exceeds a predetermined amount of force, the proximal flange  102  of the yoke  58  deflects outwardly to enable the yoke  58  to snap over the shuttle  42 , which again allows relative axial movement between the yoke  58  and the shuttle  42  while allowing relative movement between the moveable handle  16  and the fixed handle  14  without the upper jaw member  68  moving relative to the distal member  86 . 
         [0038]    In sum, the lost motion connection allows the moveable handle  16  to move away from the fixed handle  14  without the upper jaw member  68  moving relative to the distal member  86  so that the upper jaw member  68  and the distal member  86  do not move towards the open position when the moveable handle  16  moves away from the fixed handle  14 . Further, the lost motion connection allows the moveable handle  16  to move towards the fixed handle  14  without the upper jaw member  68  moving relative to the distal member  86  so that the upper jaw member  68  and the distal member  86  do not move towards the closed clamping position when the moveable handle  16  moves towards the fixed handle  14 . In certain arrangements, either flange  100  or  102  or both of them can include tapered surfaces  101  and  103 , respectively, as shown in  FIG. 9  to further enhance disengagement between the yoke  58  and the shuttle  42  to prevent the drive rod assembly from imparting excessive forces on the end effector  28 . 
         [0039]    The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.