Abstract:
A surgical device includes a handle, a drive shaft that protrudes from the handle, and an articulating applicator arm connected to the drive shaft. An articulation trigger includes at least one superelastic articulating cable that has one end connected to the articulation trigger and an opposite end connected to the articulating applicator arm.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to surgical devices that have an articulating mechanism, such as but not limited to, a tacker for applying surgical fasteners, and particularly to a superelastic articulating mechanism. 
       BACKGROUND OF THE INVENTION 
       [0002]    A number of surgical, laparoscopic and endoscopic procedures require application of rotary tacks to tissues, such as for hernia repairs and the like. 
         [0003]    Tackers for applying such rotary tacks are well known. A typical tacker drive and articulating mechanism of the prior art is shown in  FIG. 1 . A handle  1  houses a deployment trigger  2  for rotating a drive shaft  3  housed in an outer tube  3 A. The deployment trigger  2  is spring-loaded by a spring  4 . Squeezing the deployment trigger  2  (upwards, clockwise in the sense of the drawing) causes rotation of the drive shaft  3  through a gear train  5 ; the motion of the trigger causes a spur gear  6  to mesh with and turn a series of gears of the gear train  5  to cause rotation of the drive shaft  3 . Rotary tacks disposed in an applicator arm (not shown) are rotatingly connected to the drive shaft  3 . Operation of the deployment trigger  2  causes the drive shaft  3  to rotate so as to distally advance the rotary tacks from the applicator arm for deployment in tissue. 
         [0004]    The tacker mechanism of the prior art also includes an articulation trigger  7  for articulating the applicator arm at different angles. Articulating cables  8  are connected to upper and lower points on articulation trigger  7  and enter the outer tube  3 A through entry holes. The articulating cables  8  run through the length of outer tube  3 A and are connected to an articulating portion (not shown) of the applicator arm. The articulation trigger  7  pivots about a pivot  9 . Pulling the lower part of the articulation trigger  7  towards the handle  1  (upwards, counterclockwise in the sense of the drawing) puts tension on (that is, pulls) the lower of the articulating cables  8  and causes the applicator arm to articulate downwards. Conversely, pushing the lower part of the articulation trigger  7  away from the handle  1  (downwards, clockwise in the sense of the drawing) puts tension on (that is, pulls) the upper of the articulating cables  8  and causes the applicator arm to articulate upwards. 
         [0005]    A problem can occur with the articulating cables  8  and articulation trigger  7 . After using the articulation cables  8  to articulate the applicator arm, it is often desired to lock the trigger in place to fix the applicator arm at a particular orientation. The handle  1  is provided with a locking mechanism to lock the trigger  7  at a variety of places along the trigger movement. However, the articulating cables  8  are not designed to accurately place the trigger  7  at any of the locking positions; there are problems of free play and tolerances with the result that the trigger  7  does not automatically reach any of the locking positions. 
         [0006]    In the prior art, the problem is solved with coil springs  11 , which are connected to the upper and lower parts of the articulation trigger  7  and which provide tension on the trigger  7 . The motion of the springs  11  and of articulation trigger  7  is constrained by a four-bar linkage mechanism  10 , which ensures smooth, parallel movement of the springs  11  and trigger  7 . If the trigger  7  were to misalign with a desired locking position, one of the springs is in tension and this pulls the trigger to the locking position. 
         [0007]    However, the springs and four-bar linkage mechanism involve a relatively large amount of parts and high manufacturing and assembly costs. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention seeks to provide an improved articulating mechanism for surgical devices that require articulation, such as but not limited to, tackers, endoscopic devices, laparoscopic devices and others, as is described more in detail hereinbelow. In particular, the present invention seeks to provide a superelastic articulating mechanism that eliminates the drawbacks of the prior art; the number of parts is greatly reduced, and manufacturing and assembly costs are also significantly reduced. 
         [0009]    There is thus provided in accordance with a non-limiting embodiment of the present invention a surgical device including a handle, a drive shaft that protrudes from the handle, an articulating applicator arm connected to the drive shaft, and an articulation trigger including at least one superelastic articulating cable that has one end connected to the articulation trigger and an opposite end connected to the articulating applicator arm. 
         [0010]    In accordance with a non-limiting embodiment of the present invention the articulation trigger includes a locking mechanism for locking the articulation trigger at a selected operating position. 
         [0011]    In accordance with a non-limiting embodiment of the present invention the handle further includes a deployment trigger for rotating the drive shaft. 
         [0012]    In accordance with a non-limiting embodiment of the present invention, in a method for using the surgical device, the articulation trigger is operated so as to apply a tensioning force and elastically stretch the at least one superelastic articulating cable and cause articulation of the articulating applicator arm. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which: 
           [0014]      FIG. 1  is a simplified pictorial illustration of an articulating mechanism of the prior art; 
           [0015]      FIG. 2  is a simplified pictorial illustration of an articulating mechanism, constructed and operative in accordance with a non-limiting embodiment of the present invention; 
           [0016]      FIG. 3  is a simplified pictorial illustration of a trigger of the articulating mechanism; and 
           [0017]      FIG. 4  is a simplified pictorial illustration of the trigger of the articulating mechanism at one end of a drive shaft in a tube and an articulating applicator arm at the other end of the tube, in accordance with a non-limiting embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0018]    Reference is now made to  FIG. 2 , which illustrates an articulating mechanism  20 , constructed and operative in accordance with a non-limiting embodiment of the present invention. 
         [0019]    A handle  22  houses a deployment trigger  24  for rotating a drive shaft  26  housed in an outer tube  27 . The deployment trigger  24  may be spring-loaded by a spring  28 . Squeezing the deployment trigger  24  (upwards, clockwise in the sense of the drawing) causes rotation of the drive shaft  26  through a gear train  30 ; the motion of the trigger causes a spur gear  32  to mesh with and turn a series of gears of the gear train  30  to cause rotation of the drive shaft  26 . An articulating applicator arm  34  (shown in  FIG. 4 ) is connected to the drive shaft  26 . In the case of a tacker, operation of the deployment trigger  24  causes the drive shaft  26  to rotate so as to distally advance rotary tacks from applicator arm  34  for deployment in tissue. Up to this point, the construction is similar to that of the prior art. 
         [0020]    Reference is made additionally to  FIG. 3 . The articulating mechanism  20  of the illustrated embodiment includes an articulation trigger  36  for articulating the applicator arm  34  at different angles. Superelastic articulating cables  38  are connected to upper and lower points  40  and  42  on articulation trigger  36  and enter drive shaft  26  through entry holes  44  and  46 , respectively. The articulating cables  38  run through the length of drive shaft  26  and are connected to the applicator arm  34  ( FIG. 4 ). The superelastic cables  38  may be made of nitinol or any other suitable superelastic material. “Superelasticity” is an elastic reversible property of the material&#39;s response to an applied stress. In shape-memory alloys like nitinol, it is caused by a phase transformation between the austenitic and martensitic phases of the crystalline structure of the alloy. In nitinol, up to about 13% (without limitation) deformation strain can be sustained and the material can recover its original shape after removing the stress. 
         [0021]    In other embodiments, only one superelastic articulating cable  38  is employed. In other embodiments, more than one articulating cable is employed, but not all of them are superelastic (one could be made of stainless steel, for example). 
         [0022]    The articulation trigger  36  may include a lower portion  36 L and/or upper portions  36 U for easy ambidextrous operation by the surgeon. (As seen in  FIG. 2 , the upper portions  36 U may move in a curved track  37  formed in handle  22 .) The articulation trigger  36  pivots about a pivot  48 . Pulling the lower part of the articulation trigger  36  towards the handle  22  (upwards, counterclockwise in the sense of  FIG. 2 ) puts tension on (that is, pulls) the lower of the articulating cables  38  and causes the applicator arm  34  ( FIG. 4 ) to articulate downwards. Conversely, pushing the lower part of the articulation trigger  36  away from the handle  22  (downwards, clockwise in the sense of  FIG. 2 ) puts tension on (that is, pulls) the upper of the articulating cables  38  and causes the applicator arm  34  ( FIG. 4 ) to articulate upwards. 
         [0023]    The articulation trigger  36  may include a locking mechanism  50  for locking the trigger at a selected operating position. As seen in  FIG. 3 , locking mechanism  50  includes one or more lugs  52  biased by a biasing device  54  (such as a coil spring  54 ). In the illustrated embodiment of  FIG. 3 , there are a pair of lugs  52  urged outwards by biasing device  54  sandwiched between lugs  52 . The lugs  52  slide against the inner surface of the handle  22  during operation of trigger  36 . One or more dimples or depressions  56  (seen in broken lines in  FIG. 2 ) may be formed in the inner surface of the handle  22 . When the lug  52  reaches the depression  56 , the biasing device  54  urges the lug  52  to be seated and caught in depression  56 , thereby locking the trigger  36  at this position. The surgeon can push lug  52  out of depression  56  so that trigger  36  can be moved to another position or return to its original position. Lug  52  can be pushed out of depression  56  because lug  52  is chamfered or rounded at its end. 
         [0024]    The superelasticity of the cables  38  biases the articulation trigger  36  so that trigger  36  will always align with the locking position. This is an elegant solution to the problem of the prior art mentioned above, which requires coil springs and a four-bar linkage mechanism. Instead, in the present invention, no such springs or linkage mechanism are used. The superelastic cables  38  are sufficient to ensure the articulation trigger  36  aligns with the locking position with no backlash or overshoot. The superelasticity of the cable  38  provides tension in the cable  38 . The tension in the cables  38  takes the place of coil springs of the prior art and ensures the trigger  36  aligns with the locking position.