Abstract:
A medical device that includes a cannulated needle, a first knotting element portion releaseably engaged with the needle, a second knotting element portion also releaseably engaged with the needle, a knotting element deployment actuator that abuts the second knotting element portion, and an anchor deployment actuator in communication with the interior of the needle, wherein the knotting element deployment actuator and anchor actuator are slidably manipulable from a proximal handle of the device, and held in a coaxial relationship with each other. The first knotting element portion may be releaseably engaged by means including shearing posts and adhesives, and the second knotting element portion may be releaseably engaged by means including detents and adhesives.

Description:
FIELD OF THE INVENTION 
   The present application relates to surgical fasteners and devices for approximating and fastening tissue and, more particularly, to suture anchors, knotting elements, and associated devices for endoscopically suturing tissue. 
   BACKGROUND 
   Endoscopic microsurgery, including procedures performed by way of endoscopic instruments such as gastroscopes, colonoscopes, laparoscopes, and the like, may be preferred as an alternative to open surgery due to the many advantages attributed to such “minimally invasive” techniques, such as shortened hospital stays, reduced recovery time, reduced risk of complications, and diminishment of the amount of and/or visibility of scarring caused by a surgical intervention. In many endoscopic procedures, as in open surgery, there are instances where a surgeon may desire to repair damaged or diseased tissues by apposing the tissues together using a suture. However the suturing devices, stapling devices, and other fastener applicators that have been developed to aid surgeons performing open surgery generally cannot be easily redesigned to be passed through a flexible endoscopic instrument, which may have a working channel having an internal diameter in the range of about 2.5 to about 4.0 millimeters. In addition, surgeons performing endoscopic procedures generally cannot simultaneously manipulate multiple devices fed through such working channels with sufficient ease to permit them to routinely emulate the “pass and catch” suturing techniques that may be employed in open surgery. 
   To address these problems, various suture anchors and applicator devices have been developed to permit surgeons to endoscopically emplace sutures within tissues. Such suture anchors may be deployed using applicator devices that are inserted within and extended through the working channel of an endoscope, carrying a suture anchor to the site of repair. Such applicators typically include a cannulated needle portion which permits the surgeon to penetrate the tissues adjacent to diseased or damaged tissue and deploy the suture anchor within, or preferably onto a distal surface of, the tissue to be apposed in a repair. The suture anchor is generally attached to a distal end of a suture, with the bulk of the suture extending alongside or within a portion of the applicator device, and with a proximal end of the suture trailing outside the endoscopic instrument. The surgeon may deploy multiple suture anchors around the site of repair by serially passing multiple applicators through a flexible endoscope to the site of repair, or by repeatedly passing and withdrawing a single applicator that may be serially reloaded with additional suture anchors. After deploying the suture anchors, the surgeon may appose the tissue by applying traction to the proximal ends of the sutures, thereby manipulating the suture anchors and the surrounding tissue, and secure the apposed tissue by advancing a series of half hitches towards the site of repair using a knot pusher device. Alternately, the surgeon may thread the trailing ends of the sutures through one of a number of types of knotting elements and associated knotting element applicators, feed the applicator through the flexible endoscope towards the apposed tissue, and “fire” the applicator to fix or “knot” the sutures in place with the knotting element. The reader will appreciate that such procedures may require the repeated insertion, operation, and withdrawal of multiple endoscopic devices, which may increase the complexity of the endoscopic procedure as well as the complexity of equipment inventory and management within the operating environment. 
   Accordingly, there is a need for an applicator device that provides a means to deploy and implant multiple suture anchors without requiring repeated withdrawal of the device. In addition, there is a need for an applicator device that provides a means to knot the sutures associated with deployed suture anchors without requiring the withdrawal of an anchor applicator device and/or the substitution of a separate knotting element applicator device. 
   SUMMARY OF THE INVENTION 
   In one aspect, a combination knotting element and suture anchor applicator is provided and includes a cannulated needle, a first knotting element portion releaseably engaged with the needle, a second knotting element portion also releaseably engaged with the needle, a knotting element deployment actuator that abuts the second knotting element portion, and an anchor deployment actuator in communication with the interior of the needle, wherein the knotting element deployment actuator and anchor deployment actuator are slidably manipulable from a proximal handle of the applicator, and held in a coaxial relationship with each other. The first knotting element portion may be releaseably engaged by a shear post engaged with a shear port on the cannulated needle, and the second knotting element portion may be releaseably engaged by a retaining post engaged with a detent on the cannulated needle. 
   In another aspect, a combination knotting element and suture anchor applicator is provided and includes a cannulated needle, a first knotting element portion releaseably engaged with the needle, a second knotting element portion also releaseably engaged with the needle, a knotting element deployment actuator that abuts the second knotting element portion, and an anchor deployment actuator in communication with the interior of the needle, wherein the knotting element deployment actuator and anchor deployment actuator are slidably manipulable from a proximal handle of the applicator, and held in a coaxial relationship with each other. The first knotting element portion and second knotting element portion may be releaseably engaged with the cannulated needle by retention posts adhered to the cannulated needle by a frangible adhesive layer. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of a knotting element and suture anchor applicator device, illustrating a hypothetical use of the device in an endoscopic surgical procedure. The endoscope and endoscopic examination tube are omitted for clarity. 
       FIG. 2  is a cross sectional side view of the distal tip of a first aspect of the device. 
       FIG. 3  is a perspective view of the distal tip shown in  FIG. 2 . The surgical anchors are shown in an expelled state for clarity. 
       FIG. 4  is a cross sectional side view of the distal tip shown in  FIG. 2 . 
       FIG. 5  is a perspective view of a suture anchor. 
       FIG. 6  is cross sectional side view of the distal tip of a second aspect of the device. 
       FIG. 7  is a perspective view of the distal tip shown in  FIG. 6 . The surgical anchors are shown in an expelled state for clarity. 
       FIG. 8  is a cross sectional side view of the distal tip shown in  FIG. 6 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to  FIG. 1 , the knotting element and suture anchor applicator device disclosed herein generally includes a proximal handle  500  that provides a surgeon with means to manipulate the endoscopic portion of the device at the site of repair; a flexible shaft  510  that includes multiple actuators that provide means for communicating such manipulation to the endoscopic portion of the device; and a distal tip  520  that carries suture anchors, knotting elements, and the like to the site of repair. Flexible shaft  510  may be adapted for insertion into the working channel of a flexible endoscope (not shown) such as a gastroscope or a colonoscope by being flexible, having an outer diameter in a range of about 2.0 to about 3.8 millimeters, and having a length of approximately 1.5 meters. Distal tip  520  may be similarly adapted for insertion into the working channel of a flexible endoscope by having a maximum outer diameter in a range of about 2.0 to about 3.8 millimeters. The reader will appreciate that devices having various diameters and/or lengths may be inserted through other endoscopic instruments, such as laparoscopes, depending on the requirements of the surgical procedure to be performed. 
   First Aspect of the Device 
   With reference to  FIGS. 2 and 3 , in one aspect of the device the distal tip  520  of the knotting element and suture anchor applicator device may include a cannulated needle  530 , an anchor deployment actuator  540 , a knotting element deployment actuator  550 , a first knotting element portion  560 , and a second knotting element portion  570 . Cannulated needle  530  may be manufactured from 19 gage stainless steel hypodermic tubing having an outer diameter of approximately 0.043 inches (1.09 millimeters) and a wall thickness of approximately 0.003 inches (0.076 millimeters). The hypodermic tubing may extend through flexible shaft  510  to proximal handle  500 , or alternately may be joined to a second length of metal or extruded plastic polymer tubing extending through flexile shaft  510  to proximal handle  500 . Cannulated needle  530  may be joined to such a second length of tubing by welding, gluing, or other methods known in the art. The distal end of cannulated needle  530  may optionally be ground to form a penetrating tip. 
   Cannulated needle  530  may include a central channel  532 , one or more shear ports  534 , a suture slot  536  extending proximally from the distal end of the needle, and a detent  538 . Central channel  532  is open to the environment at the distal end of cannulated needle  530  and may extend proximally to handle  500 . Shear ports  534  in cannulated needle  530  may be disposed around a portion of the needle to provide a means for attaching first knotting element portion  560  to the needle. Suture slot  536  may be provided as a means for routing sutures  582  extending from suture anchors  580  out of central channel  532  and away from the distal tip of cannulated needle  530 . Such routing may advantageously reduce interference between cannulated needle  530 , suture  582 , and suture anchor  580  during the deployment of an anchor, and may advantageously reduce the potential for the distal tip of the needle to sever sutures  582  that would otherwise be routed around that tip. Optionally, the edges of suture slot  536  may be coated with a protective material  539  such as an epoxy resin or a plastic polymer to reduce any potential for the edges of suture slot  536  to sever a suture  582  during operation of the device. Detent  538  may be disposed around a portion of cannulated needle  530  to provide a means for attaching and retaining second knotting element portion  570 . Detent  538  may be formed as an integral portion of cannulated needle  530 , or alternately may be an annular ring of material affixed to the needle by gluing, welding, or other methods known in the art. Suture anchors  580  may be loaded into central channel  532  and each associated suture  582  may be routed to pass through first knotting element portion  560  and extend outward from second knotting element portion  570  at a location between first knotting element portion  560  and second knotting element portion  570 . If cannulated needle  530  includes a suture slot, sutures  582  may additionally be routed to pass through suture slot  536  between first knotting element portion  560  and second knotting element portion  570  and extend outward from second knotting element portion  570 . The remainder of each suture  582  may extend alongside knotting element actuator  550  and flexible shaft  510  within the working channel of the endoscope, exiting the instrument adjacent to the proximal handle  500  of the knotting element and suture anchor applicator device. 
   Anchor deployment actuator  540  may be manufactured from 19 gage stainless steel wire having an outer diameter of approximately 0.036 inches (0.912 millimeters). The actuator  540  may slide within central channel  532 , and may extend from approximately the distal end of cannulated needle  530 , through central channel  532  and flexible shaft  510 , to proximal handle  500 . The actuator  540  should have a length sufficient to permit suture anchors  580  to be fully ejected from cannulated needle  530  during a surgical procedure. The actuator  540  may be advanced within central channel  532  in a stepwise manner through the manipulation of a plunger or trigger control on proximal handle  500 , or by other control means known in the art. As anchor deployment actuator  540  is advanced, the distal end of the actuator abuts a suture anchor  580 , and sufficient advancement will cause the most distally disposed anchor  580  within cannulated needle  530  to be ejected from central channel  532 . 
   Knotting element deployment actuator  550  may be manufactured from a helically wound stainless steel wire or other suitable materials known in the art. The actuator  550  may slide over cannulated needle  530 , and may extend from distal tip  520 , abutting second knotting element portion  570 , to proximal handle  500 . The knotting element deployment actuator  550 , anchor deployment actuator  540 , and cannulated needle  530  may be held in a coaxial relationship along flexible shaft  510  between distal tip  520  and proximal handle  500 . The actuator  550  should have a length sufficient to permit first knotting element portion  560  and second knotting element portion  570  to be deployed off the distal end of cannulated needle  530  at the completion of a knotting step in a surgical procedure. The actuator  550  may be advanced over cannulated needle  530  through the manipulation of a control on proximal handle  500  such as a slider or a ratcheting trigger, or by other control means known in the art. 
   With reference to  FIGS. 3 and 4 , first knotting element portion  560  may be configured as a partially hollow cylinder having an outer wall  562  and one or more shear posts  564  which may extend inward from outer wall  562  to engage with shear ports  534  of cannulated needle  530 . First knotting element portion  560  may provide an interior suture path  566  which contributes to a knotting action described later. First knotting element portion  560  may be constructed from various plastic polymers approved for medical use. The width and number of shear posts  564  may be varied along with other factors, such as the elasticity of the material used to construct the element, to vary the shear force necessary to overcome the engagement of shear posts  564  with shear ports  534 . The reader will appreciate that the configuration of this element as a partially hollow cylinder is merely a matter of convenience, and that a variety of shapes may be adapted to define an interior suture path  566  and achieve similar functional results. 
   Second knotting element portion  570  may also be configured as a generally hollow cylinder having an outer wall  572  and one or more retention posts  574  which may extend inward and engage with detent  538  of cannulated needle  530 . Optionally, a single retention post  574  may extend inward from the periphery of outer wall  572  towards cannulated needle  530 , forming a retention post similar in structure to a proximal wall. Second knotting element portion  570  may be constructed from various plastic polymers approved for medical use. The width and number of retention posts may be varied along with other factors, such as the degree to which detent  538  projects outward from cannulated needle  530  and the elasticity of the material used to construct the element, to vary the force necessary to overcome the engagement of retention posts  574  with detent  538 . The reader will appreciate that the configuration of this element as a generally hollow cylinder is again merely a matter of convenience, and that a variety of shapes may be selected to complement the shape of first knotting element portion  560  and achieve similar functional results. 
   Typically, outer wall  572  of second knotting element portion  570  has an inner diameter approximately equal to the outer diameter of outer wall  562  of first knotting element portion  560  with the addition of a gap, d. Preferably, outer wall  572  has an inner diameter in the range of about the outer diameter of outer wall  562  to about the sum of the outer diameter of outer wall  562  and the diameter of a suture line. The knotting element may be engaged by slidingly joining first knotting element portion  560  and second knotting element portion  570 , such that first knotting element portion  560  nests within second knotting element portion  570 , leaving a suture gap  576  having a width approximately equal to gap d defined between the outer surface of outer wall  562  of first knotting element portion  560  and the inner surface of outer wall  572  of second knotting element portion  570 . Sutures  582  extending through interior suture path  566  of first knotting element portion  560  are bent by the joining of the knotting element portions to conform to an “S”-shaped path that runs through interior suture path  566 , around the proximal end of first knotting element portion  560 , through suture gap  576 , around the distal end of second knotting element portion  570 , and along flexible shaft  510  towards proximal handle  500 . Sutures  582  are retained or “knotted” within the joined knotting element portions by frictional engagement with the outer surface of outer wall  562  of first knotting element portion  560  and the inner surface of outer wall  572  of second knotting element portion  570 , and optionally by engagement between the proximal end of first knotting element portion  560  and the distal surface of retention posts  574 . Similarly, first knotting element portion  560  and second knotting element portion  570  are retained in a joined relation by frictional engagement with each other and sutures  582 . Optionally, the outer surface of outer wall  562  of first knotting element portion  560  and the inner surface of outer wall  572  of second knotting element portion  570  may be textured, coated, or otherwise modified to increase the apparent coefficient of friction between the two surfaces, and between the surfaces and sutures  582 . 
   A plurality of suture anchors  580  may be loaded into central channel  532  of cannulated needle  530 . With reference to  FIG. 5 , such suture anchors may include conventional T-tags having a hollow cylindrical body  584  including a longitudinal slot  586  extending along approximately one half of the length of the body. Suture  582  may be attached to suture anchor  580  by passing the suture through body  584  and forming a knot  588  in suture  582  larger than the diameter of body  584 , or alternately by crimping, gluing, or otherwise affixing suture  582  within body  584  adjacent to slot  586 . The reader will appreciate that a variety of different suture anchors may be deployed from the knotting element and suture anchor applicator device disclosed herein, including but not limited to the expandable suture anchors disclosed in my copending application, U.S. patent application Ser. No. 11/274,358, entitled “Expandable Suture Anchor” and filed on Nov. 15, 2005, the entire contents of which are incorporated herein by reference. 
   Second Aspect of the Device 
   With reference to  FIGS. 6 and 7 , in an additional aspect of the device the distal tip  520  of the knotting element and suture anchor applicator device may include a cannulated needle  630 , an anchor deployment actuator  640 , a knotting element deployment actuator  650 , a first knotting element portion  660 , and a second knotting element portion  670 . Cannulated needle  630  may be manufactured from 19 gage stainless steel hypodermic tubing having an outer diameter of approximately 0.043 inches (1.09 millimeters) and a wall thickness of approximately 0.003 inches (0.076 millimeters). The hypodermic tubing may extend through flexible shaft  510  to proximal handle  500 , or alternately may be joined to a second length of metal or extruded plastic polymer tubing extending through flexile shaft  510  to proximal handle  500 . Cannulated needle  630  may be joined to such a second length of tubing by welding, gluing, or other methods known in the art. The distal end of cannulated needle  630  may optionally be ground to form a penetrating tip. 
   Cannulated needle  630  may include a central channel  632  and a suture slot  636  extending proximally from the distal end of the needle. Central channel  632  is open to the environment at the distal end of cannulated needle  630  and may extend proximally to handle  500 . Suture slot  636  may be provided as a means for routing sutures  582  extending from suture anchors  580  out of central channel  632  and away from the distal tip of cannulated needle  630 . Such routing may advantageously reduce interference between cannulated needle  630 , suture  582 , and suture anchor  580  during the deployment of an anchor, and may advantageously reduce the potential for the distal tip of the needle to sever sutures  582  that would otherwise be routed around that tip. Optionally, the edges of suture slot  636  may be coated with a protective material  639  such as an epoxy resin or a plastic polymer to reduce any potential for the edges of suture slot  536  to sever a suture  582  during operation of the device. Suture anchors  580  may be loaded into central channel  632  and each associated suture  582  may be routed to pass through first knotting element portion  660  and extend outward from second knotting element portion  670  at a location between first knotting element portion  660  and second knotting element portion  670 . If cannulated needle  630  includes a suture slot, sutures  582  may additionally be routed to pass through suture slot  636  between first knotting element portion  660  and second knotting element portion  670  and extend outward from second knotting element portion  670 . The remainder of each suture  582  may extend alongside knotting element actuator  650  and flexible shaft  510  within the working channel of the endoscope, exiting the instrument adjacent to the proximal handle  500  of the knotting element and suture anchor applicator device. 
   Anchor deployment actuator  640  may be manufactured from 19 gage stainless steel wire having an outer diameter of approximately 0.036 inches (0.912 millimeters). The actuator  640  may slide within central channel  632 , and may extend from approximately the distal end of cannulated needle  630 , through central channel  632  and flexible shaft  510 , to proximal handle  500 . The actuator  640  should have a length sufficient to permit suture anchors  580  to be fully ejected from cannulated needle  630  during a surgical procedure. The actuator  640  may be advanced within central channel  632  in a stepwise manner through the manipulation of a plunger or trigger control on proximal handle  500 , or by other control means known in the art. As anchor deployment actuator  640  is advanced, the distal end of the actuator abuts a suture anchor  580 , and sufficient advancement will cause the most distally disposed anchor  580  within cannulated needle  630  to be ejected from central channel  632 . 
   Knotting element deployment actuator  650  may be manufactured from a helically wound stainless steel wire or other suitable materials known in the art. The actuator  650  may slide over cannulated needle  630 , and may extend from distal tip  520 , abutting second knotting element portion  670 , to proximal handle  500 . The knotting element deployment actuator  650 , anchor deployment actuator  640 , and cannulated needle  630  may be held in a coaxial relationship along flexible shaft  510  between distal tip  520  and proximal handle  500 . The actuator  650  should have a length sufficient to permit first knotting element portion  660  and second knotting element portion  670  to be deployed off the distal end of cannulated needle  630  at the completion of a knotting step in a surgical procedure. The actuator  650  may be advanced over cannulated needle  630  through the manipulation of a control on proximal handle  500  such as a slider or a ratcheting trigger, or by other control means known in the art. 
   With reference to  FIGS. 3 and 4 , first knotting element portion  660  may be configured as a partially hollow cylinder having an outer wall  662  and one or more retention posts  664  which may extend inward from outer wall  662  to abut cannulated needle  630 . First knotting element portion  660  may be engaged with cannulated needle  630  by affixing one or more retention posts  664  to cannulated needle  630  at the point where the posts abut the needle with a frangible layer of adhesive  634 . First knotting element portion  660  may provide an interior suture path  666  which contributes to a knotting action described later. First knotting element portion  660  may be constructed from various plastic polymers approved for medical use. The width and number of retention posts  664  may be varied along with other factors, such as the strength of the frangible adhesive  634  binding the posts to cannulated needle  630 , to vary the shear force necessary to overcome the engagement of retention posts  664  and cannulated needle  630 . The reader will appreciate that the configuration of this element as a partially hollow cylinder is merely a matter of convenience, and that a variety of shapes may be adapted to define an interior suture path  666  and achieve similar functional results. 
   Second knotting element portion  670  may also be configured as a generally hollow cylinder having an outer wall  672  and one or more retention posts  674  which may extend inward and abut cannulated needle  630 . Optionally, a single retention post  674  may extend inward from the periphery of outer wall  672  towards cannulated needle  630 , forming a retention post similar in structure to a proximal wall. Second knotting element portion  670  may be engaged with cannulated needle  630  by affixing one or more retention posts  674  to cannulated needle  630  at the point where the posts abut the needle with a frangible layer of adhesive  638 . Second knotting element portion  670  may be constructed from various plastic polymers approved for medical use. The width and number of retention posts  674  may be varied along with other factors, such as the strength of the frangible adhesive  638  binding the posts to cannulated needle  630 , to vary the force necessary to overcome the engagement of the retention posts  674  with cannulated needle  630 . The reader will appreciate that the configuration of this element as a generally hollow cylinder is again merely a matter of convenience, and that a variety of shapes may be selected to complement the shape of first knotting element portion  660  and achieve similar functional results. 
   Typically, outer wall  672  of second knotting element portion  670  has an inner diameter approximately equal to the outer diameter of outer wall  662  of first knotting element portion  660  with the addition of a gap, d. Preferably, outer wall  672  has an inner diameter in the range of about the outer diameter of outer wall  662  to about the sum of the outer diameter of outer wall  662  and the diameter of a suture line. The knotting element may be engaged by slidingly joining first knotting element portion  660  and second knotting element portion  670 , such that first knotting element portion  660  nests within second knotting element portion  670 , leaving a suture gap  676  having a width approximately equal to gap d defined between the outer surface of outer wall  662  of first knotting element portion  660  and the inner surface of outer wall  672  of second knotting element portion  670 . Sutures  582  extending through interior suture path  666  of first knotting element portion  660  are bent by the joining of the knotting element portions to conform to an “S”-shaped path that runs through interior suture path  666 , around the proximal end of first knotting element portion  660 , through suture gap  676 , around the distal end of second knotting element portion  670 , and along flexible shaft  510  towards proximal handle  500 . Sutures  582  are retained or “knotted” within the joined knotting element portions by frictional engagement with the outer surface of outer wall  662  of first knotting element portion  660  and the inner surface of outer wall  672  of second knotting element portion  670 , and optionally by engagement between the proximal end of first knotting element portion  660  and the distal surface of retention posts  674 . Similarly, first knotting element portion  660  and second knotting element portion  670  are retained in a joined relation by frictional engagement with each other and sutures  582 . Optionally, the outer surface of outer wall  662  of first knotting element portion  660  and the inner surface of outer wall  672  of second knotting element portion  670  may be textured, coated, or otherwise modified to increase the apparent coefficient of friction between the two surfaces, and between the surfaces and sutures  582 . 
   Illustrative Use of an Aspect of the Device 
   The knotting element and suture anchor applicator device disclosed herein may be used to endoscopically appose tissues in the following illustrative, but not limiting manner. A surgeon may guide an endoscopic instrument, such as a gastroscope and examination tube, through the gastrointestinal tract of a patient. The surgeon may then use the endoscopic instrument to survey the patent&#39;s internal tissues, such as a stomach, and to visualize damaged tissue, such as an ulcerated region. To effect a repair, the surgeon may obtain a knotting element and suture anchor applicator loaded with a plurality of suture anchors  580  and associated sutures  582 , such as the T-tags described previously, and insert distal tip  520  and flexible shaft  510  of the device into the working channel of the instrument, guiding distal tip  520  to the site of repair. The surgeon may then manipulate distal tip  520  to cause cannulated needle  530  to penetrate the tissues adjacent to the damaged tissue, and manipulate suture anchor actuator  540  to deploy a first suture anchor  580  onto a distal surface of, or optionally within, a first portion of the tissue to be apposed. The surgeon may then manipulate distal tip  520  to cause cannulated needle  530  to penetrate other tissues adjacent to the damaged tissue, and manipulate suture anchor actuator  540  to deploy a second suture anchor  580  onto a distal surface of, or optionally within, a second portion of the tissue to be apposed without withdrawing distal tip  520  from the endoscopic instrument to swap in a second device or to reload a suture anchor  580  into cannulated needle  530 . Thus, the surgeon may emplace a plurality of suture anchors  580  without withdrawing the device. Preferably, the knotting element and suture anchor applicator is loaded with 2, 3, or 4 suture anchors  580  and associated sutures  582 . After deploying the last suture anchor  580 , the surgeon may manipulate the proximal ends of the sutures  582  to appose the tissues at the site of repair. When the tissues have been properly apposed, the surgeon may “fire” the knotting element by manipulating knotting element actuator  550  and applying force to second knotting element portion  570 , which is in engagement with cannulated needle  530  as described previously. If sufficient force is applied, retention posts  574  of second knotting element portion  570  may distort and become released from engagement with detent  538  of cannulated needle  530 , permitting second knotting element portion  570  to slide towards the distal end of the needle until it abuts first knotting element portion  560 , which is in engagement with cannulated needle  530  as described previously. The joining of first knotting element portion  560  and second knotting element portion  570  will “knot” sutures  582  as described previously. Continued manipulation of knotting element actuator  550  will transmit force through second knotting element portion  570  to first knotting element portion  560 , transforming the applied force into a shear force acting across shear posts  564 . If sufficient force is transmitted, shear posts  564  may shear and become released from engagement with shear ports  534  of cannulated needle  530 , permitting first knotting element portion  560  and joined second knotting element portion  570  to slide towards the distal end of the needle until the joined knotting element portions are deployed off the distal end of cannulated needle  530 . The surgeon may withdraw distal tip  520  and flexible shaft  510  from the endoscopic instrument to clear the working channel of the instrument in preparation for additional procedures or in preparation for the withdrawal of the instrument. 
   Although various aspects of the disclosed device have been shown and described herein, modifications may occur to those skilled in the art upon reading this specification. The present application includes such modifications as are within the spirit of the invention, and is to be limited only by the scope of the appended claims.