Patent Publication Number: US-2012024482-A1

Title: System and Method of Making Tapered Looped Suture

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims benefit to and priority from U.S. Provisional Application Ser. No. 61/099,594, filed Sep. 24, 2008, the entire content of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a method of forming a looped suture. More particularly, the present disclosure relates to a method of forming a looped suture having a tapered surface. 
     2. Background of Related Art 
     A method for forming a loop in a suture during a wound closing procedure (surgery) is known. It would be beneficial to have a system and method for more effectively forming a loop on a suture prior to engagement of tissue with the suture. It would be further beneficial if the system and method could form a tapered end on the loop. 
     SUMMARY 
     Accordingly, a system for forming a looped suture having a tapered surface is provided. The system includes a base for selectively retaining a portion of thread, a clamping device for receiving a first end of the thread, a tensioning device for receiving a second end of the thread, a welding assembly configured to join a first and second section of the thread to form a loop, and a cutting assembly configured to form a tapered end on the first section of the thread. 
     The base may include a suture nest, a pin retaining member, a pin, and a pin locking member. The base may include at least one channel for receiving at least a portion of the second section of the thread. The pin retaining member may be pivotally mounted to the base. The pin may be configured to receive a portion of the thread thereabout. The welding assembly of the system may be configured to weld using ultrasonic energy. 
     The cutting assembly of the system may be configured to cut using one of ultrasonic energy, blades and lasers. The cutting assembly may be configured to form a tapered end on the first section of thread that is generally linear or generally curved. The cutting assembly may be configured to form a tapered end on the first section of thread that is convex or concave. The cutting assembly may also be configured to form a tapered end on the first section of thread that is angled downwards towards a longitudinal axis of the elongate body. Furthermore, the cutting assembly may be configured to form a tapered end on the first section of thread that forms an angle of about zero degrees (0°) to about ninety degrees (90°), preferably, five degrees (5°) to about thirty degrees (60°), relative to a longitudinal axis of the elongated body. In addition, the cutting assembly may be configured to form a tapered end on the first section of thread that is suitable for penetrating tissue. 
     Further provided is a method of forming a loop in a suture thread. The method includes the steps of providing a loop forming system including, a base for securely retaining a thread to be formed, a welding assembly for forming a loop in the thread, and a cutting assembly for forming a taper on an end of the loop, securing a portion of the thread to the base such that a first section of the thread is maintained adjacent to a second section of the thread, approximating the welding assembly and the base towards each other, approximating the welding assembly and base away from each other, approximating the cutting assembly and the base towards each other, and cutting a tapered end on a proximal end of the first section of the thread, approximating the cutting assembly and base away from each other, and removing the formed suture from the base. 
     The loop forming system of the method may further include a clamping device for receiving a first end of a thread. The loop forming system may further include a tensioning device for tensioning a thread once the thread is retained in the base. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with a general description of the disclosure given above, and the detailed description of the embodiment(s) given below, serve to explain the principles of the disclosure, wherein: 
         FIG. 1A  is a side view of a looped suture including a tapered portion; 
         FIG. 1B  is a cross-sectional end view of the looped suture of  FIG. 1A , taken along line  1 B- 1 B; 
         FIG. 1C  is an enlarged side view of portion  1 C of  FIG. 1A ; 
         FIG. 2A  is a front view of a base used in the tapered loop forming method of the present disclosure; 
         FIG. 2B  is a side view of the base of  FIG. 2A ; 
         FIG. 2C  is a top view of the base of  FIGS. 2A and 2B ; 
         FIG. 3A  is a side view of the base of  FIGS. 2A-2C  loaded with a suture and including a welding assembly, a suture retaining assembly and a suture tensioning assembly; 
         FIG. 3B  is a top view of the loaded base of  FIG. 3A ; 
         FIG. 3C  is a cross-section front view of the loaded base of  FIGS. 3A and 3B ; 
         FIGS. 4A and 4B  are enlarged views of  FIG. 3C , with the suture in a pre-welded ( FIG. 4A ) and post-welded ( FIG. 4B ) configuration; 
         FIG. 5A  is a top view of the loaded base of  FIGS. 3A-3C , post-welding and prior to the tapered cut being formed; 
         FIG. 5B  is a cross-sectional front view of the loaded base of  FIG. 5A ; 
         FIG. 5C  is a cross-sectional side view of the loaded base of  FIGS. 5A and 5B ; 
         FIG. 6A  is a cross-sectional front view of the loaded base of  FIGS. 5A-5C , post-welding and post-cutting of the suture; 
         FIG. 6B  is a cross-sectional side view of the loaded base of  FIG. 6A . 
     
    
    
     DETAILED DESCRIPTION 
     A method for forming a looped suture including a tapered surface is herein described. Referring initially to  FIG. 1A , a looped suture formed in accordance with the method of the present disclosure is shown generally as looped suture  10 . Suture  10  is formed from a monofilament thread  11 ; however, it is envisioned that suture  10  may be formed braided threads, multifilament threads and other surgical fibers. Although shown having a circular cross-sectional geometry, the cross-sectional geometry of thread  11  may be of any suitable shape, such as, round, elliptical, square, flat, octagonal, and rectangular. Thread  11  may be formed of degradable materials, non-degradable materials, and combinations thereof. Thread  11  may be formed using any technique within the purview of those skilled in the art, such as, for example, extrusion, molding and/or gel spinning. 
     With reference to  FIGS. 1A and 1B , looped suture  10  includes a loop  12  formed on a distal end  10   b  thereof. Loop  12  forms a substantially teardrop shape and may be formed of any size. A first section  13  of monofilament thread  11  overlays a second section  14  of thread  11  to form loop  12 . The adjacent surfaces of first and second sections  13 ,  14  form a joined segment or joint  15 . As shown, joined segment  15  extends beyond first section  13  of thread  11 . In this manner, first and second sections  13 ,  14  of thread  11  are less likely to separate or peel away from each other as looped suture  10  is pulled through tissue (not shown). 
     As will be described in further detail below, first and second sections  13 ,  14  of thread  11  are welded together to form joined section  15 . Energy is locally applied to first and second sections  13 ,  14  of thread  11  fusing sections  13 ,  14  together to form joined segment  15 . Various types of energy may be applied to first and second sections  13 ,  14  to form joined segment  15 , including, radio frequency (RF), ultrasonic, laser, electrical arc discharge, and thermal. Alternatively, first and second sections  13 ,  14  of thread  11  may be joined using glues, epoxies, solvents, or other adhesives. 
     With particular reference to  FIG. 1C , a proximal end  13   a  of first section  13  is angled to form a tapered surface  17 . Tapered surface  17  angles downwardly towards proximal end  10   a  of looped suture  10 . Tapered surface  17  may form an angle α relative to a longitudinal axis “X” of second section  14 , between zero degrees (0°) and ninety degrees (90°), and preferably between about five degrees (5°) to about thirty degrees (60°). Tapered surface  17  facilitates insertion of loop  12  into or through tissue. Tapered surface  17  may be formed prior to, during or following the joining of first and second sections  13 ,  14 . In one embodiment, tapered surface  17  is formed such that joined segment  15  extends beyond first section  13  of thread  11 . In this manner, tapered surface  17  forms a smooth transition with second section  14  of thread  11 , thereby decreasing the likelihood that first and second sections  13 ,  14  might separate or peel away from each other as looped suture  10  is pulled through tissue. 
     Although shown having a substantially planar taper, tapered surface  17  may include any number of configurations. For example, tapered surface  17  may be beveled, may include a laterally and longitudinally concave taper, may include a laterally and longitudinally convex taper, or may include any combination thereof. Tapered surface  17  may be selected depending on the tissue being sutured and/or the depth loop  12  is desired to be received within the tissue. 
     A system for forming loop  12  on distal end  10   b  of looped suture  10  will now be described with reference to  FIGS. 2A-6B , and is shown generally as system  100 . System  100  includes a fixture member or base  110 , a suture retaining member  120  ( FIG. 3A ), a suture tensioning member  125  ( FIG. 3A ), a welding assembly  130  ( FIGS. 3A-3C ), and a cutting assembly  140  ( FIGS. 5A-6B ). 
     Referring initially to  FIGS. 2A-2C , base  110  includes a platform  112 , a suture nest  114 , a pin retaining member  116 , a pin  116   a  extending from pin retaining member  116 , and a pin lock  118 . Platform  112  includes one or more openings  112   a  for securing base  110  to a workstation (not shown) using bolts  112   b  or other fixation means. As shown, suture nest  114  is integrally formed with platform  112 . Alternatively, suture nest  114  may be releasably attached or securely affixed to platform  112 . Nest  114  includes one or more channels  115  extending across a top surface  114   a  thereof. As will be described in further detail below, channels  115  are configured to partially receive a portion of suture thread  11 , including second section  14  ( FIG. 1 ). Nest  114  may further includes raised outer portions  113  extending along proximal and distal ends  115   a ,  115   b  of channels  115 . Raised outer portions  113  include openings  113   a  configured to receive two lengths of suture thread  11 , adjacent to or on top of one another. As shown, suture nest  114  includes three channels  115 ; however, it is envisioned that suture nest  115  may include one or more channels  115 . In one embodiment, suture nest  115  may be formed without a channel. In this manner, the first and second portions of suture thread  11  would be received in opening  113   a  and are maintained adjacent to one another through the tension applied by suture tensioning means  125  ( FIG. 3A ). 
     Still referring to  FIGS. 2A-2C , pin  116   a  extends from pin retaining member  116 . Pin retaining member  116  is pivotally attached to platform  112  such that pin  116   a  may be selectively positioned and securely retained perpendicular to channels  115  along an end thereof ( FIG. 3B ). Pin lock  118  is pivotally attached to suture nest  114  and is configured to secure pin  116   a  in the perpendicular position adjacent proximal end  115   a  of channels  115 . Alternatively, pin lock  118  may be integrally formed with suture nest  114 . In another alternate embodiment, pin retaining member  116  may be releasably attached or securely affixed to platform  112 . The diameter of pin  116   a  may be varied depending on the desired size of loop  12 . 
     Turning briefly to  FIG. 3A , as discussed above, system  100  also includes a suture retaining means  120  and a suture tensioning means  125 . Suture retaining means  120  may include a clamp or other device configured to retain a proximal end  11   a  of suture thread  11 . Suture tensioning means  125  may include a hydraulic or pneumatic tensioning spring, electrical cylinder or other tensioning device configured to receive a distal end  11   b  of suture thread  11  and to apply tension to suture thread  11  once thread  11  has been secured to suture nest  114 . Suture retaining means  120  and suture tensioning means  125  are positioned adjacent distal end  115   b  of channel  115  to securely receive respective proximal and distal ends  11   a ,  11   b  of suture thread  11  during the forming of loop  12 . 
     With reference to  FIGS. 3A-4B , welding assembly  130  includes an ultrasonic device  132  operably connected to a generator (not shown) for ultrasonically vibrating a die  134  extending from ultrasonic device  132 . Die  134  defines a substantially flat suture contacting portion  136 . In an alternative embodiment, die  134  may include a portion  136  configured to contour first section  13  of suture thread  11 . Thus, suture contacting portion  136  may include a concave, convex or beveled surface to correspond with a suture thread having a convex, concave or beveled profile. In one embodiment, welding assembly  130  is operatively mounted on a press assembly (not shown) for approximating die  134  of welding assembly  130  towards and away from base  110 . Alternatively, welding assembly  130  may be securely mounted relative to base  110  and base  110  may be raised and lowered to approximate base  110  towards and away from die  134 . 
     Turning now to  FIGS. 5A-6B , cutting assembly  140  includes an ultrasonic device  142  operably connected to a generator (not shown) for ultrasonically vibrating a blade  144  extending from ultrasonic device  142 . The generator for ultrasonically vibrating die  134  may be the same or a different generator as is operatively connected to ultrasonic device  142  for ultrasonically vibrating blade  144 . In one embodiment, blade  144  defines a substantially flat cutting surface  144   a ; however, it is envisioned that blade  144  may include a cutting surface of alternative configurations. Blade  144  may be configured to form a concave, convex, beveled or otherwise configured taper  17  on looped suture  10 . Although the following discussion will relate to a cutting assembly that includes an ultrasonic device  142 , it is envisioned that cutting assembly  140  may be used without ultrasonically vibrating blade  144 . In this manner, blade  144  may be operably connected to a heater or other apparatus for effecting cutting of suture thread  11 . In yet another embodiment, taper  17  on looped suture  10  may be cut using a laser. 
     Still referring to  FIGS. 5A-6B , in one embodiment, cutting assembly  140  is securely mounted relative to base  144  such that cutting assembly  140  is maintained stationary as base  110  is approximated towards and away from blade  144 . In an alternative embodiment, cutting assembly  140  is selectively positioned relative to base  110 , such that cutting assembly  140  moved relative to base  110 . In either embodiment, at least one of cutting assembly  140  and base  110  is configured to move laterally with respect to the other and approximate towards the other. When cutting assembly  140  is maintained stationary, base  110  is configured to move laterally, in the direction of arrow A 1  ( FIG. 6B ) and towards cutting assembly  140 , in the direction of arrow A 2 . When base  110  is maintained stationary, cutting assembly  140  is configured to move laterally, in the direction of arrow B 1  and towards base  110 , in the direction of arrow A 2 . Movement of base  110  and/or cutting assembly  140  may be computer controlled or may be effected manually. 
     The method of forming looped suture  10  utilizing system  100  will now be described with reference to  FIGS. 3A-6B . Referring initially to  FIG. 3A , a proximal end  11   a  of thread  11  is securely locked in a clamp  120 . Second section  14  of thread  11  is then positioned within a channel  115  of nest  114 . Thread  11  is next wrapped around pin  116   a  before first section  13  of thread  11  is placed on top of or adjacent second section  14 . A distal end  11   b  of thread  11  is then received in tension cylinder  125 . Tensioning cylinder  125  is then activated to tension thread  11  within base  110 . To prevent stretching of thread  11  during forming of looped suture  10 , and thereby ensuring consistency and integrity of thread  11 , thread  11  may be formed of a pre-stretched material. 
     With particular reference now to  FIGS. 3C-4B , once first and second sections  13 ,  14  are positioned adjacent one another, welding assembly  130  is approximated towards suture nest  114 . Alternatively, suture nest  114  may be approximated towards welding assembly  130 . As welding assembly  130  nears suture nest  114 , first section  13  of suture thread  11  is received within channel  136  of die  134  until first section  13  engages suture contacting portion  136   a  of channel  136  ( FIG. 4A ). Ultrasonic device  132  may be activated at any point during this process to ultrasonically vibrate die  134 . The downward pressure exerted on first and second sections  13 ,  14  of thread  11  from the continued approximation of die  134  towards nest  114  ( FIG. 4B ), in combination with ultrasonic vibration of die  134 , causes contacting portions of first and second sections  13 ,  14  to locally heat, and, in some instances, the contacting portions may begin to melt. Application of ultrasonic energy to sections  13 ,  14  creates joined section  15 . 
     Once first and second sections  13 ,  14  are fused to create joined section  15 , welding assembly  130  may be approximated away from suture nest  114 . With looped suture  10  remaining secured to base  110 , welding assembly  130  may then be replaced or exchanged for cutting assembly  140  to complete the tapered cutting of proximal end  13   a  of first section  13 . Alternatively, looped suture  10  may be removed from base  110  and affixed to a separate mount (not shown) to complete the taper forming process. 
     With reference now to  FIGS. 5A-6B , once cutting assembly  130  is properly positioned in relation to base  110 , base  110  is approximated towards cutting assembly  140 . Alternatively, cutting assembly  140  may be approximated towards base  110 . Ultrasonic device  142  may be activated at any time prior to or during approximation of cutting assembly  140  towards base  110 . With particular reference to  FIG. 6B , the travel of base  110  in relation to cutting assembly  140  includes an upward movement, as indicated by arrow A 1  and lateral movement, as indicated by arrow A 2 . In an alternative embodiment, cutting assembly  140  is moved in a downward movement, as indicated by arrow B 1  and a lateral movement, as indicated by arrow B 2 . The rate at which base  110  moves relative to cutting assembly  140  may be varied depending on the desired configuration of tapered surface  17  ( FIG. 1C ). In this manner, when the lateral movement is increased relative to the up/down movement, tapered surface  17  defines an angle α ( FIG. 1C ) of a lesser degree. Conversely, when the lateral movement of is decreased relative to the up/down movement, angle α of tapered surface  17  is increased. In either embodiment, cutting assembly  130  and base  110  are approximated toward one another until blade  144  completely severs first section  13  of thread  11 . Distal end  11   b  of thread  11  is then pulled away by tension cylinder  125 . 
     Cutting assembly  130  and base  110  are then approximated away from each other and looped suture  10  is removed from pin  116   a . Suture  10  may include flash or debris (not shown) formed during the welding and/or cutting process. The flash may need to be removed before looped suture  10  may be used. 
     Although the illustrative embodiments of the present disclosure have been described herein with reference to the accompanying drawings, it is to be understood that the disclosure is not limited to those precise embodiments, and that various other changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the disclosure. For example, it is envisioned that system  100  may include more than one welding assembly  130  and a corresponding number of cutting assemblies  140  to produce more than one suture  10  per activation. It is further envisioned that system  100  may include a separate base for maintaining suture  10  during the cutting process.