Patent Publication Number: US-2005119696-A1

Title: Braided suture

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims the benefit of U.S. Provisional Application No. 60/526,665, filed on Dec. 2, 2003. The disclosure of the above application is incorporated herein by reference. 
    
    
     INTRODUCTION  
      Surgical sutures are available in a variety of materials in monofilament or multifilament forms, including braided structures. Braided sutures can be, for example, solid, or spiroid or include a cover surrounding a core. To maintain their strength, such sutures can be stiff and difficult to manipulate during surgical procedures, especially during those procedures that involve minimally invasive surgery. Cylindrically shaped sutures may also be difficult to knot or to retain a knot due to the type of suture material that is employed.  
      Improved braided sutures that are strong, flexible, easy to knot and that retain a knot are still desirable.  
     SUMMARY  
      The present teachings provide a suture that can be used with a suture anchor and/or a surgical needle. The suture has a tubular braided sheath having a flattened annular cross-section defining an empty bore. The sheath is braided using biocompatible fibers of the same or different materials.  
      The present teachings also provide a method of making a suture. The method includes providing a mandrel, braiding pluralities of first and second filaments around the mandrel to form a sheath, and removing the mandrel.  
      The present teaching provide a method of suturing. The method includes providing a flattened tubular braided suture, loading the suture to a suture anchor; implanting the suture anchor; and tying a suture knot.  
      Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
       FIG. 1  is an environmental isometric view of a suture according to the present teachings, shown in the process of braiding;  
       FIG. 2  is an isometric view of a finished suture according to the present teachings;  
       FIG. 3  is a schematic diagram of a braiding pattern according to the present teachings;  
       FIG. 4  illustrates a suture attached to an anchor, according to the present teachings;  
       FIG. 5A  illustrates a suture threaded to a needle, according to the present teachings;  
       FIG. 5B  a cross-sectional view of a suture swaged to a needle, according to the present teachings;  
       FIG. 6  illustrates forming a knot with a suture according to the present teachings; and  
       FIG. 7  illustrates the knot of  FIG. 6  in the process of being tightened. 
    
    
     DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS  
      The following description of the various embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
      Referring to  FIGS. 1 and 2 , a suture  100  for use in any medical applications, such as orthopaedic applications, can be made as a flattened tubular sheath that defines a hollow bore  102 . The suture  100  has a longitudinal axis “A” and can be braided as a three-dimensional structure around a mandrel  90 , which is removed after braiding, leaving the empty bore  102 . Removal of the mandrel  90  causes the suture  100  to take a flattened sleeve-like shape with an annular cross-section, as shown in  FIG. 2 . The finished suture  100  contains no core material and is flexible. The width “w” of the suture  100  can be about twice the thickness “t” of the suture  100 .  
      Referring to  FIGS. 1 and 3 , the suture  100  can be braided around the mandrel  90  using a plurality of first filaments  110  oriented along an axis “B” and a plurality of second filaments  120  oriented along an axis “C”. The first and second filaments  110 ,  120  are spirally braided around the mandrel  90  and are oppositely (counterclockwise and clockwise) spirally inclined relative to the axis A at angles β, for example 45° or any other angle, resulting in a biaxial braid. The suture  100  can also be braided in a triaxial pattern including a plurality of axial filaments  130 , which are interlaced with the first and second filaments  110 ,  120 . The axial filaments  130  retain their straight orientation parallel to the direction of the axis A. Although the braiding structure of  FIG. 3  is shown to be symmetric and balanced about the axis A, the suture need not be thus limited.  
      Depending on the size of the suture  100  and the size of the filaments selected, two, four, eight, etc., of each of the first, second and axial filaments can be used to form the braided structure. For example, eight first filaments having a denier of about 120, eight second filaments having a denier of about 120, and eight axial filaments having a denier of about 120, can be used to obtained a suture  100  with width of about 0.045 inches and thickness of about 0.015 inches, for a diameter or a USP (United States Pharmacopoeia) size of 3. Of course, any size or denier is contemplated herein. The braided structure itself can be of any pattern, such as “one filament over and one filament under”, “two filaments over and two filaments under” and so on. The braiding itself can be done using commercially available machines.  
      The first, second, and axial filaments  110 ,  120 ,  130  can be made from the same or different materials. The materials of the first, second and axial filaments  110 ,  120 ,  130  can be selected in any combination from a group of biocompatible, bioabsorbable or non-bioabsorbable, and natural or artificial materials, depending on the particular application. The filaments  110 ,  120 ,  130  can be made for example from ultra high molecular weight polyethylene, nylon, polyesters, polyamides, polyolefins, fluorocopolymers, cotton, linen, silk, to name but a few. Filaments of ultra high molecular weight polyethylene filaments are commercially available from DSM under the tradename Dyneema. As an example, the first and second filaments  110 ,  120  can be made of the same or different polyester materials, including high tenacity polyester materials, and the axial filaments  130  can be made of ultra high molecular weight polyethylene that has high tenacity and low elongation. This type of combination results in a flattened suture  100  which is flexible, smooth, easy to tie in knots, and yet maintains its axial strength, length, and its shape by the reinforcing action of low elongation/high tenacity axial filaments  130 . In this regard, the axial filaments  130  prevent the suture  100  from elongating and shrinking in width and thickness upon applying a tension along the axis A.  
      Any of the first, second and axial filaments,  110 ,  120 ,  130  and or the suture  100  itself can be coated with natural or artificial coatings to improve lubricity. Any of the filaments can also be provided with color for coding the suture  100  or for improving its visibility during the procedure. For example, a single filament can be a colored fiber that will impart color to the suture  100  when the other fibers are translucent or will provide contrasting color when the other fibers are of other opaque color or colors. Alternatively, the entire suture  100  can be dyed in a single color.  
      The suture  100  can be used in combination with a suture device including suture anchors, surgical needles, suture passers, suture retrievers, suture management systems, and/or any devices that can pass, pull or push suture through tissue. The suture  100  can be used, for example, with the exemplary suture anchor  140  shown in  FIG. 4 , in which the suture  100  is threaded through an eyelet  142  of the anchor  140 . The suture  100  can also be used with any type of other similar fixation devices, including screws, pins, nails, etc., and also with a surgical needle  150  having an eyelet  152 , as shown in  FIG. 5A , or with a surgical needle  150  having a bore  154  into which the suture  100  is inserted and then retained by swaging or crimping the lateral surface  156  of the bore  154 , as shown in  FIG. 5B . To accommodate the flatness of the suture  100 , as defined by the ratio of width w over thickness t, the eyelet  142  of the anchor  140  and the eyelet  152  of the needle may be modified to take a flatter, elongated shape. The flatter shape of the suture  100  reduces the wear and tear of the suture  100  by having a larger contact surface with the eyelets  142 ,  152 , thereby distributing the load over a larger surface area. Similarly, when the suture is used tie ligaments and/or other soft tissue to bone, the load is distributed over a larger area of soft tissue reducing impinging, tearing or cutting of the soft tissue. The cut ends of the suture  100  can be coated with a protective coating, such as an adhesive, to prevent fraying.  
      Referring to  FIGS. 6 and 7 , the flatness of the suture  100  contributes to its ability to tie knots  160  that do not back out. This is because when the knot  160  is tightened, the width of the suture  100 , which is equal to w before the knot  160  is tightened in  FIG. 6 , is reduced to w′, which is less than w, in the area of the knot  160 . The wider width w outside the knot  160  prevents suture back-out and unknotting, as shown in  FIG. 7 . The width w′ is reduced due to compressive forces in the area of the knot  160  as the suture  100  is compressed relative to the empty bore  102 .  
      In operation, the suture  100  is threaded through the eyelet  142  of the suture anchor  140 , such that the suture  100 , facilitated by its hollow, ribbon-like shape, lays flat against the sides of the eyelet  142  for more even load distribution. The anchor  140  loaded with the suture  100  is implanted in a prepared surgical site or bone portion. The eyelet  142  can be elongated for better load distribution, although other eyelet shapes, such as circular or rounded can be used. In practice, the suture anchor  140  with the suture  100  loaded thereon may be implanted using an inserter, of the type known in the art (not shown). The suture  100  can also be threaded through the eyelet  152  or swaged or crimped into the bore  154  or preloaded to the surgical needle  150 , to pass the suture  100  through soft tissue or to help knot the suture  100  after the suture anchor  140  is implanted. The eyelet  152  of the surgical needle  150  can also be elongated for better load distribution. After the inserter is removed, the free ends of the suture  100  can be tied to provide knots  160  that will not easily back out, because the flattened shape of the hollow suture  100  provides localized crimping or width reduction upon knotting, as shown in  FIG. 7 . The flattened shape of the suture  100  also distributes the load as the flattened hollow suture  100  passes through soft tissue to reduce or prevent tearing of the soft tissue.  
      The suture  100  can be used in various orthopaedic procedures, including microplasty procedures that involve small incisions and minimally invasive surgery. Examples include, ACUPCL reconstruction, hip and shoulder replacement, tendon repair, etc.  
      The description of the invention is merely exemplary in nature and, thus, 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.