Patent Publication Number: US-2002011508-A1

Title: Fused constructs of filamentous material for surgical applications

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
     [0001] This application is a continuation-in-part of co-pending U.S. application Ser. No. 09/118,395, filed on Jul. 17, 1998, which is a division of U.S. application Ser. No. 08/919,297, filed on Aug. 28, 1997 (now U.S. Pat. No. 5,893,880), both of which are assigned to the assignee of the present invention and incorporated herein by reference. The present application also claims priority from provisional U.S. application Ser. No. 60/221,407, filed on Jul. 28, 2000, which is also assigned to the assignee of the present invention and incorporated herein by reference. 
    
    
     
       FIELD OF THE INVENTION  
       [0002] The invention relates to improvements in sutures and suturing techniques, and more particularly to materials and devices for making high-strength fused suture loops during surgical procedures.  
       BACKGROUND OF THE INVENTION  
       [0003] In surgical procedures, a monofilamentous suture is typically used to stitch or secure the edges of tissue together to maintain them in proximity until healing is substantially completed. The suture is generally directed through the portions of the tissue to be joined and formed into a single loop or stitch, which is then knotted or otherwise secured in order to maintain the wound edges in the appropriate relationship to each other for healing to occur. In this manner a series of stitches of substantially uniform tension can be made in tissue. Because the stitches are individual and separate, the removal of one stitch does not require removal of them all or cause the remaining stitches to loosen. However, each individual stitch requires an individual knot or some other stitch-closing device for securing the stitch around the wound.  
       [0004] It is sometimes necessary or desirable to close a wound site with sutures without having to form knots or incorporate loop-closing devices in the sutures, such as, for example, in surgical repair of delicate organs or tissues, where the repair site is relatively small or restricted. A fused suture loop must provide the appropriate tension on the wound edges and the appropriate strength to maintain the wound edges in sufficient proximity for a sufficient time to allow healing to occur.  
       [0005] Polymer sutures are particularly amenable to various fusing or joining processes, such as, for example, welding, whereby sections of the sutures can be fused together upon application of sufficient heat to the sections to cause partial melting and fusion of the sections. Because the direct application of heat to sutures in-situ may produce undesirable heating of the surrounding tissue, it is preferred to apply non-thermal energy to the suture material in-situ to induce localized heating of the suture material in the areas or sections to be fused. In particular, ultrasonic energy may be effectively applied to sections of suture materials to induce frictional heating of the sections in order to fuse or weld them together.  
       [0006] While sutures typically fail under tensile loads applied along the principal axis of the suture, suture welds often fail in shear, i.e., in the plane of the fused region between the overlapped segments of suture material. It is desirable to have the failure strength of the suture joint be at least as great as the failure strength of the suture material away from the joint.  
       [0007] U.S. Pat. No. 5,417,700 to Egan and U.S. Pat. No. 3,515,848 to Winston et al. disclose apparatus and methods for ultrasonic welding of sutures. The Winston et al. patent discloses, for example, the application of mechanical energy to a segment of material to be joined in either of two different directions. For joining plastic suture materials, mechanical energy is applied in a direction substantially parallel to the axis of the segments to be joined. For joining metallic suture materials, mechanical energy is applied in a direction substantially normal to this axis. The Winston et al. patent further discloses the use of a spherical welding tip for use in joining metallic suture materials.  
       [0008] Although ultrasonic welding of sutures is known, it has heretofore been difficult or impossible to control the suture welding process in order to produce suture welds of sufficient strength and reliability to replace, or enhance the strength of, suture knots or other loop closure devices.  
       [0009] It is therefore an object of the present invention to overcome the disadvantages inherent in prior art suture loop joints and joining processes.  
       [0010] The present invention also seeks to extend the benefits of suture welding to new and unique stitch forms and stitch deployment constructs that can only be realized by welding of filamentous suture materials. These constructs are analogous to stitch forms and deployment constructs used in conventional surgery and represent significant improvements over the traditional form.  
       [0011] The present invention also seeks to provide an improved form of the running stitch using weld(s) in place of knots, and to join intermediate running stitch loops in-situ and form a running or continuous stitch from individual suture segments.  
       SUMMARY OF THE INVENTION  
       [0012] The present invention, accordingly, provides a fused construct of an elongated material, such as a polymeric or monofilamentous suture material, which has a strength in joint regions which is at least equal to, if not greater than, the strength of the parent material.  
       [0013] The fused construct includes a first end formed into a fused loop, a second end formed into a fused loop, and an intermediate part extending between the loops, wherein the loops and the intermediate part include at least one segment of elongated material. Each of the loops includes a joint region having overlapped portions of the elongated material, and layer of fused material from the overlapped portions.  
       [0014] The term “fused”, as used herein, refers to material which has been heated to a plastic or fluid state and subsequently allowed to cool, so that the relatively highly-oriented molecular structure of the parent material is transformed into a relatively randomly-oriented molecular structure characterizing the fused portion of the joint region.  
       [0015] The elongated material may comprise a substantially monofilamentous material, such as, for example, a polymer. In a preferred embodiment, the elongated material is a thermoplastic polymer, such as a surgical suture material.  
       [0016] The segments of elongated material are preferably joined in a weld at the joint region. The weld can be effected with various types of energy, such as, for example, ultrasonic, laser, electrical arc discharge, and thermal energy.  
       [0017] The loops of elongated material can be made by joining portions of a single segment of the elongated material. Alternatively, the loops can be made by joining portions of multiple segments of the material.  
       [0018] The elongated material itself can comprise a single strand of a substantially monofilamentous material. Alternatively, the elongated material can comprise multiple strands of a substantially monofilamentous material which can be twisted, braided or otherwise interlinked.  
       [0019] These and other features of the invention will be more fully appreciated with reference to the following detailed description which is to be read in conjunction with the attached drawings.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0020] The invention is further described by the following description and figures, in which:  
     [0021]FIG. 1 is a perspective view of a fused loop of an elongated material;  
     [0022]FIG. 2A is an axial view of the fused loop of FIG. 1;  
     [0023]FIG. 2B is an axial view of several fused loops formed by joining multiple segments of material together;  
     [0024]FIG. 2C is a simplified perspective view of a multiple-stranded segment of elongated material;  
     [0025]FIG. 3 is a cross-sectional view of the joint region of the fused loop of FIG. 2A, taken along section lines A-A;  
     [0026]FIG. 4 is a cross-sectional view of the joint region of the fused loop of FIG. 2A, taken along section lines B-B;  
     [0027]FIG. 5 is a cross-sectional view of an end of the joint region of the fused loop of FIG. 2A, taken along section lines C-C;  
     [0028]FIG. 6 is a cross-sectional view of a segment of elongated material in the fused loop of FIG. 2A, taken along section lines D-D;  
     [0029]FIG. 7A is a side elevational view of a joint region of a fused loop made by ultrasonic welding;  
     [0030]FIG. 7B is a series of sectional views of a portion of the joint region of the loop shown in FIG. 7A;  
     [0031]FIG. 8A is a side elevational view of a joint region of a different type of fused loop made by laser welding or controlled coupling ultrasonic welding;  
     [0032]FIG. 8B is a series of sectional views of a portion of the joint region of the loop shown in FIG. 8A;  
     [0033]FIG. 9A is an axial view of a fused loop loaded in tension, in which the strength of the joint region exceeds the tensile failure strength of the elongated material;  
     [0034]FIG. 9B is an axial view of a fused loop loaded in tension, in which the strength of the joint region is less than the tensile failure strength of the elongated material;  
     [0035]FIGS. 10A, 11A,  12 A,  13 A and  14 A are exploded perspective views of ultrasonic welding members of various geometries, and segments of material to be welded in the gaps between their respective surfaces;  
     [0036]FIGS. 10B, 11B,  12 B,  13 B and  14 B are exploded side elevational views corresponding to the views of FIGS. 10A, 11A,  12 A,  13 A and  14 A;  
     [0037]FIGS. 15A, 16 and  17 A are side elevational views of ultrasonic welding members of various geometries engaged about a pair of segments of material to be welded;  
     [0038]FIG. 15B is a simplified side elevational view of the second welding member of FIG. 15A, uncoupled to show means for releasing the welded loop from the welding apparatus;  
     [0039]FIG. 17B is a side elevational view of the second welding member of FIG. 17A, uncoupled to show means for releasing the welded loop from the welding apparatus;  
     [0040]FIG. 18 is an exploded perspective view of a segment of an elongated material with its ends aligned within an ultrasonic welding apparatus designed to produce a contoured lap weld;  
     [0041]FIG. 19A is an axial view of the segments of material within the ultrasonic welding apparatus of FIG. 18, prior to welding; and  
     [0042]FIG. 19B is an axial view of the segments of material within the ultrasonic welding apparatus of FIG. 18, immediately after the welding process and prior to release of the loop;  
     [0043]FIG. 20 is a perspective view of a running stitch of filamentous material closing a living tissue wound, wherein both ends of the running stitch are terminated in a welded loop;  
     [0044]FIG. 21 is a perspective view of a running stitch of filamentous material closing a living tissue wound, wherein both ends are terminated in a welded loop and intermediate turns of the running stitch are fused;  
     [0045]FIG. 22 is a sectional view of a straight stitch of filamentous material joining two layers of living tissue, wherein both ends of the straight stitch are terminated in a welded loop and the straight stitch includes intermediate lengths of filamentous material joined with fused ends;  
     [0046]FIG. 23 is a perspective view of a length of filamentous material attached to first and second tissue portions such that the filamentous material is under tension, and wherein both ends of the filamentous material are terminated in a welded loop;  
     [0047]FIG. 24 is a perspective view of a length of filamentous material attached to first and second tissue portions such that the filamentous material is under tension, and wherein both ends of the filamentous material are terminated in a welded loop and fused end-to-end;  
     [0048]FIG. 25 is a perspective view of a sliding loop of filamentous material positioned on a living vessel, wherein one end of the filamentous material is terminated in a welded loop and the other end is slid through the loop;  
     [0049]FIG. 26 is a perspective view of a fixed loop of filamentous material positioned on a living vessel, wherein both ends of the filamentous material are terminated in welded loops that are interlock;  
     [0050]FIG. 27 is a side elevation view of a surgical needle with a first length of filamentous material attached to the needle by swaging and a second length of filamentous material attached to the first length by welding;  
     [0051]FIG. 28 is a side elevation view of a surgical needle with a first length of filamentous material attached to the needle by swaging and second and third lengths of filamentous material attached to the first length by welding;  
     [0052]FIG. 29 is a side elevation view of a surgical needle with a first end of a length of filamentous material is attached to the needle by swaging and a second end of the length is attached to the length near the first end by welding to form a loop;  
     [0053]FIG. 30 is a side elevation view of a plurality of surgical needles and a plurality of lengths of filamentous material, wherein first ends of each length are attached to the needle by swaging and second ends are attached to the adjacent length of filamentous material near the first ends by welding;  
     [0054]FIG. 31 is a sectional view of a mattress stitch formed between two layers of living tissue using the arrangement of needles and filamentous material of FIG. 30;  
     [0055]FIG. 32 is a sectional view of another mattress stitch formed using the arrangement of needles and filamentous material of FIG. 30; and  
     [0056]FIG. 33 is a top plan view of a construct employing multiple embodiments of the present invention in combination.  
     [0057] Like elements in the respective FIGURES have the same reference numbers. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0058] The present invention provides a fused loop of an elongated material, such as a surgical suture. The loop has at least comparable strength to knotted loops or loops closed by other means by virtue of the properties of the fused portion of the joint region of the loop, as detailed more fully below.  
     [0059] As shown in FIG. 1, the fused loop  10  of the present invention comprises one or more segments  12  of an elongated material, such as a surgical suture material or other substantially monofilamentous material, which is amenable to bonding through the application of heat or energy thereto. Suitable materials for the elongated material include polymers, especially thermoplastic materials such as, for example, nylon (polyamide), polypropylene, Dacron® (polyester), polyglycolic acid (PGA), polyglyconate, and polydioxanone.  
     [0060] The fused loop of the present invention is preferably formed through a welding process, in which segments of the material to be joined are locally heated through the application of energy thereto until the segments fuse together. Various types of welded joints can be formed by the application of, for example, ultrasonic, thermal, laser, electrical arc discharge, or thermal energy to the segments, which can be joined, for example, in an overlapped joint.  
     [0061]FIG. 2A is an axial view of the fused loop shown in FIG. 1. The segment  12  of elongated material extends along a principal axis X of the material, which can be straight or curved. One or more segments  12  of the material are typically formed into a loop by, for example, overlapping portions of the respective ends  12 A,  12 B of the segment, as shown in FIGS. 1 and 2A, to form a joint region  14 . Alternatively, as shown in FIG. 2B, both terminal and nonterminal portions of the segments of the material can be overlapped to form several fused loops joined in a single joint region  14 .  
     [0062] The segments may already be knotted in preparation for fusion by welding, or they may simply be overlapped.  
     [0063] The elongated material can be made of a single strand of a substantially monofilamentous material, or it can comprise multiple strands, as indicated in FIG. 2C. The multi-stranded material can be twisted, braided or otherwise interlinked to increase the density, and thus the strength, of the composite strand.  
     [0064] The joint region  14  extends between first and second ends  14 A,  14 B and includes a first portion  16  of elongated material extending from the first end  14 A, and a second portion  18  extending from the second end  14 B. The joint region  14  further includes a fused portion  20  which has a substantially uniform thickness and which is disposed between the first portion  16  and second portion  18  of the joint region. The fused portion  20  is made of material from the first and second portions  16 ,  18  which has been fused together. In a preferred embodiment, all of the fused material is disposed within a fused layer or portion  20 . However, some of the melted and fused material may form outside of the fused portion  20  as a result of forces applied to the segments  16 ,  18  to compress them together during the welding process.  
     [0065] As mentioned previously, the elongated material of the type used in surgical sutures is substantially monofilamentous, and preferably polymeric. Because the molecular structure of monofilamentous materials is highly oriented along the principal axis of the material, the material exhibits relatively high strength in the direction of its principal axis. The elongated material in the loop segment outside the joint region  14 , as well as in the first and second portions  16 ,  18  of the joint region, is characterized by a relatively high degree of molecular orientation in the direction of the principal axis X of the material. As a consequence of this highly oriented molecular structure, the strength of the elongated material outside the joint region, and in the first and second portions  16 ,  18  of the joint region, is also relatively great in the direction of the principal axis X. On the other hand, the material which makes up the fused portion  20  of the joint region  14  is characterized by a relatively random molecular orientation, by virtue of its having been heated locally to a plastic state by the application of energy, such as ultrasonic energy, to the segment portions  16 ,  18  which make up the joint region  14 . As a consequence of this relatively nonoriented molecular structure, the strength of the material in the fused portion  20  of the joint region is relatively low in the direction of the principal axis.  
     [0066] The shear area of the fused portion  20  is approximately defined as the product of the length L and the width W of the fused portion  20 , as shown in FIG. 4. As will be detailed more fully below, for maximum joint strength, it is desirable to have a relatively large shear area of the fused portion  20  of the joint region.  
     [0067]FIG. 6 indicates the cross-sectional area of a typical segment of elongated material outside the joint region. Although the elongated material can be a strand or filament having a substantially circular cross-section, the invention is not limited to such geometries and can include elongated materials having eccentric or other cross-sectional geometries, such as, for example, relatively flat ribbons having elliptical or rectangular cross-sections, or others. FIG. 5 indicates the cross-sectional area of the elongated material at the ends of the joint region, outside of the fused portion  20 . As can be seen in FIG. 3, 7 and  8 , the total cross-sectional area of the portions  16 ,  18  abutting the fused portion  20  of the joint region  14  is somewhat less than the total cross-sectional area of the first and second portions  16 ,  18  in the joint region but outside of, and not abutting, the fused portion  20 . As is clearly shown in FIGS. 2A and 3, some of the elongated material in portions  16  and  18  of the joint region is transformed during the welding process from an elongated, relatively highly oriented material, to a fused, relatively randomly-oriented material in the fused portion  20 . Compression of the portions  16 ,  18  during the welding process ensures that the fused portion  20  has a relatively large shear area and a relatively small thickness.  
     [0068] The change in cross-sectional area of the overlapping segments  16 ,  18  in the joint region is preferably uniform and gradual over the length of the fused portion  20 . FIGS. 7A, 7B,  8 A and  8 B illustrate the change in cross-sectional area of the overlapping segments of elongated material in the joint region  14  throughout the length of the fused portion  20  for different types of welded joints. At the ends  14 A,  14 B of the joint region, outside of or beyond the fused portion  20 , the cross-sectional area of the segment portions  16 ,  18  is a maximum value, as the segment portions have not been caused to deform plastically at these points. As the cross-hatched areas  21   a - 21   e  in the joint region  14  indicate in FIG. 7B, the cross-sectional area of each of the overlapped segment portions  16 ,  18  decreases gradually from a maximum value at the ends of the fused portion  20  to a minimum value at or near the midpoint of the fused portion. Preferably, at the midpoint of the fused portion  20 , the total cross-sectional area of the segments  16 ,  18  not sacrificed to form the fused portion is approximately half the total cross-sectional area of the segments  16 ,  18  at the first and second ends  14 A,  14 B of the joint region and beyond, or outside of, the fused portion  20 .  
     [0069] The lap welded joint shown in FIG. 8A is characterized by a continuously varying cross-sectional area of the segments  16  and  18  in the region of the fused portion  20 . As indicated in FIG. 8B, the cross-sectional area  21   a - 21   e  of one segment  16  continuously decreases from a maximum value at end  14 B to a minimum value at the opposite end  14 A, whereas the cross-sectional area of the other segment  18  continuously increases from a minimum value at end  14 B to a maximum value at the opposite end  14 A. At approximately the midpoint of the fused portion  20 , the cross-sectional areas of the segment portions  16 ,  18  are approximately equal and are preferably equal to about half the total cross-sectional areas of the segment portions  16 ,  18  at the first and second ends  14 A,  14 B of the joint region and outside the fused portion  20 .  
     [0070] Other geometries of the first and second portions  16 ,  18  in the joint region  14  which provide a uniform change in cross-sectional area of the joined segments in the joint region are also considered to be within the scope of the invention.  
     [0071] In a preferred embodiment of the invention, the shear area of the fused portion  20  of the joint region is sufficiently large to ensure that the joint will not fail prematurely, i.e., before the parent elongated material fails. The joint preferably has a failure strength of approximately the strength of the parent material. Most preferably, the joint has a failure strength in shear which is approximately equal to the failure strength in tension of the parent material.  
     [0072] Upon application of a tensile force to the joint region  14  in the direction of the principal axis X of the material, the first and second portions  16 ,  18  of the joint region are loaded substantially in tension and the fused portion  20  of the joint region is loaded substantially in shear. In this situation, the following equation,  
     A wfw =A ufu    
     [0073] is substantially satisfied, wherein A w  is the shear area of the fused portion  20  (i.e., the area of the layer of the fused portion which is between the first and second portions  16 ,  18 , not the cross-sectional area of this layer),  fw  is the shear stress to failure of the fused portion, A u  is the total cross-sectional area of the first and second portions  16 ,  18  near the first and second ends of the joint region  14 , outside of and not abutting the fused portion, and  fu  is the tensile stress to failure of the first and second portions near the first and second ends, outside of and not abutting the fused portion.  
     [0074] If the above equation is not satisfied, the strength of the fused portion  20  may be either stronger or weaker than the strength of the parent elongated material. It is of course preferred that the fused portion  20  be at least as strong as the unfused parent material. If it is stronger, when the joint is loaded in tension, as indicated by force arrows F in FIGS. 9A and 9B, the material will fail in tensile mode, and the loop will break at a point which is outside the fused portion, and possibly outside the joint region, as indicated in FIG. 9A. If the fused portion  20  is weaker than the parent material, the fused material within the joint will fail in shear mode, and the loop will separate at the fused portion, as indicated in FIG. 9B.  
     [0075] FIGS.  10 A- 14 B illustrate various geometries for ultrasonic welding apparatus, and more particularly for the vibratory and stationary members of an ultrasonic welding tip, which includes a first member  30  and a second member  32 . The first member  30  is capable of vibrating and delivering mechanical energy at ultrasonic frequencies, as is known in the art. The first member  30  is movable relative to the second member  32 , so that a gap or space can be defined between the first and second members. The gap is sufficiently large to accommodate two or more segments  16 ,  18  of material to be joined together. The ultrasonic welding apparatus further includes fixture means for aligning and maintaining the segments  16 ,  18  in a predetermined alignment and orientation during the welding process.  
     [0076] The first and second members  30 ,  32  each have respective surfaces  30 A,  32 A which are contoured to promote acoustic coupling between the first member  30  and the segment  16  of material to be joined, and to provide substantially continuous contact between at least the first surface  30 A and at least one of the segments to be welded. The size of the shear area of the fused portion  20 , and thus the strength of the joint region, is determined by the length and width of the surfaces  30 A,  32 A, the extent of contact between these surfaces and the segments  16 ,  18 , and particularly between the first surface  30 A and the segment  16  closest to the first surface, and the pressure exerted on the segments by the first member  30  in the direction of arrow  35  during welding.  
     [0077] In addition to the geometries of the surfaces of the first and second members, the geometry of the material to be joined must be considered. Fused portions having the largest shear areas and the greatest joint strengths can be obtained by configuring the surface  30 A of the first member  30  to have a contour which corresponds to the contour of the material to be joined so as to ensure maximum contact with the segment portion  16 . For example, if the material is a filament having a substantially circular cross-section, the surface  30 A should have a rounded contour to match the contour of the filament in contact with it. If the material is a substantially flat ribbon, the surface  30 A should be substantially flat to ensure maximum contact with the segment. If the material has a polygonal or elliptical cross-section, the contour of the surface  30 A should be grooved or channeled or otherwise shaped to correspond as closely as possible to the geometry of the cross-section of the material.  
     [0078] It is generally preferred to configure the ultrasonic welding tip members  30 ,  32  so that their respective surfaces  30 A,  32 A engage the segment portions  16 ,  18  so as to provide a maximum shear area for the fused portion  20 . Various geometries for the surfaces  30 A,  32 A are illustrated in FIGS.  10 A- 14 B.  
     [0079] As shown in FIGS. 10A and 10B, the surface  30 A of the first member  30  is concave about the z and x axes, whereas the surface  32 A of the second member  32  is convex about the z axis. The illustrated segments  16 ,  18  have a circular cross-section but need not be limited to a particular geometry. Contact between the first surface  30 A and the top segment  16  is substantially continuous over the entire length and width of the surface  30 A as a result of the contour of that surface. The shear area of the resulting fused portion  20  is relatively large, and thus the strength of the fused portion can be expected to be relatively high.  
     [0080] An advantage of incorporating a convex curvature to the second surface  32 A is that the length of the joint region  14  in the direction of the principal axis of the material can be reduced, thereby decreasing the diameter of the resulting fused loop of suture material.  
     [0081] The surfaces  30 A,  32 A of the embodiment illustrated in FIGS. 14A and 14B have the same relationship to each other as in the embodiment of FIGS. 10A and 10B. The resulting fused portion  20  is relatively large, with relatively high strength.  
     [0082] As shown in FIGS. 15A, 16 and  17 A, the first surface  30 A of the first member  30  can have a channeled or grooved geometry to increase the extent of contact between the first surface  30 A and the segment  16 . As also indicated in FIGS. 15B, 16 and  17 B, the second member  32  may be comprised of multiple parts which act to confine and maintain the alignment of the segments  16 ,  18  during the welding process. The coupling portions of the second member separate after the welding process to release the joined material from the confines of the welding apparatus without requiring the loop to be moved or otherwise manipulated. FIGS. 15A, 15B and  16 A illustrate one type of ultrasonic welding apparatus, in which the second member  32  couples together beneath the segments of material joined at the joint region. The coupled members remain engaged during the welding process, as shown in FIGS. 15A and 16A, and separate after the welding process by a hinging or pivoting action to release the loop, as shown in FIG. 15B.  
     [0083]FIGS. 17A and 17B illustrate another type of apparatus, in which the multiple parts of the second member  32  slide away from each other to release the joined loop. Other configurations for the second member  32  which permit the loop to be released after the welding operation is completed are considered to be within the scope of the invention.  
     [0084]FIGS. 18, 19A and  19 B illustrate still another configuration for the welding apparatus, in which the segment portions  16 ,  18  to be welded are confined and aligned or oriented relative to each other within the walls of the second member  32 . This apparatus produces welded joints having a fused portion  20  in a vertical orientation instead of a horizontal orientation. In this apparatus, the first member  30  is complementary with and fits inside two sections of the second member  32 , which extend vertically on either side of the first member. The surfaces  30 A,  32 A of the first and second members are substantially flat, although they can be cambered and contoured otherwise, as previously discussed. As shown in FIG. 19A, the overlapping portions  16 ,  18  of segment  12  of material to be joined together are oriented in a vertically diagonal alignment within the multiple parts of the second member  32 . During the welding process ultrasonic energy is delivered from a power supply and converted to mechanical energy to establish local frictional heating between the segment portions  16 ,  18 . Pressure is exerted on the segment portions  16 ,  18  in the direction of arrow  35  as the segments are heated to a plastic state, causing portions of the segments to flow and to fuse in a vertically oriented fused portion  20 . Because the first and second members  30 ,  32  are configured to confine and maintain the alignment of the overlapping segments during the welding process, the joint region  14  and fused portion  20  are relatively dense and compact, with little, if any, fused material disposed in regions outside of the fused portion  20 . It is desirable to minimize the extrusion of fused material beyond the fused portion  20  so as to maximize the strength of the loop joint region and to avoid irritation of the surrounding tissue. As in the above embodiments, the coupling portions of the second member  32  can be separated after the welding process to release the joined loop.  
     [0085] The present invention also seeks to extend the benefits of suture welding to new and unique stitch forms and stitch deployment constructs that can be realized by welding of filamentous suture materials as described hereinbefore. These fused constructs represent significant improvements over the traditional knotted and tied stitch forms and stitch deployment constructs.  
     [0086]FIG. 20 shows a new and improved construct  50  of filamentous material according to the present invention. The construct, or running stitch  50 , is shown closing a wound  40  in living tissue  42 , and includes first and second ends  52 ,  54  formed into fused loops  60  and an intermediate part  62  extending between the loops  60 . In the embodiment shown, the construct  50  is formed from a single segment of the filamentous material, which preferably comprises at least one strand of a substantially monofilamentous thermoplastic material. The intermediate part  62  is formed in a running spiral of stitch turns passing through the tissue  42  to close and hold together the wound  40 , and the intermediate part  62  is anchored by the loops  60 .  
     [0087] The fused loops  60  are similar to the fused loop  10  of FIG. 1, and each includes a joint region  64  similar to the joint region  14  of FIG. 1 (i.e., having overlapped portions of the elongated material and a layer fused material from the overlapped portions). The construct  50  of FIG. 20 includes “O” loops  60 , and is used when significant forces transverse to the wound  40  are present. Alternatively, “tear-drop” shaped loops (not shown) can be used to anchor the ends of the construct  50  when significant forces are present along the axis of the wound  40 .  
     [0088]FIG. 21 shows another fused construct  70  of filamentous material according to the present invention. The construct  70  is similar to the construct  50  of FIG. 20, but includes an intermediate part  72  having joint regions  74  securing together adjacent pairs  76  of stitch turns. The joint regions  74  are created in-situ between the adjacent stitch turns  76  after formation of the end loops  60 , and are also preferably formed similar to the joint region  14  of FIG. 1.  
     [0089]FIG. 22 shows a new and improved “over-under” straight stitch construct  80  according to the present invention. The stitch  80  is shown holding first and second layers  44 ,  46  of living tissue  42  together. The construct  80  is similar to the construct  50  of FIG. 20, but includes an intermediate part  82  having multiple segments  82   a ,  82   b ,  82   c ,  82   d  of the filamentous material and wherein the segments are joined with fused ends to form a continuous piece. The fused ends of the segments include joint regions  84  preferably formed similar to the joint region  14  of FIG. 1.  
     [0090]FIG. 23 shows another fused construct  90  according to the present invention. The construct  90  includes a single length of filamentous material secured between first and second tissue portions  92 ,  94  such that the filamentous material is under tension, and wherein both ends  52 ,  54  of the filamentous material are terminated in separate fused loops  60  passing through the tissue. As shown, the welded loops  60  are “tear-drop” shaped, and an intermediate part  62  extends in a straight line between the loops  60 . This configuration results in the stresses on the joint regions being substantially in shear, as indicated by arrows “F” showing force direction. FIG. 24 shows an additional fused construct  100  according to the present invention. The construct  100  is similar to the construct  90  of FIG. 23 but includes loops  60  sharing a single joint region  64 .  
     [0091]FIGS. 25 and 26 show another construct  110  of a single length of filamentous material in accordance with the present invention. The construct  110  includes a “tear-drop” loop  60  deployed as a sliding loop or ligature by passing the free end  54  of the length of filamentous material around a vessel or object  112 , and through the eye of the loop  60 . Tension is then applied to the free end  54  in a direction opposite the loop  60 , as shown by arrow “T”, to tighten the construct  110  around the vessel  112 . The length of filamentous material is then secured in place around the vessel  112  or object by forming the free end  56  into a second “tear-drop” loop  60  with a weld so that the two loops  60  of the construct  110  are inter-linked.  
     [0092]FIGS. 27 through 30 show fused needle assemblies  120 ,  122 ,  124 ,  126  for use in creating fused constructs according to the present invention. Each assembly includes a surgical needle  128  and at least one length  130  of filamentous material having an end  132  secured to the needle  128 , such as by swaging the needle onto the end  132  of the filamentous material. Another end  134  of filamentous material is attached to the filamentous material  130  with a joint region  136  near the needle  128 . In the embodiment of FIG. 27, the assembly  120  includes two segments  130 ,  138  of filamentous material. FIG. 28 shows another embodiment  122  having three attached segments  130 ,  138 ,  140 . FIG. 29 shows a further embodiment  124  including a single segment  130  of filamentous material forming a loop  142 . The assembly  126  of FIG. 30 includes multiple needle  128  and segment  130  assemblies connected successively end-to-end. In one possible embodiment, the assembly  126  can be provided as linear and the first and last needles  128  in the chain have only one suture  130  attached to the needle, as shown. In another embodiment (not shown) the last suture segment can be provided joined to the first suture segment to complete a circular construct, which is particularly useful for installing a series of mattress or continuous sutures around an annulus, such as a valve assembly.  
     [0093]FIG. 31 illustrates the creation of a fused construct  140  using the fused needle assembly  126  of FIG. 30. Once deployed at a regular interval, the needles  128  and joined portion of the suture segments  130  are trimmed and the resulting ends are welded in pairs to yield a series of fused “O” loops  142 , in this case deployed as a series of mattress stitches. FIG. 32 shows a similar fused construct  150  with segment ends welded in a different order to yield a different embodiment of the invention comprised of an overlapping over-under stitch made up of individual segments welded together to form a continuous filament.  
     [0094]FIG. 33 shows a construct  250  incorporating several aspects of the present invention in combination. A mesh  252  comprised of multiple (two) strands  254 ,  256  of filamentous material joined by a welded region  258  and having intermediate welds  260  at adjoining portions and secured by welded “tear-drop” loops  262  in tension “T”. The mesh  252  is secured on its right side by a running stitch  264  secured at each end by welded loops  266  comprised of individual segments  267  of elongated material joined by welds  268 . The mesh  252  is secured on its left side by a series stitch  270  deployed by a chain of needled sutures joined by a weld  272  tail-end to needle-end. The needles and joined regions have been trimmed and the resulting ends joined by welds  274  such that the resulting stitch  252  is a continuous filament made up of individual segments joined by welds.  
     [0095] The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of the equivalency of the claims are therefore intended to be embraced therein.