US 9,237,889 B2Grant
Suture
Issue Date:2016-01-19
•25 Claims
•18 Drawing Sheets
Abstract
A medical device includes a surgical needle attached to a hollow tubular suture. The suture is constructed of macroporous hollow tubular wall that facilitates and allows tissue integration into the suture core subsequent to introduction to the body, thereby preventing suture pull-through and improving biocompatibility.
Metadata
Assignee
- NORTHWESTERN UNIVERSITY
Inventors
- Gregory Dumanian
- Anandev Gurjala
Application Information
Application Number:US 13/713,665
Filing Date:2012-12-13
Priority Date:2012-02-23
Art Unit:3734
Classifications
IPC:
A61B17/06A61L17/00A61B17/00A61B17/04
Field of Search:
A61B 17/06A61B 17/06166A61B 2017/0417A61B 2017/06185A61B 2017/06152A61B 2017/06157A61B 17/0057A61B 17/04A61B 17/0401A61B 17/0469A61B 17/06114A61B 2017/00579A61B 2017/00592A61B 2017/00646A61B 2017/00663A61B 2017/00831A61B 2017/00862A61B 2017/00884A61B 2017/0464A61B 2017/06052A61B 2017/06176A61B 2017/0618A61L 17/00A61L 17/005A61L 17/04A61L 17/06A61L 17/08A61L 17/10A61L 17/105A61L 17/12A61L 17/14A61L 17/145D01D 5/24D01D 5/247D01D 5/36A61F 2/08A61F 2/0805A61F 2/0811A61F 2002/0882A61F 2002/0835A61F 2210/0004A61K 8/0208
Patent Drawings (18 sheets)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The priority benefit of U.S. Provisional Patent Application No. 61/602,183, filed Feb. 23, 2012, is hereby claimed and the entire contents thereof are incorporated herein by reference.
FIELD OF THE DISCLOSURE
[0002] The present disclosure provides sutures with increased surface area and/or tissue integrative properties and methods of use and manufacture thereof. In particular, provided herein are sutures with cross-section profiles and other structural characteristics that strengthen closure, prevent suture pull-through, and/or resist infection, and methods of use thereof.
BACKGROUND
[0003] One of the foundations of surgery is the use of suture to re-appose tissue, i.e., to hold tissue in a desired configuration until it can heal. In principle, suturing constitutes introducing a high tensile foreign construct (looped suture) into separate pieces of tissue in order to hold those pieces in close proximity until scar formation can occur, establishing continuity and strength between tissues. Sutures initially provide the full strength of the repair, but then become secondarily reinforcing or redundant as the tissue heals. The time until tissue healing reaches its maximal strength and is dependent on suture for approximation, therefore, is a period of marked susceptibility to failure of the repair due to forces naturally acting to pull the tissues apart.
[0004] Conventional sutures provide a circular or single-point cross-sectional profile extended over the length of the suture material. Such a suture has the great benefit of radial symmetry, which eliminates directional orientation, allowing the user (e.g., physician, surgeon, medic, etc.) to not have to worry about orienting the suture during use. However, a considerable disadvantage of the currently used single-point cross-section is that it does not effectively distribute force, and actively concentrates force at a geometric point (e.g., the point at the leading edge of the circle) creating a sharp edge in the axial dimension. Under these conditions, the tissue is continuously exposed to tension, increasing the likelihood that stress concentration at a geometric point or sharp edge will cut through the tissue.
[0005] Indeed, studies of surgical closures, a most prominent example being hernia repairs, demonstrate that the majority of failures or dehiscences occur in the early post-operative period, in the days, weeks, or months immediately following the operation, before full healing can occur. Sutures used to close the abdominal wall have high failure rates as demonstrated by the outcome of hernia formation. After a standard first-time laparotomy, the postoperative hernia occurrence rate is between 11-23%. The failure rate of sutures after hernia repair is as high as 54%. This is a sizeable and costly clinical problem, with approximately 90,000 post-operative hernia repairs performed annually in the United States. Surgical failures have been blamed on poor suture placement, suture composition, patient issues such as smoking and obesity, and defects in cellular and extracellular matrices. Clinical experience in examining the cause of these surgical failures reveals that it is not breakage of suture as is commonly thought; in the majority of cases the cause is tearing of the tissue around the suture, or from another perspective, intact stronger suture cutting through weaker tissue. Mechanical analysis of the suture construct holding tissue together shows that a fundamental problem with current suture design is stress concentration at the suture puncture points through the tissue. That is, as forces act to pull tissues apart, rather than stress being more evenly distributed throughout the repair, it is instead concentrated at each point where the suture pierces through the tissue. The results are twofold: (1) constant stress at suture puncture points causes sliding of tissue around suture and enlargement of the holes, leading to loosening of the repair and an impairment of wound healing, and (2) at every puncture point where the stress concentration exceeds the mechanical strength of the tissue, the suture slices through the tissue causing surgical dehiscence. In addition, high pressure on the tissue created during tightening of the surgical knot can lead to local tissue dysfunction, irritation, inflammation, infection, and in the worst case tissue necrosis. This tissue necrosis found within the suture loop is one additional factor of eventual surgical failure.
[0006] There has been no commercial solution to the aforementioned problems with conventional sutures. Rather, thinner sutures continue to be preferred because it is commonly thought that a smaller diameter may minimize tissue injury. However, the small cross-sectional diameter in fact increases the local forces applied to the tissue, thereby increasing suture pull-through and eventual surgical failure.
[0007] One alternative to the conventional suture is disclosed by Calvin H. Frazier in U.S. Pat. No. 4,034,763. The Frazier patent discloses a tubular suture manufactured from loosely woven or expanded plastic material that has sufficient microporosity to be penetrated with newly formed tissue after introduction into the body. The Frazier patent does not expressly describe what pore sizes fall within the definition of “microporosity” and moreover it is not very clear as to what tissue “penetration” means. The Frazier patent does, however, state that the suture promotes the formation of ligamentous tissue for initially supplementing and then ultimately replacing the suture's structure and function. Furthermore, the Frazier patent describes that the suture is formed from Dacron or polytetrafluoroethylene (i.e., Teflon®), which are both commonly used as vascular grafts. From this disclosure, a person having ordinary skill in the art would understand that the suture disclosed in the Frazier patent would have pore sizes similar to those found in vascular grafts constructed from Dacron or Teflon®. It is well understood that vascular grafts constructed of these materials serve to provide a generally fluid-tight conduit for accommodating blood flow. Moreover, it is well understood that such materials have a microporosity that enables textured fibrous scar tissue formation adjacent to the graft wall such that the graft itself becomes encapsulated in that scar tissue. Tissue does not grow through the graft wall, but rather, grows about the graft wall in a textured manner. Enabling tissue in-growth through the wall of a vascular graft would be counterintuitive because vascular grafts are designed to carry blood; thus, porosity large enough to actually permit either leakage of blood or in-growth of tissue, which would restrict or block blood flow, would be counterintuitive and not contemplated. As such, these vascular grafts, and therefore the small pore sizes of the microporous suture disclosed in the Frazier patent, operate to discourage and prevent normal neovascularization and tissue in-growth into the suture. Pore sizes less than approximately 200 microns are known to be watertight and disfavor neovascularization. See, e.g., Mühl et al., New Objective Measurement to Characterize the Porosity of Textile Implants, Journal of Biomedical Materials Research Part B: Applied Biomaterials DOI 10.1002/jbmb, Page 5 (Wiley Periodicals, Inc. 2007). Accordingly, one skilled in the art would understand that the suture disclosed in the Frazier patent has a pore size that is at least less than approximately 200 microns. Thus, in summary, the Frazier patent seeks to take advantage of that microporosity to encourage the body's natural “foreign body response” of inflammation and scar tissue formation to create a fibrous scar about the suture.
GENERAL DESCRIPTION
[0008] In contrast, the present disclosure is directed to sutures designed to discourage that “foreign body response” of inflammation and fibrotic tissue formation about the suture by utilizing a macroporous structure. The macroporous structure seeks to minimize the foreign body response to the suture. In direct contrast to the microporous structure, the macroporous structure is optimized to achieve maximal biocompatibility by permitting neovascularization and local/normal tissue ingrowth into the suture itself.
[0009] In some embodiments, the present disclosure provides surgical sutures comprising a cross-sectional profile lacking radial symmetry. In some embodiments, the surgical suture comprises a ribbon-like geometry. In some embodiments, the suture is between 0.1 mm and 1 cm wide (e.g. >0.1 mm, >0.2 mm, >0.3 mm, >0.4 mm, >0.5 mm, >0.6 mm, >0.7 mm, >0.8 mm, >0.9 mm, >1 mm, >2 mm, >3 mm, >4 mm, >5 mm, >6 mm, >7 mm, >8 mm, >9 mm), although other dimensions may be used. In some embodiments, the suture is about 3.75 mm wide (e.g., 3 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm, 3.6 mm, 3.7 mm, 3.8 mm, 3.9 mm, 4.0 mm, 4.1 mm, 4.2 mm, 4.3 mm, 4.4 mm, 4.5 mm). In some embodiments, the suture comprises a 2D cross-sectional profile. In some embodiments, the 2D cross-sectional profile comprises an ellipse, half ellipse, gibbous, half circle, crescent, concave ribbon, or rectangle; although other shapes may be used. In some embodiments, the suture comprises polyethylene terephthalate, nylon, polyolefin, polypropylene, silk, polymers p-dioxanone, co-polymer of p-dioxanone, ε-caprolactone, glycolide, L(−)-lactide, D(+)-lactide, meso-lactide, trimethylene carbonate, polydioxanone homopolymer, and combinations thereof, although other materials may be used. In some embodiments, the suture comprises polypropylene. In some embodiments, a suture is sterile, surgical grade, medical grade, etc.
[0010] In some embodiments, the present disclosure provides surgical sutures comprising a flexible material containing one or more internal voids (e.g., hollow core, honeycomb, single or multiple lumen, etc.) that extend the length of the suture. In some embodiments, the surgical suture adopts a first cross-sectional profile in the absence of lateral stress, and a second cross-sectional profile in the presence of lateral stress. In some embodiments, the first cross-sectional profile exhibits substantial radial symmetry. In some embodiments, the second cross-sectional profile exhibits partially or wholly collapsed conformation.
[0011] In some embodiments, the present disclosure provides surgical sutures comprising material and structure configured to permit tissue in-growth upon placement of the suture into the tissue of a subject. In some embodiments, the material comprises pores that permit tissue in-growth. In some embodiments, the pores comprise macropores (e.g., pores having a diameter >200 μm, >300 μm, >400 μm, >500 μm, >600 μm, >700 μm, >800 μm, >900 μm, >1 mm, >2 mm, or more). In some embodiments, the pores comprise micropores (e.g., pores having a diameter <200 μm, <150 μm, <100 μm, <75 μm, <70 μm, <50 μm, <25 μm, <10 μm, <1 μm, <0.5 μm, <0.1 μm, or less). In some embodiment, the pores can include a combination of macropores and micropores. In some embodiments, the pores may be of any suitable shape (e.g., circular, diamond, amorphous, etc. In some embodiments, the material comprises a textured surface (e.g., grooves, web, mesh, ribs, barbs, etc.). In some embodiments, the suture comprises a cross-sectional profile lacking radial symmetry. In some embodiments, the suture comprises a cross-sectional profile lacking substantially radial symmetry. In some embodiments, the suture comprises a ribbon-like geometry. In some embodiments, the suture is between 1 mm and 1 cm wide. In some embodiments, the suture comprises a 2D cross-sectional profile. In some embodiments, the 2D cross-sectional profile comprises an ellipse, half ellipse, gibbous, half circle, crescent, concave ribbon, or rectangle. In some embodiments, the suture comprises polypropylene. In some embodiments, a suture is sterile, surgical grade, medical grade, etc.
[0012] In some embodiments, the present disclosure provides suturing needles comprising a distal end and a proximal end, wherein the proximal end is configured for attachment to a suture material, wherein the distal end in configured for insertion into tissue, and wherein the needle transitions from a radially symmetric cross-sectional profile (or substantially radially symmetric) or so-called triangular “cutting” configurations at the distal end to a cross-sectional profile lacking radial symmetry at the proximal end. In some embodiments, the needle produces a puncture lacking radial symmetry when inserted through a tissue. In some embodiments, the cross-sectional profile lacking radial symmetry comprises a ribbon-like geometry. In some embodiments, the ribbon-like geometry is between 1 mm and 1 cm wide. In some embodiments, the cross-sectional profile lacking radial symmetry comprises a 2D cross-sectional profile. In some embodiments, the 2D cross-sectional profile comprises an ellipse, half ellipse, gibbous, half circle, crescent, concave ribbon, or rectangle. In some embodiments, a suturing needle is sterile, surgical grade, medical grade, etc.
[0013] In some embodiments, the present disclosure comprises a suturing system comprising: (a) a suturing needle (e.g., as described above), comprising a distal end and a proximal end, wherein the proximal end is configured for attachment to a suture material, wherein the distal end is configured for insertion into tissue, and wherein the needle comprises a cross-sectional profile lacking radial symmetry at the proximal end of the needle; and (b) a surgical suture (e.g., as described above) comprising a cross-sectional profile lacking radial symmetry.
[0014] In some embodiments, the present disclosure provides methods of using any of the above sutures, suturing needles, and/or systems to suture a tissue and/or close an opening in a tissue (e.g., epidermal tissue, peritoneum, adipose tissue, cardiac tissue, or any other tissue in need of suturing).
[0015] In some embodiments, the present disclosure provides methods of suturing an opening in a tissue comprising: (a) providing a suture with distal and proximal ends, wherein said proximal end is attached to a needle, and wherein said distal end comprises an integrated loop structure; (b) inserting said needle through said tissue adjacent to a first end of said opening; (c) pulling said suture through said tissue until said distal end of said suture is adjacent to said tissue; (d) placing said needle and said suture through said loop to create a lasso at the distal end of said suture; (e) suturing closed said opening from said first end to a second end; (f) stapling said suture at a second end; and (g) cutting remaining suture material and needle proximal to the staple.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 shows a schematic of incision and suture geometry.
[0017] FIG. 2 shows a schematic demonstrating the effect of tension between a suture and the surrounding tissue.
[0018] FIG. 3 shows finite element analysis of the suture/tissue interface.
[0019] FIG. 4 shows finite element analysis demonstrating that increasing suture size decreases the forces at the suture/tissue interface.
[0020] FIG. 5 shows finite element analysis demonstrating that suture shape impacts the local forces applied on the tissue by suture.
[0021] FIGS. 6 and 7 show graphs demonstrating the relative equivalence of the tensile strength of an O polypropylene suture and 2 mm wide nonradially symmetric (ribbon-shaped) suture.
[0022] FIG. 8 is an image showing a set-up for a tensometry experiment conducted using traditional 2D sutures and porcine linea alba.
[0023] FIG. 9 is an image of the tensometry experiment of FIG. 8 , illustrating tension being applied to the porcine linea alba.
[0024] FIG. 10 shows an illustration of an exemplary integrated needle and suture comprising: (1) a sharp needle point, (2) needle body, (3) transition area, (4) flattened profile, (5) porous suture wall, and (6) hollow core.
[0025] FIG. 10A is a detailed view of a portion of the porous suture wall of FIG. 10 .
[0026] FIG. 11 shows an illustration of an exemplary anchor end comprising a crimped loop: (1) crimpled joint, (2) circular profile.
[0027] FIG. 12 shows an illustration of an exemplary anchor end comprising a flattened loop: (1) flattened loop, (2) transition area, (3) circular profile.
[0028] FIG. 13 shows an illustration of an exemplary anchor end comprising a formed loop: (1) formed joint, (2) circular profile.
[0029] FIG. 14 shows a schematic demonstrating an altered cross-sectional profile upon application of non-axial force to a hollow core suture.
[0030] FIG. 15 shows a graph of the effect of suture width on maximum suture load in ex vivo porcine linea alba.
[0031] FIG. 16 shows a graph of the effect of suture width on maximum suture load in synthetic foam sheeting.
[0032] FIGS. 17 and 18 show comparison images of the tissue integration that is achieved with a macroporous suture of the present disclosure versus the failure suffered with a conventional suture when used to repair a rat hernia.
[0033] FIG. 19 shows a graph comparing the mean defect area of thirty rat hernias repaired in FIGS. 17 and 18 randomized to repair either with a macroporous suture of the present disclosure or with a conventional suture. The data analyzes defect size one month after repair.
DETAILED DESCRIPTION
[0034] The present disclosure provides a medical suture having a macroporous tubular construct that advantageously promotes neovascularization and normal tissue in-growth and integration subsequent to introduction into the body. Additionally, the present disclosure provides various sutures with increased surface area and/or tissue integrative properties and methods of use and manufacture thereof. In particular, provided herein are sutures with cross-section profiles and other structural characteristics that strengthen closure, prevent suture pull-through, and/or resist infection, and methods of use thereof. In some embodiments, sutures are provided that strengthen closure, prevent suture pull-through, and/or resist infection by, for example: (1) having a cross sectional profile that reduces pressure at suture points, (2) having a structural composition that allows tissue in-growth into the suture, or both (1) and (2). The present disclosure is not limited by any specific means for achieving the desired ends.
[0035] In some embodiments, conventional sutures exhibit a cross-sectional profile with radial symmetry or substantially radial symmetry. As used herein, the term “substantially radial symmetry” refers to a shape (e.g., cross-sectional profile) that approximates radial symmetry. A shape that has dimensions that are within 10% error of a shape exhibiting precise radial symmetry is substantially radially symmetric. For example, an oval that is 1.1 mm high and 1.0 mm wide is substantially radially symmetric. In some embodiments, the present disclosure provides sutures that lack radial symmetry and/or substantial radial symmetry.
[0036] In some embodiments, sutures are provided comprising cross-section shapes (e.g. flat, elliptical, etc.) that reduce tension against the tissue at the puncture site and reduce the likelihood of tissue tear. In some embodiments, devices (e.g., sutures) and methods provided herein reduce suture stress concentration at suture puncture points. In some embodiments, sutures with shaped cross-sectional profiles distribute forces more evenly (e.g., to the inner surface of the suture puncture hole) than traditional suture shapes/confirmation. In some embodiments, cross-sectionally-shaped sutures distribute tension about the suture puncture points. In some embodiments, rather than presenting a sharp point or line of suture to tissue, as is the case with traditional sutures, the sutures described herein present a flat or gently rounded plane to the leading edge of tissue, thereby increasing the surface area over which force can be distributed. In some embodiments, one cross-sectional dimension of the suture is greater than the orthogonal cross-sectional dimension (e.g., 1.1× greater, 1.2× greater, 1.3× greater, 1.4× greater, 1.5× greater, 1.6× greater, 1.7× greater, 1.8× greater, 1.9× greater, >2× greater, 2.0× greater, 2.1× greater, 2.2× greater, 2.3× greater, 2.4× greater, 2.5× greater, 2.6× greater, 2.7× greater, 2.8× greater, 2.9× greater, 3.0× greater, >3.0× greater, 3.1× greater, 3.2× greater, 3.3× greater, 3.4× greater, 3.5× greater, 3.6× greater, 3.7× greater, 3.8× greater, 3.9× greater, 4.0× greater, >4.0× greater . . . >5.0× greater . . . >6.0× greater . . . >7.0× greater . . . >8.0× greater . . . >9.0× greater . . . >10.0× greater). In some embodiments, sutures provided herein are flat or ellipsoidal on cross section, forming a ribbon-like conformation. In some embodiments, sutures are provided that do not present a sharp leading edge to the tissue. In some embodiments, use of the sutures described herein reduces the rates of surgical dehiscence in all tissues (e.g., hernia repairs, etc.). In some embodiments, sutures are provided with cross-sectional profiles that provide optimal levels of strength, flexibility, compliance, macroporosity, and/or durability while decreasing the likelihood of suture pull-through. In some embodiments, sutures are provided with sizes or shapes to enlarge the suture/tissue interface of each suture/tissue contact point, thereby distributing force over a greater area.
[0037] In some embodiments, sutures of the present disclosure provide various improvements over conventional sutures. In some embodiments, sutures provide: reduced likelihood of suture pull-through, increased closure strength, decreased number of stitches for a closure, more rapid healing times, and/or reduction in closure failure relative to a traditional suture. In some embodiments, relative improvements in suture performance (e.g., initial closure strength, rate of achieving tissue strength, final closure strength, rate of infection, etc.) are assessed in a tissue test model, animal test model, simulated test model, in silico testing, etc. In some embodiments, sutures of the present disclosure provide increased initial closure strength (e.g., at least a 10% increase in initial closure strength (e.g., >10%, >25%, >50%, >75%, >2-fold, >3-fold, >4-fold, >5-fold, >10-fold, or more). As used herein, “initial closure strength” refers to the strength of the closure (e.g., resistance to opening), prior to strengthening of the closure by the healing or scarring processes. In some embodiments, the increased initial closure strength is due to mechanical distribution of forces across a larger load-bearing surface area that reduces micromotion and susceptibility to pull through. In some embodiments, sutures of the present disclosure provide increased rate of achieving tissue strength (e.g., from healing of tissue across the opening, from ingrowth of tissue into the integrative (porous) design of the suture, etc.). In some embodiments, sutures of the present disclosure provide at least a 10% increase in rate of achieving tissue strength (e.g., >10%, >25%, >50%, >75%, >2-fold, >3-fold, >4-fold, >5-fold, >10-fold, or more). In some embodiments, increased rate of return of tissue strength across the opening further increases load bearing surface area, thereby promoting tissue stability and decreased susceptibility to pull through. In some embodiments, sutures of the present disclosure establish closure strength earlier in the healing process (e.g., due to greater initial closure strength and/or greater rate of achieving tissue strength) when the closure is most susceptible to rupture (e.g., at least a 10% reduction in time to establish closure strength (e.g., >10% reduction, >25% reduction, >50% reduction, >75% reduction, >2-fold reduction, >3-fold reduction, >4-fold reduction, >5-fold reduction, >10-fold reduction, or more)). In some embodiments, sutures of the present disclosure provide increased final closure strength (e.g., at least a 10% increase in final closure strength (e.g., >10%, >25%, >50%, >75%, >2-fold, >3-fold, >4-fold, >5-fold, >10-fold, or more). In some embodiments, the strength of fully healed closure is created not only by interface between the two apposed tissue surfaces, as is the case with conventional suture closures, but also along the total surface area of the integrated suture. In some embodiments, tissue integration into the suture decreases the rate of suture abscesses and/or infections that otherwise occur with solid foreign materials of the same size (e.g., at least a 10% reduction in suture abscesses and/or infection (e.g., >10% reduction, >25% reduction, >50% reduction, >75% reduction, >2-fold reduction, >3-fold reduction, >4-fold reduction, >5-fold reduction, >10-fold reduction, or more)). In some embodiments, sutures provide at least a 10% reduction (e.g., >10%, >20%, >30%, >40%, >50%, >60%, >70%, >80%, >90%, or more) in suture pull-through (e.g. through tissue (e.g., epidermal tissue, peritoneum, adipose tissue, cardiac tissue, or any other tissue in need of suturing), or through control substance (e.g., ballistic gel)).
[0038] In some embodiments, sutures are provided with any suitable cross-section profile or shape that provides reduced stress at the tissue puncture site, point of contact with tissue, and/or closure site. In some embodiments, sutures have cross-sectional dimensions (e.g., width and/or depth) or between 0.1 mm and 1 cm (e.g., 0.1 mm . . . 0.2 mm . . . 0.5 mm . . . 1.0 mm . . . 2.0 mm . . . 5.0 mm . . . 1 cm). In some embodiments, the suture dimensions (e.g., width and/or depth) that minimize pull-through and/or provide maximum load are utilized. In some embodiments, optimal suture dimensions are empirically determined for a given tissue and suture material. In some embodiments, one or both cross-sectional dimensions of a suture are the same as the cross-sectional dimensions of a traditional suture. In some embodiments, a suture comprises the same cross-sectional area as a traditional suture, but with different shape and/or dimensions. In some embodiments, a suture comprises the greater cross-sectional area than a traditional suture. In some embodiments, a suture cross-section provides a broad leading edge to spread pressure out over a broader portion of tissue. In some embodiments, a suture cross-section provides a shaped leading edge (e.g., convex) that evenly distributes force along a segment of tissue, rather than focusing it at a single point. In some embodiments, shaped sutures prevent pull-through by distributing forces across the tissue rather than focusing them at a single point. In some embodiments, sutures prevent pull-through by providing a broader cross-section that is more difficult to pull through tissue.
[0039] In some embodiments, ribbon-like suture or flat sutures are provided. In some embodiments, sutures provided herein comprise any suitable cross-sectional shape that provides the desired qualities and characteristics. In some embodiments, suture cross-sectional shape provides enhanced and/or enlarged leading edge surface distance and/or area (e.g. to reduce localized pressure on tissue). In some embodiments, suture cross-sectional shape comprises: an ellipse, half-ellipse, half-circle, gibbous, rectangle, square, crescent, pentagon, hexagon, concave ribbon, convex ribbon, H-beam, I-beam, dumbbell, etc. In some embodiments, a suture cross-sectional profile comprises any combination of curves, lines, corners, bends, etc. to achieve a desired shape. In some embodiments, the edge of the sutures configured to contact the tissue and/or place pressure against the tissue is broader than one or more other suture dimensions. In some embodiments, the edge of the sutures configured to contact the tissue and/or place pressure against the tissue is shaped to evenly distribute forces across the region of contact.
[0040] In some embodiments, hollow core sutures are provided such as that depicted in FIG. 10 . More specifically, FIG. 10 depicts a medical device 10 that includes a surgical needle 12 and an elongated suture 14. In FIG. 10 , the needle 12 includes a contoured or curved needle with a flattened cross-sectional profile, but needles with generally any geometry could be used. The suture 14 can be a hollow core suture with a first end 14a attached to the needle 12 and a second end 14b located a distance away from the needle 12. As shown, the entire length of the suture 14 between the first and second ends 14a, 14b can include a tubular wall 16 that defines a hollow core 18. In other versions, however, less than the entire length of the suture 14 can be tubular. For example, it is foreseeable that either or both of the first and second ends 14a, 14b can have a non-tubular portion or portion of other geometry. Such non-tubular portions could be for attaching the first end 14a of the suture 14 to the needle 12 or for tying off the second end 14b, for example. In versions where the entire length of the suture 14 is tubular, as shown, the entire length of the suture 14 including the ends and central portion also has generally a constant or uniform diameter or thickness in the absence of stresses. That is, no portion of the suture 14 is meaningfully larger in diameter than any other portion of the suture 14. Moreover, no aspect, end, or other portion of the suture 14 is intended to be or is actually passed through, disposed in, received in, or otherwise positioned inside of the hollow core 18. The hollow core 18 is adapted for receiving tissue in-growth only.
[0041] In some embodiments, the tubular wall 16 can have a diameter in a range of approximately 1 mm to approximately 10 mm and can be constructed of a material such as, for example, polyethylene terephthalate, nylon, polyolefin, polypropylene, silk, polymers p-dioxanone, co-polymer of p-dioxanone, ε-caprolactone, glycolide, L(−)-lactide, D(+)-lactide, meso-lactide, trimethylene carbonate, polydioxanone homopolymer, and combinations thereof. So constructed, the tubular wall 16 of the suture 14 can be radially deformable such that it adopts a first cross-sectional profile in the absence of lateral stresses and a second cross-sectional profile in the presence of lateral stresses. For example, in the absence of lateral stresses, the tubular wall 16 and therefore the suture 14 depicted in FIG. 10 , for example, can have a circular cross-sectional profile, thereby exhibiting radial symmetry. In the presence of a lateral stress, such a suture 14 could then exhibit a partially or wholly collapsed conformation.
[0042] In at least one version of the medical device 10, at least some of the tubular wall 16 can be macroporous defining a plurality of pores 20 (e.g., openings, apertures, holes, etc.), only a few of which are expressly identified by reference number and lead line in FIG. 10 for clarity. The pores 20 extend completely through the mesh wall 16 to the hollow core 18. In some versions, the tubular wall 16 can be constructed of a woven or knitted mesh material. In one version, the wall 16 can be constructed of a knitted polypropylene mesh material similar or identical to that which is available under the trade name Prolene Soft Mesh and offered for sale by Ethicon. Other similarly constructed mesh materials would be suitable as well.
[0043] As used herein, the term “macroporous” can include pore sizes that are at least greater than or equal to approximately 200 microns and, preferably, greater than or equal to 500 microns. In some versions of the medical device 10, the size of at least some the pores 20 in the suture 14 can be in a range of approximately 500 microns to approximately 4 millimeters. In another version, at least some of the pores 20 can have a pore size in the range of approximately 500 microns to approximately 2.5 millimeters. In another version, at least some of the pores 20 can have a pore size in the range of approximately 1 millimeter to approximately 2.5 millimeters. In another version, the size of at least some of the pores 20 can be approximately 2 millimeters. Moreover, in some versions, the pores 20 can vary in size. For example, as mentioned above and as also illustrated in FIG. 10A , in some versions, some of the pores 20a can be macroporous (e.g., greater than approximately 200 microns) and some of the pores 20b can be microporous (e.g., less than approximately 200 microns). The presence of microporosity (i.e., pores less than approximately 200 microns) in such versions of the disclosed suture may only be incidental to the manufacturing process, which can including knitting, weaving, extruding, blow molding, or otherwise, but not necessarily intended for any other functional reason regarding biocompatibility or tissue integration. The presence of microporosity (i.e, some pores less than approximately 200 microns in size) as a byproduct or incidental result of manufacturing does not change the character of the disclosed macroporous suture (e.g., with pores greater than approximately 200 microns, and preferably greater than approximately 500 microns, for example), which facilitates tissue in-growth to aid biocompatibility, reduce tissue inflammation, and decrease suture pull-through.
[0044] In versions of the disclosed suture that has both macroporosity and microporosity, the number of pores 20 that are macroporous can be in a range from approximately 1% of the pores to approximately 99% of the pores (when measured by pore cross-sectional area), in a range from approximately 5% of the pores to approximately 99% of the pores (when measured by pore cross-sectional area), in a range from approximately 10% of the pores to approximately 99% of the pores (when measured by pore cross-sectional area), in a range from approximately 20% of the pores to approximately 99% of the pores (when measured by pore cross-sectional area), in a range from approximately 30% of the pores to approximately 99% of the pores (when measured by pore cross-sectional area), in a range from approximately 50% of the pores to approximately 99% of the pores (when measured by pore cross-sectional area), in a range from approximately 60% of the pores to approximately 99% of the pores (when measured by pore cross-sectional area), in a range from approximately 70% of the pores to approximately 99% of the pores (when measured by pore cross-sectional area), in a range from approximately 80% of the pores to approximately 99% of the pores (when measured by pore cross-sectional area), or in a range from approximately 90% of the pores to approximately 99% of the pores (when measured by pore cross-sectional area).
[0045] So configured, the pores 20 in the suture 14 are arranged and configured such that the suture 14 is adapted to facilitate and allow tissue in-growth and integration through the pores 20 in the mesh wall 16 and into the hollow core 18 when introduced into a body. That is, the pores 20 are of sufficient size to achieve maximum biocompatibility by promoting neovascularization and local/normal tissue in-growth through the pores 20 and into the hollow core 18 of the suture 14. As such, tissue growth through the pores 16 and into the hollow core 20 enables the suture 14 and resultant tissue to combine and cooperatively increase the strength and efficacy of the medical device 10, while also decreasing irritation, inflammation, local tissue necrosis, and likelihood of pull through. Instead, the suture 14 promotes the production of healthy new tissue throughout the suture construct including inside the pores 20 and the hollow core 18.
[0046] While the suture 14 in FIG. 10 has been described as including a single elongated hollow core 18, in some embodiments, a suture according to the present disclosure can comprise a tubular wall defining a hollow core including one or more interior voids (e.g., extending the length of the suture). In some versions, at least some of the interior voids can have a size or diameter > approximately 200 microns, > approximately 300 microns, > approximately 400 microns, > approximately 500 microns, > approximately 600 microns, > approximately 700 microns, > approximately 800 microns, > approximately 900 microns, > approximately 1 millimeter, or > approximately 2 millimeters. In some embodiments, a suture according to the present disclosure can comprise a tubular wall defining a hollow core including one or more (e.g., 1, 2, 3, 4, 5, 6, 7, 8, or more) lumens (e.g., running the length of the suture). In some embodiments, a suture according to the present disclosure can comprise a tubular wall defining a hollow core including a honeycomb structure, a 3D lattice structure, or other suitable interior matrix, which defines one or more interior voids. In some versions, at least some of the interior voids in the honeycomb structure, 3D lattice structure, or other suitable matrix can have a size or diameter > approximately 200 microns, > approximately 300 microns, > approximately 400 microns, > approximately 500 microns, > approximately 600 microns, > approximately 700 microns, > approximately 800 microns, > approximately 900 microns, > approximately 1 millimeter, or > approximately 2 millimeters. In some embodiments, a void comprises a hollow core. In some embodiments, a hollow core can include a hollow cylindrical space in the tubular wall, but as described, the term “hollow core” is not limited to defining a cylindrical space, but rather could include a labyrinth of interior voids defined by a honeycomb structure, a 3D lattice structure, or some other suitable matrix. In some embodiments, sutures comprise a hollow, flexible structure that has a circular cross-sectional profile in its non-stressed state, but which collapses into a more flattened cross-sectional shape when pulled in an off-axis direction. In some embodiments, sutures are provided that exhibit radial symmetry in a non-stressed state. In some embodiments, radial symmetry in a non-stressed state eliminates the need for directional orientation while suturing. In some embodiments, sutures are provided that exhibit a flattened cross-sectional profile when off-axis (longitudinal axis) force is applied (e.g., tightening of the suture against tissue) (SEE FIG. 14 ), thereby more evenly distributing the force applied by the suture on the tissue. In some embodiments, sutures are provided that exhibit a flattened cross-sectional profile when axial force is applied. In some embodiments, sutures comprise flexible structure that adopts a first cross-sectional profile in its non-stressed state (e.g., suturing profile), but adopts a second cross-sectional shape when pulled in an off-axis direction (e.g., tightened profile). In some embodiments, a suture is hollow and/or comprises one or more internal voids (e.g., that run the length of the suture). In some embodiments, internal voids are configured to encourage the suture to adopt a preferred conformation (e.g., broadened leading edge to displace pressures across the contacted tissue) when in a stressed states (e.g., tightened profile). In some embodiments, internal voids are configured to allow a suture to adopt radial exterior symmetry (e.g., circular outer cross-sectional profile) when in a non-stressed state. In some embodiments, varying the size, shape, and/or placement of internal voids alters one or both of the first cross-sectional profile (e.g., non-stressed profile, suturing profile) and second cross-sectional profile (e.g., off-axis profile, stressed profile, tightened profile).
[0047] Sutures, which are substantially linear in geometry, have two distinct ends, as described above with reference to FIG. 10 , for example. In some embodiments, both ends are identical. In some embodiments, each end is different. In some embodiments, one or both ends are structurally unadorned. In some embodiments, one or more ends is attached to or at least configured for attachment to a needle via swaging, sonic welding, adhesive, tying, or some other means (as shown FIG. 10 ). In some embodiments, the second end 14b of the suture 14 is configured to include an anchor 22 (e.g., FIGS. 11 , 12, 13) for anchoring the suture 14 against the tissue through which the suture 14 is inserted. In some embodiments, the second end 14b of the suture 14 is configured to anchor the suture at the beginning of the closure. In some embodiments, the second end 14b of the suture 14 includes an anchor 22 that is a structure that prevents the suture 14 from being pulled completely through the tissue. In some embodiments, the anchor 22 has a greater dimension than the rest of the suture 14 (at least 10% greater, at least 25% greater, at least 50% greater, at least 2-fold greater, at least 3-fold greater, at least 4-fold greater, at least 5-fold greater, at least 6-fold greater, at least 10-fold greater, etc.). In some embodiments, the anchor 22 comprises a structure with any suitable shape for preventing the suture 14 from being pulled through the hole (e.g., ball, disc, plate, cylinder), thereby preventing the suture 14 from being pulled through the insertion hole. In some embodiments, the anchor 22 of the suture 14 comprises a closed loop, as depicted in FIG. 11 , for example. In some embodiments, the closed loop is of any suitable structure including, but not limited to a crimpled loop (FIG. 11 ), flattened loop (FIG. 12 ), or a formed loop (FIG. 13 ). In some embodiments, a loop can be integrated into the end of the suture 14. In some embodiments, a separate loop structure can be attached to the suture 14. In some embodiments, the needle 12 can be passed through the closed loop anchor 22 to create a cinch for anchoring the suture 14 to that point. In some embodiments, the anchor 22 can comprise one or more structures (e.g., barb, hook, etc.) to hold the end of the suture 14 in place. In some embodiments, one or more anchor 22 structures (e.g., barb, hook, etc.) are used in conjunction with a closed loop to ratchet down the cinch and hold its position. In some embodiments, a knotless anchoring system can be provided.
[0048] In some embodiments, and as briefly mentioned relative to FIG. 10 , the present disclosure provides suturing needles with cross-sectional profiles configured to prevent suture pull-through and methods of use thereof. In some embodiments, suturing needles are provided comprising cross-section shapes (e.g. flat, elliptical, transitioning over the length of the needle, etc.) that reduce tension against the tissue at the puncture site and reduce the likelihood of tissue tear. In some embodiments, one cross-sectional dimension of the needle is greater than the orthogonal cross-sectional dimension (e.g., 1.1× greater, 1.2× greater, 1.3× greater, 1.4× greater, 1.5× greater, 1.6× greater, 1.7× greater, 1.8× greater, 1.9× greater, >2× greater, 2.0× greater, 2.1× greater, 2.2× greater, 2.3× greater, 2.4× greater, 2.5× greater, 2.6× greater, 2.7× greater, 2.8× greater, 2.9× greater, 3.0× greater, >3.0× greater, 3.1× greater, 3.2× greater, 3.3× greater, 3.4× greater, 3.5× greater, 3.6× greater, 3.7× greater, 3.8× greater, 3.9× greater, 4.0× greater, >4.0× greater . . . >5.0× greater . . . >6.0× greater . . . >7.0× greater . . . >8.0× greater . . . >9.0× greater . . . >10.0× greater). In some embodiments, suturing needles are provided circular in shape at its point (e.g., distal end), but transition to a flattened profile (e.g., ribbon-like) to the rear (e.g. proximal end). In some embodiments, the face of the flattened area is orthogonal to the radius of curvature of the needle. In some embodiments, suturing needles create a slit (or flat puncture) in the tissue as it is passed through, rather than a circle or point puncture. In some embodiments, suturing needles are provided circular in shape at its point (e.g., distal end), but transition to a 2D cross-sectional profile (e.g., ellipse, crescent, half moon, gibbous, etc.) to the rear (e.g. proximal end). In some embodiments, suturing needles provided herein find use with the sutures described herein. In some embodiments, suturing needles find use with sutures of the same shape and/or size. In some embodiments, suturing needles and sutures are not of the same size and/or shape. In some embodiments, suturing needles provided herein find use with traditional sutures. Various types of suture needles are well known in the art. In some embodiments, suturing needles provided herein comprise any suitable characteristics of suturing needles known to the field, but modified with dimensions described herein.
[0049] In some embodiments, the present disclosure also provides compositions, methods, and devices for anchoring the suture at the end of the closure (e.g., without tying the suture to itself). In some embodiments, one or more securing elements (e.g., staples) are positioned over the terminal end of the suture to secure the end of the closure. In some embodiments, one or more securing elements (e.g., staples) are secured to the last “rung” of the suture closure (e.g., to hold the suture tight across the closure. In some embodiments, a securing element is a staple. In some embodiments, a staple comprises stainless steel or any other suitable material. In some embodiments, a staple comprises a plurality of pins that can pass full thickness through 2 layers of suture. In some embodiments, staple pins are configured to secure the suture end without cutting and/or weakening the suture filament. In some embodiments, a staple forms a strong joint with the suture. In some embodiments, a staple is delivered after the needle is cut from the suture. In some embodiments, a staple is delivered and the needle removed simultaneously
[0050] In some embodiments, the present disclosure provides devices (e.g., staple guns) for delivery of a staple into tissue to secure the suture end. In some embodiments, a staple deployment device simultaneously or near-simultaneously delivers a staple and removes the needle from the suture. In some embodiments, a staple deployment device comprises a bottom lip or shelf to pass under the last rung of suture (e.g., between the suture and tissue surface) against which the pins of the staple can be deformed into their locked position. In some embodiments, the bottom lip of the staple deployment device is placed under the last rung of suture, the free tail of the suture is placed within the stapling mechanism, and the suture is pulled tight. In some embodiments, while holding tension, the staple deployment device is activated, thereby joining the two layers of suture together. In some embodiments, the device also cuts off the excess length of the free suture tail. In some embodiments, the staple deployment device completes the running suture and trims the excess suture in one step. In some embodiments, a suture is secured without the need for knot tying. In some embodiments, only 1 staple is needed per closure. In some embodiments, a standard stapler is used to apply staples and secure the suture end. In some embodiments, a staple is applied to the suture end manually.
[0051] In some embodiments, sutures provided herein provide tissue integrative properties to increase the overall strength of the repair (e.g., at an earlier time-point than traditional sutures). In some embodiments, sutures are provided with enhanced tissue adhesion properties. In some embodiments sutures are provided that integrate with the surrounding tissue. In some embodiments, tissue integrative properties find use in conjunction with any other suture characteristics described herein. In some embodiments, sutures allow integration of healing tissue into the suture. In some embodiments, tissue growth into the suture is promoted (e.g., by the surface texture of the suture). In some embodiments, tissue growth into the suture prevents sliding of tissue around suture, and/or minimizes micromotion between suture and tissue. In some embodiments, tissue in-growth into the suture increases the overall strength of the repair by multiplying the surface area for scar in establishing continuity between tissues. Conventionally, the strength of a repair is dependent only on the interface between the two tissue surfaces being approximated. In some embodiments in-growth of tissue into the suture adds to the surface area of the repair, thereby enhancing its strength. In some embodiments, increasing the surface area for scar formation, the closure reaches significant strength more quickly, narrowing the window of significant risk of dehiscence.
[0052] In some embodiments, the surface and/or internal texture of a suture promote tissue adhesion and/or ingrowth. In some embodiments, as discussed above specifically with reference to FIG. 10 , a suture of the present disclosure can comprise a porous (e.g., macroporous) and/or textured material. In some embodiments, a suture comprises a porous (e.g., macroporous) and/or textured exterior. In some embodiments, pores in the suture allow tissue in-growth and/or integration. In some embodiments, a suture comprises a porous ribbon-like structure, instead of a tubular like structure. In some embodiments, a porous suture comprises a 2D cross-sectional profile (e.g., elliptical, circular (e.g., collapsible circle), half moon, crescent, concave ribbon, etc.). In some embodiments, a porous suture comprises polypropylene or any other suitable suture material. In some embodiments, pores are between 500 μm and 3.5 mm or greater in diameter (e.g., e.g., >500 μm in diameter (e.g., >500 μm, >600 μm, >700 μm 800 μm, >900 μm, >1 mm, or more). In some embodiments pores are of varying sizes. In some embodiments, a suture comprises any surface texture suitable to promote tissue in-growth and/or adhesion. In some embodiments, suitable surface textures include, but are not limited to ribbing, webbing, mesh, grooves, etc. In some embodiments, the suture may include filaments or other structures (e.g., to provide increased surface area and/or increased stability of suture within tissue). In some embodiments, interconnected porous architecture is provided, in which pore size, porosity, pore shape and/or pore alignment facilitates tissue in-growth.
[0053] In some embodiments, a suture comprises a mesh and/or mesh-like exterior. In some embodiments, a mesh exterior provides a flexible suture that spreads pressure across the closure site, and allows for significant tissue in-growth. In some embodiments, the density of the mesh is tailored to obtain desired flexibility, elasticity, and in-growth characteristics.
[0054] In some embodiments, a suture is coated and/or embedded with materials to promote tissue ingrowth. Examples of biologically active compounds that may be used sutures to promote tissue ingrowth include, but are not limited to, cell attachment mediators, such as the peptide containing variations of the “RGD” integrin binding sequence known to affect cellular attachment, biologically active ligands, and substances that enhance or exclude particular varieties of cellular or tissue ingrowth. Such substances include, for example, osteoinductive substances, such as bone morphogenic proteins (BMP), epidermal growth factor (EGF), fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), insulin-like growth factor (IGF-I and II), TGF-β, etc. Examples of pharmaceutically active compounds that may be used sutures to promote tissue ingrowth include, but are not limited to, acyclovir, cephradine, malfalen, procaine, ephedrine, adriomycin, daunomycin, plumbagin, atropine, guanine, digoxin, quinidine, biologically active peptides, chlorin e.sub.6, cephalothin, proline and proline analogues such as cis-hydroxy-L-proline, penicillin V, aspirin, ibuprofen, steroids, nicotinic acid, chemodeoxycholic acid, chlorambucil, and the like. Therapeutically effective dosages may be determined by either in vitro or in vivo methods.
[0055] Sutures are well known medical devices in the art. In some embodiments, sutures have braided or monofilament constructions. In some embodiments sutures are provided in single-armed or double-armed configurations with a surgical needle mounted to one or both ends of the suture, or may be provided without surgical needles mounted. In some embodiments, the end of the suture distal to the needle comprises one or more structures to anchor the suture. In some embodiments, the distal end of the suture comprises one or more of a: closed loop, open loop, anchor point, barb, hook, etc. In some embodiments, sutures comprise one or more biocompatible materials. In some embodiments, sutures comprise one or more of a variety of known bioabsorbable and nonabsorbable materials. For example, in some embodiments, sutures comprise one or more aromatic polyesters such as polyethylene terephthalate, nylons such as nylon 6 and nylon 66, polyolefins such as polypropylene, silk, and other nonabsorbable polymers. In some embodiments, sutures comprise one or more polymers and/or copolymers of p-dioxanone (also known as 1,4-dioxane-2-one), ε-caprolactone, glycolide, L(−)-lactide, D(+)-lactide, meso-lactide, trimethylene carbonate, and combinations thereof. In some embodiments, sutures comprise polydioxanone homopolymer. The above listing of suture materials should not be viewed as limiting. Suture materials and characteristics are known in the art. Any suitable suture materials or combinations thereof are within the scope of the present disclosure. In some embodiments, sutures comprise sterile, medical grade, surgical grade, and or biodegradable materials. In some embodiments, a suture is coated with, contains, and/or elutes one or more bioactive substances (e.g., antiseptic, antibiotic, anesthetic, promoter of healing, etc.).
[0056] In some embodiments, the structure and material of the suture provides physiologically-tuned elasticity. In some embodiments, a suture of appropriate elasticity is selected for a tissue. In some embodiments, suture elasticity is matched to a tissue. For example, in some embodiments, sutures for use in abdominal wall closure will have similar elasticity to the abdominal wall, so as to reversibly deform along with the abdominal wall, rather than act as a relatively rigid structure that would carry higher risk of pull-through. In some embodiments, elasticity would not be so great however, so as to form a loose closure that could easily be pulled apart. In some embodiments, deformation of the suture would start occurring just before the elastic limit of its surrounding tissue, e.g., before the tissue starts tearing or irreversibly deforming.
[0057] In some embodiments, sutures described herein provide a suitable replacement or alternative for surgical repair meshes (e.g., those used in hernia repair). In some embodiments, the use of sutures in place of mesh reduces the amount of foreign material placed into a subject (e.g., 50 cm2 (suture) v. 240 cm2 (mesh)). In some embodiments, the decreased likelihood of suture pull-through allows the use of sutures to close tissues not possible with traditional sutures (e.g., areas of poor tissue quality (e.g., friable or weak tissue) due to conditions like inflammation, fibrosis, atrophy, denervation, congenital disorders, attenuation due to age, or other acute and chronic diseases). Like a surgical mesh, sutures described herein permit a distribution of forces over a larger area thereby delocalizing forces felt by the tissue and reducing the chance of suture pull-though and failure of the closure.
[0058] In some embodiments, sutures are permanent, removable, or absorbable. In some embodiments, permanent sutures provide added strength to a closure or other region of the body, without the expectation that the sutures will be removed upon the tissue obtaining sufficient strength. In such embodiments, materials are selected that pose little risk of long-term residency in a tissue or body. In some embodiments, removable sutures are stable (e.g., do not readily degrade in a physiological environment), and are intended for removal when the surrounding tissue reaches full closure strength. In some embodiments, absorbable sutures integrate with the tissue in the same manner as permanent or removable sutures, but eventually (e.g., >1 week, >2 weeks, >3 weeks, >4 weeks, >10 weeks, >25 weeks, >1 year) biodegrade and/or are absorbed into the tissue after having served the utility of holding the tissue together during the post-operative and/or healing period. In some embodiments absorbable sutures present a reduced foreign body risk.
[0059] Although prevention of dehiscence of abdominal closures (e.g., hernia formation) is specifically described at an application of embodiments of the present disclosure, the sutures described herein are useful for joining any tissue types throughout the body. In some embodiments, sutures described herein are of particular utility to closures that are subject top tension and/or for which cheesewiring is a concern. Exemplary tissues within which the present disclosure finds use include, but are not limited to: connective tissue, muscle, dermal tissue, cartilage, tendon, or any other soft tissues. Specific applications of sutures described herein include placation, suspensions, slings, etc. Sutures described herein find use in surgical procedures, non-surgical medical procedures, veterinary procedures, in-field medical procedures, etc. The scope of the present disclosure is not limited by the potential applications of the sutures described herein.
[0060] Yet, from the foregoing, it should also be appreciated that the present disclosure additionally provides both a novel method of re-apposing soft tissue and a novel method of manufacturing a medical device.
[0061] Based on the present disclosure, a method of re-apposing soft tissue can first include piercing a portion of the soft tissue with the surgical needle 12 (as shown in FIG. 10 , for example) attached to a first end 14a of a tubular suture 14. Next, a physician can thread the tubular suture 14 through the soft tissue and make one or more stitches, as is generally known. Finally, the physician can anchor the tubular suture 14 in place in the soft tissue. As disclosed hereinabove, the tubular suture 14 comprises a tubular mesh wall 16 defining a hollow core 18. The tubular mesh wall 16 defines a plurality or pores 20, each with a pore size that is greater than or equal to approximately 500 microns. So configured, the tubular suture 14 is adapted to accommodate the soft tissue growing through the tubular mesh wall 16 and into the hollow core 18, thereby integrating with the suture. In some versions, the method can further and finally include anchoring the tubular suture 14 in place by passing the surgical needle 12 through a closed loop anchor 22 (as seen in FIG. 11 , for example) at the second end 14b of the tubular suture 14 and creating a cinch for anchoring the suture 14 to the soft tissue. Once anchored, the suture 14 can be cut off near the anchor 22 and any remaining unused portion of the suture 14 can be discarded.
[0062] A method of manufacturing a medical device in accordance with the present disclosure can include forming a tubular wall 16 having a plurality or pores 20 and defining a hollow core 18, each pore 20 having a pore size that is greater than or equal to approximately 500 microns. Additionally, the method of manufacturing can include attaching a first end 14a of the tubular wall 14 to a surgical needle 12, such as that illustrated in FIG. 10 . Forming the tubular wall 14 can include forming a tube from a mesh material. The tubular mesh wall 16 may be formed by directly weaving or knitting fibers into a tube shape. Alternatively, forming the tubular mesh wall 16 can include weaving or knitting fibers into a planar sheet and subsequently forming the planar sheet into a tube shape. Of course, other manufacturing possibilities exist and knitting and weaving fibers are not the only possibilities for creating a porous tube within the scope of the present disclosure, but rather, are mere examples.
[0063] Still further, a method of manufacturing a medical device 10 in accordance with the present disclosure can include providing an anchor 22 on an end of the tubular wall 16 opposite the needle 12. In some versions of the method, and as one example only, providing the anchor can be as simple as forming a loop, such as to resemble the anchor 22 depicted in FIG. 11 .
[0064] To substantiate some characteristics of the medical device 10 described herein, a number of experiments were conducted and the character and results of some of those experiments are presented below.
EXPERIMENTAL WORK
Example 1
Finite Element Analyses of the Suture/Tissue Interface for Sutured Abdominal Wall Closures
[0065] Experiments were conducted during development of embodiments of the present disclosure to perform finite element analyses of the suture/tissue interface for sutured abdominal wall closures. A theoretic basis was created for intuitive concepts and clinical observations as the first step in the design of this line of inquiry (See FIGS. 1,2). Finite element analysis of the suture/tissue interface was performed (FIG. 3 ). Experiments demonstrated that increasing suture size (i.e., diameter) decreases the forces at the suture/tissue interface as hypothesized (FIG. 4 ). Suture shape was also shown to impact the local forces applied on the tissue by suture (FIG. 5 ).
Example 2
[0066] Creating “equivalency” between conventional and macroporous suture of the present disclosure.
[0067] A size O-polypropylene suture is commonly used in hernia repair for its features of handling and high strength. Experiments were conducted to determine a cross-sectionally shaped suture that is the relative equivalent to such a suture. The two-dimensional suture was compared to this commonly used standard suture for load at yield, maximal load, and Young's modulus. An Instron 5964 was used for mechanical testing. Experiments demonstrated a relative equivalency between O-polypropylene and a two-dimensional ribbon suture of 5 mm in width (FIGS. 6 and 7 ). A 5-0 polypropylene suture, used in experimental rat hernia repair, had an equivalency to a 2 mm wide sample of a macroporous suture of the present disclosure.
Example 3
Creating and Validating an Acute Suture Pull-Through Model Using Biologic Tissue and Tensometry
[0068] Porcine linea alba is available from local slaughterhouses to provide realistic testing of acute suture pull-through. Standard suture and macroporous suture of the present disclosure were placed uniformly through porcine tissue. To decrease biologic variability, adjacent pieces of fascia were randomized to either standard suture or two-dimensional suture, with the width of the suture bite mimicking what is done clinically (1 cm from the edge). Tensometry using an Instron 5964 testing suture pull-through at both slow and fast speeds to simulate both baseline suture tension and episodic high tension (e.g., coughing, stairs, etc.) were performed. Considering biologic variability and the readily accessible biologic materials, a suitable number of tests were performed for both standard and macroporous suture of the present disclosure.
Example 4
Rat Hernia Model
[0069] Experiments were conducted during development of embodiments of the present disclosure reproducing an established rat hernia model to in order to assess pull-through of standard suture and our experimental macroporous suture.
[0070] A well-established rat hernia model was reproduced (Dubay D A, Ann Surg 2007; 245: 140-146; herein incorporated by reference in its entirety). Rat ventral hernias were randomized to repair with two standard sutures (5-0 polypropylene), and with two integrated sutures with equivalent tensile strength. One month after hernia repair, the rats were sacrificed and analyzed for hernia recurrence, hernia size, and suture pull-through. Histology of the abdominal wall for analysis of suture integration was assessed by blinded observers. In these experiments, none of the macroporous sutures of the present disclosure pulled through in 17 rat hernias (i.e., 34 of 34 integrated macroporous sutures maintained their hold on the abdominal wall without failure, with the image on the left-hand side of FIG. 17 as a typical example). The macroporous suture of the present disclosure facilitated tissue integration for every suture of every rat in which it was used. On the left of FIG. 18 , in one instance there is an 82% reduction in the defect area one month after repair with macroporous suture. In contrast, in 13 rat hernias repaired with a conventional suture, 11 of 13 rats had at least one suture completely pull-through the abdominal wall. The right-hand side of FIG. 17 is an example of a hernia repair failure with both sutures pulling through. On the right-hand side of FIG. 18 , it is shown that hernia size increased 42% one month after repair with standard suture in one test animal. FIG. 19 shows a graph comparing the mean defect area of 30 rat hernias repaired according to FIGS. 17 and 18 randomized to repair either with the macroporous suture of the present disclosure or with a conventional suture. One month after repair, average hernia size decreased 54% with the experimental macroporous suture of the present disclosure, while hernia size increased 5% with the conventional suture. Some element of recurrent hernia with both standard and experimental sutures was expected—only two sutures were used in this model, while 6 would be required to achieve a completely closed abdominal wall.
Example 5
Suture Width
[0071] Experiments conducted to evaluate the effect of suture width demonstrated that increased suture width resulted in an increase in maximum load of the suture, resulting in decreased pull-through of the suture. Tinned copper flat braided wire was used as a prototype for suture of varying widths. Relative to tissue, metal wire is essentially noncompliant, creating a system that isolates the effect of the variable of width on pull-through of suture placed in tissue. Wires of varying width were placed into two different substances: fresh animal tissue (porcine abdominal wall) and synthetic foam sheeting, and an Instron 5942 tensometer was used to precisely measure the breaking strength of this system. Wire was tested from widths of 0.36 mm (equivalent to O prolene suture) to 5 mm. These experiments was to examined the effects of increasing suture width in both animal tissue and synthetic “tissue” to determine if there were any differences between an ex vivo and synthetic substrate.
[0072] FIG. 15 demonstrates that with increasing suture width greater force is required to pull-through porcine abdomen. Unexpectedly, the benefits of increasing suture width began peaking at a width of around 3 mm. At a width of 3.75 mm, pull-through resistance (maximum load of the system) actually decreased; video time lapse analysis shows that at this width tissue began fracturing on both sides of wire, tending to come off as a segment of tissue. In contrast, at smaller widths, wire would cut through tissue in a single fracture line. Fracture pattern therefore has a bearing on the maximum strength of the system.
[0073] FIG. 16 demonstrates that the same relationship is preserved in synthetic tissue. In this so-called “clean” system, utilizing foam instead of animal tissue (foam being a homogenous substance with fewer mechanical variables than animal tissue), benefits of wider than conventional suture were demonstrated, further confirming that increased load-bearing surface area at the suture-tissue interface decreases pull-through. However, in a similar manner to porcine tissue, the benefit of increasing width was demonstrated up to 3.75 mm, at which point the foam substrate began fracturing as a segment.
[0074] While it was initially hypothesized that the wider the suture the less it will tear through, in some embodiments, suture width is not the only consideration. For example, it is clear that tissue integration (i.e., in-growth through the suture 14 pores 20 and into the hollow core 28) into the suture 14 further increases the strength of the repair and reduces and/or completely eliminates the risk of suture pull-through. Moreover, as shown above, experiments conducted during development of various embodiments of the present disclosure demonstrate that increasing the load-bearing surface area will further reduce the occurrence of pull through. Wire pulling experiments in porcine abdomen, confirmed such findings. In some experiments, with widths above 3.75 mm, pull-through resistance reduced. Rather than the suture tearing through the tissue in a straight line, it started breaking off the tissue as a segment or block. This finding was unexpected. These experiments were repeated using a homogenous/synthetic substance to test whether the benefit of increasing width would also peak. A rubber foam which was about the same thickness as porcine linea alba was used. Unexpectedly, the force required to pull the suture through the foam peaked at the same suture width, and the foam even tore in the same pattern as the porcine tissue. The suture width to max load relationship was preserved in both animal and synthetic tissue.
[0075] Both these experiments indicate that the suture width/max load relationship is due to mechanical phenomena; although, the present disclosure is not limited to any particular mechanism of action and an understanding of the mechanism of action is not necessary to practice the present disclosure.
[0076] Various modifications and variations of the described method and system of the disclosure will be apparent to those skilled in the art without departing from the scope and spirit of the disclosure. Although the disclosure has been described in connection with specific preferred embodiments, it should be understood that the disclosure as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the disclosure that are obvious to those skilled in the relevant fields are intended to be within the scope of the present disclosure.
Claims
We claim:
1. A medical device comprising:
a surgical needle; and
an elongated mesh suture having a first end and a second end located away from the first end, wherein the first end is selected from the group consisting of (a) an end directly attached to the surgical needle, (b) a free end, and (c) an end having a loop;
the elongated suture including a tubular wall, a hollow core inside of the tubular wall, and a plurality of pores extending through the tubular wall, at least some of the pores having a pore size that is greater than or equal to approximately 500 microns such that the pores are adapted to facilitate tissue integration through the tubular wall of the suture when introduced into a body, wherein the suture is uniform in diameter along substantially its entire length and the diameter is in a range of approximately 1 mm to approximately 5 mm.
2. The medical device of claim 1, wherein the tubular wall of the suture extends along the entirety of the suture between the first and second ends.
3. The medical device of claim 1, wherein the pore size is in a range of approximately 500 microns to approximately 4 millimeters.
4. The medical device of claim 1, wherein the pore size is in the range of approximately 500 microns to approximately 2.5 millimeters.
5. The medical device of claim 1 wherein the pore size is in the range of approximately 1 millimeter to approximately 2.5 millimeters.
6. The medical device of claim 1, wherein the pore size is approximately 2 millimeters.
7. The medical device of claim 1, wherein the plurality of pores vary in pore size.
8. The medical device of claim 1, wherein the suture is constructed of a material selected from the group consisting of: polyethylene terephthalate, nylon, polyolefin, polypropylene, silk, polymers p-dioxanone, co-polymer of p-dioxanone, ε-caprolactone, glycolide, L(−)-lactide, D(+)-lactide, meso-lactide, trimethylene carbonate, polydioxanone homopolymer, and combinations thereof.
9. The medical device of claim 1, wherein the suture is radially deformable such that the suture adopts a first cross-sectional profile in the absence of lateral stress and a second cross-sectional profile in the presence of lateral stress.
10. The medical device of claim 9, wherein the first cross-sectional profile exhibits radial symmetry.
11. The medical device of claim 10, wherein the second cross-sectional profile exhibits partially or wholly collapsed conformation.
12. The medical device of claim 1, wherein the suture has a circular cross-sectional profile when in a non-stressed state.
13. The medical device of claim 1, further comprising an anchor attached to the second end of the suture for preventing suture pull through during use, the anchor having a dimension that is larger than a diameter of the suture.
14. The medical device of claim 13, wherein the anchor comprises a loop, a ball, a disc, a cylinder, a barb, and/or a hook.
15. The medical device of claim 1, wherein the tubular wall comprises a woven or knitted mesh material.
16. The medical device of claim 1, wherein the hollow core is a hollow cylindrical space.
17. The medical device of claim 1, wherein the hollow core includes a honeycomb structure, a 3D lattice structure, or other suitable matrices defining one or more interior voids.
18. The medical device of claim 1, wherein the second end of the elongated mesh suture is not connected to a needle.
19. The medical device of claim 1, wherein the second end of the elongated mesh suture is one of (a) a free end, (b) an end connected to an anchor, (c) an end having a loop, (d) an end connected to a barb, or (e) an end connected to another surgical needle.
20. A method of re-apposing soft tissue, the method comprising:
piercing a portion of the soft tissue with a surgical needle; and
threading an elongated mesh suture through the soft tissue, the elongated mesh suture having a first end and a second end located away from the first end, wherein the first end is selected from the group consisting of (a) an end directly attached to the surgical needle, (b) a free end, and (c) an end having a loop,
wherein the tubular elongated mesh suture further comprises a tubular wall, a hollow core inside of the tubular wall, and a plurality of pores extending through the tubular wall, at least some of the pores having a pore size that is greater than or equal to approximately 500 microns such that the tubular suture is adapted to accommodate the soft tissue growing through the tubular mesh wall and into the hollow core, thereby integrating with the suture, the elongated mesh suture further being uniform in diameter along substantially its entire length and with a diameter in a range of approximately 1 mm to approximately 5 mm.
21. The method of claim 20, wherein threading the tubular suture through the soft tissue comprises making a plurality of stitches.
22. The method of claim 20, further comprising anchoring the tubular suture in place in the soft tissue after threading the tubular suture through the soft tissue.
23. The method of claim 22, wherein anchoring the tubular suture in place comprises passing the surgical needle through a closed loop anchor at the second end of the tubular suture and creating a cinch for anchoring the suture to the soft tissue.
24. The method of claim 20, wherein a second end of the tubular mesh suture, which is opposite from the first end, is not connected to a needle.
25. The method of claim 20, wherein a second end of the tubular mesh suture is one of (a) a free end, (b) an end connected to an anchor, (c) an end having a loop, (d) an end connected to a barb, or (e) an end connected to another surgical needle.
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