Two-sides gripping knit

Abstract

The invention relates to a knit having barbs protruding outwards from both faces obtained by knitting yarns of biocompatible material in guide-bars B2, B3 and B4 of a knitting machine, wherein the knitting patterns followed by guide-bars B2 and B3 involve at least two needles and produce an arrangement of yarns defining two faces of the knit, the knitting pattern followed by guide-bar B4 making stitches generating loops protruding outwards from each of the faces of the knit, guide-bar B4 being threaded with a hot-melt monofilament yarn, heat-setting the knit, forming barbs by cutting the loops via melting.

Claims

1. A method for manufacturing a prosthetic porous knit comprising an arrangement of yarns of biocompatible material defining at least two faces of the knit, said knit provided with barbs protruding outwards from each of the at least two faces, said method comprising: i) providing a warp knitting machine comprising one needle-bed comprising a first guide-bar B1, a second guide-bar B2, a third guide-bar B3, and a fourth guide-bar B4, ii) knitting yarns of biocompatible material on the warp knitting machine to form the knit, wherein: the first guide-bar B1 is either unthreaded or threaded with the yarns of biocompatible material and follows a knitting pattern involving at least two needles, the second guide-bar B2 and the third guide-bar B3 are threaded with the yarns of biocompatible material and follow knitting patterns involving at least two needles and producing the arrangement of yarns defining the at least two faces of the knit, the fourth guide-bar B4 is threaded with a hot-melt monofilament yarn of biocompatible material and follows a knitting pattern making stitches generating loops protruding outwards from each of the at least two faces of the knit, iii) heat-setting the knit obtained at ii), iv) forming barbs by melting the loops.

2. The method according to claim 1, wherein the knitting patterns each followed by the second guide-bar B2 and the third guide-bar B3 involve between two and eight needles.

3. The method according to claim 1, wherein the knitting patterns each followed by the second guide-bar B2 and the third guide-bar B3 involve between three and seven needles.

4. The method according to claim 1, wherein the knitting patterns each followed by the second guide-bar B2 and the third guide-bar B3 involve between six and seven needles.

5. The method according to claim 1, wherein the knitting patterns each followed by the second guide-bar B2 and the third guide-bar B3 make stitches.

6. The method according to claim 1, wherein the knitting pattern followed by the fourth guide-bar B4 involves between three and six needles.

7. The method according to claim 1, wherein the knitting pattern followed by the fourth guide-bar B4 involves between four and five needles.

8. The method according to claim 1, wherein the first guide-bar B1 is unthreaded.

9. The method according to claim 1, wherein the second guide-bar B2 and the third guide-bar B3 are each threaded two full, three empty, according to the following knitting pattern: B2: 5-6/3-4/1-0/4-3// B3: 1-0/3-2/5-6/2-3//.

10. The method according to claim 9, wherein the fourth guide-bar B4 is threaded one full, four empty, according to the following knitting pattern: B4: 5-4/2-3/0-1/3-2//.

11. The method according to claim 1, wherein the second guide-bar B2 and the third guide-bar B3 are each threaded one full, two empty, according to the following knitting pattern: B2: 0-1/3-4/7-6/4-3/0-1/2-1// B3: 7-6/4-3/0-1/3-4/7-6/5-6//.

12. The method according to claim 11, wherein the fourth guide-bar B4 is threaded one full, two empty, according to the following knitting pattern: B4: 4-3/1-2/0-1/2-1/4-3/2-2//.

13. The method according to claim 1, wherein the hot-melt material forming the monofilament yarn threaded in the fourth guide-bar B4 is poly-L-lactic acid.

14. The method according to claim 1, wherein the diameter of the monofilament yarn threaded in the fourth guide-bar B4 varies from 0.12 to 0.18 mm.

15. The method according to claim 1, wherein yarns threaded on the second guide-bar B2 and the third guide-bar B3 are made of polyethylene terephthalate.

16. The method according to claim 1, wherein the knit displays a tensile breaking elongation in a warp direction of at least 50%.

17. The method according to claim 16, wherein the tensile breaking elongation in the warp direction is at least 70%.

18. The method according to claim 16, wherein the tensile breaking elongation in the warp direction is at least 100%.

19. A prosthetic porous knit made from the method of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood from the following detailed description and examples, and also from the figures, in which:

(2) FIG. 1A is a schematic view of a knitting pattern suitable for guide-bar B2 of the method and knit of the invention,

(3) FIG. 1B is a schematic view of a knitting pattern suitable for guide-bar B3 of the method and knit of the invention,

(4) FIG. 1C is a schematic view of a knitting pattern suitable for guide-bar B4 of the method and knit of the invention,

(5) FIG. 2 is a schematic view of the knitting patterns of FIGS. 1A-1C shown together, permitting production of a knit according to the invention.

EXAMPLE 1

(6) A prosthetic knit according to the invention is produced on a warp knitting machine with four guide bars B1, B2, B3 and B4, as described above, where the bar B1 is in position 1 on the knitting machine, the bar B2 is in position 2, the bar B3 is in position 3, and the bar B4 is in position 4.

(7) Guide-bar B1 is unthreaded.

(8) Guide-bars B2 and B3 are threaded two full, three empty, according to the following knitting pattern according to the standard ISO 11676 (publication year 2014): B2: 5-6/3-4/1-0/4-3// B3: 1-0/3-2/5-6/2-3//

(9) And Guide-bar B4 is threaded one full, four empty, according to the following knitting pattern according to the standard ISO 11676 (publication year 2014): B4: 5-4/2-3/0-1/3-2//

(10) The yarns threaded in guide-bars B2 and B3 are monofilaments made of polyethylene terephthalate (PET) having a diameter of 0.09 mm.

(11) The yarns threaded in guide-bar B4 are monofilaments of poly-L-lactic acid (PLLA) having a diameter of 0.15 mm.

DETAILED DESCRIPTION OF EMBODIMENTS

(12) The respective knitting patterns for B2, B3 and B4 are illustrated in FIGS. 1A to 1C in a representation well known to a person skilled in the art, where wa indicates the warp direction and we indicates the weft direction. For each Figure, the graphic shows the movement of the guide-bar. The guide-bars' movement is read from bottom to top, the first knitted course being at the bottom.

(13) As appears on these figures, six needles (numbered from 1 to 6 on the figures) are used for each knitting pattern of B2 and B3. A set of five needles (numbered from 1 to 5 on the figure) is used for the knitting pattern of B4.

(14) In FIG. 2 is illustrated the combination of the three knitting patterns indicated by a fine line for B2, by a dot-and-dash line for B3, and by a solid line for B4, where wa indicates the warp direction and we indicates the weft direction.

(15) The yarns threaded in B2 and B3 constitute the base of the knit of the present knit, since the hot-melt monofilament yarn, intended to generate the barbs, will be regularly cut during the melting step. The knitting patterns of guide-bars B2 and B3 produce an arrangement of yarns defining the two faces of the knit. They make stitches.

(16) The combination of the knitting patterns, as described in this example, makes it possible to directly produce, by knitting, a porous knit which, on each of its two faces, has loops capable of giving rise to outwardly protruding barbs.

(17) On FIG. 2 are shown two stitches 101 and 102 produced by guide-bar B4. Stitch 101 is for example the stitch produced on a first side of the knit, that will generate a loop on said first side of the knit, and further on barbs, after melting of the loop. Stitch 102 is the stitch produced on the opposite side of the knit that will generate a loop on said opposite side of the knit, and further on barbs, after melting of the loop.

(18) Once the knit has been produced as indicated above, it is heat-set, for example at 110 C., in order to stabilize it in length and width.

(19) After the heat-setting step, each face of the knit is placed in contact with a cylinder containing an electrical heating resistor so as to melt the loops present on said face.

(20) In the present example, the melting point of poly-L-lactic acid being 165 C., the cylinder is heated at a temperature T of 250 C.

(21) On melting, each loop produced by monofilaments of guide-bar B4 cuts in two and gives rise to two barbs protruding outwards from the face of the knit, each barb preferably having a head with dimensions greater than those of the diameter of the monofilament yarn forming the initial loop.

(22) The following properties of the knit of the invention of the present example have been determined as follows:

(23) Linear density (g/m.sup.2): measured according to ISO 3801: 1977 Determination of mass per unit length and mass per unit area, 5 samples, 1 dm.sup.2 disk,

(24) pore size (widthheight) (mm): knit biggest pores width and height are measured making one measurement on 5 individual samples of dimensions 10050 mm, with a profile projector such as a projector,

(25) Thickness: is measured according to ISO 9073-2: 1997 Textilestest methods for nonwovensPart 2: Determination of thickness, method used for voluminous nonwovens with a thickness less than 20 mm, 10 samples, 10050 mm,

(26) Tensile strength (N), tensile elongation (%) and elongation under 50 N (%): are measured according to ISO 13934-1: 1999 Determination of breaking strength and elongation, 5 samples, width: 50 mm, length: 200 mm between the jaws, Crosshead speed: 100 mm/min, Pre-load: 0.5 N, using a traction testing machine such as the Hounsfield model H5KS (Hounsfield, Redhill, England),

(27) Bursting strength (kPa): measured according to ISO 13938-2: 1999 TextilesBursting properties of fabricsPneumatic method for determination of bursting strength and bursting deformation, 5 samples using a Bursting strength tester, heal model Truburst,

(28) Suture pull out strength in the warp direction and in the weft direction measured as follows: a USP 2 suture yarn is passed through a pore of a 50100 mm sample, at 10 mm from the edge of a small side of the sample, and is tracted away using a traction testing machine such as the Hounsfield model H5KS (Hounsfield, Redhill, England) with the following conditions: 5 samples, width 50 mm, 100 mm between the jaws, crosshead speed: 100 mm/min,

(29) Tear strength (N) in the warp direction and in the weft direction: measured according to superseded ISO 4674:1977 Determination of tear resistance of coated fabrics Method A2, 5 samples, width: 75 mm, Tear length145 mm, crosshead speed: 100 mm/min.

(30) The results are collected in the following table:

(31) TABLE-US-00001 TABLE I properties of the knit Property Knit of present example Surface density (g/m.sup.2) 87 Thickness (mm) 4.1 Pore size (mm.sup.2) (width height) 1.7 1.6 Bursting strength (kPa) 132 8 Warp Weft Tensile breaking strength (N) 112 8 239 6 Tensile breaking elongation (%) 108 6 49 1 Tensile Elongation under 50N (%) 85 2 19 1 Tear strength (N) 29 2 27 3 Suture pull-out strength (N) 41 4 35 4

(32) The knit of the invention of the present example therefore shows a tensile breaking elongation of 108% in the warp direction and a tensile breaking elongation of 49% in the weft direction. This knit further shows a tensile elongation under 50 N of 85% in the warp direction and a tensile elongation under 50 N of 19% in the weft direction.

(33) The knit of the present example is therefore particularly adapted for approximating two tissue layers that have been previously separated, by gripping one tissue layer via the barbs of one of its faces, and gripping the other tissue layer via the barbs of its other face. Thanks to the elongation properties of the knit, the approximated tissue layers are free to move with respect to each other, while being firmly attached to each other, thereby being capable of smoothly adapting to pressures of various directions and intensities generated by the movements of a patient in its daily life.

(34) Such a knit can be used as it is, directly as a two-sides fixation patch for approximating two tissue layers which have been previously separated or as a prosthesis in parietal or visceral surgery for wall reinforcement. Alternatively, this knit can be combined with another textile, with two textiles (one on each face), or with an anti-adhesion film on one or both of its faces. The barbs can be covered with an anti-adhesion coating to prevent them from becoming entangled in the body of the knit when the latter is folded up on itself, for example in order to be introduced into a trocar.

(35) The knit of the present example further allows preventing the apearance of seroma subsequent to surgery.

EXAMPLE 2 (COMPARATIVE)

(36) A comparative knit, having barbs protruding outwards from both faces, has been manufactured according to the following method: the comparative knit is produced on a warp knitting machine with four guide bars B1, B2, B3 and B4, where the bar B1 is in position 1 on the knitting machine, the bar B2 is in position 2, the bar B3 is in position 3, and the bar B4 is in position 4.

(37) Guide-bar B1 is threaded one full, three empty according to the following knitting pattern according to the standard ISO 11676 (publication year 2014): B1: 2-3/2-1/1-0/1-2//

(38) Guide-bar B2 is threaded one full, one empty according to the following knitting pattern according to the standard ISO 11676 (publication year 2014): B2: 1-0/0-1//

(39) The knitting pattern of guide-bar B2 therefore involves only one needle.

(40) Guide-bar B3 is threaded one full, one empty according to the following knitting pattern according to the standard ISO 11676 (publication year 2014): B3: 1-0/5-5/1-0/3-3//

(41) Guide-bar B4 is threaded one full, three empty according to the following knitting pattern according to the standard ISO 11676 (publication year 2014): B4: 2-1/5-5/3-4/0-0//

(42) The yarns threaded in guide-bars B2 and B3 are monofilaments made of polyethylene terephthalate (PET) having a diameter of 0.09 mm.

(43) The yarns threaded in guide-bars B1 and B4 and intended to generate the barbs are monofilaments of poly-L-lactic acid (PLLA) having a diameter of 0.15 mm.

(44) The tensile breaking elongation and the tensile elongations under 50 N in the warp direction and in the weft direction have been measured for the comparative knit according to the methods described at Example 1.

(45) The results are collected in the following table:

(46) TABLE-US-00002 TABLE II comparison of elongation parameters between a knit of the invention and a comparative knit Comparative knit of Knit of Example 2 Example 1 Property Warp Weft Warp Weft Tensile breaking 45 4 108 8 108 6 49 1 elongation (%) Tensile 12 2 45 2 85 2 19 1 Elongations under 50N (%)

(47) As appears from these results, the knit of the invention shows a tensile breaking elongation in the warp direction more than two times higher than that of the comparative knit. The knit of the invention further shows tensile elongation under 50 N in the warp direction more than six times higher than that of the comparative knit.

(48) The knit of the invention is therefore particularly adapted to conform to the variations of intensity and of direction of pressures in the anatomy of a person subsequent to the movements of this person during his daily life.