- the mass per unit area of a knit is measured according to ISO 3801,
- the breaking strength of a knit in the longitudinal direction and in the transverse direction is measured according to ISO 13934-1,
- the elongation under 2 daN in the longitudinal direction is measured according to ISO 13934-1.

In a preferred embodiment of the invention, the knit comprises at least one percent of free chain yarns spaced regularly or irregularly along the transverse dimension of the knit.

More preferably, the knit comprises at least ten percent of free chain yarns spaced regularly along the transverse dimension of the knit.

Advantageously, the knit according to the invention comprises a non-meshing sheet with the following chart: 0-0/2-2//.

In a preferred embodiment of the invention, the knit according to the invention comprises at least two non-meshing sheets. The reason for this is that the presence of two non-meshing sheets, in particular of two intersecting non-meshing sheets, that is to say sheets whose respective guide bars move symmetrically in relation to one another, offset from one another in the direction of production of the knit on the knitting machine, makes it possible to obtain tapes and/or implants exhibiting very good resistance to lateral compression. Thus, when the two opposite longitudinal edges of a textile medical device, in particular of a tape and/or implant, obtained from the knit according to the invention, are compressed, for example between two fingers, this textile medical device, in particular this tape and/or implant, retains significantly the same width. Preferably, the loss of width of a medical device, in particular of a tape and/or implant, according to the invention, under the effect of its two opposite longitudinal edges being compressed between two fingers, is less than 10%. The medical devices, in particular the tapes and/or implants, according to the invention are therefore particularly stable with respect to their manipulation and to their passage through possible auxiliary equipment (eyes of needles, cannulas, etc.) and through the patient's tissue (limitation of cord effect).

In a preferred embodiment of the invention, the knit comprises a first non-meshing sheet and a second non-meshing sheet, said first non-meshing sheet having the chart 1-1/3-3/2-2/0-0//, said second non-meshing sheet having the chart 3-3/2-2/0-0/1-1//.

Preferably, the distance between said free chain yarns, along the transverse dimension of the knit, ranges from 0.5 cm to 2 cm, preferably from 0.5 cm to 1.5 cm.

Preferably, the knit according to the invention is a prosthetic knit. Thus, preferably, the knit is made from monofilament or multifilament yarns of a biocompatible polymer material chosen from polypropylene, polyester, polyamide and mixtures thereof. Advantageously, said biocompatible polymer material is polypropylene.

In another embodiment, the knit according to the invention is made from monofilament or multifilament yarns of a biocompatible and bioabsorbable polymer material.

In yet another embodiment, the knit according to the invention is made from a mixture of biocompatible yarns that are bioabsorbable and of biocompatible yarns that are not bioabsorbable.

Preferably, the knit according to the invention is made from monofilament yarns having a diameter ranging from 0.05 mm to 0.15 mm, preferably of approximately 0.10 mm.

Preferably, the knit according to the invention has a thickness ranging from 0.20 mm to 0.40 mm, preferably of approximately 0.30 mm.

Preferably, the knit according to the invention is an openworked knit. Thus, in a preferred embodiment of the invention, the knit according to the invention comprises holes having a diameter ranging from 0.3 to 1.5 mm, preferably ranging from 0.3 to 0.9 mm. Such a knit permits production of a support implant that has good tissue anchoring.

Preferably, the knit according to the invention is thermoset.

Preferably, the textile medical device according to the invention has a width ranging from 0.5 cm to 2 cm, preferably ranging from 0.5 cm to 1.5 cm.

Advantageously, the textile medical device according to the invention has a mass per unit area ranging from 40 to 100 g/m², preferably from 50 to 75 g/m², and more preferably from 50 to 60 g/m².

Preferably, the textile medical device according to the invention has a thickness ranging from 0.20 mm to 0.40 mm, preferably of approximately 0.30 mm.

Preferably, the textile medical device according to the invention comprises holes having a diameter ranging from 0.3 to 1.5 mm, preferably ranging from 0.3 to 0.9 mm.

Preferably, the textile medical device according to the invention has a breaking strength, in the longitudinal direction and transverse direction, ranging from 20 to 90 N, preferably from 40 to 90 N, preferably from 55 to 75 N, more preferably from 60 to 70 N, measured according to ISO 13934-1.

Thus, the textile medical device according to the invention has excellent mechanical strength, or breaking strength, and at the same time quite a low mass per unit area. A textile medical device of this kind is particularly advantageous as a support implant, because it provides effective support of the organs to be treated and at the same time reduces to a minimum the mass of the implanted foreign body.

Preferably, the textile medical device according to the invention has an elongation under 2 daN, in the longitudinal direction, of less than or equal to 15%, more preferably of less than or equal to 10%, measured according to ISO 13934-1. Such a textile medical device is thus particularly stable dimensionally.

Preferably, the textile medical device according to the invention is an openworked prosthetic device and constitutes a support implant for the treatment of stress urinary incontinence and/or prolapses.

Moreover, since the textile medical device according to the invention preferably corresponds to a zone of the knit according to the invention that is situated between two consecutive free chain yarns, it does not comprise free chain yarns. There is therefore no risk of its unraveling.

Preferably, the knit according to the invention is produced by a method comprising the following step:

Preferably, the chart followed for knitting the yarns of each non-meshing sheet is such that for at least one percent, preferably for at least ten percent, of the yarns of the chain structure, called free chain yarns, seen in the direction of production of the knit, all yarn of said non-meshing sheets approaching said free chain yarns makes a 180 degree turn at these free chain yarns.

Therefore, according to the method of manufacture of the knit according to the invention, all chain yarns, be they free or not, are knitted with the same guide bar.

In one embodiment of the method according to the invention, a single non-meshing sheet is used, the yarns of the first sheet for the chain structure being knitted according to a chart 1-0/0-1//, the yarns of the non-meshing sheet being knitted according to a chart 0-0/2-2//.

Preferably, the guide bar of the first sheet is drawn continuously and full, and the guide bar of the non-meshing sheet is drawn continuously and full.

In a preferred embodiment of the method according to the invention, at least two non-meshing sheets are used. Preferably, two non-meshing sheets are used, the guide bars of said two non-meshing sheets moving symmetrically in relation to one another, offset from one another in the direction of production of the knit.

Advantageously, a first non-meshing sheet and a second non-meshing sheet are used, the yarns of the first sheet for the chain structure being knitted according to a chart 1-0/0-1//, the yarns of the first non-meshing sheet being knitted according to a chart 1-1/3-3/2-2/0-0//, the yarns of the second non-meshing sheet being knitted according to a chart 3-3/2-2/0-0/1-1//.

Preferably, the guide bar of the first sheet for the chain structure is drawn continuously and full, the guide bar of the first non-meshing sheet is drawn continuously and 1 full, 1 empty, 3 full, 1 empty, 1 full, 3 empty, and the guide bar of the second non-meshing sheet is drawn continuously and 1 full, 1 empty.

Advantageously, the two guide bars of the two non-meshing sheets move in partial weft under three needles, symmetrically in relation to one another, and offset from one another in the direction of production of the knit. Such knitting, with the weft bars moving symmetrically in relation to one another and thus intersecting, makes it possible to obtain better holding of the chains and thus better resistance to lateral compression of the implants and/or tapes that are obtained from the knit according to the invention.

The knit, on leaving the knitting machine, is preferably subjected to a thermosetting operation. The knit is therefore easy to manipulate, in particular for the unraveling step. Moreover, all the tapes and implants obtained from the same thermoset knit exhibit a homogenous thermosetting, making it possible to better guarantee the homogeneity of the physico-mechanical properties from one tape to another after unraveling.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood from the following description in which reference is made to the attached drawings, where:

FIG. 1 is a simplified schematic representation of a knit comprising a first sheet of chain structure, and two non-meshing sheets,

FIG. 2 represents a prosthetic knit according to the invention in which two free chain yarns are partially unraveled,

FIG. 3 is a drawing of a view taken with a Hitachi S 800 scanning electron microscope at a magnification of ×20, showing the unraveling of a free chain yarn in a knit according to the invention,

FIG. 4 is a drawing of a view taken with a Hitachi scanning electron microscope at a magnification of ×20, showing the core of an implant according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

InFIG. 1, for a knit according to the invention, E-E′ defines the transverse direction or dimension of the knit, F-F′ the longitudinal direction or dimension of the knit, and G-G′ the diagonal direction or dimension of the knit.

This figure shows the movements of the chain yarns and of the weft yarns for a knit according to the invention having a chain sheet and two non-meshing sheets. The yarns A and A1 of the chain structure are indicated by thick solid lines. The yarn A1 is a free chain yarn within the meaning of the present invention. Yarns A are chain yarns which are not free within the meaning of the present invention. The yarns of the first non-meshing sheet are indicated by thin solid lines: these are the yarns B. The yarns of the second non-meshing sheet are shown by a broken line: these are the yarns C.

In this example, the first guide bar, corresponding to the chain structure, is drawn continuously and full. The second guide bar, corresponding to the first non-meshing sheet and to the yarns B, is drawn continuously and 1 full, 1 empty, 3 full, 1 empty, 1 full, 3 empty. The third guide bar, corresponding to the second non-meshing sheet and to the yarns C, is drawn continuously and 1 full, 1 empty.

The knitting charts for these three sheets are as follows:

- the chain sheet (yarns A and A1): 1-0/0-1//,
- the first non-meshing sheet (yarns B): 1-1/3-3/2-2/0-0//,
- the second non-meshing sheet (yarns C): 3-3/2-2/0-0/1-1//.

Thus, the chain yarn A1, as it is shown inFIG. 1, is not completely crossed by any weft yarn, or, to put it another way, all weft yarn, that is to say all yarn B or C, approaching said chain yarn A1, is optionally linked with said chain yarn A1, and then makes a 180 degree turn at this chain yarn A1.

The free chain yarn A1 can thus be unraveled without affecting the adjacent chain yarns A, which are not free within the meaning of the present application, and, therefore, without destructuring the knit on either side of this yarn A1. By pulling the chain yarn A1, the part of the knit situated to the left of this yarn A1 is separated from the part situated to the right of this yarn A1 without unraveling these two parts.

Moreover, because all weft yarn approaching the yarn A1 makes a 180 degree turn at this yarn A1, the edges of the separated parts have only one yarn B or C making an 180 degree turn and for this reason are smooth. No fraying takes place.

This unraveling of a free chain yarn A1 in a knit according to the invention can be seen inFIG. 3, which is the drawing of a photograph, taken with the Hitachi S 800 scanning electron microscope, at a magnification of ×20, of a zone of unraveling of a knit according toFIG. 1 and of Example 1 of the present application. In the upper part of the figure, the yarn A1 is unraveled and the parts of the knit on either side of this yarn A1 have not been destructured. Their edges are smooth: only one yarn C makes a 180 degree turn. No yarn of the knit is cut or frayed. As appears clearly fromFIG. 3, thanks to the specific threading of the yarns of the non-meshing sheets, the yarn C doing a one hundred and eighty degree turn at the edge of a separated part is integral with the core of said separated part. In this figure, the yarn A1 is in the process of unraveling. Thus, at the bottom of the figure, the yarn A1 is still meshed with the yarns C approaching it.

At the end of the unraveling, that is to say when the yarn A1 has been unraveled along the entire length of the knit, the yarn A1 is removed from the knit according to the invention, and the two parts of the knit situated on either side of this yarn A1 are completely separated. By unraveling a second free chain yarn in the same way, a tape is separated completely from the knit. The distribution of the yarns A1 allows the width of each tape to be determined with great precision.

FIG. 2 is a schematic representation of a knit1 according to the invention for which the free chain yarns A1 are spaced regularly within the knit. Two of these yarns, the yarns A11 and A12, are partially unraveled. Thus, by completely unraveling these free chain yarns A11 and A12, a textile medical device2 according to the invention is obtained.

The core of a textile medical device according to the invention is shown inFIG. 4, which is the drawing of a photograph taken with the Hitachi S 800 scanning electron microscope at a magnification of ×20. The core of a textile medical device according to the invention preferably corresponds to a zone of the knit according to the invention situated between two consecutive free chain yarns. Therefore, the textile medical device itself does not comprise free chain yarns. There is therefore no risk of its unraveling.

EXAMPLE

A knit according to the invention was produced from a monofilament yarn of polypropylene, diameter 0.10 mm, on a Raschel machine, with a chain sheet and two non-meshing sheets, the following charts being used for the various sheets:

- the chain sheet: 1-0/0-1//,
- the first non-meshing sheet: 1-1/3-3/2-2/0-0//,
- the second non-meshing sheet: 3-3/2-2/0-0/1-1//.

The first guide bar, corresponding to the chain structure, was drawn continuously and full. The second guide bar, corresponding to the first non-meshing sheet, of partial weft, was drawn continuously and 1 full, 1 empty, 3 full, 1 empty, 1 full, 3 empty. The third guide bar, corresponding to the second non-meshing sheet, of partial weft, was drawn continuously and 1 full, 1 empty. The two partial wefts were drawn so as to move under nine chain yarns, by which means it was possible to finally obtain tapes separated by approximately 1 cm of width each. Therefore, in this example, 1 chain yarn in 10, that is to say ten percent, was a free chain yarn within the meaning of the invention.

The gauge used was 24 needles.

The guide bars of the two non-meshing sheets moved in partial weft under three needles, symmetrically in relation to one another, offset from one another in the direction of production of the knit.

This knit corresponds to the structure represented inFIG. 1 of the present application.

On leaving the knitting machine, the knit was subjected to a thermosetting operation.

The knit had the following characteristics:

- thickness: approximately 0.3 mm,
- diameter of the meshes: approximately 1 mm.

Tapes were obtained from this knit by unraveling at least two consecutive free chain yarns. The tapes had the following characteristics:

- thickness: approximately 0.3 mm,
- diameter of the meshes: approximately 1 mm,
- width: approximately 1 cm,
- mass per unit area: approximately 50 g/m²,
- breaking strength measured by the method according to ISO 13934-1 on a tape with a width of 1 cm and a length of 20 cm: 66 N.

The tape thus obtained by unraveling of at least two free, and preferably consecutive, chain yarns of the knit according to the invention has excellent tensile strength and is thus eminently suitable for use as, or for production of, a support implant for treating stress urinary incontinence and prolapses.

For example, an implant measuring 20 cm in length, or cm in length, or even 40 cm in length, can be prepared from this tape.

Moreover, by virtue of its method of production, this implant has edges, in particular longitudinal edges, which are smooth and do not cause trauma. Finally, all the tapes or implants obtained from the same knit have undergone homogeneous thermosetting and are easy to manipulate.