Patent Description:
Meshes are used in many medical applications, including as implants to repair or restructure tissue, such as skin, fat, fascia, and/or muscle. One common application for such meshes is in hernia repair, such as abdominal wall hernia repairs. A hernia is a protrusion of an organ or tissue through an opening or weakness in the walls that normally retain the organ or tissue within a confined space. Most commonly, hernias occur in the abdominal region; however, hernias may occur in many locations throughout the body, including but not limited to the head, thorax/chest, pelvis, groin, axilla, and upper and lower extremities. Traditionally, there are two main types of surgical hernia repairs: open and laparoscopic hernioplasty. In both types, the hernia defect is closed and reinforced by surrounding tissues.

<CIT> relates to a prosthetic open knit fabric made as a single piece, based on an arrangement consisting of several sets of yarns of a biocompatible polymer material, comprising, continuously in the direction of production of the knit, a central strip and two lateral strips, one on each side of the central strip, characterized in that it comprises one or more set(s) of pillar stitch yarns defining a pillar stitch pattern, the said one or more set(s) of pillar stitch yarns extending across the entire width of the central strip and of the lateral strips and together forming a first threading across the width of the central strip and a second threading across the width of the lateral strips, the said first and second threading being different, and at least two partial weft stitching sets. <CIT> relates to a knitted fabric consisting of weft composed of chains of knitted loops and a warp of filling threads in which the loops are so formed in that it is reportedly impossible, by cutting or removing one loop, to ravel the corresponding chain, and in which the open spaces are rendered less pronounced by causing the weft threads, at intervals, to extend between adjacent chains. The resulting fabric is described as especially adapted for towels, wash cloths and similar goods.

In one embodiment, a warp knitted fabric is a biocompatible implantable mesh for use in reconstructing tissue and includes a first knitted portion formed of a first knitting sequence in a lengthwise direction, and a second knitted portion formed of a second knitting sequence in the lengthwise direction, the second knitted portion comprising at least two strips extending in the lengthwise direction, the at least two strips being detached from one another along their lengthwise edges such that the fabric has slits or holes between the strips and that run the length of the strips, which is approximately or nearly the length of the second knitted portion. The second knitted portion has the same width as the first knitted portion, and the first knitted portion and the second knitted portion alternate sequentially in the lengthwise direction and are formed of a single set of continuous biocompatible textile strands characterised in that the strands are not cut at the juncture between the knitted portions where the warp knit fabric changes from having a unitary width to forming two or more strips.

Also disclosed herein is a method of manufacturing a warp knitted fabric includes knitting a set of textile strands in a first knitting sequence in a machine direction on a warp knitting machine to form a first knitted portion, the first knitted portion having a width, and then knitting the set of textile strands in a second knitting sequence in the machine direction on the warp knitting machine to form a second knitted portion, the second knitted portion having the same width as the first knitted portion. The second knitted portion comprises at least two strips extending lengthwise in the machine direction, wherein the at least two strips are detached from one another along their lengthwise edges. The first knitting sequence and the second knitting sequence are alternately knitted sequentially in the machine direction to form a length of fabric.

In one embodiment, an implantable mesh comprises a mesh body formed using a first knitting sequence in a lengthwise direction, the mesh body having a width. The implantable mesh further includes a first set of two mesh extensions extending parallel to one another in the lengthwise direction from a first side of the mesh body, the at least two mesh extensions formed using a second knitting sequence, wherein the first knitted portion and the second knitted portion are formed continuously from a single set of textile strands.

The current recommendation for ventral hernia repair includes the use of mesh. Various factors contribute to the hernia recurrence; however, the inventors have recognized that failure of the mesh-either through degradation or mechanical failure-remains a significant problem. The inventors have recognized that one source of the problem of hernia repair failures is the construction of the mesh, as prior art meshes are typically a woven piece of material that gets sewn in to the repaired area with sutures. This causes problems, as the material can become unraveled and/or the connections between the sutures and the material can slip. Similar issues occur with other types of mesh or fabric implants.

Upon recognition of the problems and challenges in the relevant field, the inventors developed a warp knit fabric from which an implantable mesh of unitary construction can be created. The implantable mesh of the present disclosure minimizes possible failure points by minimizing the number of separate and/or cut strands in the fabric and by eliminating the need for sutures to fasten the mesh to the affected area. The inventors have further recognized that the developed warp knit fabric has multiple possible embodiments and possible applications, including various medical applications and industrial textile applications. Exemplary industrial textile applications include, but are not limited to, industrial netting for shipping and/or cargo restraint applications, netting for marine or aquatic applications, agricultural and hydroponic applications, or the like.

As illustrated in the figures, the warp knit fabric <NUM> has two different knitted portions <NUM> and <NUM> created using strategically differing knitting sequences, each knitted portion <NUM> and <NUM> extending across the width W of the fabric <NUM>. The first knitted portion <NUM> is formed using a first knitting sequence <NUM> and the second knitted portion <NUM> is formed using a second knitting sequence <NUM>, wherein the same textile strands are used in both the first and second sequences <NUM> and <NUM>. The two knitted portions are alternated in the lengthwise direction along the length L of the fabric <NUM>, and may be alternated at various interval lengths along the fabric as required based on the particular application of use for the fabric <NUM>. Whereas the first knitted portion <NUM> is constructed to form a fabric portion that is continually connected across the width W, the second knitted portion <NUM> is characterized by forming at least two strips <NUM> extending parallel and lengthwise in the lengthwise direction. The strips <NUM> are detached from one another along their lengths L", such that the fabric <NUM> has slits <NUM> or holes between the strips <NUM> and that run the length L" of the strips <NUM>, which is approximately or nearly the length of the second knitted portion <NUM>.

The strips <NUM> extend from the first knitted portion <NUM> and may generally continue the knitting sequence, or pattern, of the first knitted portion <NUM>, with only a change in the pattern along the lengthwise edges <NUM> of the strips <NUM>. Thus, portions of the second knitting sequence <NUM> may be the same as the first knitting sequence <NUM>-i.e., the pattern executed by certain guide bars may remain the same for both the first knitting sequence <NUM> and the second knitting sequence <NUM> (<FIG>). Thus, a middle portion <NUM> of the strips <NUM> (see <FIG>) may continue the same pattern used for the first knitted portion <NUM> in an uninterrupted fashion. In certain embodiments, the only change made in transitioning between the first knitting sequence <NUM> and the second knitting sequence <NUM> (and vice versa) is with respect to the guide bars knitting the lengthwise edges <NUM> of the strips <NUM>. In one embodiment, the first knitting sequence <NUM> differs from the second knitting sequence <NUM> for only a number of guide bars necessary to create the strips <NUM>. Thus, any guide bar executing a pattern that crosses over the slits <NUM> between the strips <NUM> is changed. Further, the number of textile strands <NUM> that change is dependent on the number of strips <NUM> in the second knitted portion <NUM>.

Since the warp knit fabric <NUM> is knitted from a single set of textile strands, and the strands are not cut anywhere along their lengths, the disclosed fabric <NUM> has excellent durability and avoids fraying or failures, including at the juncture between the knitted portions <NUM> and <NUM> where the warp knit fabric <NUM> changes from having a unitary width to forming two or more strips <NUM>. Depending on the intended application of use, the disclosed warp knit fabric <NUM> may be constructed using any number of warp knitting patterns, or sequences, using any type of textile strand, including any filament, filament yarn (including single filament or multi-filament yarns), or spun yarn. Likewise, the textile strands may be of a synthetic or natural material. For example, in certain embodiments of the warp knit fabric <NUM> for medical applications, the textile strands <NUM> may be of a synthetic biocompatible material such as, but not limited to, polypropylene, polyethylene terephthalate polyester, expanded polytetrafluroethylene (ePTFE), polyglactin, polyglycolic acid, trimethylene carbonate, poly-<NUM>-hydroxybutyrate (P4HB), polyglycolide, polyactide, and trimethylene carbonate (TMC). In other embodiments, the textile strands <NUM> may be from biocompatible and biological materials, including, but not limited to, human dermis, porcine dermis, porcine intestine, bovine dermis, and bovine pericardium. The textile strands <NUM> may also comprise a combination of synthetic and biologic materials.

The warp knit fabric <NUM> may be a tightly knitted, solid-looking fabric, or may be an openwork knit, such as a mesh, having openings, or pores, throughout. <FIG> exemplify one embodiment of the warp knit fabric <NUM> being an openwork mesh having diamond-shaped openings. <FIG> exemplify another embodiment of the warp knit fabric <NUM> wherein different knitting sequences are used to form the first and second knitted portions <NUM> and <NUM>. Any of various other embodiments are possible, and the knitting patterns shown are merely exemplary ways of forming the first and second knitted portions <NUM> and <NUM>, wherein the second knitted portion comprises two or more strips.

Referring to <FIG>, the warp knit fabric <NUM> is shown wherein the first knitted portion <NUM> is relatively short lengthwise compared to the length L" of the second portion <NUM> comprising the strips <NUM>. The fabric has a width W, and both the first knitted portion <NUM> and the second knitted portion <NUM> span, or at least approximately span, that same width W. In the depicted embodiment, the second knitted portion <NUM> comprises seven strips <NUM>, wherein each strip has the same width, represented as W". In other embodiments, the second knitted portion <NUM> may be formed by any number of two or more strips <NUM>, such as three strips, four strips, five strips, and so on. For example, the second knitted portion <NUM> may be divided into just two strips, and therefore having just one slit <NUM> in each second knitted portion <NUM> of the warp knit fabric <NUM>. The strips may be any width W" that is less than the width W. The strips may be of equal widths W" to one another, or the widths of the strips <NUM> may vary across the fabric. <FIG> provides an example wherein the second knitted portion <NUM> comprises strips <NUM> having varying widths, including narrower strips of width W<NUM>" and wider strips of width W<NUM>".

The lengths of the respective first and second knitted portion <NUM> and <NUM> may vary. In the embodiment of <FIG>, the length L' of the first knitted portion <NUM> is comparatively shorter than the length L" of the second knitted portion <NUM>. However, the lengths L and L' may be any value and any proportion with respect to one another. Thus, in other embodiments, the length L' of the first knitted portion <NUM> may be comparatively longer than the length L" of the second knitted portion <NUM>, or the lengths L' and L" of the first and second knitted portions <NUM> and <NUM> may be the same. Similarly, the lengths L' and L" may be varied along the length L of the entire fabric.

<FIG> exemplify knitting sequences that may be used to form the exemplary embodiment of <FIG>. The exemplary embodiment shown in <FIG> is constructed using a Raschel warp knitting machine having at least four guide bars. The exemplary embodiment shown in <FIG> is also constructed using a Raschel warp knitting machine having at least four guide bars. For example, embodiments may be knitted on a single needle bar or a double needle bar Raschel warp knitting machine, or a tricot knitting machine. In certain embodiments, an electronic guide bar control machine may be preferable because of the length of the two alternating knitted portions. The warp knitting machine is configured to alternate between the depicted first knitting sequences <NUM> and second knitting sequences <NUM> at predetermined intervals.

<FIG> are sequence diagrams depicting the first knitting sequence <NUM> and the second knitting sequence <NUM>, each of which may be repeated any number of times in the machine direction before transitioning to the other knitting sequence. For example, in <FIG> the first knitting sequence <NUM> is repeated twice, and then the second knitting sequence follows, such as for eight repetitions. Each knitting sequence <NUM>, <NUM> includes a repeatable ten-stitch pattern involving five guide bars (GB2 through GB6). <FIG> depicts the sequence for each guide bar GB2 through GB6. As can be seen from <FIG> and <FIG>, the first knitting sequence <NUM> and the second knitting sequence <NUM> are the same for three of the five guide bars. GB2, GB3, and GB5 execute the same pattern in both the first knitting sequence <NUM> and the second knitting sequence <NUM>. The pattern changes for two of the guide bars, GB4 and GB6. Namely, in the first knitting sequence <NUM>, GB4 and GB6 cross over a neighboring needle every fifth stitch in order to connect, or create joints, with the strands in the neighboring row. This forms the mesh connections across the width of the mesh. In the second knitting sequence <NUM>, the cross connections made by guide bars GB4 and GB6 are dropped and the stitch stays on the same needle row for the length of the second knitting sequence <NUM>.

<FIG> provides another diagram showing the knitting sequences <NUM> and <NUM> showing repetition of the guide bar stitch patterns. In various embodiments, the stitches created by each guide bar may be repeated any number of times to create any width W of fabric <NUM>. Moreover, the edge stitch may vary from that shown, depending on how the edge is finished. As shown in the embodiment of <FIG>, the fabric edge <NUM> may be formed by a constant and continuous stitch sequence that remains the same for the first knitted portion <NUM> and the second knitted portion <NUM>, which may be the same or similar stitch sequence as used to form the lengthwise edges <NUM> of the strips <NUM>.

The color ledger at the bottom of <FIG> corresponds to the stitching sequences shown above, where the colored boxes in the guide bar ledger vertically align with and indicate the presence of the stitch in the needle rows above the ledger. The textile strands on guide bar GB2 are shown in green, those on guide bar GB3 are shown in dark blue, those on guide bar GB4 are shown in yellow, those on guide bar GB5 are indicated in light blue, and those on guide bar GB6 are indicated in purple. For the purposes of the international application, these colors are shown in the ledger as differential hatching. For clarity, the left-most portion of <FIG> shows the textile strands <NUM> of only guide bars GB4 and GB6 separated from the textile strands on guide bar GB2 so that the pattern executed by guide bars GB4 and GB6 can be seen more clearly (because that portion changes between the first knitting sequence <NUM> and the second knitting sequence <NUM>). It will be understood by a person having ordinary skill in the art that in actual implementation, the textile strands on guide bars GB4 and GB6 would each interlace with textile strands following the pattern on guide bar GB2, but that guide bar GB2 is not shown on the two left-most rows for clarity purposes so that aspect of the sequences <NUM> and <NUM> are more visible.

<FIG> depicts another embodiment, or execution of the first and second knitting sequences. In the depicted embodiment, the second knitted portion <NUM> includes strips <NUM> of varying widths W<NUM>" and W<NUM>'', and the second knitting sequence is repeated sequentially for a predetermined number of times (which in the depicted embodiment is at least three repetitions), whereas the first knitting sequence <NUM> is repeated only twice before returning to the second knitting sequence <NUM>. Thus, the length of the first knitted portion <NUM> is much shorter than the second knitted portion <NUM> having the strips. As described above, this relationship of lengths can be changed such that the first knitted portion <NUM> and the second knitted portion <NUM> have any length and are repeated at any interval with respect to one another.

<FIG> depicts a portion of the warp knit fabric <NUM> showing an alternating sequence of the first knitted portion <NUM> and the second knitted portion <NUM>. As described above, the fabric may be used for any number of medical, industrial, and/or technical textile applications. The warp knit fabric <NUM> may be used as an implantable mesh <NUM>. Namely, the strips <NUM> may be used to form mesh extensions <NUM> extending from a mesh body <NUM>, which is formed by the first knitted portion <NUM>. The warp knit fabric <NUM> may be cut along its width W to form individual implantable fabric pieces, or mesh implants, that are biocompatible and surgically implantable in a patient, such as that shown in <FIG>. In the embodiment of <FIG>, dashed lines 36a and 36b show exemplary cut locations where the warp knit fabric <NUM> may be cut to create an implantable mesh <NUM>, an embodiment of which is shown in <FIG>.

<FIG> depicts one embodiment of an implantable mesh <NUM> comprising the warp knit fabric <NUM>. The implantable mesh <NUM> has a mesh body <NUM> and multiple mesh extensions <NUM> extending from opposing sides of the mesh body <NUM>. At the end of each mesh extension <NUM> is a fixation device <NUM>, which in the depicted embodiment is a surgical needle. Each mesh extension <NUM> has a first end <NUM> that is part of and extends from the mesh body <NUM>. Each mesh extension <NUM> also has a second end <NUM> that attaches to the fixation device <NUM>. Each mesh extension <NUM> has a length L'' between the first end <NUM> and the second end <NUM> and a width W''.

The implantable mesh is formed by cutting the fabric <NUM> widthwise along the second knitted portion <NUM>, such as along dashed lines 36a and 36b. For example, cuts may be made across the entire width W of the fabric <NUM>, thereby cutting each of the strips <NUM>. For example, the cuts may be made half way along the length L" of each second knitted portion <NUM>, such as with a heated knife so that the ends <NUM> of each extension do not fray. Thereby, the fabric <NUM> is cut into several implantable meshes <NUM>.

The mesh body <NUM> has a surrounding edge <NUM> from which the mesh extensions <NUM> extend. At least two mesh extensions <NUM> extend from the mesh body <NUM>, and, in various embodiments, the implantable mesh <NUM> may have any number of additional mesh extensions <NUM>. In the embodiment of <FIG>, the implantable mesh <NUM> has ten mesh extensions <NUM> arranged in opposing pairs extending oppositely from surrounding edges <NUM> of the mesh body <NUM>. In <FIG>, the mesh extensions <NUM> extend from only two of the surrounding edges <NUM>.

The mesh extensions <NUM> of the implantable mesh <NUM> have sufficient length L' to permit multiple anchor points with surrounding tissue upon implantation. An anchor point is a position where the mesh extension passes through some portion of the surrounding tissue in order to provide a force against migration or dehiscence. Multiple anchor points refers to more than one anchor point. For example, each mesh extension <NUM> may be passed through the surrounding tissue multiple times, such as by weaving or sewing the mesh extensions <NUM> into the tissue with the fixation device <NUM>. Additionally, in some embodiments the distal end <NUM> of the mesh extension <NUM> may be secured to bone. Thereby, the implantable mesh <NUM> of the present disclosure is configured such that, upon implantation, it can withstand substantial forces, including tensile stress, without failure. This device and implantation method is especially applicable for providing a durable reconstruction or repair of a tissue defect, such as a repair of an abdominal hernia or a breast reconstruction.

A properly implantable mesh <NUM> is able to withstand increased tensile stress compared to prior art devices that are sutured to surrounding tissue by conventional anchoring methods. One force distribution mechanism at play is frictional resistance, which is distributed across numerous points of contact between the implantable mesh <NUM> and the surrounding tissue. The amount of frictional resistance between the implantable mesh <NUM> and the tissue may depend on numerous factors, including, but not limited to, the area over which the tensile stress is distributed, forces that press the mesh into the tissue, the relative roughness of the mesh and the tissue, the method of fixation, and the extent of bioincorporation of the mesh into the tissue. As long as frictional resistance exceeds tensile stress at each of the anchor points, or points of contact, the mesh will not migrate or dehisce.

In an exemplary embodiment, the length L' of the mesh extensions <NUM> is at least <NUM>. In another embodiment, the length L'' of the mesh extensions <NUM> is at least <NUM>, <NUM> or <NUM> long and may be up to <NUM>, <NUM>, <NUM> or <NUM> long; and in still other embodiments the mesh extensions <NUM> may be even longer than <NUM> to allow for fixation to certain tissues or for the distal end <NUM> of the mesh extension <NUM> to be fixed to bone. However, in certain applications, the mesh extensions may be less than <NUM>, such as where the implantable mesh <NUM> is small and/or intended for repair or reconstruction of tissue that does not withstand significant forces. The mesh extensions <NUM> of the implantable mesh do not need to all be the same length. In one embodiment, at least one mesh extension is at least <NUM>, <NUM> or <NUM> long, but the implantable mesh may include additional mesh extensions that are less than <NUM> long or longer than <NUM> long.

The mesh extensions <NUM> may have any of various widths. For the embodiment of <FIG>, the width W'' of each mesh extension <NUM> may be between <NUM> and <NUM>, or more. For example, experimentation and research by the inventor relating to abdominal hernia repairs has revealed that mesh extensions <NUM> having a width W'' between <NUM> and <NUM> are advantageous and provide desirable durability results for use in hernia repair, which include mesh extensions <NUM> having a width W'' of <NUM>, <NUM>, and <NUM>. It will be understood by one of skill in the art that any number of extensions <NUM> having a wide variety of widths W'' are possible, and that the number of extensions <NUM> will depend on the widths W'' of each extension and the overall width W of the fabric <NUM>.

In <FIG>, the implantable mesh <NUM> is depicted as including ten mesh extensions <NUM> with five mesh extensions <NUM> extending from the surrounding edge <NUM> on opposite sides of the mesh body <NUM>. As noted above, the mesh extensions <NUM> may extend from one or more of the surrounding edges <NUM> of the mesh body <NUM>. In addition, various embodiments may include various numbers of mesh extensions <NUM>. For example, the implantable mesh may include two, three, four, five, six, seven, ten, twelve, fourteen or even more mesh extensions. The number and width of mesh extensions required may depend on characteristics known to those skilled in the art, such as the size and placement of the tissue defect or reconstruction site and the availability or proximity of the surrounding tissue to the tissue defect or site of reconstruction.

Claim 1:
A warp knitted fabric (<NUM>) which is a biocompatible implantable mesh for use in reconstructing tissue, the warp knitted fabric (<NUM>) comprising:
a first knitted portion (<NUM>) formed of a first knitting sequence (<NUM>) in a lengthwise direction, the first knitted portion having a width (W);
a second knitted portion (<NUM>) formed of a second knitting sequence (<NUM>) in the lengthwise direction, the second knitted portion (<NUM>) comprising at least two strips (<NUM>) extending in the lengthwise direction, the at least two strips (<NUM>) being detached from one another along their lengthwise edges (<NUM>) such that the fabric (<NUM>) has slits (<NUM>) or holes between the strips and that run the length (L") of the strips (<NUM>), which is approximately or nearly the length of the second knitted portion (<NUM>);
wherein the second knitted portion (<NUM>) has the same width (W) as the first knitted portion (<NUM>);
and
wherein the first knitted portion (<NUM>) and the second knitted portion (<NUM>) alternate sequentially in the lengthwise direction and are formed of a set of continuous biocompatible textile strands (<NUM>);
characterised in that the strands (<NUM>) are not cut at the juncture between the knitted portions (<NUM>, <NUM>) where the warp knit fabric (<NUM>) changes from having a unitary width to forming two or more strips (<NUM>).