HK40032744B - Time dependent physiologic tissue scaffold - Google Patents

Description

Time-dependent physiological tissue scaffold

This application is a divisional application of Chinese Patent Application No. 201680063840.X, filed on November 4, 2016, entitled "Time-dependent Physiological Tissue Scaffold".

Cross-reference to related applications

This application claims the benefit of U.S. Provisional Patent Application No. 62/250,568, filed November 4, 2015, pursuant to 35 U.S.C. § 119(e), which is incorporated herein by reference in its entirety.

Technical Field

This disclosure relates to fabric or mesh structures and methods for preparing the same, said structures allowing early wound stability, then transitioning to a more compliant state exhibiting a substantially constant macroporous structure throughout the implant's lifespan to promote good tissue incorporation without bridging.

Background Technology

Absorbable and non-absorbable fibrous materials can provide enhanced scaffolds for a range of membrane applications, including, in particular, tissue dissection, hernia repair, peritoneal replacement, dural replacement, and pelvic floor reconstruction. Of these types of tissue repairs and supports, hernia repair is one of the most frequently performed surgical procedures in the United States, with approximately 1,000,000 procedures performed annually.

The vast majority of these repairs utilize synthetic surgical mesh, composed of various arrangements of absorbable and non-absorbable films, fibers, and yarns, primarily based on traditional knitted and braided structures. Although these materials have reduced the frequency of hernia recurrence, the reported rates in the literature remain high, with inguinal and incisional hernia repairs reportedly accounting for as much as 15%. Furthermore, long-term complications such as chronic pain, increased abdominal wall stiffness, fibrosis, and mesh contracture persist even after the use of current surgical meshes, significantly impacting patients' quality of life.

The movement to develop synthetic hernia repair meshes involves creating materials that incorporate a portion of absorbable material. However, in practice, the absorbable component of these meshes is not intended to alter the mechanical properties of the hernia mesh within physiologically relevant limits, but rather to reduce the total amount of permanent material at the implantation site. Furthermore, the use of these partially absorbable meshes can lead to new product failure modes due to the rigidity of the remaining implant associated with less durable materials, as well as reduced strength and stability.

Typically, for some absorbable meshes currently on the market, significant strength loss is observed after the absorbable components degrade, due to their simple lay-up or layering into knitted patterns. Mesh tearing or tear strength is becoming a key characteristic, as this is a typical failure mode for this type of surgical device. Furthermore, since hernia recurrence usually occurs at the mesh edges (i.e., where the mesh is sutured into the natural tissue), a significant loss of mesh suture pull-out strength may be a contributing factor to hernia recurrence at this location.

What is needed in the art is a mesh that leaves less residual material at the implantation site to reduce chronic inflammatory responses. Furthermore, the art needs a mesh that provides initial support, ultimately better compliance, and eliminates the high-tension transition between a flexible abdominal wall and a relatively inflexible mesh/tissue complex.

All topics discussed in the Background section are not necessarily prior art and should not be considered prior art simply because they are discussed in the Background section. According to these aspects, any awareness of problems in the prior art discussed in the Background section or related to these topics should not be considered prior art unless explicitly stated otherwise. Instead, the discussion of any topic in the Background section should be considered as part of the inventor's method of dealing with a particular problem, which may itself be inventive.

Overview

In short, the present invention relates to meshes, and more particularly to meshes that can be used in medical applications, such as surgical meshes and hernia meshes. The meshes disclosed herein are particularly suitable for medical applications.

In one embodiment, this disclosure provides a partially absorbable mesh comprising at least one bioabsorbable fiber and at least one biostabilizing fiber. The mesh is partially absorbable, meaning that after implantation into a subject, the bioabsorbable fibers degrade, or in other words, are absorbed into the host, leaving behind a mesh formed by the biostabilizing fibers. The partially absorbable mesh has properties highly suitable for initial implantation in the host, while the residual mesh formed by the biostabilizing fibers has different properties, namely, properties highly suitable for maintaining implantation in the host even after the healing process has progressed to the desired extent.

Bioabsorbable fibers and biostabilized fibers combine to form a partially absorbable web. When laid flat, the partially absorbable web is essentially a two-dimensional structure with a considerable length, a considerable width, and a relatively small thickness. For convenience, the partially absorbable web can be described as having an X-direction and a perpendicular Y-direction, i.e., the X and Y directions are perpendicular to each other. In one embodiment, the web can be described as having a waist direction and a course direction, where the waist direction corresponds to the X-direction and the course direction corresponds to the Y-direction. In another embodiment, when the web is prepared on a knitting machine, the resulting web can be described as having a machine direction and a cross-machine direction, where the machine direction corresponds to the X-direction and the cross-machine direction corresponds to the Y-direction.

Partially absorbable meshes include pores. After the absorbable fibers are absorbed or otherwise removed or separated from the partially absorbable mesh, the remaining amount of the partially absorbable mesh contains bio-stabilized fibers. These bio-stabilized fibers are in the form of a bio-stabilized mesh. The bio-stabilized mesh also contains pores. According to this disclosure, the pores of the mesh can be characterized by pore size, and multiple pores in the mesh can be characterized by an average pore size. Methods for determining pore size and the resulting average pore size are described herein. Therefore, partially absorbable meshes contain pores, and multiple pores are characterized as having an average diameter.

Advantageously, one embodiment of the mesh is such that the degradation of the partially bioresorbable mesh does not significantly alter the size of the pores present in the original mesh. For example, after removing the bioresorbable fibers from the partially bioresorbable mesh, the average diameter change of multiple pores (compared to the original partially bioresorbable mesh) is less than 25%, or less than 20%, or less than 15%, or less than 10%, or less than 5%. In other words, the average pore size of the biostabilized mesh, which is a component of the partially bioresorbable mesh, is substantially the same as the average pore size of the partially bioresorbable mesh.

According to this disclosure, this maintenance of pore size can be partially achieved by interlacing bioabsorbable fibers around, rather than through, the pores formed by biostabilizing fibers. In other words, the bioabsorbable fibers do not cross or otherwise block the pores formed by the biostabilizing fibers. Instead, the bioabsorbable fibers reinforce the pores present in the biostabilizing network. Therefore, when the bioabsorbable fibers undergo bioabsorption in the host, the tissue adjacent to the network does not experience changes in its interaction with the pores of the network. This is highly desirable because tissues tend to grow into the major pores of adjacent networks, and if the size of these major pores remains constant or nearly constant, the growing tissue is less likely to be disturbed by the bioabsorption of the partially absorbable network. Therefore, in one embodiment, the bioabsorbable fibers are interlaced with the biostabilizing fibers. In another embodiment, the bioabsorbable fibers reinforce the edges of the pores of the partially absorbable network.

As described above, in one embodiment, biostabilizing fibers form a biostabilizing mesh, and said biostabilizing mesh is a component of a partially absorbable mesh. Optionally, the biostabilizing fibers form a biostabilizing mesh with a weight of 35-70 g/ ^m² . Within this weight range, the biostabilizing mesh has ideally high strength to remain within the host as a supporting mesh, but it is not so large as to cause undesirable irritation within the host. This weight range is also ideal because bioabsorbable fibers can be added to a biostabilizing mesh of this weight without creating a mesh that is particularly heavy (>140 g/ ^m² ).

Bioabsorbable fibers are preferably interwoven into a biostabilized network formed of biostabilized fibers. This does not mean that a biostabilized network must first be formed and then the bioabsorbable fibers added to it, although this is an option. However, simultaneously forming a biostabilized network and a partially absorbable network, for example by concentrating the biostabilized fibers and the bioabsorbable fibers together while forming the partially absorbable network, is also an option. Therefore, the statement that bioabsorbable fibers are interwoven into a biostabilized network describes the structure rather than a method of preparing the network.

Similarly, in terms of pattern, bioabsorbable fibers can be described as existing within a partially absorbable mesh. For example, bioabsorbable fibers can exist in a recognized stitch pattern, such as a pillar stitch. In one embodiment, the bioabsorbable fibers exist as a pillar stitch within a partially absorbable mesh. In another embodiment, the pillar stitch runs through a biostabilizing mesh, wherein the pillar stitch is formed by the bioabsorbable fibers, such that the resulting mesh is a partially absorbable mesh. In one embodiment, the bioabsorbable fibers in the form of a pillar stitch are interwoven with biostabilizing fibers.

In one embodiment, the partially absorbable mesh is anisotropic. In other words, the value of the mesh performance measured in the X direction differs from the value of the same mesh performance observed when measured in the Y direction. As an example, when elongation is measured under standard conditions such as 16 N/cm, the elongation (mesh performance) of the mesh in the Y direction can be greater than the elongation in the X direction. Optionally, the biostabilized mesh of the components forming the partially absorbable mesh is itself anisotropic. However, in one embodiment, the addition of bioabsorbable fibers induces or modifies anisotropy in the partially absorbable mesh that is not observed in the absence of bioabsorbable fibers. As another example of anisotropy, in one embodiment, the mesh of this disclosure has elongation in the X direction when measured at 16 N/cm, wherein said elongation increases by at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 90% after the removal of bioabsorbable fibers.

The structure of the mesh can also be, or optionally, anisotropic. For example, in one embodiment, the bioabsorbable fibers extend in the X direction of the mesh. In another embodiment, the bioabsorbable fibers extend in the X direction of the mesh but not in the Y direction. In yet another embodiment, the mesh comprises colored and colorless bioabsorbable fibers, wherein the colored bioabsorbable fibers extend in the X direction of the mesh but not in the Y direction. Alternatively, in one embodiment, the bioabsorbable fibers extend in the Y direction of the mesh, while in another embodiment, the bioabsorbable fibers extend in the Y direction of the mesh but not in the X direction. In yet another embodiment, the mesh comprises colored and colorless bioabsorbable fibers, wherein the colored bioabsorbable fibers extend in the Y direction of the mesh but not in the X direction.

By extending the colored lines in one direction rather than perpendicularly, the surgeon can visualize the anisotropy of the mesh, which can be translated into its anisotropic physical properties. This allows the surgeon to position the mesh in a manner consistent with the preferred placement, without having to guess which direction provides which physical properties.

After the mesh is placed in the patient's body, some of the bio-stabilized fiber components of the absorbable mesh do not degrade in vivo. Examples of bio-stabilized polymers from which bio-stabilized fibers can be prepared include polyolefins such as polypropylene and polyethylene. Optionally, the bio-stabilized fiber components may be wholly or partially replaced by slow-absorbing bio-fibers. Slow-absorbing bio-fibers retain at least 90% of their physical properties after being placed in the host for at least 6 months. Examples of slow-absorbing bio-fibers include polylactic acid, PLLA, segmented block copolymers containing a majority of L-lactide-derived units (e.g., 88% L-lactide and 12% trimethylene carbonate), and polyesters such as poly(4-hydroxybutyrate).

After a partially absorbable mesh is placed in a patient, the bioabsorbable fiber component of the mesh degrades in vivo. For example, degradation may begin once the mesh comes into contact with the patient's fluid environment and typically proceeds well within two weeks of placement. In one embodiment, the absorbable component of the mesh is completely degraded within a timeframe of 2–16 weeks. In another embodiment, the absorbable component of the mesh is completely degraded within a timeframe of 6–12 weeks. In one embodiment, the bioabsorbable fibers are completely dissolved after the partially absorbable mesh has been immersed in phosphate-buffered saline at 37°C and pH 7.4 for 12 weeks.

The following are six additional exemplary implementations of this disclosure:

1. A mesh comprising: at least one bioabsorbable fiber; at least one biostabilized fiber; wherein the bioabsorbable fiber and the biostabilized fiber are co-woven to form a porous structure; and the size of the pores remains substantially unchanged after absorption by the bioabsorbable fiber.

2. A method for forming a biostable/bioabsorbable composite, comprising: co-weaving biostable fibers and bioabsorbable fibers using a stitch pattern to form a porous structure; and the bioabsorption of the bioabsorbable fibers substantially does not alter the size of the pores in the structure.

3. A mesh comprising: at least one bioabsorbable fiber; at least one biostabilized fiber; wherein the bioabsorbable fiber and the biostabilized fiber are co-woven to form a pattern containing pores; and the bioabsorbable fiber reinforces the edges of the pores.

4. A mesh comprising: at least one bioabsorbable fiber; at least one biostabilized fiber; wherein the bioabsorbable fiber and the biostabilized fiber are co-woven to form an initial pattern containing pores; and wherein the pattern remains substantially unchanged after absorption by the bioabsorbable fiber.

5. A mesh comprising: at least one bioabsorbable fiber; at least one biostabilized fiber; wherein the bioabsorbable fiber and the biostabilized fiber are co-woven to form a porous pattern; wherein the remaining mesh after degradation of the bioabsorbable fiber exhibits a reduced elongation in the Y direction compared to the mesh before degradation of the bioabsorbable fiber; and wherein the elongation in the X direction increases by about 100%, or in another embodiment, by more than about 80%.

6. A mesh comprising: at least one bioabsorbable fiber; at least one biostabilized fiber; wherein the bioabsorbable fiber and the biostabilized fiber are co-woven to form a pattern containing pores; wherein the remaining mesh after degradation of the bioabsorbable fiber exhibits increased elongation in the Y direction compared to the mesh before degradation of the bioabsorbable fiber; and wherein the elongation in the X direction increases by about 100%, or in another embodiment, by more than about 80%.

In addition to providing a mesh, this disclosure also provides uses for the mesh, particularly its medical uses. For example, in one embodiment, this disclosure provides a method of placing the mesh described herein within a patient, and particularly placing the mesh adjacent to tissues that would benefit from physical support. A hernia is an example, which occurs when an organ, intestine, or adipose tissue squeezes through an opening or weakness in surrounding muscle or connective tissue. The mesh of this disclosure can be placed near or within the abdominal wall to reinforce the opening or weakness in muscle or connective tissue, providing scaffolding and support for healing while protecting the organ, intestine, or adipose tissue from passing through the abdominal wall. Examples of hernias treatable according to the methods of this disclosure include: inguinal hernias (occurring in the internal groin); femoral hernias (occurring in the upper thigh/external groin); incisional hernias (occurring through an incision or scar in the abdomen); abdominal hernias (occurring in the general abdomen/abdominal wall); umbilical hernias (occurring at the navel); and hiatal hernias (occurring inside the abdomen, along the upper stomach/diaphragm). In one implementation, a mesh is placed on the tissue requiring support, wherein the tissue is anisotropic in terms of its elongation, and the mesh is positioned such that the direction in which the mesh exhibits a greater rate of elongation matches the direction in which the tissue exhibits a greater rate of elongation. In this way, the mesh better accommodates the movement of the tissue.

In addition to providing networks and methods of using them, this disclosure also provides methods for preparing networks. For example, in one embodiment, biostabilized fibers and bioabsorbable fibers are used simultaneously to form a network, wherein the biostabilized fibers form a biostabilized network, and the bioabsorbable fibers are interwoven with the biostabilized network while the biostabilized network is being formed. Optionally, the biostabilized fibers are introduced into a portion of the bioabsorbable network using a braided structure, i.e., the bioabsorbable fibers are interwoven in the form of a braided structure.

This overview has been provided to introduce certain concepts in a simplified form, which will be further described in detail below. Unless otherwise expressly stated, this overview is not intended to identify key or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter.

Details of one or more embodiments are set forth in the following description. Features shown or described in conjunction with an exemplary embodiment may be combined with features of other embodiments. Therefore, any of the various embodiments described herein may be combined to provide further embodiments. If necessary, aspects of the embodiments may be modified to further provide further embodiments using the concepts of the various patents, applications, and publications identified herein. Other features, objects, and advantages will become apparent from the specification, drawings, and claims.

Brief description of the attached figures

The construction and other features designed for implementing this disclosure will be described below. This disclosure will be more readily understood by reading the following specification and referring to the accompanying drawings that form a part of this specification, in which examples of this disclosure are shown, and wherein:

Figure 1 illustrates the features of a prior art mesh structure in which one type of fiber blocks the pores formed by different fiber types.

Figure 2 illustrates the features of the mesh structure of this disclosure, wherein one type of fiber reinforces the pores formed by different fiber types.

Figures 3A, 3B, and 3C show identical exemplary samples of the mesh of this disclosure, wherein Figure 3A focuses on the pores of the mesh; Figure 3B focuses on how to determine the pore size of the mesh; and Figure 3C focuses on an exemplary placement of bioabsorbable fibers in the mesh.

Figure 4 shows a diagram depicting current mesh hernia repair techniques.

Figure 5A is a photograph of the mesh disclosed herein.

Figure 5B is a photograph of the degraded network of this disclosure that has lost its bioabsorbable components.

Those skilled in the art will understand that one or more aspects of this disclosure can satisfy certain objectives, while one or more other aspects can satisfy certain other objectives. Each objective may not be equally applicable to each aspect of this disclosure in all its aspects. Therefore, the foregoing objectives may be viewed alternatively with respect to any aspect of this disclosure. These and other objectives and features of this disclosure will become more apparent when read in conjunction with the accompanying drawings and embodiments in the following detailed description. However, it should be understood that the foregoing overview and the following detailed description of this disclosure are preferred embodiments and not limitations on the disclosure or other alternative embodiments. In particular, although this disclosure has been described herein with reference to several specific embodiments, it should be understood that the description is illustrative and does not constitute a limitation on this disclosure. Various modifications and applications will be apparent to those skilled in the art without departing from the spirit and scope of this disclosure as set forth in the appended claims. Similarly, other objectives, features, benefits, and advantages of this disclosure will be apparent from the foregoing, in conjunction with the accompanying embodiments, data, drawings, and all reasonable inferences derived therefrom (either individually or in consideration of the references cited herein).

Invention Details

This disclosure will now be described in more detail with reference to the accompanying drawings. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the subject matter of this disclosure pertains. Although any methods, apparatus, and materials similar to or equivalent to those described herein may be used in the practice or testing of the subject matter disclosed herein, representative methods, apparatus, and materials are described herein.

Unless otherwise stated, the terms, phrases, and variations thereof used herein should be interpreted as open-ended rather than restrictive, unless explicitly stated otherwise. Similarly, a group of items associated with the conjunction “and” should not be interpreted as requiring each of these items to be present in the group, but rather as “and/or”, unless explicitly stated otherwise. Likewise, a group of items associated with the conjunction “or” should not be interpreted as requiring mutual exclusivity within the group, but rather as “and/or”, unless explicitly stated otherwise.

Furthermore, although items, elements, or components of this disclosure may be described or claimed in the singular, the plural form is contemplated within its scope unless expressly stated to be limited to the singular. In certain circumstances, the presence of extended words and phrases such as “one or more,” “at least,” “but not limited to,” or other similar phrases should not be interpreted as indicating a desire or need for a narrower scope in situations where such extended phrases might not exist.

The advantage of partially absorbable meshes is that they leave less residual material at the implantation site, thereby reducing chronic inflammatory responses associated with long-term implants. In one embodiment, this disclosure provides a non-absorbable mesh, i.e., a mesh formed of non-absorbable fibers, also referred to herein as bio-stabilized fibers, and the corresponding mesh may be referred to herein as a bio-stabilized mesh, wherein the non-absorbable mesh is combined with absorbable fibers. The absorbable fibers are interwoven into the mesh structure formed of the non-absorbable fibers, thereby providing a partially absorbable mesh.

The amount of residual material remaining at the implantation site depends in part on the amount of non-absorbable mesh present in the partially absorbable mesh of this disclosure. Optionally, in this and other embodiments disclosed herein, the non-absorbable mesh component of the partially absorbable mesh of the present invention is an ultralight mesh, i.e., a mesh with a mass less than 35 g/ ^m² . Alternatively, the non-absorbable mesh component of the partially absorbable mesh of the present invention is a lightweight mesh, i.e., a mesh with a mass in the range of 35-70 g/ ^m² . In yet another option, the non-absorbable mesh component of the partially absorbable mesh of the present invention is a standard weight mesh, i.e., a mesh with a mass of ^70-140 g/ ^m² . Another option specifies that the non-absorbable mesh component of the partially absorbable mesh of the present invention is a heavyweight mesh, i.e., a mesh with a mass greater than 140 g/m².

In one mesh embodiment, as discussed in more detail herein, when neither the partially absorbable mesh nor the non-absorbable mesh is under external stress, the average pore size of the partially absorbable mesh is substantially the same as the average pore size of the non-absorbable mesh, which is a component of the partially absorbable mesh. To achieve this, absorbable fibers can be interwoven near the edges of the mesh formed by the non-absorbable (biostable) fibers. Thus, it can be said that the bioabsorbable fibers reinforce the edges of the pores formed by the non-absorbable fibers.

In one embodiment of this disclosure, the mesh is formed of at least one bioabsorbable fiber and at least one biostabilized fiber. In one embodiment, a partially non-degradable mesh knitted fabric can be produced, thereby providing permanent preventative protection against re-herniation. In one embodiment, the mesh fabric of this disclosure will stretch when subjected to traction, i.e., it exhibits elongation; however, it is not elastic, i.e., it will not spring back to its original shape after stretching.

Bioabsorbable fibers can be multifilament fibers or monofilament fibers. In one embodiment, the bioabsorbable fiber comprises or is composed of multifilament fibers. In another embodiment, the bioabsorbable fiber comprises or is composed of monofilament fibers. In yet another embodiment, both monofilament and multifilament bioabsorbable fibers are present in a portion of the absorbable mesh of this disclosure.

Bioabsorbable fibers lose their strength and/or structural integrity after implantation in a patient. Bioabsorbable fibers can also be referred to as biodegradable fibers. Exemplary bioabsorbable fibers can be formed from segmented multiaxial copolyesters, which are formed from an amorphous multiaxial polymerization initiator of a mixture of terminally grafted ε-caprolactone and at least one cyclic monomer selected from the group consisting of L-lactide, DL-lactide, glycolide, and trimethylene carbonate, the mixture forming crystallizable terminal segments. Simultaneously, the amorphous polymerization initiator can be formed by ring-opening polymerization of trimethylene carbonate in the presence of a catalyst (preferably stannous octoate) and a single-center multifunctional initiator selected from triethanolamine, trimethylolpropane, and pentaerythritol. Alternatively, the amorphous polymerization initiator can be formed by ring-opening polymerization of trimethylene carbonate and a mixture of at least one monomer selected from p-dioxanone, ε-caprolactone, and 1,5-dioxane-2-one.

As alternatives, bioabsorbable fibers can be formed from silk fibroin, linear segmented lactide-derived copolyesters, or poly(3-hydroxyalkanoates). More specifically, bioabsorbable fibers can be formed from silk fibroin in the form of degummed white Brazilian silkworm (Bombyx mori) silk fibers. Alternatively, bioabsorbable fibers can be formed from segmented copolymers composed of: lactide and at least one monomer selected from glycolide, ε-caprolactone, trimethylene carbonate, p-dioxanone, or morpholinodione; and/or (3) poly(3-hydroxyalkanoates) selected from poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate).

Biostabilized fibers may comprise at least one multifilament or monofilament yarn made of one or more polymers. In one embodiment, the biostabilized fiber is a monofilament fiber. In another embodiment, the biostabilized fiber is a multifilament. In yet another embodiment, the mesh of this disclosure is formed from monofilament biostabilized fibers and multifilament biostabilized fibers.

Exemplary biostabilized fibers include polyethylene, such as ultra-high molecular weight polyethylene (UHMWPE), polypropylene, polyamides such as aliphatic polyamides (e.g., nylon 6 and nylon 66) and aromatic polyamides, polyether-ether ketone (PEK), and polyalkylene terephthalates such as polyethylene terephthalate (PET). Other biostabilized polymers that can be used to prepare biostabilized fibers include poly(tetrafluoroethylene) and poly(hexafluoropropylene-VDF), also known as PTFE. Biostabilized fibers do not need to be made from organic polymers, but can be formed from metals, such as stainless steel monofilaments or twisted multifilaments.

Possible weight ratios of biostabilized polymers to bioabsorbable polymers can include 90:10, 80:20, 70:30, 60:40, and 50:50, and ranges selected from these values and options. Typically, bioabsorbable fibers limit the elongation of the partially absorbable mesh; therefore, when the ratio of biostabilized fibers to bioabsorbable fibers decreases from 90:10 to 50:50, the elongation of the partially absorbable mesh decreases. This is advantageous because when the mesh is initially implanted into the host, it is expected to provide high support to the tissue in need of support when the tissue is in dire need of support. However, as the tissue heals and better supports itself and adjacent tissues, the need for stable support from the mesh decreases. In fact, it is advantageous for the mesh to have an increased elongation rate to accommodate the natural elongation that occurs during the healing process of the host. If the mesh continues to constrain the tissue, even after the tissue has healed and is less in need of external support, the healed tissue will not fully redevelop its ability to undergo natural elongation without damage.

The initial support provided by the partially absorbable mesh of this disclosure can be adjusted in part by selecting an appropriate amount of bioabsorbable fibers present in the partially absorbable mesh. In other words, as described above, when the weight ratio of the biostabilized polymer to the bioabsorbable polymer decreases from 90:10 to 80:20, to 70:30, to 60:40, to 50:50, and to a range selected from these values and options, the mesh has a relatively larger amount of bioabsorbable fibers and therefore provides relatively more support, for example, with a smaller elongation. In one embodiment, the majority of the weight of the partially absorbable mesh is attributed to the biostabilized fibers. In various alternative embodiments, the bioabsorbable fibers contribute 10%, or 15%, or 20%, or 25%, or 30%, or 35%, or 40%, or 45%, or up to 49% of the weight of the partially absorbable mesh, wherein the remaining weight is provided by the biostabilized fibers. This disclosure provides an embodiment in which bioabsorbable fibers contribute a certain amount of weight to a portion of the absorbable mesh, said amount of weight falling within a range defined by a lower and upper limit of weight percentage, each of said lower and upper limits being selected from the aforementioned weight percentage values. For example, the bioabsorbable fibers may contribute 10-49%, or 10-40%, or 15-35% of the weight of the absorbable mesh (as two other alternatives).

As used herein, woven fibers are considered interwoven. In other words, fibers are combined in such a way that one fiber wraps around or weaves around another fiber. Interwoven fibers can also be considered as staggered or entangled. Interwoven fibers can be produced by hand sewing or machine weaving or sewing, or by embroidery or any combination thereof. By interweaving and thus becoming part of a partially absorbable web, bioabsorbable fibers effectively influence the physical properties of the partially absorbable web, such as the elongation of the web, unlike biostabilized webs where bioabsorbable fibers only come into contact with the partially absorbable web.

In one embodiment, biostabilized fibers and bioabsorbable fibers are combined using a knitting process, wherein the biostabilized fibers and bioabsorbable fibers are simultaneously (i.e., in a one-step knitting process) fed into a knitting machine. Alternatively, biostabilized fibers may be fed into a knitting machine to form a biostabilized web, and then bioabsorbable fibers may be added to the biostabilized web by, for example, knitting, hand weaving, or embroidery.

Knitting is a technique used to produce fabrics made of fibers, yarns, or threads. In weaving, the threads are typically parallel in the longitudinal direction (warp) or parallel in the transverse direction (weft). In contrast, knitted fabrics are formed by threads along curved paths (courses), creating loops above and below the neutral path of the yarn. These curved loops can stretch in different directions compared to woven meshes, thus offering the potential for increased flexibility. For this reason, knitting was initially developed for materials that must be elastic or stretchable in response to user movement. In contrast, woven materials are primarily stretched in one or the other of a pair of related directions that lie roughly diagonally between the warp and weft, while contracting in the other direction (oblique stretching and contraction), and are generally not very elastic unless they are woven from stretchable materials. In one embodiment, bio-stabilized fibers and bioabsorbable fibers are not significantly elastic; that is, the fibers have little or no elasticity.

There are two main types of knitting: weft knitting and warp knitting. In weft knitting, the wales are perpendicular to the horizontal stripes of the yarn, and the entire fabric can be made from a single yarn, created by adding stitches sequentially to each wale, moving through the fabric as if in a raster scan. Conversely, in warp knitting, each wale requires at least one yarn. For this reason, warp-knitted fabrics can offer greater cut and tear resistance than weft-knitted fabrics.

In one embodiment, the partially absorbent mesh of this disclosure is warp-knitted. Therefore, in one embodiment, the partially absorbent mesh of this disclosure includes raised stripes and horizontal stripes. Suitable warp-knitted pattern types may include tricot, Milanese, raschel, marquisette, sand-fly, bobbie, crossed, herringbone, linen, cable, satin, atlas, Charmeuse, voile, accordion, and English net.

In one embodiment, a 1-bar or 2-bar knitting pattern is used to form the bio-stabilized fibers into a stable knitted structure. In another embodiment, a 2-bar knitting pattern can be used because it provides higher tear resistance. In yet another embodiment, bioabsorbable fibers can be added with a 1-bar knitting pattern to stabilize/reinforce the structure, or with a 2-bar knitting pattern.

In another embodiment, a pillar stitching technique can be used to add bioresorbable fibers to a biostabilizing mesh to provide the partially absorbable mesh of this disclosure. In this embodiment, the bioresorbable fibers do not form a mesh independently; that is, if the biostabilizing fibers are removed from the partially absorbable mesh of this disclosure, the resulting structure will not be a mesh but will instead present as loosely bound bioresorbable threads. Thus, for example, in one embodiment, the mesh of this disclosure includes a first fiber and a second fiber, the first and second fibers arranged together in a mesh structure; the first fiber is arranged in a pillar stitching technique; and the second fiber forms a mesh rather than being arranged in a pillar stitching technique. This disclosure also provides a method for forming a mesh, comprising: incorporating the first fiber and the second fiber into a structure having the form of a mesh; wherein the first fiber is incorporated into the mesh using pillar stitching; and wherein the second fiber forms a biostabilizing mesh and is incorporated into the partially absorbable mesh without using pillar stitching.

In another embodiment, the pattern can be (1 bar - absorbable (Bar 1-Abs))/(2 bar - absorbable (Bar 2-Abs))/(3 bar - non-absorbable (Bar 3-Abs))/(4 bar - non-absorbable (Bar 4-Abs)). In yet another embodiment, the pattern can be (1 bar - non-absorbable (Bar 1-Non-Abs))/(2 bar - absorbable (Bar 2-Abs))/(3 bar - non-absorbable (Bar 3-Non-Abs))/(4 bar - absorbable (Bar 4-Abs)). Even further, the pattern can be (1 bar - non-absorbable (Bar 1-Non-Abs) layered with absorbable (Abs))/(2 bar - non-absorbable (Bar 2-Non-Abs)). As is known to those skilled in the art, many variations of this pattern are possible. In a preferred embodiment, the pattern can be (1 bar - non-absorbent (Bar 1 – Non-Abs))/(2 bar - non-absorbent (Bar 2 – Non-ABS))/(3 bar - absorbable (Bar 3 – Abs)).

Current synthetic techniques used for mesh manufacturing include the production of: (1) co-knitted structures, for example, fibers layered together in the same knitting pattern or co-extruded to form bicomponent fibers; (2) co-knitted textiles that rely on variations in macropores to produce compliance/mechanical transitions; and (3) layered structures including films that promote early stability. Alternatively, the bio-stable and bioabsorbable fibers described herein can be formed into textile products via a one-step manufacturing process, in contrast to layered processes or other post-fabric forming processes that increase production complexity. For illustrative purposes only and not intended to be limiting, in one embodiment, the mesh or fabric can be knitted in a one-step process, wherein absorbable and non-absorbable yarns form the mesh in a co-knitting pattern, wherein the non-absorbable yarns form the base of the mesh and the macropore network of the mesh, while the absorbable yarns are knitted in a minimal knitting pattern, such as a chain stitch, without clogging the macropore network. Thus, a one-step process is one in which all knitting is performed in a single step: all fibers/yarns are fed into the structure during the knitting process; they are not added in subsequent process steps.

In one embodiment, this disclosure provides a method for forming a mesh, the method comprising: co-knitting bio-stabilized fibers and bioabsorbable fibers using a knitting pattern to form a mesh structure having pores; wherein bioabsorption of the bioabsorbable fibers substantially does not change the size of the pores in the structure.

In another embodiment, this disclosure provides a method for forming a mesh, comprising: co-knitting bio-stabilized fibers and bioabsorbable fibers using a knitting pattern to form a mesh structure having pores; wherein the bioabsorbable fibers are knitted in a chain braided structure.

In another embodiment, this disclosure provides a method for constructing a mesh, comprising: performing a one-step knitting process wherein biostabilized fibers and bioabsorbable fibers are simultaneously fed into a knitting machine to form a mesh; wherein the biostabilized fibers of the mesh are arranged in a pattern including pores; and wherein the bioabsorbable fibers of the mesh are arranged in a pattern that does not block the pores formed by the biostabilized fiber pattern.

In one embodiment, this disclosure provides a biostabilized mesh formed of biostabilized fibers. Bioabsorbable fibers can be woven into the biostabilized mesh such that the bioabsorbable fibers are woven around the biostabilized fibers, which form the biostabilized mesh independently of the bioabsorbable fibers.

Existing techniques in the field of surgical mesh do not allow for a more compliant early wound stability that closely matches the elongation and anisotropy of the natural abdominal wall and exhibits a macroporous open-pore structure throughout the implant's lifespan to facilitate good tissue integration without bridging. This can be defined as encapsulating the mesh as a whole, in contrast to actual collagen integrating into and passing through the pores of the mesh. Therefore, "bridging" exists through the pores of the mesh.

For example, in one embodiment, this disclosure provides a mesh comprising: at least one bioabsorbable fiber and at least one biostabilized fiber; wherein the bioabsorbable fiber and the biostabilized fiber are combined to form a porous structure having an average size; and wherein the average size of the pores remains substantially unchanged after absorption by the bioabsorbable fiber.

As another example, this disclosure provides a mesh comprising: at least one bioabsorbable fiber and at least one biostabilized fiber; wherein the bioabsorbable fiber and the biostabilized fiber are co-knitted to form a pattern containing holes having edges; and the bioabsorbable fiber reinforces the edges of the holes.

In another instance, this disclosure provides a mesh comprising: at least one bioabsorbable fiber and at least one biostabilized fiber; wherein the bioabsorbable fiber and the biostabilized fiber are co-knitted to form an initial pattern containing pores; and wherein the initial pattern remains substantially unchanged after absorption by the bioabsorbable fiber.

In yet another example, this disclosure provides a mesh comprising: at least one bio-stabilized fiber, said bio-stabilized fiber taking the form of a mesh structure containing pores, the pores having an average pore size when the mesh is in a resting state; and at least one bioabsorbable fiber incorporated into the mesh; wherein when the bioabsorbable fiber is removed from the mesh, the change in the average pore size of the mesh does not exceed 25%, or 20%, or 15%, or 10%.

In one embodiment of this disclosure, at least one absorbable fiber may be placed as a braided structure that restricts a portion of the non-absorbable mesh. When the bioabsorbable component is absorbed, the resulting or final mesh structure exhibits similar and generally higher strength under many fabric strength test conditions (ball bursting, stretching, tearing, seam pull-out). While not intended to limit and to be understood as including the following ranges within the scope of this disclosure, in one embodiment, the following measurements were determined: tensile strength (convex stripe) = 155.6 N (initial), 189.6 N (post-deg); tensile strength (transverse stripe) = 188.3 N (initial), 202.8 N (post-deg); tear strength (convex stripe) = 66.13 N (initial), 78.52 N (post-deg); tear strength (transverse stripe) = 65.41 N (initial), 78.11 N (post-deg); suture pull-out strength (convex stripe) = 34.73 N (initial), 31.53 N (post-deg); suture pull-out strength (transverse stripe) = 33.79 N (initial), 32.52 N (post-deg); ball rupture strength = 362.35 N (initial), 341.85 N (post-deg). Typically, for some absorbable meshes currently on the market, significant strength loss can be observed as the bioabsorbable component degrades because it is simply laid out or layered into a knitted pattern. Mesh tearing or tear strength is becoming a critical characteristic, as this is a typical failure mode for this type of surgical instrument.

In one embodiment, the fibers can form a mesh structure with a pore size greater than 0.7 mm, greater than 1 mm, or greater than 2 mm. In one embodiment, a pore size greater than 2 mm is preferred. The pore size is conveniently determined by placing a virtual circle within the pore, wherein the largest circle that can fit within the pore is characterized by one or both of its diameter and area. This diameter and area can be used as characterizing features of the corresponding pore, such that the pore itself can be described as having a distance (corresponding to the diameter of the virtual circle) and an area (corresponding to the area of the virtual circle). The virtual circle should not be so large that it covers any fibers defining the edge of the pore. However, the circle should be large enough that it is adjacent to the fibers defining the edge of the pore, i.e., it is the largest circle that can fit perfectly within the pore. The virtual circle is placed within the pore of the resting mesh, i.e., the mesh is in equilibrium without being pulled or stretched in any direction. The pore size can be determined using image analysis software.

Biostabilizing networks contain macroporous patterns, in which macropores are formed by being surrounded by surrounding biostabilizing fibers. The term "macropore" is used to distinguish them from the small gaps that may exist between the fiber regions, which can be referred to as "pores".

The circle and the corresponding hole itself can be described according to area (e.g., square millimeters ( ^mm² )), or the hole can be described according to diameter, such as millimeters (mm). In either case, the largest circle is fully applicable within the hole. When described according to the circle diameter, in various embodiments, the aperture of the mesh of this disclosure is greater than 0.1 mm, or greater than 0.5 mm, or greater than 0.6 mm, or greater than 0.7 mm, or greater than 0.8 mm, or greater than 0.9 mm, or greater than 1.0 mm, or greater than 1.1 mm, or greater than 1.2 mm, or greater than 1.3 mm, or greater than 1.4 mm, or greater than 1.5 mm, or greater than 1.6 mm, or greater than 1.7 mm, or greater than 1.8 mm, or greater than 1.9 mm, or greater than 2.0 mm, or greater than 2.1 mm, or greater than 2.2 mm, or greater than 2.3 mm, or greater than 2.4 mm, or greater than 2 mm. The aperture can be 0.5 mm, or greater than 2.6 mm, or greater than 2.7 mm, or greater than 2.8 mm, or greater than 2.9 mm, or greater than 3.0 mm, or greater than 3.1 mm, or greater than 3.2 mm, or greater than 3.3 mm, or greater than 3.4 mm, or greater than 3.5 mm, or greater than 3.6 mm, or greater than 3.7 mm, or greater than 3.8 mm, or greater than 3.9 mm, or greater than 4.0 mm, up to approximately 5.0 mm, wherein the aperture can alternatively be described by a range of possible apertures defined by a lower limit and an upper limit of the aperture, each limit being selected from the values mentioned above, for example, as two options, 0.7–2.0 mm, or 1.5–2.5 mm.

Aperture size depends on the knitting pattern and post-knitting treatment. Different aperture sizes can be produced through a range of warp knitting parameters, including the runner feed-in length (the amount of yarn fed from the yarn comb into the knitting machine), the knitting pattern (i.e., the stitch symbols), and post-treatment activities including annealing. As listed above, different warp knitting patterns can be used, and varying the stitch length can also produce different aperture sizes. Finally, annealing helps impart different aperture sizes and dimensional stability to the fabric. Different aperture sizes can be produced depending on the degree of extension or stretch applied to the fabric. However, as mentioned above, aperture size is determined based on the properties of the resting web, which is a web that is in equilibrium in any direction during characterization and is not subjected to traction or stretching.

The mesh disclosed herein includes pores, also referred to as apertures. In one embodiment, the mesh includes a plurality of pores of substantially the same size. In various embodiments, "a plurality" refers to at least 100 pores, or at least 200 pores, or at least 300 pores, or at least 400 pores, or at least 500 pores. The actual number of pores should depend on the total surface area of the mesh and the average area size of the pores.

Optionally, the holes can be arranged in rows. In other words, the mesh can have a first row of holes, wherein one row comprises 10-100 or more holes, and the mesh also has a second row of holes, which also comprises 10-100 or more holes, wherein the first and second rows of holes are parallel to each other, i.e., the first and second rows do not intersect each other. The mesh of this disclosure can have multiple rows of holes, wherein the number of parallel rows of holes can optionally be at least 10 rows, or at least 15 rows, or at least 20 rows, or at least 25 rows, or at least 30 rows, or at least 35 rows, or at least 40 rows, or at least 45 rows, or at least 50 rows, and wherein optionally, the number of parallel rows can be described as falling within a range of possible values defined by upper and lower limits, wherein these limits can be selected from the values above, such as 10-50 rows. The number of rows of holes will depend in part on the area size of the mesh and the area size of the holes.

The mesh disclosed herein can be anisotropic. Anisotropic meshes exhibit different physical properties when their physical properties are measured in the X direction compared to when measured in the Y direction perpendicular to the mesh. For example, the mesh may exhibit a greater elongation in the X direction than in the Y direction. More generally, in one embodiment, the disclosure provides a mesh comprising: at least one bioabsorbable fiber and at least one biostabilized fiber; wherein the bioabsorbable fiber and the biostabilized fiber are combined to form a mesh pattern including pores, the mesh having an X direction and a perpendicular Y direction; and wherein, after degradation of the bioabsorbable fiber, the tensile elongation in the X direction of the mesh increases by about 100%. Optionally, after degradation of the bioabsorbable fiber, the tensile elongation in the X direction of the mesh increases by at least 80%. Optionally, after degradation of the bioabsorbable fiber, the change in tensile elongation in the Y direction of the mesh is less than 50%. Optionally, after degradation of the bioabsorbable fiber, the change in tensile elongation in the Y direction of the mesh is less than 25%. Optionally, after the bioabsorbable fibers degrade, the tensile elongation in the Y direction of the mesh decreases. Optionally, after the bioabsorbable fibers degrade, at least one of the X and Y directions causes a change of at least 50% in elongation at 16 N/cm.

In one embodiment of this disclosure, the absorption of the bioabsorbable fibers does not alter or disrupt the pore size of the final mesh structure. This can be achieved by constructing the mesh such that one or more absorbable fibers restrict movement of the mesh at its edges, but do not penetrate the void space of the pores.

In one embodiment, the fabric manufactured according to this disclosure exhibits substantially the same pore size after the degradation of the bioabsorbable components. Figure 1 shows a prior art mesh 101 formed from two different types of fibers. One fiber type, namely 102a and 102b, is represented by white (non-shaded) fibers, while the other fiber type, 103a and 103b, is represented by black (spotted, shaded) fibers. Observing the arrangement of fibers 103a and 103b, it can be seen that they cross each other at multiple locations, such as locations 104 and 105, such that between, including, locations 104 and 105, fibers 103a and 103b define a hole 106. However, this hole is partially blocked because a portion of fiber 102a passes through hole 106, with the crossing portion of fiber 102a surrounded by dashed lines 107. Therefore, an object that can barely pass through the aperture 106 in the absence of fiber 102a cannot pass through the aperture 106 in the prior art mesh 101 due to the obstruction of fiber 102a. In Figure 1, portion 107 of line 102a effectively divides the aperture 106 into two approximately equal-sized gaps, such that the size of the aperture 106 is effectively cut in half by the presence of portion 107 that divides the aperture 106 equally. In prior art meshes, two different fiber types, such as 102a/102b and 103a/103b, are conventionally combined without actively controlling the influence of one fiber type (in this case, 102a) on the size of the aperture formed by the other fiber type (in this case, 103a/103b). In this case, and when one of the fiber types (e.g., fiber 102a) is a bioabsorbable fiber, the bioabsorption of the mesh causes a change in the pore size of the mesh because portion 107 disappears after fiber 102a degrades and no longer divides the aperture 106 equally.

Meanwhile, Figure 2 illustrates a possible mesh 201 of this disclosure. Figure 2 shows a mesh 201 formed by two different fiber types. One fiber type, namely 202a, 202b, and 202c, is represented by white (non-shaded) fibers, while the other fiber type, namely 203a and 203b, is represented by black (spotted, shaded) fibers. Observing the arrangement of fibers 203a and 203b, it can be seen that they cross each other at multiple locations, such as locations 204 and 205, such that between, including, locations 204 and 205, fibers 203a and 203b define a hole 206. Compared to the case depicted in Figure 1, this hole 206 is not blocked by any portion of fibers 202a, 202b, or 202c, because none of these fibers pass through any part of the hole 206. Instead, fibers 202a are essentially interwoven around fibers 203a and 203b. Therefore, an object that can barely pass through the hole 206 in the absence of fiber 202a can still easily pass through the hole 206 in the mesh 201 of the present invention due to the absence of obstruction from fiber 202a. Compared to the case shown in FIG1, there is no portion of wire 202a passing through the hole 206, so the presence of wire 202a does not reduce the size of the hole 206 formed by wires 203a and 203b. In the mesh of this disclosure, two different fiber types, such as 202a/202b and 203a/203b, are conventionally used, while actively controlling the influence of one fiber type (in this case, 202a) on the size of the hole formed by the other fiber type (in this case, 203a/203b). In this case, and when one of the fiber types (e.g., fiber 202a) is a bioabsorbable fiber, partial bioabsorption of the mesh causes a small change or no change at all in the mesh pore size, because after fiber 202a degrades, fiber 202a does not affect the size of the hole 206. The absorbable yarn 202a is confined to the edge of the macroporous network formed by the non-absorbable yarns 203a/203b and does not penetrate or bisect the main macroporous network. Therefore, the pore size remains substantially constant when the bioabsorbable fiber is absorbed.

In one implementation, it is desirable that the pore size remains unchanged or unobstructed after the mesh partially degrades. The benefit of maintaining the pore size is that the device allows tissue ingrowth into a permanent scaffold, which promotes earlier remodeling and maturation of newly deposited tissue compared to bioresorbable scaffold materials. Bioresorbable scaffold materials exhibit temporal changes, particularly in pore size and mechanical properties, thus requiring additional tissue deposition at the wound site over a longer period. By maintaining the scaffold structure (i.e., porosity and pore size), the integration of the mesh into the surrounding tissue can occur at a faster rate due to the dependence on and maintenance of the mesh structure.

Figure 3A illustrates an exemplary portion of the mesh of this disclosure. In Figure 3A, the mesh 300 includes adjacent holes 301, 302, and 303 arranged in rows 304. The mesh 300 also includes adjacent holes 305, 306, and 307 arranged in rows 308. The mesh 300 further includes adjacent holes 309, 310, and 311 arranged in rows 312. Notably, rows 304, 308, and 312 are parallel to each other, i.e., one row of holes does not intersect with another row of holes.

Figure 3B illustrates how the pore size can be determined. As shown in Figure 3B, a circle 313 can be placed in a hole, such as hole 305, where the circle has the largest possible diameter that does not cause the periphery of the circle to lie above the fibers surrounding and defining the hole. The diameter of this circle can be used to describe the size of the hole. In Figure 3B, the largest circle suitable for hole 305 has a diameter of 1900 μm. The pores in the mesh of Figure 3B all have substantially the same size, so the average pore size of the mesh of Figure 3B can be considered to be 1900 μm. This method can also be used even if the pores themselves are not circular, but rather take on non-circular shapes, such as squares, rhombuses, or hexagons.

Figure 3C illustrates how absorbable fibers 314 and 315 (black dashed lines) are combined with a mesh formed of bio-stabilized fibers (white lines). In Figure 3C, absorbable fibers 314 and 315 are located at the edges of the pores and do not cross or block any pores. Also as shown in Figure 3C, bio-absorbable fibers 314 and 315 are located above and below a pair of adjacent rows of pores 304 and 308, respectively. In one embodiment, this disclosure provides a mesh as shown in Figure 3C, wherein the bio-absorbable fibers extend along the top and bottom of a pair of adjacent rows of pores. In another embodiment, this disclosure provides a mesh in which the bio-absorbable fibers extend along the top or bottom of a row of pores, but not both. In yet another embodiment, the bio-absorbable fibers extend between adjacent rows of pores.

Mesh/wound compliance can be increased by incorporating absorbable components into structurally supported knitted constructs. Thus, as this component degrades, the mesh transforms into a more compliant and less restrictive knitted construct. Tear strength propagation and suture pull-out can be controlled by resisting the spread of the mesh in a chosen pattern. It is necessary to reduce mesh contraction, i.e., the ability of the pores (cells) to sense tension, to prevent disease conditions. For example, in the case of a skin incision, the tissue immediately surrounding the incision “loses” the tension that signals a problem in the body. Therefore, placing a rigid construct on soft tissue prevents the tissue from recognizing the “load” and maintains the sensation of a problem, causing the soft tissue to contract in order to re-establish tension.

In one aspect of this disclosure, after a significant loss of strength, absorbable material is placed to achieve a significant increase in elongation in one direction of the mesh, thereby making the final structure anisotropic. Examination of the tissue containing the abdominal wall reveals that the tissue is highly anisotropic: the tissue adapts to stretching more in a particular direction. This disclosure mimics this function by allowing greater elongation in the longitudinal direction after the bioabsorbable component has biodegraded.

In another embodiment, the mesh or fabric prepared according to this disclosure may be marked. For example, in one embodiment, a portion of the absorbable braided structure may be dyed a bright color or otherwise made visible to the user, thereby indicating the direction of increased compliance after the selective absorbable mesh device has partially degraded.

In another embodiment, the entire mesh, a portion of the mesh, or selected fibers within the mesh can be coated with a drug-containing coating to form a reservoir for local delivery of an active agent. For example, at least one bioactive agent may be selected from antimicrobial agents, anti-inflammatory agents, antitumor agents, anesthetics, tissue growth promoters, or combinations thereof.

If the fabric is produced according to the disclosure herein, it can be used as a surgical mesh, a reconstruction mesh, a hernia mesh, a drug delivery fabric, a support scaffold, or a reinforced scaffold. For example, the fabric can be: (1) a tissue-engineered scaffold for repairing or replacing maxillofacial tissues; (2) a surgical mesh for soft tissue repair or tissue engineering; or (3) a hernia repair mesh containing a knitted construct.

This disclosure can also produce fabrics that exhibit an initial relatively high modulus/low elasticity compared to natural tissue, for example, an elongation of 10-14% under physiological load (16 N/cm) initially in a ball-burst test construct. After placement in vivo, the fabric can transform into a relatively stretchable material compared to the initial fabric and exhibit properties similar to natural tissue. For the purposes of illustration and understanding only, and for the inclusion of ranges of these quantities within the scope of this disclosure, elongation (convex stripes) = 34.6% (initial) and 71.3% (after degradation) and/or elongation (transverse stripes) = 33.6% (initial), 39.5% (after degradation). When observing natural abdominal wall tissue, strength and elongation are highly directional (i.e., more stretched in one direction than in another). The mesh of this disclosure achieves this property. Therefore, physicians can position the mesh in the direction they wish to make it more stretchable.

Following degradation of the bioabsorbable component, the fabrics of this disclosure can be relatively compliant and stretchable. Degradation can occur at any time between 2 and 16 weeks, depending on the bioabsorbable fibers used and the fabric construction. Degradation can be modified to prevent modulus mismatch at the implant edges, thereby reducing the likelihood of restenosis or complications at the implantation site. Bioabsorbability can range from less than two weeks, two to six weeks, six to twelve weeks, twelve to sixteen weeks, more than twelve weeks, and more than sixteen weeks. As mentioned above, these properties can be generated not only by the type of mesh designed but also by the yarn input. For example, high-glycolic acid absorbable components may exhibit strength loss between 2 and 4 weeks. In other embodiments, the use of polydioxanone can produce products where the absorbable component experiences strength loss between 6 and 11 weeks. A faster transition time may be more suitable for younger individuals who heal faster. For older patients with poorer healing abilities or those who are overweight, a longer transition time may be required.

This technology can be used in a range of markets that utilize absorbable and/or non-absorbable polymer systems. This can include, but is not limited to, hernia repair meshes, implant support scaffolds, tissue replacement devices, tissue augmentation devices, tissue scaffolds, and drug delivery systems.

Rigid surgical mesh constructions are not ideal throughout a patient's life and may be the cause of many long-term complications currently observed in mesh hernia repair. A unique, selectively absorbable mesh design is preferred, which modulates mesh properties in situ, resulting in highly compliant long-term constructions and subsequent repairs. Furthermore, poor tissue integration is associated with many clinical problems; therefore, surface coatings with high porosity and rapid degradation characteristics can be developed to increase the surface bioactivity of the developed mesh construction.

Figure 4 illustrates a scenario of mesh hernia repair, where mesh 401 is secured to tissue 402. Tissue 402 can be, for example, abdominal wall tissue, and mesh 401 can be secured to the tissue using, for example, sutures or pins. Mechanical testing of human abdominal wall samples revealed an elongation (sometimes referred to as elasticity) of approximately 18-32% under a physiological force of 16 N/cm, and a maximum burst strength of 120 N. In contrast, typical prior art surgical mesh exhibits an elongation of less than 16% under a physiological force of 16 N/cm and a maximum burst strength greater than 400 N. In this case, due to the difference in mechanical properties, for example, the elasticity of mesh 401 is lower than that of the underlying tissue 402, and the edges 403 of mesh 401 encounter high shear forces and tensions. Conversely, the tissue surrounded by mesh 401, i.e., the tissue 404 covered by mesh 401, is stress-shielded. The low tensile strength of the prior art mesh/tissue composite 401 contrasts with the highly elastic abdominal wall tissue 402. This generates high shear forces at the edge 403 of the mesh/tissue complex 401. As shown in Figure 4, the mechanical properties of the prior art hernia mesh are significantly different from those of the natural abdominal wall being repaired.

Furthermore, collagen deposition within and around these reticular structures inevitably further reduces compliance. In one study, mechanical testing of the explanted polypropylene mesh showed a 30-fold increase in rigidity compared to the original device. This chronic lack of compliance reduces patient mobility and increases discomfort at the implantation site, giving patients the sensation of a mesh prosthesis. The mesh of this disclosure addresses these problems by placing absorbable fibers within and around a non-absorbable mesh, for example, by providing a lightweight non-absorbable mesh with constrained tensile strength.

The optional advantage of the mesh disclosed is its transformation into a more compliant state, allowing the final mesh/tissue complex to be more compliant and avoiding a high-tension transition between the flexible abdominal wall and the relatively inflexible mesh/tissue complex, which could lead to high stress and ultimately recurrence, foreign body sensation, and other related complications in hernia applications. To generate a material that provides temporary performance and function within physiologically relevant limits, a combination of stable “permanent” fibers and absorbable fibers can be knitted into a mesh fabric, where the absorbable fibers provide temporary mesh stability. Temporary mesh stability is observed, for example, because the extensibility of the component mesh formed from non-absorbable fibers is greater than that of the initial partially absorbable mesh. After implantation, as the absorbable fibers lose their mechanical integrity, the mesh transforms into a more extensible/compliant material.

In the mesh of this disclosure, the absorbable fibers limit the stretchability of the mesh formed from the non-absorbable fibers. Therefore, the stretchability of the partially absorbable mesh is less than that of the non-absorbable mesh component, or in other words, the non-absorbable mesh component is more stretchable than the partially absorbable mesh.

The following are exemplary embodiments of this disclosure:

1) A partially absorbable mesh comprising: at least one bioabsorbable fiber and at least one biostabilized fiber; wherein the bioabsorbable fiber and the biostabilized fiber are combined to form a partially absorbable mesh having an X direction and a perpendicular Y direction; wherein the partially absorbable mesh comprises pores, and a plurality of the pores are characterized in having an average diameter; and wherein the average diameter of the pores changes by less than 25% after the bioabsorbable fiber is removed.

2) The mesh according to embodiment 1, wherein the bioabsorbable fibers are interwoven with the biostabilized fibers.

3) The mesh according to embodiments 1-2, wherein the bioabsorbable fibers reinforce the edges of the pores.

4) The mesh according to embodiments 1-3, wherein the bio-stabilized fibers form a bio-stabilized mesh, and the bio-stabilized mesh is a component of the partially absorbable mesh.

5) The mesh according to embodiments 1-4, wherein the bio-stabilized fibers form a bio-stabilized mesh with a weight of 35-70 g/ ^m² , and the bio-stabilized mesh is a component of the partially absorbable mesh.

6) The mesh according to embodiments 1-5, wherein the bioabsorbable fibers are interwoven into the biostabilized mesh formed by the biostabilized fibers, wherein the bioabsorbable fibers are interwoven by a braided structure.

7) The mesh described in Implementation Scheme 1-6 is anisotropic.

8) The mesh according to embodiments 1-7, wherein the bioabsorbable fibers cause an increase in the degree of anisotropy of the partially absorbable mesh compared to the anisotropy of the biostable mesh components of the partially absorbable mesh.

9) According to the mesh described in Implementation Scheme 1-8, when measured at 16 N/cm, its elongation in the Y direction is greater than its elongation in the X direction.

10) The mesh according to embodiments 1-9 has an elongation in the X direction when measured at 16 N/cm, and the elongation increases by at least 50% after the bioabsorbable fibers are removed.

11) The mesh according to embodiments 1-10, wherein the bioabsorbable fibers extend in the X direction of the mesh.

12) The mesh according to embodiments 1-11, wherein the bioabsorbable fibers extend in the X direction of the mesh and do not extend in the Y direction of the mesh.

13) The mesh according to embodiments 1-12 comprises colored and colorless bioabsorbable fibers, wherein the colored bioabsorbable fibers extend in the X direction of the mesh and do not extend in the Y direction of the mesh.

14) The mesh according to embodiments 1-13, wherein the bio-stabilized fiber is prepared from a polymer selected from the group consisting of polyethylene, polyethylene terephthalate and polypropylene.

15) The mesh according to embodiments 1-14, wherein the bioabsorbable fibers are completely dissolved after the portion of the absorbable mesh is immersed in a phosphate buffer solution at 37°C and pH 7.4 for 12 weeks.

16) The mesh described in Implementation Scheme 1-15 is sterile.

17) The mesh as described in embodiments 1-16 is packaged in a foil bag.

The embodiments provided below further illustrate and exemplify the invention. It should be understood that the scope of the invention is not limited in any way by the scope of the embodiments described below. In characterizing the mesh and/or its components, one or more of the following test schemes may be used: area weighting in ASTM D3776M-09a Standard Test Methods for Mass Per Unit Area (Weight) of Fabric; and ASTM D6797-07 Standard Test Method for Bursting Strength of Fabrics Constant-Rate-of-Extension (CRE) Ball B for the constant-rate-of-extension (CRE) ball burst test. The tensile strength and elongation of textile fabrics are measured in the following parameters: breaking load in the Grab Test (ASTM D5034-09 Standard Test Method for Breaking Strength and Elongation of Textile Fabrics); tensile strength and elongation of textile fabrics in the Grab Test (ASTM D5034-09 Standard Test Method for Breaking Strength and Elongation of Textile Fabrics); and tear resistance in the Trapezoid Procedure (ASTM D5587-14 Standard Test Method for Tearing Strength of Fabrics).

Example

A mesh is prepared from absorbable and non-absorbable monofilaments. The absorbable monofilaments are formed from absorbable semi-crystalline triaxial block copolyester, as described in U.S. Patent No. 7,129,319, using a two-step process with triethanolamine as an initiator and glycolide/trimethylene carbonate/L-lactide as monomers in a weight ratio of 86/9/5. This polymer is available from Poly-Med, Inc. as Product 8609 in the form of oriented monofilaments, having a diameter of 40-100 μm, a breaking strength of 90-120 KSI, and a strength retention of approximately 10-20 days. Some other properties of the monofilament are: a fiber count of 1 (indicating a monofilament, not a multifilament); a denier of 117 g/9000 m; a breaking strength of 6.8 gf/denier (60.2 cN/tex; see ASTM D-3217-01a); a limiting elongation of 21%; and a translucent/off-white color unless the dye has been added to the polymer before extrusion into monofilament form, in which case the monofilament will exhibit the color of the dye. In this example, some monofilaments dyed with D&C Violet #2 were used to prepare the mesh.

Biostable monofilaments were prepared from semi-crystalline polypropylene homopolymer. This polymer and/or its monofilament form are available from many suppliers, such as Mountainside Medical Equipment (Marsey Hill, New York, USA), SMB Corp. (India), and Fitco (Ostend, Belgium). The polypropylene monofilaments used in this example are characterized by: a fiber count of 1 (indicating a monofilament, not a multifilament); a denier of 130 g/9000 m; a breaking strength of 6.1 gf/denier (54.0 cN/tex); a limiting elongation of 21%; and a color ranging from transparent to translucent white.

The mesh was prepared by knitting absorbable and non-absorbable monofilaments together. Knitting was performed in a one-step process using an 18-gauge Raschel Warp Knitting Machine, with one-in-one-out threading. The knitted pattern was a 2-bar diamond mesh for polypropylene monofilaments and a 1-bar chain weave for 8609 monofilaments. Dyed (purple) 8609 fibers were used for every four chain weaves to provide contrasting stripes. The mesh was heat-treated to stabilize its structure. The mesh was then sterilized by exposure to ethylene oxide, dried, and finally packaged in sealed foil bags.

The table shows the properties of the obtained mesh, where initial properties refer to the properties of the mesh removed from the sealed foil bag, and final properties refer to the properties of the mesh after in vitro conditioning for 12 weeks in phosphate buffer at 37°C and pH 7.4.

Figure 5A shows an image of the initial mesh, and Figure 5B shows an image of the final mesh. Notably, the image of the initial mesh shows additional fibers extending in a substantially horizontal direction, positioned above and below every two adjacent rows of pores. These additional fibers are not visible in the image of the final mesh because they dissolved during in vitro conditioning. It is also noteworthy that the pore size remained substantially unchanged between the initial and final conditions of the mesh.

Mesh Performance Table

^* Tearing is not considered according to ASTM D5587-14 standard.

As can be seen from the data in the table, this disclosure provides a partially absorbable mesh (“initial” mesh) in which the bioabsorbable fibers cause an increased degree of anisotropy compared to the biostabilized mesh component (“final” mesh) of the partially absorbable mesh. The final mesh, which does not contain bioabsorbable fibers, exhibits approximately the same tensile elongation at 16 N/cm in both the X (machine direction) and Y (machine transverse) directions: the average of the two elongation values is (43% + 38%)/2 = 40.5%, and the deviation from this average is 43% - 40.5% = 2.5%, where 2.5%/40.5% × 100 = 6.2%. Therefore, the elongation in either the X or Y direction deviates from the average elongation of the final mesh by 6.2%. However, the average elongation of the initial network was (22% + 34%) / 2 = 28%, with a deviation from this average of 34% - 28% = 6.0%, where 6.0% / 28% × 100 = 21.4%. Therefore, although the final biostabilized network exhibits a slight degree of anisotropy in elongation (a 6.2% variation between the X and Y directions compared to the average elongation), the initial partially absorbable network exhibits a greater degree of anisotropy in elongation (a 21.4% variation between the X and Y directions compared to the average elongation). On the other hand, the final network elongates 5% more in the X direction than in the Y direction (43% - 38%), while the initial network elongates 12% more in the Y direction than in the X direction (34% - 22%). Therefore, this disclosure provides a partially absorbable mesh (e.g., an "initial" mesh) wherein the bioabsorbable fibers cause an increased degree of anisotropy in the partially absorbable mesh compared to the biostabilized mesh component (e.g., a "final" mesh). In one embodiment, this disclosure provides a mesh having a greater elongation in the Y direction than in the X direction when measured at 16 N/cm, and in another embodiment, this disclosure provides a partially absorbable mesh having elongation in the X direction when measured at 16 N/cm, wherein the elongation increases by at least 50%, or about 100%, after the removal of the bioabsorbable fibers (in this embodiment, the elongation in the X direction increases by (43% - 22%) / 22% x 100 = 95%).

While the subject matter of the invention has been described in detail with respect to specific exemplary embodiments and methods, it should be understood that those skilled in the art, upon gaining an understanding of the foregoing, can readily modify, alter, and create equivalents of such embodiments. Therefore, the scope of this disclosure is by way of example only and is not in any way limiting, and the disclosure does not exclude such modifications, alterations, and/or additions to the subject matter of the invention, which should be apparent to those skilled in the art utilizing the teachings disclosed herein.

All U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications, and non-patent publications cited in and/or listed in the application data sheet are incorporated herein by reference in their entirety. Materials and methods described in publications may be incorporated herein by reference for the purpose of description and disclosure, for example, in conjunction with the invention described herein. The publications discussed above and throughout this document are provided only because their publication predates the filing date of this application. Nothing herein should be construed as an admission that the inventor has no prior right to any referenced publication.

Generally, the terminology used in the following claims should not be construed as limiting the claims to the specific embodiments disclosed in the specification and claims, but rather as encompassing all possible embodiments and the full scope of equivalents claimed by these claims. Therefore, the claims are not limited by this disclosure.

Claims (17)

1. A partially absorbable mesh comprising: at least one bioabsorbable fiber and at least one biostabilized fiber; wherein the bioabsorbable fiber comprises: Segmented multiaxial copolyester, wherein the segmented multiaxial copolyester is formed from an amorphous multiaxial polymerization initiator of a mixture of end-grafted ε-caprolactone and at least one cyclic monomer, wherein the at least one cyclic monomer is selected from L-lactide, DL-lactide, glycolide, or trimethylene carbonate; or Segmented multiaxial copolyester, the segmented multiaxial copolyester being formed from an amorphous multiaxial polymerization initiator, the amorphous multiaxial polymerization initiator being formed by ring-opening polymerization of a mixture of trimethylene carbonate and at least one monomer selected from p-dioxane, ε-caprolactone and 1,5-dioxane-2-one; or Silk protein; or Segmented copolymers, said segmented copolymers being formed from: lactide and at least one monomer selected from glycolide, ε-caprolactone, trimethylene carbonate, p-dioxanone, or morpholinone; or Straight-chain segmented lactide-derived copolyesters; or Poly(3-hydroxyalkanoate); or Poly(3-hydroxybutyrate) or poly(3-hydroxybutyrate-co-3-hydroxyvalerate), The bioabsorbable fibers and the biostabilized fibers are combined to form a partially absorbable mesh having an X direction and a perpendicular Y direction; The absorbent mesh portion comprises pores, and the plurality of pores are characterized in that they have an average diameter; The bio-stabilized fibers form a bio-stabilized network, and the bio-stabilized network is a component of the partially absorbable network; and By interlacing the bioabsorbable fibers around the pores formed by the biostabilizing fibers rather than through those pores, the average diameter of the pores changes by less than 25% after the bioabsorbable fibers are removed. 2. The mesh according to claim 1, wherein the bioabsorbable fibers are interwoven with the biostabilized fibers. 3. The mesh according to claim 1, wherein the bioabsorbable fibers reinforce the edges of the pores. 4. The mesh according to claim 1, wherein the bio-stabilized fibers form a bio-stabilized mesh with a weight of 35-70 g/ ^m² , and the bio-stabilized mesh is a component of the partially absorbable mesh. 5. The mesh according to claim 1, wherein the bioabsorbable fibers are interwoven into a biostabilized mesh formed of the biostabilized fibers, wherein the bioabsorbable fibers are interwoven by a braided structure. 6. The mesh according to claim 1, when measured at 16 N/cm, has a greater elongation in the Y direction than in the X direction. 7. The mesh according to claim 1, which has elongation in the X direction when measured at 16 N/cm, and whose elongation increases by at least 50% after the removal of the bioabsorbable fibers. 8. The mesh according to claim 1, wherein the bioabsorbable fibers extend in the X direction of the mesh. 9. The mesh according to claim 1, wherein the bioabsorbable fibers extend in the X direction of the mesh and do not extend in the Y direction of the mesh. 10. The mesh of claim 1, comprising colored and colorless bioabsorbable fibers, wherein the colored bioabsorbable fibers extend in the X direction of the mesh and not in the Y direction of the mesh. 11. The mesh according to claim 1, wherein the bio-stabilized fiber is prepared from a polymer selected from the group consisting of: polyethylene, poly(tetrafluoroethylene), aliphatic polyamide, aromatic polyamide, polyether-ether ketone (PEK), polyethylene terephthalate, poly(hexafluoropropylene-VDF), and polypropylene. 12. The mesh according to claim 11, wherein the polyethylene is ultra-high molecular weight polyethylene (UHMWPE). 13. The mesh according to claim 1, wherein the bioabsorbable fibers are completely dissolved after the portion of the absorbable mesh has been impregnated in a phosphate buffer solution at 37°C and pH 7.4 for 12 weeks. 14. The mesh according to claim 1, wherein it is sterile. 15. The mesh according to claim 1, wherein the silk fibroin is degummed white Brazilian primitive silkworm (Bombyx mori) silk fiber. 16. The mesh according to claim 1, wherein the bio-stabilized fiber is a monofilament or a multifilament. 17. The mesh according to claim 1, wherein the bioabsorbable fiber is a monofilament or a multifilament.