Patent Description:
The present invention relates generally to a braided structure, and, more particularly, to a small diameter braided structure that is creep resistant and abrasion resistant while at the same time having high strength and low elongation.

Braided structures are often used in the medical field for sutures, load bearing orthopedic applications, artificial tendons/ligaments, device fixation, actuation cables, tissue repair, etc. Because of the small diameter required for many applications, other properties of the braided structure are compromised. For example, while it may be possible to develop a braided structure with a small diameter (e.g., less than <NUM> millimeter, such as less than about <NUM> micrometers), there have been difficulties in designing such a structure to also be creep resistant and/or abrasion resistant. Challenges have also arisen in developing a braided structure having a small diameter that also has low elongation and high strength.

As such, a need exists for a braided structure having a small diameter such that it is suitable for use in medical applications while at the same time having the desired mechanical properties (e.g., creep resistance, abrasion resistance, low elongation, and/or high strength).

<CIT> discloses sterilized bicomponent fiber braids useful for the preparation of surgical sutures, ligatures and other medical devices.

In one aspect, the present invention is directed to a braided structure that includes a core composed of a yarn, wherein the yarn includes an aromatic polymer; and a sheath braided around the core, wherein the sheath includes a plurality of ultra high molecular weight polyolefin yarns. Further, the braided structure has an overall diameter ranging from about <NUM> micrometers to about <NUM> micrometers.

In one particular embodiment, the aromatic polymer can include a liquid crystalline polymer, an aramid polymer, or a combination thereof.

In still another aspect, the sheath can include from <NUM> yarns to about <NUM> yarns or carriers and each of the plurality of yarns or carriers in the sheath can include from <NUM> filament to about <NUM> filaments.

In yet another aspect, the sheath can include at least two sheath layers.

In one more aspect, the yarn can include from about <NUM> filaments to about <NUM> filaments.

In an additional aspect, the core can include a single yarn or at least one yarn. Further, when the core includes a single yarn, it is to be understood that the core can include at least one additional yarn (e.g., the single yarn can be <NUM>-ply where the yarn acts as a single yarn).

In one aspect, the core can have a first diameter and the sheath can have a second diameter, where the ratio of the first diameter to the second diameter ranges from about <NUM>:<NUM> to about <NUM>:<NUM>.

In still another aspect, the ultra high molecular weight polyolefin can include an ultrahigh molecular weight polyethylene (UHMWPE) having a weight average molecular weight (Mw) of at least about <NUM>,<NUM> grams/mole (g/mol).

In yet another aspect, the braided structure can exhibit a creep of less than about <NUM> inches (about <NUM> millimeters) when subjected to a constant load of <NUM> pounds-force (about <NUM> Newtons) for about <NUM> minutes at an about <NUM> inch (<NUM> centimeter) gage length on a horn grip. In another aspect, the braided structure can exhibit a creep of less than about <NUM> percent elongation after about <NUM> minutes.

In one more aspect, the braided structure can exhibit resistance to abrasion after cycling the braided structure <NUM> millimeters in a backwards direction and <NUM> millimeters in a forwards direction for a total of <NUM> cycles across a metal edge having a <NUM> millimeter radius with <NUM> grams of weight applied to the braided structure, wherein the braided structure includes less than <NUM> broken filaments per linear inch (<NUM>) after cycling.

In an additional aspect, the braided structure can exhibit a load at break ranging from about <NUM> pounds-force (about <NUM> Newtons) to about <NUM> pounds-force (about <NUM> Newtons).

In one aspect, the braided structure can exhibit an extension at break ranging from about <NUM>% to about <NUM>%.

In another aspect, the braided structure can exhibit a stiffness ranging from about <NUM> pounds-force per inch (about <NUM> Newtons/millimeter) to about <NUM> pounds-force per inch (about <NUM> Newtons/millimeter).

In an additional aspect, the braided structure can exhibit an ultimate tensile strength ranging from about <NUM> x <NUM><NUM> pounds per square inch (about <NUM> megapascals) to about <NUM> x <NUM><NUM> pounds per square inch (about <NUM> megapascals). In another aspect, the braided structure can exhibit an ultimate tensile strength ranging from about <NUM> grams/denier (/<NUM> dTex) yarn to about <NUM> grams/denier (/<NUM> dTex) yarn.

In still another aspect, the braided structure can include from about <NUM> picks per inch (per <NUM>) (PPI) to about <NUM> picks per inch (per <NUM>) (PPI).

In yet another aspect, the sheath yarn can include from about <NUM> twists per inch (per <NUM>) (TPI) to about <NUM> twists per inch (per <NUM>) (TPI).

In one more aspect, the core yarn can include zero twists per inch (per <NUM>) (TPI) to about two TPI.

In an additional aspect, each of the plurality of yarns in the sheath can have a linear mass density ranging from about <NUM> denier (<NUM> dTex) to about <NUM> denier (<NUM> dTex).

In one more aspect, the yarn in the core can have a linear mass density ranging from about <NUM> denier (<NUM> dTex) to about <NUM> denier (<NUM> dTex).

In another aspect, the present invention is directed to a medical device, a suture, a load bearing orthopedic application, an artificial tendon, an actuation cable, a component for tissue repair, or a fixation device that includes a braided structure as set forth above.

In still another aspect, the present invention is directed to a braided structure composed of a core that includes a yarn, where the yarn includes an aromatic polymer and a sheath braided around the core, where the sheath includes a plurality of ultra high molecular weight polyolefin yarns. Further, the braided structure exhibits an ultimate tensile strength ranging from about <NUM> x <NUM><NUM> pounds per square inch (about <NUM> megapascals) to about <NUM> x <NUM><NUM> pounds per square inch (about <NUM> megapascals). In another aspect, the braided structure can exhibit an ultimate tensile strength ranging from about <NUM> grams/denier (about <NUM> grams /<NUM> dTex) yarn to about <NUM> grams/denier (about <NUM> grams/<NUM> dTex) yarn.

In yet another aspect, the present invention is directed to a braided structure composed of a core that includes a yarn, where the yarn includes an aromatic polymer and a sheath braided around the core, where the sheath includes a plurality of ultra-high molecular weight polyolefin yarns. Further, the braided structure exhibits a creep of less than about <NUM> inches (about <NUM> millimeters) when subjected to a constant load of <NUM> pounds-force (about <NUM> Newtons) for about <NUM> minutes and at an about <NUM> inch (<NUM> centimeter) gage length on a horn grip. In another aspect, the braided structure exhibits a creep of less than about <NUM>% elongation after about <NUM> minutes.

Generally speaking, the present invention is directed to a braided structure that includes a core and a sheath. The core includes a yarn formed from an aromatic polymer (e.g., a liquid crystalline polymer, an aramid polymer, or a combination thereof), and the sheath, which includes a plurality of ultra-high molecular weight polyolefin yarns, is braided around the core. In some embodiments, the core can be a single yarn, although in other embodiments, it is to be understood that the core can include more than one yarn. The sheath has an overall diameter ranging from about <NUM> micrometers to about <NUM> micrometers. Despite its small diameter, the braided structure can be creep resistant and abrasion resistant while at the same time exhibiting low elongation, a high load at break, and high stiffness. The braided structure can be used in medical applications such as sutures, load bearing orthopedic applications, artificial tendons/ligaments, device fixation, actuation cables for medical devices, components for tissue repair, etc..

Referring now to the drawings, <FIG> illustrates a side view of a braided structure <NUM> contemplated by the present invention, while <FIG> illustrates a cross-sectional view of the braided structure <NUM> taken at line C-C. The braided structure <NUM> includes a core <NUM> surrounded by a sheath <NUM> and is braided in a 1x1 pattern. However, other braid patterns known in the art can alternatively be used (e.g., 1x2, 2x2, etc.). The core <NUM> can include a single strand of yarn, where the yarn can include from about <NUM> filaments to about <NUM> filaments, such as from about <NUM> filaments to about <NUM> filaments, such as from about <NUM> filaments to about <NUM> filaments, such as from about <NUM> filaments to about <NUM> filaments. In one particular embodiment as shown in <FIG>, the core <NUM> can include a single yarn. However, it is also to be understood that the core <NUM> can include more than a single yarn, such as at least one additional yarn, such that the core <NUM> can include from about <NUM> yarns to about <NUM> yarns, such as from about <NUM> yarns to about <NUM> yarns, such as from about <NUM> yarns to about <NUM> yarns, such as from about <NUM> yarns to about <NUM> yarns, such as from about <NUM> yarns to about <NUM> yarns, where the yarns can be braided or unbraided. The sheath <NUM> can include from <NUM> yarns to about <NUM> yarns, such as from <NUM> yarns to about <NUM> yarns, such as from about <NUM> yarns to about <NUM> yarns.

It is also to be understood that the sheath yarns and/or core yarns may contain twist or no twist or no intentional twist or unintentional twist. Yarn twist can include from <NUM> to <NUM> intentional or unintentional twists per inch (per <NUM>), such as from <NUM> to <NUM> intentional or unintentional twists per inch (per <NUM>), such as from <NUM> to <NUM> intentional or unintentional twists per inch (per <NUM>), such as from <NUM> to <NUM> intentional or unintentional twists per inch (per <NUM>), such as from <NUM> to <NUM> intentional or unintentional twists per inch (per <NUM>). It is to be understood that unintentional twist may include twist that accumulates in the yarn during normal manufacturing processes. A non-limiting example of unintentional twist is twist that is obtained once the yarn is wrapped or spun on the spool.

Meanwhile, the sheath <NUM> can include a plurality of S yarns <NUM> or Z yarns <NUM> wrapped around the core <NUM>. During manufacturing of a braided structure, a portion of the machine yarn carriers can move in a clockwise direction, and the other portion of the carriers can move in a counter-clockwise direction. In a non-limiting example, half of the carriers move in the clockwise direction and the other half of the carriers move in the counter-clockwise direction. As the machine carriers move around the braided structure, yarn is pulled off each carrier and gathered at the braiding point. The sheath yarn may be naturally twisted or unintentionally twisted due to the movement of the carriers around the machine. For optimal braid strength and minimal braid creep, the yarn filaments must remain close to parallel with the braided structure by using sheath yarn with S twist moving clockwise direction around the braided structure and sheath yarn with Z twist moving counter-clockwise direction around the braided structure.

In other words, the sheath yarn <NUM> can exhibit twist in both the S and Z directions. For instance, the sheath yarn <NUM> can include from <NUM> to about <NUM>, such as from about <NUM> to about <NUM>, such as from about <NUM> to about <NUM> or Z yarns braided clockwise <NUM> and from <NUM> to about <NUM>, such as from about <NUM> to about <NUM>, such as from about <NUM> to about <NUM> opposing S or Z yarns braided counterclockwise <NUM>. In other words, the sheath can include from <NUM> yarns to about <NUM> yarns, such as from about <NUM> yarns to about <NUM> yarns, such as from about <NUM> yarns to about <NUM> yarns, where half of the yarns are wrapped around the core in a clockwise direction and half of the yarns are wrapped around the core in a counterclockwise direction.

In one particular embodiment as shown in <FIG>, the sheath <NUM> can include three S or Z yarns <NUM>, <NUM>, and <NUM> and three opposing S or Z yarns <NUM>, <NUM>, and <NUM>. Moreover, each clockwise carrier of S, Z, or untwisted yarn <NUM> or counterclockwise carrier of S, Z, or untwisted yarn <NUM> can include from <NUM> filament to about <NUM> filaments, such as from <NUM> filaments to about <NUM> filaments, such as from about <NUM> filaments to about <NUM> filaments, such as from about <NUM> filaments to about <NUM> filaments. The overall stiffness and flexibility of the braided structure <NUM> can be optimized based on the number of yarn filaments. In one embodiment, increasing the number of yarn filaments can improve the abrasion resistance of the braided structure <NUM>.

Further, the braided structure <NUM> can have an overall diameter D1 ranging from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers), such as from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers), such as from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers), such as from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers), such as from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers), such as from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers).

Meanwhile, the core <NUM> can have a diameter D2 ranging from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers), such as from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers), such as from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers), such as from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers), while each of the individual sheath yarns <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> can have a diameter D3 ranging from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers), such as from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers), such as from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers), such as from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers).

In one particular embodiment, the ratio of the diameter D2 of the core <NUM> to the diameters D3 of each of the yarns in <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> in the sheath <NUM> (D2:D3) can range from about <NUM>:<NUM> to about <NUM>:<NUM>, such as from about <NUM>:<NUM> to about <NUM>:<NUM>, such as from <NUM>:<NUM> to about <NUM>:<NUM>, such as from <NUM>:<NUM> to about <NUM>:<NUM>. Without intending to be limited by any particular theory, the present inventors have found that such a balance between the diameter D2 of the core <NUM> and the diameter D3 of each of the yarns in the sheath <NUM>, in conjunction with other characteristics such as the materials used for the core <NUM> and the sheath <NUM>, results in a braided structure <NUM> that has a small diameter such that it can be used as a suture or other medical application (e.g., actuation cables) without sacrificing the mechanical properties of the braided structure (e.g., creep resistance, abrasion resistance, low elongation, high strength, etc.).

In applications where a braided structure is used with, within, or in conjunction with a medical device, the material properties and mechanical properties of the core <NUM> and sheath <NUM> effect the braided structure and the overall device containing the braided structure. In one embodiment, by utilizing the balance of diameter D2 of the core <NUM> and the diameter D3 of the sheath <NUM>, the preferred overall diameter of the braided structure <NUM> can be achieved to fit through a small designated lumen within a medical device and still met the requirements for adequate strength and creep resistance. Furthermore, a braided structure <NUM> containing a core <NUM> and sheath <NUM> larger than the preferred diameter range of the present invention would not fit within a designated lumen for specific medical device applications. Additionally, braided structures with tensile strength higher than the preferred range of the present invention may result in damage to the final medical device that contains a braided structure <NUM>. Moreover, to protect the core <NUM> from abrasion and yarn misalignment, the diameter D2 of the core <NUM> and diameter D3 of the sheath <NUM> are selected to provide adequate sheath coverage around the core <NUM> with a desired picks per inch (per <NUM>).

Moreover, the linear mass density of the core <NUM> and sheath <NUM> can also be controlled to obtain the desired properties of the braided structure. Specifically, the linear mass density of the core <NUM> can range from about <NUM> denier (<NUM> dTex) to about <NUM> denier (<NUM> dTex), such as from about <NUM> denier (<NUM> dTex) to about <NUM> denier (<NUM> dTex), such as from about <NUM> denier (<NUM> dTex to about <NUM> denier (<NUM> dTex. Further, the linear mass density of each of the yarns in the sheath <NUM> can range from about <NUM> denier (<NUM> dTex) to about <NUM> denier (<NUM> dTex)
, such as from about <NUM> denier to about <NUM> denier, such as from about <NUM> denier to about <NUM> denier, such that the overall linear mass density of the sheath <NUM> can also range from about <NUM> denier (<NUM> dTex) to about <NUM> denier (<NUM> dTex), such as from about <NUM> denier (<NUM> dTex to about <NUM> denier (<NUM> dTex, such as from about <NUM> denier (<NUM> dTex) to about <NUM> denier (<NUM> dTex.

Moreover, although in some embodiments the core <NUM> comprises a single yarn have <NUM> twist per inch (per <NUM>), when a single or plurality of yarns are utilized, the core yarn <NUM> can have from <NUM> twist per inch (per <NUM>) (TPI) to about <NUM> TPI, such as from <NUM> TPI to about <NUM> TPI, such as from <NUM> TPI to about <NUM> TPI, such as from about <NUM> TPI to about <NUM> TPI, such as from about <NUM> TPI to about <NUM> TPI. In addition, the sheath yarn <NUM> can be formed so that it includes from <NUM> twist per inch (per <NUM>) (TPI) to about <NUM> TPI, such as from <NUM> TPI to about <NUM> TPI, such as from <NUM> TPI to about <NUM> TPI, <NUM> TPI to about <NUM> TPI, such as from about <NUM> TPI to about <NUM> TPI, such as from about <NUM> TPI to about <NUM> TPI. The TPI of the braided structure effects the abrasion resistance of the braided structure <NUM>, where abrasion during manufacturing of the braided structure can be minimized without compromising the tensile strength by using the preferred TPI range of the disclosed invention. Twists may include unintentional twist obtained once the yarn is wrapped or spun on the spool or intentional twist incorporated into the yarn by a manufacturing process.

Further, the braided structure <NUM> can include from about <NUM> picks per inch (per <NUM>) (PPI) to about <NUM> picks per inch (per <NUM>), such as from about <NUM> PPI to about <NUM> PPI, such as from about <NUM> PPI to about <NUM> PPI. By using the preferred PPI range, low creep, low elongation, and desired stiffness of the braided structure can be achieved. For example, a PPI greater than the preferred range can result in an undesired high creep and elongation, which, in turn, decreases the stiffness of the braided structure outside of the desired stiffness range. Moreover, utilizing a PPI lower than the preferred range can result in an undesired low creep and elongation, which, in turn, increases the stiffness of the braided structure outside of the desired stiffness range. Further, while a PPI value lower than the preferred range may result in a braided structure with minimal creep, this low PPI value may not provide adequate sheath yarn coverage around the core, which may result in poor abrasion resistance.

Based on the specific combination of sheath and core yarn characteristics described above, a small diameter braided structure having a diameter ranging from about <NUM> micrometers to about <NUM> micrometers can be formed that exhibits desired abrasion resistance, creep resistance, load at break, load at break with <NUM>° bend, extension at break, and stiffness.

For instance, the braided structure <NUM> of the present invention can be abrasion resistant in that it exhibits little to no fraying. In one embodiment, the braided structure includes less than <NUM> broken filaments per linear inch (<NUM>), such as less than <NUM> broken filaments per linear inch (<NUM>), such less than <NUM> broken filaments per linear inch (<NUM>), such as less than <NUM> broken filaments per linear inch (<NUM>) after cycling the braided structure <NUM> millimeters in a backwards direction and <NUM> millimeters in a forwards direction for a total of <NUM> cycles across a metal edge having a <NUM> millimeter radius with <NUM> grams of weight applied to the braided structure.

Further, the braided structure <NUM> of the present invention can exhibit a creep of less than about <NUM> inches (about <NUM> millimeters), such as less than about <NUM> inches (about <NUM> millimeters), such as less than about <NUM> inches (about <NUM> millimeters), such as less than about <NUM> millimeters (about <NUM> millimeters) when subjected to a constant load of <NUM> pounds-force (about <NUM> Newtons) for about <NUM> minutes and at an about <NUM> inch (<NUM> centimeter) gage length on a horn grip. In one particular embodiment, the creep can range from about <NUM> inches (about <NUM> millimeters) to about <NUM> inches (about <NUM> millimeters).

Further, the braided structure <NUM> of the present invention can exhibit a creep of less than about <NUM>% elongation after about <NUM> minutes, such as less than about <NUM>% elongation after about <NUM> minutes, such as less than about <NUM>% elongation after about <NUM> minutes, such as less than about <NUM>% elongation after about <NUM> minutes, such as less than about <NUM>% elongation after about <NUM> minutes, such as less than about <NUM>% elongation after about <NUM> minutes, such as less than about <NUM>% elongation after about <NUM> minutes, such as less than about <NUM>% elongation after about <NUM> minutes, such as less than about <NUM>% elongation after about <NUM> minutes. In one embodiment, the braided structure <NUM> can exhibit a creep between about <NUM>% and about <NUM>% elongation after about <NUM> minutes.

In addition, when undergoing tensile testing, the braided structure <NUM> of the present invention can exhibit a load at break ranging from about <NUM> pounds-force (about <NUM> Newtons) to about <NUM> pounds-force (about <NUM> Newtons), such as from about <NUM> pounds-force (about <NUM> Newtons) to about <NUM> pounds-force (about <NUM> Newtons), such as from about <NUM> pounds-force (about <NUM> Newtons) to about <NUM> pounds-force (about <NUM> Newtons), such as from about <NUM> pounds-force (about <NUM> Newtons) to about <NUM> pounds-force (about <NUM> Newtons).

Further, when subjected to tensile testing, the braided structure <NUM> of the present invention can exhibit a load at break with an <NUM>° bend ranging from about <NUM> pounds-force (about <NUM> Newtons) to about <NUM> pounds force (about <NUM> Newtons), such as from about <NUM> pounds-force (about <NUM> Newtons) to about <NUM> pounds-force (about <NUM> Newtons), such as from about <NUM> pounds-force (about <NUM> Newtons) to about <NUM> pounds-force (about <NUM> Newtons) when the braided structure is wrapped around a pin or wire having a diameter ranging from about <NUM> inches (about <NUM> micrometers) to about <NUM> inches (about <NUM> micrometers), such as about <NUM> inches (about <NUM> micrometers).

Moreover, when subjected to tensile testing, the braided structure <NUM> of the present invention can exhibit an extension or elongation at break ranging from about <NUM>% to about <NUM>%, such as from about <NUM>% to about <NUM>%, such as from about <NUM>% to about <NUM>%, such as from about <NUM>% to about <NUM>%.

Additionally, when subjected to tensile testing, the braided structure <NUM> of the present invention can exhibit a stiffness ranging from about <NUM> pounds-force/inch (about <NUM>. 75Newtons/millimeter) to about <NUM> pounds-force/inch (about <NUM> Newtons/millimeter), such as from about <NUM> pounds-force/inch (about <NUM> Newtons/millimeter) to about <NUM> pounds-force/inch (about <NUM> Newtons/millimeter), such as from about <NUM> pounds-force/inch (about <NUM> Newtons/millimeter) to about <NUM> pounds-force/inch (about <NUM> Newtons/millimeter, such as from about <NUM> pounds-force/inch (about <NUM> Newtons/millimeter) to about <NUM> pounds-force/inch (about <NUM> Newtons/millimeter).

Further, when subjected to tensile testing, the braided structure can exhibit an ultimate tensile strength ranging from about <NUM> x <NUM><NUM> pounds per square inch (about <NUM> megapascals) to about <NUM> x <NUM><NUM> pounds per square inch (about <NUM> megapascals), such as from about <NUM> x <NUM><NUM> pounds per square inch (about <NUM> megapascals) to about <NUM> x <NUM><NUM> pounds per square inch (about <NUM> megapascals), such as from about <NUM> x <NUM><NUM> pounds per square inch (about <NUM> megapascals) to about <NUM> x <NUM><NUM> pounds per square inch (about <NUM> megapascals), such as from about <NUM> x <NUM><NUM> pounds per square inch (about <NUM> megapascals) to about <NUM> x <NUM><NUM> pounds per square inch (about <NUM> megapascals).

In another aspect, the braided structure can exhibit an ultimate tensile strength ranging from about <NUM> grams/denier (grams/<NUM> dTex) yarn to about <NUM> grams/denier (grams/<NUM> dTex) yarn, such as to about <NUM> grams/denier (grams/<NUM> dTex) yarn to about <NUM> grams/denier (grams/<NUM> dTex) yarn, such as to about <NUM> grams/denier (grams/<NUM> dTex) yarn to about <NUM> grams/denier (grams/<NUM> dTex) yarn, such as to about <NUM> grams/denier yarn (grams/<NUM> dTex) to about <NUM> grams/denier yarn (grams/<NUM> dTex), such as to about <NUM> grams/denier (grams/<NUM> dTex) yarn to about <NUM> grams/denier (grams/<NUM> dTex) yarn.

The various components of the braided structure will now be described in more detail.

According to the present invention, the core of the braided structure can include a single aromatic polymer yarn. For instance, the aromatic polymer can include a liquid crystalline polymer, an aramid polymer, or a combination thereof. The term "liquid crystalline polymer" or "LCP" refers to a polymer that can possess a rod-like structure that allows it to exhibit liquid crystalline behavior in its molten state (e.g., thermotropic nematic state). The polymer may contain aromatic units (e.g., aromatic polyesters, aromatic polyesteramides, etc.) so that it is wholly aromatic (e.g., containing only aromatic units) or partially aromatic (e.g., containing aromatic units and other units, such as cycloaliphatic units). The polymer may also be fully crystalline or semi-crystalline in nature. In some embodiments, suitable thermotropic liquid crystalline polymers may include, for instance, aromatic polyesters (e.g., liquid crystalline aromatic polyesters or liquid crystalline polyesters), aromatic poly(esteramides), aromatic poly(estercarbonates), aromatic polyamides, etc., and may likewise contain repeating units formed from one or more aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, aromatic diols, aromatic aminocarboxylic acids, aromatic amines, aromatic diamines, etc., as well as combinations thereof.

Aromatic polyesters, for instance, may be obtained from (<NUM>) two or more aromatic hydroxycarboxylic acids; (<NUM>) at least one aromatic hydroxycarboxylic acid, at least one aromatic dicarboxylic acid, and at least one aromatic diol; and/or (<NUM>) at least one aromatic dicarboxylic acid and at least one aromatic diol. Examples of suitable aromatic hydroxycarboxylic acids include, <NUM>-hydroxybenzoic acid; <NUM>-hydroxy-<NUM>'-biphenylcarboxylic acid; <NUM>-hydroxy-<NUM>-naphthoic acid; <NUM>-hydroxy-<NUM>-naphthoic acid; <NUM>-hydroxy-<NUM>-naphthoic acid; <NUM>-hydroxy-<NUM>-naphthoic acid; <NUM>'-hydroxyphenyl-<NUM>-benzoic acid; <NUM>'-hydroxyphenyl-<NUM>-benzoic acid; <NUM>'-hydroxyphenyl-<NUM>-benzoic acid, etc., as well as alkyl, alkoxy, aryl and halogen substituents thereof. Examples of suitable aromatic dicarboxylic acids include terephthalic acid; isophthalic acid; <NUM>,<NUM>-naphthalenedicarboxylic acid; diphenyl ether-<NUM>,<NUM>'-dicarboxylic acid; <NUM>,<NUM>-naphthalenedicarboxylic acid; <NUM>,<NUM>-naphthalenedicarboxylic acid; <NUM>,<NUM>'-dicarboxybiphenyl; bis(<NUM>-carboxyphenyl)ether; bis(<NUM>-carboxyphenyl)butane; bis(<NUM>-carboxyphenyl)ethane; bis(<NUM>-carboxyphenyl)ether; bis(<NUM>-carboxyphenyl)ethane, etc., as well as alkyl, alkoxy, aryl and halogen substituents thereof. Examples of suitable aromatic diols include hydroquinone; resorcinol; <NUM>,<NUM>-dihydroxynaphthalene; <NUM>,<NUM>-dihydroxynaphthalene; <NUM>,<NUM>-dihydroxynaphthalene; <NUM>,<NUM>'-dihydroxybiphenyl; <NUM>,<NUM>'-dihydroxybiphenyl; <NUM>,<NUM>'-dihydroxybiphenyl; <NUM>,<NUM>'-dihydroxybiphenyl ether; bis(<NUM>-hydroxyphenyl)ethane, etc., as well as alkyl, alkoxy, aryl and halogen substituents thereof. In one particular embodiment, the aromatic polyester is derived from <NUM>-hydroxybenzoic acid and <NUM>,<NUM>-hydroxynaphthoic acid. The monomer units derived from <NUM>-hydroxybenzoic acid may constitute from about <NUM>% to about <NUM>% (e.g., <NUM>%) of the polymer on a mole basis and the monomer units derived from <NUM>,<NUM>-hydroxynaphthoic acid may constitute from about <NUM>% to about <NUM>% (e.g., <NUM>%) of the polymer on a mole basis. The synthesis and structure of these and other aromatic polyesters may be described in more detail in <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>.

Liquid crystalline polyesteramides may likewise be obtained from (<NUM>) at least one aromatic hydroxycarboxylic acid and at least one aromatic aminocarboxylic acid; (<NUM>) at least one aromatic hydroxycarboxylic acid, at least one aromatic dicarboxylic acid, and at least one aromatic amine and/or diamine optionally having phenolic hydroxy groups; and (<NUM>) at least one aromatic dicarboxylic acid and at least one aromatic amine and/or diamine optionally having phenolic hydroxy groups. Suitable aromatic amines and diamines may include, for instance, <NUM>-aminophenol; <NUM>-aminophenol; <NUM>,<NUM>-phenylenediamine; <NUM>,<NUM>-phenylenediamine, etc., as well as alkyl, alkoxy, aryl and halogen substituents thereof. In one particular embodiment, the aromatic polyesteramide is derived from <NUM>,<NUM>-hydroxynaphthoic acid, terephthalic acid, and <NUM>-aminophenol. The monomer units derived from <NUM>,<NUM>-hydroxynaphthoic acid may constitute from about <NUM>% to about <NUM>% of the polymer on a mole basis (e.g., <NUM>%), the monomer units derived from terephthalic acid may constitute from about <NUM>% to about <NUM>% (e.g., <NUM>%) of the polymer on a mole basis, and the monomer units derived from <NUM>-aminophenol may constitute from about <NUM>% to about <NUM>% (e.g., <NUM>%) of the polymer on a mole basis. In another embodiment, the aromatic polyesteramide contains monomer units derived from <NUM>,<NUM>-hydroxynaphthoic acid, and <NUM>-hydroxybenzoic acid, and <NUM>-aminophenol, as well as other optional monomers (e.g., <NUM>,<NUM>'-dihydroxybiphenyl and/or terephthalic acid). The synthesis and structure of these and other aromatic poly(esteramides) may be described in more detail in <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>.

Meanwhile, the term "aramid polymer" refers to a class of polymers known as aromatic polyamides. Such polymers are typically prepared by the reaction between an amine group and a carboxylic acid halide group. Examples of suitable aramid polymers contemplated by the present invention include poly-metaphenylene isophthalamides and p-phenylene terephthalamides.

In one particular embodiment, the aromatic polymer can be formed into a core <NUM> having a single yarn with zero turns per inch (per <NUM>) that has a linear mass density ranging from about <NUM> denier (<NUM> dTex) to about <NUM> denier (<NUM> dTex). The yarn can also include from about <NUM> to about <NUM> filaments and can have a diameter ranging from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers). Further, the single yarn of the core <NUM> can exhibit a percent elongation (extension at break) ranging from about <NUM>% to about <NUM>%. In addition, the yarn can exhibit a tenacity ranging from about <NUM>/denier (g/<NUM> dTex) to about <NUM>/denier (g/<NUM> dTex) and can have a maximum force ranging from about <NUM> grams to about <NUM> grams.

In another particular embodiment, the aromatic polymer can be formed into a core <NUM> having a single yarn with zero turns per inch (per <NUM>) that has a linear mass density ranging from about <NUM> denier (<NUM> dTex)to about <NUM> denier (<NUM> dTex). The yarn can also include from <NUM> to about <NUM> filaments and can have a diameter ranging from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers). Further, the single yarn of the core <NUM> can exhibit a percent elongation (extension at break) ranging from about <NUM>% to about <NUM>%. In addition, the yarn can exhibit a tenacity ranging from about <NUM>/denier (g/<NUM> dTex) to about <NUM>/denier (g/<NUM> dTex) and can have a maximum force ranging from about <NUM> grams to about <NUM> grams.

According to the present invention, the sheath of the braided structure can include a plurality of sheath yarns formed from a high molecular weight polymer, such as a high molecular weight polyolefin.

In one particular embodiment, the sheath can include a plurality of sheath yarns formed from an ultra high molecular weight polyethylene (UHMWPE) polymer that can have a weight average molecular weight (Mw) of at least about <NUM>,<NUM> grams/mole (g/mol). In some embodiments, the average molecular weight of the UHMWPE polymer can range from about <NUM>,<NUM>/mol to about <NUM>,<NUM>,<NUM>/mol, such as from about <NUM>,<NUM>,<NUM>/mol to about <NUM>,<NUM>,<NUM>/mol, such as from about <NUM>,<NUM>,<NUM>/mol to about <NUM>,<NUM>,<NUM>/mol, such as from about <NUM>,<NUM>,<NUM>/mol to about <NUM>,<NUM>,<NUM>/mol.

In addition, the UHMWPE polymer may be a homopolymer of ethylene or a copolymer of ethylene and at least one comonomer. Suitable comonomers that may be used to form a UHMWPE copolymer include, but are not limited to, an alpha-olefin or cyclic olefin having <NUM> to <NUM> carbon atoms. Non-limiting examples of suitable comonomers include <NUM>-butene, <NUM>-pentene, <NUM>-hexene, <NUM>-heptene, <NUM>-octene, cyclohexene, and dienes with up to <NUM> carbon atoms (e.g. butadiene or <NUM>,<NUM>-hexadiene). Comonomers may be present in the UHMWPE copolymer in an amount from about <NUM> mole % to about <NUM> mole %, from about <NUM> mole % to about <NUM> mole %, or from about <NUM> mole % to about <NUM> mole %.

In one particular embodiment, the sheath <NUM> can include <NUM> UHMWPE yarns having between <NUM> and <NUM> turns per inch (per <NUM>) (TPI), where each yarn has a linear mass density ranging from about <NUM> denier (<NUM> dTex) to about <NUM> denier (<NUM> dTex) so that the overall linear mass density of the sheath <NUM> also ranges from about <NUM> denier (<NUM> dTex) to about <NUM> denier (<NUM> dTex). Each of the yarns in the sheath <NUM> can also include from about <NUM> to about <NUM> filaments and can have a diameter ranging from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers). Further, each of the yarns in the sheath <NUM> can exhibit a percent elongation (extension at break) ranging from about <NUM>% to about <NUM>%. In addition, each of the yarns can exhibit a tenacity ranging from about <NUM>/denier (g/<NUM> dTex) to about <NUM>/denier (g/<NUM> dTex) and can have a maximum force ranging from about <NUM> grams to about <NUM> grams.

In one particular embodiment, the sheath <NUM> can include from <NUM> to <NUM> UHMWPE untwisted yarns, where each yarn has a linear mass density ranging from about <NUM> denier (<NUM> dTex) to about <NUM> denier (<NUM> dTex) so that the overall linear mass density of the sheath <NUM> also ranges from about <NUM> denier (<NUM> dTex) to about <NUM> denier (<NUM> dTex). Each of the yarns in the sheath <NUM> can also include from about <NUM> to about <NUM> filaments and can have a diameter ranging from about <NUM> inches to about <NUM> inches (about <NUM> micrometers to about <NUM> micrometers). Further, each of the yarns in the sheath <NUM> can exhibit a percent elongation (extension at break) ranging from about <NUM>% to about <NUM>%. In addition, each of the yarns can exhibit a tenacity ranging from about <NUM>/denier (g/<NUM> dTex) to about <NUM>/denier (g/<NUM> dTex) and can have a maximum force ranging from about <NUM> grams to about <NUM> grams.

In another embodiment, the yarns in the sheath <NUM> can include another polymer in addition to a high molecular weight polyolefin. For instance, one or more of the yarns in the sheath <NUM> can include a blend of the high molecular weight polyolefin and an additional polymer, or one or more of the yarns can be formed solely from the additional polymer. In one embodiment, the additional polymer can be an aromatic polymer. For instance, the aromatic polymer can include a liquid crystalline polymer, an aramid polymer, or a combination thereof. The term "liquid crystalline polymer" or "LCP" refers to a polymer that can possess a rod-like structure that allows it to exhibit liquid crystalline behavior in its molten state (e.g., thermotropic nematic state). The polymer may contain aromatic units (e.g., aromatic polyesters, aromatic polyesteramides, etc.) so that it is wholly aromatic (e.g., containing only aromatic units) or partially aromatic (e.g., containing aromatic units and other units, such as cycloaliphatic units). The polymer may also be fully crystalline or semi-crystalline in nature. In some embodiments, suitable thermotropic liquid crystalline polymers may include, for instance, aromatic polyesters (e.g., liquid crystalline aromatic polyesters or liquid crystalline polyesters), aromatic poly(esteramides), aromatic poly(estercarbonates), aromatic polyamides, etc., and may likewise contain repeating units formed from one or more aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, aromatic diols, aromatic aminocarboxylic acids, aromatic amines, aromatic diamines, etc., as well as combinations thereof.

However, in order to achieve the desired abrasion resistance, it is to be understood that the additional polymer should be present in an amount of less than about <NUM> wt. % of the total weight of the sheath <NUM>, such as in an amount of less than about <NUM> wt. % of the total weight of the sheath <NUM>, such as in an amount of less than about <NUM> wt. % of the total weight of the sheath <NUM>.

The braided structure of the present invention can be utilized in various medical applications. For instance, in some embodiments, the braided structure can be utilized as a suture material. Further, in other embodiments, the braided structure can be used as an actuation cable for a medical device. In addition, the braided structure can be used for any other application as known to one of skill in the art. For example, the braided structure can be used in load bearing orthopedic applications, artificial tendons/ligaments, device fixation, actuation cables, components for tissue repair, etc..

The present invention may be better understood by reference to the following example.

Several braided structures were formed as shown below in Table <NUM>, included comparative examples C1a-C17 and examples 1a-<NUM> and S1-S5, and the braided structures exhibited the physical and mechanical properties summarized in Table <NUM>. Details as to the specific test procedures utilized to determine each property are set forth below.

As shown above in Table <NUM>, which summarizes the various braided structures and their resulting physical and mechanical properties, although comparative samples C1 through C17 had the small diameter required for the braided structure for use in medical applications, none of the comparative samples C1 through C17 exhibited the most preferred mechanical properties across all categories. For instance, comparative samples C4, C8, C9, and C13 exhibited high extension at break percentages, C11 and C12 exhibited low ultimate tensile strengths, and samples C1a, C1b, C1c, C2a, C2b, C2c, C3, C6, C7, C10, C11, and C17 exhibited poor abrasion resistance as evidenced by fraying of the braided structure after cycling the braided structure <NUM> millimeters in a backwards direction and <NUM> millimeters in a forwards direction for a total of <NUM> cycles across a metal edge having a <NUM> millimeter radius with <NUM> grams of weight applied to the braided structure.

On the other hand, surprisingly, the specific arrangement of the braided structures of samples 1a, 1b, 1c, <NUM>, <NUM>, and <NUM> and samples S1, S2, S3, S4, and S5 were abrasion resistant, exhibited high loads at break in the normal and <NUM>° bend testing configurations, exhibited low extension at break, exhibited increased stiffness, and had low creep values, all while having a small diameter suitable for use in suture or actuation cable applications and maintaining a high ultimate tensile strength ranging from <NUM> x <NUM><NUM> pounds per square inch (about <NUM> megapascals) to <NUM> x <NUM><NUM> pounds per square inch (about <NUM> megapascals). In another aspect, the braided structure can exhibit an ultimate tensile strength ranging from about <NUM> grams/denier (about <NUM> grams/<NUM> dTex) yarn to about <NUM> grams/denier (about <NUM> grams/<NUM> dTex) yarn.

<FIG> will now be discussed in more detail to demonstrate the improved abrasion resistance of the braided structure of the present invention compared to other braided structures. Specifically, <FIG> is a photograph of a braided structure having a liquid crystalline polymer sheath as in comparative examples C1a-C3, C6-C7, and C10 after cycling the braided structure <NUM> millimeters in a backwards direction and <NUM> millimeters in a forwards direction for a total of <NUM> cycles across a metal edge having a <NUM> millimeter radius with <NUM> grams of weight applied to the braided structure; <FIG> is a photograph of a braided structure having a liquid crystalline polymer sheath as in comparative examples C1a-C3, C6-C7, and C10 after cycling the braided structure <NUM> millimeters in a backwards direction and <NUM> millimeters in a forwards direction for a total of <NUM> cycles across a metal edge having a <NUM> millimeter radius with <NUM> grams of weight applied to the braided structure; <FIG> is a photograph of a braided structure having a liquid crystalline polymer sheath as in comparative examples C1a-C3, C6-C7, and C10 after cycling the braided structure <NUM> millimeters in a backwards direction and <NUM> millimeters in a forwards direction for a total of <NUM> cycles across a metal edge having a <NUM> millimeter radius with <NUM> grams of weight applied to the braided structure; and <FIG> is a photograph of a braided structure having a liquid crystalline polymer sheath as in comparative examples C1a-C3, C6-C7, and C10 after cycling the braided structure <NUM> millimeters in a backwards direction and <NUM> millimeters in a forwards direction for a total of <NUM> cycles across a metal edge having a <NUM> millimeter radius with <NUM> grams of weight applied to the braided structure. As shown, even after only <NUM> cycles, the braided structure as in comparative examples C1a-C3, C6-C7, and C10 exhibits fraying, which is even far more pronounced after <NUM> cycles, indicating that the braided structures of comparative examples C1a-C3, C6-C7, and C10 lack abrasion resistance.

On the other hand, <FIG> is a photograph of a braided structure having an ultra high molecular weight polyethylene polymer sheath as in examples 1a-<NUM> and S1-S5 after cycling the braided structure <NUM> millimeters in a backwards direction and <NUM> millimeters in a forwards direction for a total of <NUM> cycles across a metal edge having a <NUM> millimeter radius with <NUM> grams of weight applied to the braided structure; <FIG> is a photograph of a braided structure having an ultra high molecular weight polyethylene polymer sheath as in examples 1a-<NUM> and S1-S5 after cycling the braided structure <NUM> millimeters in a backwards direction and <NUM> millimeters in a forwards direction for a total of <NUM> cycles across a metal edge having a <NUM> millimeter radius with <NUM> grams of weight applied to the braided structure; <FIG> is a photograph of a braided structure having an ultra high molecular weight polyethylene polymer sheath as in examples 1a-<NUM> and S1-S5 after cycling the braided structure <NUM> millimeters in a backwards direction and <NUM> millimeters in a forwards direction for a total of <NUM> cycles across a metal edge having a <NUM> millimeter radius with <NUM> grams of weight applied to the braided structure; and <FIG> is a photograph of a braided structure having an ultra high molecular weight polyethylene polymer sheath as in examples 1a-<NUM> and S1-S5 after cycling the braided structure <NUM> millimeters in a backwards direction and <NUM> millimeters in a forwards direction for a total of <NUM> cycles across a metal edge having a <NUM> millimeter radius with <NUM> grams of weight applied to the braided structure. As shown, even after <NUM> cycles, the braided structures as in examples 1a-<NUM> and S1-S5 show no fraying, indicating the braided structures of the present invention are abrasion resistant.

Claim 1:
A braided structure comprising:
a core comprising at least one yarn, wherein the at least one yarn comprises an aromatic polymer; and
a sheath braided around the core, wherein the sheath comprises a plurality of ultra-high molecular weight polyolefin yarns, wherein the braided structure has an overall diameter ranging from about <NUM> micrometers to about <NUM> micrometers.