Filament having cellulose fibers with non resorbable features less radio pacifier

Abstract

The filament and suture products disclosed are to be implanted in the body, having non re sorbable ingredients with absorbent qualities to disperse an antibiotic and strong enough to hold tissue securely but flexible enough to be printed or knotted. The products are biocompatible and consist of two dissimilar polymers having unmelted cellulose fiber. These dissimilar polymers and the unmelted fibers are densified by compression and the removal of moisture having fiber orientation and alignment, showing low levels of radiopacity. These products will have radiopacity in household units (HU) ranging from −200 to 200 HU and produce meshes, bone grafts, scaffolds or wound care products where bone bridging can be observed.

Claims

1. A non re sorbable suture strand having densified cellulose fibers with two dissimilar thermoplastic polymers comprising of polyamide and polyolefin and compatibalizer has moisture and is compressed at pressures greater than 175 psi, and, wherein the cellulose fibers have unmelted fibers with alignment and have radiopacity in the body.

2. The non re sorbable suture strand in claim 1, wherein the non re sorbable suture strand having a size range of 0.1 mm to 0.9 mm O.D.

3. The non re sorbable suture strand in claim 1, wherein the non re sorbable suture strand before compression has a moisture content range of 0.04 to 0.15%.

4. The non re sorbable suture strand in claim 1, wherein the non re sorbable suture strand is biocompatible with radiopacity range of −200 HU to 200 HU

5. A non re sorbable filament strand with a cellulose fiber glass transition temperature above 100 and two dissimilar polymers comprising of polyamide and polyolefin and compatibalizer having a specific gravity no less than 1, wherein the cellulose fiber has unmelted fibers with orientation and the composition requires 6% moisture removal and is densified for printing pores above 60 micron.

6. A non re sorbable filament strand in claim 4, wherein the non re sorbable filament strand is biocompatible with a dyne level range of 50 dynes/cm to 100 dynes/cm.

7. A non re sorbable filament, suture, thread implant with cellulose fibers having radiopacity with a range of −200 to 200 HU, and wherein the cellulose fiber is densified with two dissimilar polymers comprising of polyamide and polyolefin and compatibalizer and the fibers are unmelted and melted with an absence of agglomeration at 2× to 4× magnification at 4 mm field of view.

8. A non re sorbable filament, suture, thread implant in claim 6, wherein the non re sorbable filament, suture, thread implant has cellulose fiber particle sizes ranging from 30 to 50 micron with purity above 98%

Description

DETAILED DESCRIPTION OF INVENTION

[0024] The inventive non re sorbable filaments and suture strands implantable in the body are constructed of a cellulose fiber thermoplastic composition that comprises unmelted cellulose fiber with two dissimilar thermoplastic polymers. The products are biocompatible for implanting in the body and exhibit low levels of radiopacity. The suture strands can be a monofilaments or braided to having an O.D. size range of 0.1 mm to 0.9 mm with sizes #5 (heavy braided suture for orthopedics) to #11-0 (fine monofilament suture for ophthalmics). The cellulose fibre thermoplastic braided suture can comprise two or more strands twisted together. The non braided sutures, also known as monofilament, can be made of single strand comprising cellulose fiber with two dissimilar thermoplastic polymers and compatibalizer. These products will lack the traditional or common radio pacifiers like barium sulfate, bismuth or metals i.e. tungsten and will have a surface energy greater than 50 dynes/cm and below 100 dynes/cm. In order to achieve a desirable product strength and flexibility, moisture removal is controlled in the composition before processing the filaments and suture stand and products.

[0025] The cellulose fiber in the thermoplastic composition is required to have less than <120 micron particle size with an aspect ratio ranging from 12:1 to 3:1 and a moisture content not to exceed 10%. The cellulose fiber is preferably extracted from wood pulp but can also be a cotton derivative. The cellulose fiber that is a organic polymer and isn't degradable by hydrolysis in the human body. The cellulose fiber is similar to collagen fiber and when compressed with the thermoplastic polymers, fibers are densified, moisture is removed and the fibers are oriented and aligned by the extrusion or a spinning process. A microcrystalline cellulose with a particle size less than 20 micron can be blended independently or with the cellulose fiber in the thermoplastic polymer compound. In the thermoplastic compound, a polar polyamide comprises a semi crystalline and or amorphous Nylon 6 or 6/6, 11,12, 6i6t. The non polar polyolefin can be a homo or co polymer polypropylene and or polyethylene. The compatibalizer can be identified as a processing aid comprising fatty acids, salts or esters and amides with a fluoropolymer for melt blending the polyamide and polyolefin.

[0026] The polyamide and polyolefin with compatibalizer are compounded to generate a pelletized thermoplastic composition. Then, the cellulose fibers are blended, heated with the thermoplastic composition and densified to form the pelletized cellulose fiber thermoplastic composition. The pelletized composition is preferred to be desiccant dried to 0.05% and not completely dry before extruding and compressed above 175 psi for densification to produce filaments, sutures or threads. The extruded composition to produce the filaments or suture products will be a semi solid state, wherein the cellulose fiber has unmelted fibers oriented through a die with at least a 10:1 LAN length ratio and a polymer drawdown at 15-60%. This die drawing of the thermoplastic cellulose fiber alloy composition can be independent of the extruder or through a die attached to the extruder. If the die drawing of the composition is performed independently, a heat method utilizing a heat induction mechanism is desired. The heat induction mechanism will be able to bring the solid state profile to desired melt quickly. Once the cellulose fiber thermoplastic composition has fiber orientation and alignment through a die drawing, there is an increase in tensile modulus of the filament and suture strand. The tensile modulus increase is 15-30% of the cellulose fiber thermoplastic composition's molded and tested value of 1615 MPa using the ISO 527 method. The tensile strength of a suture is measured pounds of tension that the strand will withstand before it breaks when knotted. This innovative high strength filament strand can be seen under X Ray and CT scan not utilizing any common radio pacifier as identified.

[0027] The cellulose fiber thermoplastic composition requires multiple processing to achieve optimum performance for a filament, suture or thread or mesh. The polyamide and polyolefin is processed with a compatibilizer by a single or twin screw extrusion method or a high intensity mixer. The melt blending and shearing of the dissimilar polymers will produce a thermoplastic pellet. A secondary extrusion process is preferred, where the cellulose fiber is compounded, blended with the pelletized composition comprising of a polyamide and polyolefin and compatibalizer. The cellulose fiber is added to the polyamide and polyolefin composition in line or side fed downstream at temperatures not greater than the melting temperature of the cellulose fiber at 250-260 C. The preferred temperature or optimized processing temperature of the cellulose fibers with the thermoplastic pelletized composition is a range of 190-210 C. The cellulose fiber is preferred to have less than 8% moisture content when side fed to disperse with the thermoplastics composition. The cellulose fiber can be pre dried before extruding for improved dispersion in the composition. A vacuum and vent is required to remove 6-7% moisture in the cellulose fiber thermoplastic composition.

[0028] Example: The extruded semi crystalline polymers with an amorphous polymer is pelletized. The composition comprises 4 pellets, having 85% polyamide, a Nylon 6 with Nylon 6i6t and 10% polyolefin and 5% compatibalizer. These pellets are extruded to produce one pelletized thermoplastic compound. The thermoplastic pellet is then processed with additives at the throat of the secondary extruder, preferably a twin screw, having shear elements at the throat and very low shear elements where the cellulose fibers are fed into the side of the extruder barrel. The cellulose fibers are processed with the thermoplastic composition at 400 F or 204 C at zone 5 or 6. The operator controls the temperature zones in either a reverse profile −270 C at the throat or zone 1 and 193-210 C near breaker plate. Or, a bell shaped profile, which are include zone 1 at 260 C, 254 C in zone 2, 254 C, in zone 3, 237 C zone 4, 215 C, zone 5 side feeder, 204 C F, zone 6, 204 C, zone 7, 198 C and zone 8 198 C.

[0029] The secondary extrusion process melt blends and removes 6-7% moisture from the composition and produces a pelletized cellulose fiber thermoplastic composition. The pelletized composition will have less than 2% moisture and unmelted cellulose fibers for producing the filament, suture, thread.

[0030] This pelletized thermoplastic cellulose fiber composition would then be desiccant dried to a preferred pellet moisture content of 0.05 to 0.18% before processing into a filament strand. This filament strand, as well as, suture strands will be continuous until cut to predetermined lengths. The cellulose fiber thermoplastic filament strand or suture strand would be extruded at temperatures below 260 C so that the cellulose fiber would have unmelted fibers. This heat profile for processing filament would have a temperature range from 204 C to 255 C and would require a high compression screw and or profile die with a 10:1 LAN. The preferred die pressure exceeds 230 psi for producing an oriented fiber filament with a 0.70 mm O.D. By compressing the cellulose fiber with the thermoplastic composition, moisture is removed and the density was increased, having a 1.06 specific gravity. A test plaque was produced showing no agglomeration or clumping in a 2×, 4× magnification range with a 4 mm field of view.

[0031] Most preferably, a cellulose fiber particle size to produce the filament strand in example 1 comprises a 20 to 30 micron range and has 99.5% purity with 0.5% ash content. Any filament, suture, thread products can have cellulose fiber particle sizes to include 30 and 50 micron with aspect ratio ranging from 3:1 to 6:1 and may include aspect ratios of 10:1 and 12:1. Threads can comprise microcrystalline cellulose having a particle size of 1 to 13 micron with aspect ratios of 3:1 and 2:1.