Non-curling polyhydroxyalkanoate sutures

• US 20060058470A1
• Filed: 07/29/2005
• Published: 03/16/2006
• Est. Priority Date: 08/03/2004
• Status: Active Grant

• Current Assignee: Tepha Incorporated (Becton, Dickinson & Co)
• Original Assignee: Tepha Incorporated (Becton, Dickinson & Co)
• Inventors: Rizk, Said
• Granted Patent: US 7,641,825 B2
• Time in Patent Office: Days
• US Class Current: 525/450
• CPC Class Codes: A61L 17/105 Polyesters not covered by A61L17/12
• CPC Class Codes: C08G 63/06 derived from hydroxycarboxylic acids
• CPC Class Codes: D01F 6/625 derived from hydroxy-carboxylic acids, e.g. lactones
• CPC Class Codes: Y10T 428/2913 Rod, strand, filament or fiber
• CPC Class Codes: Y10T 442/10 Scrim [e.g., open net or mesh, gauze, loose or open weave or knit, etc.]

Abstract

Absorbable polyester fibers, braids, and surgical meshes with improved handling properties have been developed. These devices are preferably derived from biocompatible copolymers or homopolymers of 4-hydroxybutyrate. These devices provide a wider range of in vivo strength retention properties than are currently available and have a decreased tendency to curl, in the preferred embodiment, due to the inclusion of relaxation and annealing steps following extrusion and orientation of the fiber. Filaments prepared according to these methods are characterized by the following physical properties: (i) elongation to break from about 17% to about 85% (ii) Young'"'"'s modulus of less than 350,000 psi, (iii) knot to straight ratio (knot strength/tensile strength) of 55-80% or (iv) load at break from 1100 to 4200 grams.

Claims

1. A polymeric filament comprising 4-hydroxybutyrate or copolymers thereof, wherein the filament has an elongation to break from 17% to 85%, a Young'"'"'s modulus of less than 350,000 psi, tenacity to modulus ratio between 0.25 to 1.0, and a load at break between 1100 and 4200 kg, and is produced by extrusion, orientation, relaxation and annealing of the extruded filament.

2. The filament of claim 1 wherein the filament has an elongation to break from 17% to 85%.

3. The filament of claim 1 wherein the filament has a Young'"'"'s modulus of less than 350,000 psi.

4. The filament of claim 1 wherein the filament has a knot to straight conversion of 55-80%.

5. The filament of claim 1 in the form of a suture.

6. The filament of claim 1 formed into a mesh.

7. The filament of claim 1 in the form of a medical device.

8. The filament of claim 1 in the form of a device for repair of tendons or ligaments.

9. A method of making a polyhydroxyalkanoate filament comprising

a) drying the water content of polyhydroxyalkanoate pellets to less than 0.01% (w/w);

b) feeding the dried polyhyroxyalkanoate pellets into an extruder barrel under a blanket of nitrogen to melt the polyhydroxyalkanoate;

c) passing the molten polyhydroxyalkanoate through a heated block to a metering pump;

d) extruding the polyhydroxyalkanoate from a die with a single hole spinneret to produce a spun extrudate filament;

e) drawing the spun extrudate filament into a heat zone, maintained at a temperature above the melting temperature of the filament, to orient and relax the filament.

10. The method of claim 9 further comprises constraining the filament during orientation and relaxation.

11. The method of claim 9 further comprising annealing the filament.

12. The method of claim 9 further comprising an aging step wherein the extruded polyhydroxyalkanoate filament is partially drawn and is stored for a time period ranging from 2 to 72 hours at a temperature between 0 and −

80°

C.

13. The method of claim 9 further comprising prior to step a) blending into the polyhydroxyalkanoate an additive selected from the group consisting of calcium stearate and calcium phosphate, wherein the additive comprises up to 15% (w/w) of the polyhydroxyalkanoate blend.

14. The method of claim 9 further comprising forming the filament into a suture.

15. The method of claim 9 further comprising forming the filament into a mesh.

16. The method of claim 9 further comprising forming the filament into a medical device.