WO2010100488A1

WO2010100488A1 - High strength suture

Info

Publication number: WO2010100488A1
Application number: PCT/GB2010/050369
Authority: WO
Inventors: David Beevers; Lauren Calloway
Original assignee: Xiros Limited
Priority date: 2009-03-04
Filing date: 2010-03-03
Publication date: 2010-09-10
Also published as: GB0903641D0; GB2468307A

Abstract

A suture comprising an elongate tubular sheath formed from a plurality of braided yarn strands a plurality of axial yarn strands overlapping the braided yarn strands and aligned with the longitudinal axis of the elongate tubular sheath and transverse to the braided yarn strands and a core positioned within the tubular sheath, the core formed from a plurality of yarn strands extending longitudinally within the tubular sheath. Additionally, both axial and braided yarns may be incorporated within the suture having different denier. Different coloured yarn strands may also be incorporated within the outer tubular sheath to create repeating patterns along regions of the suture.

Description

HIGH STRENGTH SUTURE

The present invention relates to a suture having an elongate tubular sheath formed from a plurality of overlapping yarn strands and additional axial yarn strands that are aligned with the longitudinal axis of the suture.

Sutures are elongate implantable devices that are commonly used within the body to hold tissue together to promote healing. Accordingly, sutures are required to be non-toxic and must have acceptable tensile strength in order to withstand the loading forces applied within the body whilst being capable of forming and holding a conventional knot configuration. Sutures may be bioabsorbable or non-bioabsorbable depending upon the specific application.

Accordingly, sutures are constructed from a wide variety of materials and comprise monofilament or multifilament structures. Multifilament sutures typically comprise overlapping braided yarn strands to form a solid spiroid or tubular structure. It is also known to incorporate a core within conventional tubular sutures.

EP 0523743 discloses a braided multifilament suture having a tubular sheath formed from at least one biocomponent fibre and a central core formed from longitudinally extending yarns. The core functions to both increase strength and reduce flattening of the suture during use.

EP 0449431 discloses a spiroid braided suture comprising a pattern of interlocking yarns which extend from the surface of the cylinder to its centre so as to provide a substantially solid structure.

EP 01541181 discloses a tubular suture braided according to a triaxial pattern in which a plurality of axial yarn strands are interlaced with first and second strands that define the tubular braid. The axial strands are configured to retain their straight orientation parallel to the direction of the longitudinal axis of the suture. In order to provide the desired flexibility, the suture does not comprise a core. However, conventional sutures of the type identified above, are disadvantageous for a number of reasons. In particular, a balance has to be found between the suture having enough flexibility so as to provide ease of manipulation whilst possessing the required tensile strength to withstand the applied loading forces without appreciable distortion or breakage. What is required therefore is a suture that is both flexible and strong.

Additionally, a particular procedure may require a suture of a particular flexibility, thickness and/or strength. There is therefore a requirement for a set of sutures, in which different individual sutures may be easily identified.

The inventors provide a suture comprising the desired flexibility, tensile strength and visual markings to provide ease of identification. A high tensile strength is achieved by overlapping braided yarn strands that make-up an elongate tubular sheath with axial yarn strands aligned with the longitudinal axis of the tubular sheath, and preferably extend substantially parallel to the tubular sheath or main length of the suture. These axial yarn strands contribute significantly to the resultant tensile strength of the suture whilst maintaining suture flexibility and ease of manipulation.

According to a first aspect of the present invention there is provided a suture comprising: an elongate tubular sheath formed from a plurality of braided yarn strands; a plurality of axial yarn strands overlapping the braided yarn strands and aligned with the longitudinal axis of the elongate tubular sheath and transverse to the braided yarn strands; and a core positioned within the tubular sheath, the core formed from a plurality of yarn strands extending longitudinally within the tubular sheath.

Optionally, the yarn strands of the core comprise parallel, twisted or braided yarns. Moreover, the braided, axial and core yarns may be made from parallel, twisted or braided fibres.

Optionally, the braided, axial and/or core yarns comprise different physical and/or mechanical properties. In particular, the different mechanical properties include any one or a combination of: strength; stiffness; speed of absorption; and/or flexibility. Moreover, the different physical properties include any one or a combination of: cross sectional size; cross sectional shape; material type; and/or density.

According to specific implementations, some of the yarn strands may comprise an enhanced surface roughness, possibly to facilitate tissue in growth.

Optionally, the axial yarn strands comprise a different denier to the braided yarn strands including in particular a greater or smaller denier. Optionally, the axial yarn strands may comprise any combination of yarns having denier being equal to, greater than and/or smaller than the denier of the braided yarns. The core yarn strands comprise the same denier and/or cross sectional area as the axial and/or braided yarn strands.

In particular, the axial yarn strands may comprise a different cross sectional area than that of the braided yarn strands including a greater or smaller cross sectional area. Optionally, the axial yarn strands may comprise yarns having different cross sectional areas being equal to, greater than and/or smaller than the cross sectional area of the braided yarns.

The suture may comprise an equal, greater or smaller number of axial yarn strands relative to the braided yarn strands. Moreover, at a cross section through the suture, the axial yarn strands may be substantially equally or substantially unequally spaced relative to one another.

Optionally, the core yarn strands comprise the same denier as the axial and/or braided yarn strands. Alternatively the core yarn strands may comprise a different denier and/or a different cross sectional area to the axial and/or braided yarn strands.

Optionally, the axial, braided and core yarn strands may comprise the same material. Alternatively, each or a combination of the axial, braided and core yarn strands may comprise different materials. In particular, the different materials may be selected from any one or a combination of the following bioabsorable or non-bioabsorbablejnaterials including: surgical gut; silk; cotton; polyamide; polyester; polyethylene terephthalate; polyethylene; ultrahigh molecular weight polyethylene; polypropylene; high molecular weight polyethylene; polyetheretherketone; polydioxanone; polytetrafluoroethylene; polyaramid; polyglycolic acid; polylactic acid.

Preferably, the axial, braided and core yarns comprise polyethylene terephthalate. Optionally, the axial, braided and core yarns comprise ultrahigh molecular weight polyethylene. Optionally, the braided yarns comprise polyethylene terephthalate and the axial and core yarns comprise ultrahigh molecular weight polyethylene. Optionally, the braided yarns comprise a bioabsorbable material and the axial and core yarns comprise ultrahigh molecular weight polyethylene. Optionally, the braided yarns comprise a bioabsorbable material and the axial and core yarns comprise polyethylene terephthalate.

Optionally, any one or a combination of the axial, braided and/or core yarns is coloured relative to other respective axial, braided or core yarns. Optionally, any one or a combination of the axial, braided and/or core yarns comprise different colours. Optionally, at a cross section through the suture, any coloured axial and/or braided yarns are equally or unequally spaced from one another. Preferably, coloured axial yarns create coloured stripes extending along the length of the suture. Preferably, the coloured yarns are incorporated in the suture to create at least one repeating pattern extending over a region of the suture.

According to a second aspect of the present invention there is provided a suture comprising: an elongate tubular sheath formed from a plurality of braided yarn strands; a plurality of axial yarn strands overlapping the braided yarn strands and aligned with the longitudinal axis of the elongate tubular sheath and transverse to the braided yarn strands; wherein the axial yarn strands comprise a different denier to the braided yarn strands.

According to a third aspect of the present invention there is provided a suture comprising: an elongate tubular sheath formed from a plurality of braided yarn strands; a plurality of axial yarn strands overlapping the braided yarn strands and aligned with the longitudinal axis of the elongate tubular sheath and transverse to the braided yarn strands; wherein the axial yarn strands comprise a different cross-sectional area to the braided yarn strands. According to a fourth aspect of the present invention there is provided a suture comprising: an elongate tubular sheath formed from a plurality of woven yarn strands; a plurality of axial yarn strands overlapping the woven yarn strands and aligned with the longitudinal axis of the elongate tubular sheath; and a core positioned within the tubular sheath, the core formed from a plurality of yarn strands extending longitudinally within the tubular sheath.

According to a fifth aspect of the present invention there is provided a suture comprising: an elongate tubular sheath formed from a plurality of knitted yarn strands; a plurality of additional axial yarn strands overlapping the knitted yarn strands and aligned with the longitudinal axis of the elongate tubular sheath; and a core positioned within the tubular sheath, the core formed from a plurality of yarn strands extending longitudinally within the tubular sheath.

According to a sixth aspect of the present invention there is provided a suture comprising: an elongate tubular sheath formed from a plurality of woven yarn strands; a plurality of axial yarn strands overlapping the woven yarn strands and aligned with the longitudinal axis of the elongate tubular sheath; wherein the axial yarn strands comprise a different denier to the woven yarn strands.

According to a seventh aspect of the present invention there is provided a suture comprising: an elongate tubular sheath formed from a plurality of knitted yarn strands; a plurality of axial yarn strands overlapping the knitted yarn strands and aligned with the longitudinal axis of the elongate tubular sheath; wherein the axial yarn strands comprise a different denier to the knitted yarn strands.

According to an eighth aspect of the present invention there is provided a suture set comprising a plurality of sutures as described herein wherein some of the sutures of the set comprise coloured axial yarn strands and/or coloured yarn strands that form the elongate tubular sheath; wherein different sutures of the suture set comprise different repeating patterns formed from the coloured yarn strands. Preferably, the different patterns created by the coloured yarn strands distinguish different sutures of the suture set with regard to their physical and/or mechanical properties. In particular, these physical and/or mechanical properties include tensile strength, flexibility, cross sectional area (diameter), denier, abrasion resistance and/or constituent materials including the various bioabsorbable and non-bioabsorbable materials described herein

A specific implementation of the present invention will now be described, by way of example of only and with reference to the accompanying drawings in which: figure IA illustrates an external view along the length of a suture according to a specific implementation of the present invention comprising braided yarn strands to form a tubular sheath and a plurality of axial yarn strands interwoven amongst the braided yarns extending along the length of the suture; figure IB illustrates schematically a cross section through the suture of figure 1 illustrating a core enclosed by the outer tubular sheath; figure 2 illustrates schematically a cross sectional view of a further embodiment of the present invention in which the axial strands are distributed equally around the sheath with an equal number of axial and braided yarns; figure 3 illustrates schematically a cross sectional view of a suture according to a further embodiment comprising a greater number of inlaid equally spaced axial yarns relative to braided yarns; figure 4 illustrates schematically a cross sectional view of a suture according to a future specific implementation comprising a fewer number of equally spaced inlaid axial yarns relative to the braided yarns; figure 5 illustrates schematically a cross sectional view of a suture according to a further specific implementation having unequally spaced inlaid axial yarns relative to the braided yarns; figure 6 illustrates schematically a cross sectional view of a suture according to a further specific embodiment having an equal number of equally spaced axial yarns relative to the braided yarns where the axial yarns comprise a greater denier (and cross sectional area) than the braided yarns; figure 7 illustrates schematically a cross sectional view of a suture according a further specific embodiment having an equal number of equally spaced axial yarns relative to the braided yarns where the axial yarns comprise a smaller denier (and cross sectional area) than the braided yarns; figure 8 illustrates schematically a cross sectional view of a suture according a further specific embodiment having an equal number of equally spaced axial yarns relative to the braided yarns where the axial yarns comprise a combination of equally spaced larger and smaller denier axial yarns relative to the braided yarns; figure 9 illustrates schematically a cross sectional view and external view of a suture according to a further specific embodiment comprising unequally spaced coloured braided yarns, each coloured braided yarn extending in the same single direction; figure 10 illustrates schematically a cross sectional view and external view of a suture according to a further specific embodiment comprising equally spaced coloured braided yarns, each coloured braided yarn extending in the same single direction; figure 11 illustrates schematically a cross sectional view and external view along the length of a suture comprising one or more braided yarn strands extending in both directions being coloured and unequally spaced; figure 12 illustrates schematically a cross sectional view and external view along the length of a suture comprising two coloured unequally spaced braided yarn strands extending in both directions; figure 13 illustrates schematically a cross sectional view and external view along the length of a suture comprising a single coloured braided yarn strand equally spaced and extending in both directions over the length of the suture; figure 14 illustrates schematically a cross sectional view and external view along the length of a suture comprising an outer sheath having two differently coloured braided yarns, a first coloured yarn equally spaced in one direction and a second coloured yarn unequally spaced in the opposite direction over the length of the suture; figure 15 illustrates schematically a cross sectional view and external view of the outer sheath along the length of a suture according to a specific embodiment in which the axial yarn strands are coloured and spaced unequally at the outer sheath; figure 16 illustrates schematically a cross sectional view and external view of the outer sheath of a suture comprising uncoloured braided yarns and regularly spaced uncoloured axial yarns together with two coloured axial yarns spaced unequally at the outer sheath; figure 17 illustrates schematically a cross sectional view and external view of the outer sheath of a suture comprising uncoloured braided yarns and regularly spaced coloured axial yarns; figure 18 illustrates schematically a cross sectional view and external view of the outer sheath of a suture comprising uncoloured braided yarns and regularly spaced coloured axial yarns; figure 19 illustrates schematically a cross sectional view and external view of the outer sheath along the length of the suture in which one of the braided yarn strands is coloured and extends in both directions and in which all of the axial yarn strands are coloured; figure 20 illustrates schematically a cross sectional view and external view of the outer sheath along the length of the suture wherein some of the braided yarn strands are clustered together and comprise a greater denier than other braided yarn strands with some of these clustered strands being coloured; figure 21 illustrates schematically a cross sectional view and external view of the outer sheath along the length of the suture wherein some of the braided yarn strands comprise a greater denier than other braided yarn strands and are coloured with the thicker coloured strands extending in a single direction; figure 22 illustrates schematically a cross sectional view and external view of the outer sheath along the length of the suture wherein one some of the braided yarn strands comprises a greater denier and is coloured and one of the axial yarn strands comprises a greater denier and is coloured relative to other braided and axial yarns, respectively.

Referring to figures IA and IB, suture 100 comprises a plurality of braided yarn strands

101 that overlap in a first direction 102 and in a second direction 103 to define a tubular textile sheath 105. A plurality of axial yarn strands 102 are inlaid to overlap the braided yarn strands 101 extending over the length of suture 100. In particular, axial yarn strands

102 are aligned with the longitudinal axis of suture 100 and may be regarded as extending substantially parallel to this longitudinal axis.

In particular, axial strands 102 are aligned approximately 45° relative to the braided strands 102, 103. That is, braided strands 102, 103 extend transverse to the longitudinal axis of suture 100 and axial strands 102. As will be appreciated, braided yarn strands 102, 103 may be aligned at any angle relative to axial strands 102 within the approximate range 20° to 70° when suture 100 is not subject to an applied tensile loading force.

A core 104 extends along the length of suture 100 internally within sheath 105. Core 104 comprises a plurality of core yarn strands 106 that may comprise parallel, twisted or braided yarns or a combination of these configurations. According to the embodiment of figures IA and IB, the suture comprises fewer axial yarn strands 102 than the corresponding braided yarn strands 101 defining sheath 105.

Variations of the specific implementation of the suture 100 will now be described with reference to figures 2 to 22. Referring to figure 2, suture 100 comprises an equal number of axial yarns 200 and braided yarns 101 surrounding core 102. Referring to figure 3, suture 100 comprises a greater number of axial yarns 300 relative to braided yarns 101. In contrast, figure 4 illustrates suture 100 having a fewer number of axial yarns 400 relative to braided yarns 101. The axial and braided strands of figures 2 to 4 are equally spaced throughout sheath 105. In contrast, figure 5 illustrates axial yarns 500 being unequally spaced when overlapping the braded yarn strands 101.

Figures 6 to 8 illustrate suture 100 comprising axial yarn strands having different denier and/or cross sectional size relative to the braided yarn strands 101. Referring to figure 6, axial strands 600 comprise a greater denier than braided strands 101. Referring to figure 7, axial yarns 700 comprise a smaller denier than braided yarns 101. Figure 8 illustrates suture 100 comprising a combination of axial strands having greater 600 and smaller 700 denier than braided yarn strands 101.

Figures 9 to 22 disclose variations of suture 100 comprising coloured axial and/or braided yarn strands which may be equally or unequally spaced and comprise the same or different denier relative to other axial and/or braided strands.

Uncoloured braided yarn strands may be braided with strand 900 of a first colour and a strand 901 of a second colour that are unequally spaced among the braided strands 101. According to the embodiment of figure 9, both coloured braided yarns 900, 901 extend in the same single direction. Figure 10 illustrates a variation of the embodiment of figure 9 in which two coloured braided strands 900, 1000 are equally spaced and extend in the same single direction.

Figures 11 to 14 illustrate different coloured braided yarn strands that extend in both directions to create a crisscross pattern. Referring to figure 11 , a first coloured strand extends in a first direction 1101 and a second direction 1103 whilst a second coloured strand extends in a first direction 1100 and a second direction 1102 with each coloured yarn being unequally spaced. The alternative embodiment is illustrated in figure 12 wherein a braided yarn strand of a first colour 1200 is equally spaced relative to a braided yarn strand 1201 of a second colour. Figure 13 illustrates suture 100 comprising a single coloured braided yarn strand 1300 equally spaced and extending in both directions. Figure 14 illustrates suture 100 comprising a braided yarn strand 1401 equally spaced in a first direction and a yarn strand 1400 of a second colour being unequally spaced in the opposite direction.

Referring to figures 15 to 19, combinations of the axial strands and braided strands may be coloured to create an identification pattern of the tubular after sheath 105. Referring to figure 15, axial strands 1501 are coloured and unequally spaced when overlapping braided yarn strands 101. The axial yarn strands may be coloured 1600 and may be spaced unequally relative to other axial yarns 1601 as illustrated in figure 16. Alternatively the coloured axial yarn strands 1700 may be spaced equally relative to unco loured axial strands 1601 referring to figure 17. Referring to figure 18, all axial yarn strands 1800 are coloured relative to braided strands 101. Referring to figure 19, both the axial and braided yarn strands may be coloured where a first braided strand 1900 is coloured and extends in a first direction and a second braided yarn strand 1902 is coloured and extends in a second direction whilst axial yarn 1901 is coloured and is accordingly aligned substantially parallel with the longitudinal axis of the suture.

Referring to figure 20, the braided yarn strands 101 may be arranged into clusters 2001, 2003, each cluster comprising individual yarn strands 2002, 2004 and 2005. In particular, some of the clustered yarn strands 2005 are coloured. Moreover, the clustered braided yarn strands 2002, 2003 comprise strands of a greater denier than other braided strands 101 and axial strands 2000.

Referring to figure 21, some braided strands 2100 comprise a greater denier than other braided strands 101 and the axial yarns 2000. Alternatively and referring to figure 22, some of the axial yarn strands 2200 may comprise a greater denier than other axial strands 1601 whilst some braided strands 2201 may comprise a greater denier than other braided strands 101.

Referring to figures IA to 22, it would be appreciated that the strength and in particular the tensile strength of the suture may be tailored to suit the requirements of a user by firstly incorporating the axial strands 102 with variation of the number and relative denier (cross sectional area) of the inlaid axial yarns 102. In particular, by variation of the number and size of the axial yarns and also the braided yarns, the strength and abrasion resistance of the suture at different regions along its length may be adjusted. In turn, the flexibility of the suture may be specifically configured by variation of the axial yarns 102 and braided yarns 101 as illustrated in figures IA to 22. Moreover, by variation of the pattern created in the outer sheath 105 by incorporating coloured axial yarns 102 and/or braided yarns 101 a set of sutures is provided in which each different suture of the set is distinguished from other different sutures by the pattern of their respective sheath 105. For example, sutures may be distinguished based on overall size (thickness), tensile strength, amount of bioabsorbance or non-bioabsorbance, flexibility, abrasion resistance etc.

Referring to the embodiments of figures 6 to 8 and 20 to 22, the suture 100 is configured to promote tissue in-growth at the suture following implantation. Conventional sutures typically comprise a smooth outer surface which does not encourage tissue ingrowth. By incorporating axial fibres 102 and/or braided fibres 101 of different denier, cross sectional profile and/or spatial positioning, it is possible to create ridges and/or grooves to provide a profiled exterior surface of outer sheath 105. The contoured external surface of sheath 105 therefore facilitates cell ingrowth and enhances the post surgical repair rate. It has been found that clustering the axial strands 102 and/or braided strands 101 is very effective to create a ridged outer surface profile at sheath 105. Such clustering 2001, 2003 illustrated in figure 20 may comprise yarn strands of the same or different denier (cross sectional size).

Suture 100 according to the various specific implementations of the present invention may comprise axial 102, braided 101 and/or core 106 strands that are uncoated or coated with materials such as wax, silicone, silcone rubbers, polytetrafluoroethylene, glycolide, caprolactone, polybutylate acid or other coatings known in the art.

Claims

CLAIMS:

1. A suture comprising: an elongate tubular sheath formed from a plurality of braided yarn strands; a plurality of axial yarn strands overlapping the braided yarn strands and aligned with the longitudinal axis of the elongate tubular sheath and transverse to the braided yarn strands; and a core positioned within the tubular sheath, the core formed from a plurality of yarn strands extending longitudinally within the tubular sheath.

2. The suture as claimed in claim 1 wherein the yarn strands of the core comprise parallel, twisted or braided yarns.

3. The suture as claimed in claim 1 or 2 wherein the braided, axial and/or core yarns comprise different mechanical properties.

4. The suture as claimed in any preceding claim wherein the braided, axial and/or core yarns comprise different physical properties.

5. The suture as claimed in claim 3 wherein the mechanical properties include any one or a combination of:

• strength;

• stiffness;

• speed of absorption;

• flexibility.

6. The suture as claimed in claim 4 wherein the physical properties include any one or a combination of:

• cross sectional size;

• cross sectional shape;

• material type;

• density.

7. The suture as claimed in any preceding claim wherein the axial yarns comprise a different denier to the braided yarns.

8. The suture as claimed in claim 7 wherein the denier of the axial yarns is greater than the denier of the braided yarns.

9. The suture as claimed in claim 7 wherein the denier of the axial yarns is smaller than the denier of the braided yarns.

10. The suture as claimed in claims 1 wherein the axial yarns comprise a combination of yarns having denier being equal to, greater than and/or smaller than the denier of the braided yams.

11. The suture as claimed in any preceding claim wherein the axial yarns comprise a different cross sectional area to that of the braided yarns.

12. The suture as claimed in claim 10 wherein the axial yarns comprise a greater cross sectional area than the braided yarns.

13. The suture as claimed in claim 10 wherein the axial yarns comprise a smaller cross sectional area than the braided yarns.

14. The suture as claimed in claims 1 wherein the axial yarns comprise yarns having different cross sectional areas being equal to, greater than and/or smaller than the cross sectional area of the braided yarns.

15. The suture as claimed in any preceding claim comprising a greater number of the axial yarns than the braided yarns.

16. The suture as claimed in any one of claims 1 to 8 comprising a smaller number of the axial yarns to the braided yarns.

17. The suture as claimed is any preceding claim wherein at a cross section through the suture, the axial yarns are substantially equally spaced relative to one another.

18. The suture as claimed is any one of claims 1 to 16 wherein at a cross section through the suture, the axial yarns are substantially unequally spaced relative to one another.

19. The suture as claimed in any preceding claim wherein the core yarns comprise the same denier as the axial and/or braided yarns.

20. The suture as claimed in any one of claims 1 to 18 wherein the core yarns comprise a different denier to the axial and/or braided yarns.

21. The suture as claimed in any of preceding claim wherein the core yarns comprise the same cross sectional area as the axial and/or braided yarns.

22. The suture as claimed in any one of claims 1 to 20 wherein the core yarns comprise a different cross sectional area to the axial and/or braided yarns.

23. The suture as claimed in any preceding claim wherein the axial, braided and core yarns comprise the same material.

24. The suture as claimed in any one of claims 1 to 22 wherein each or a combination of the axial, braided and core yarns comprise a different material.

25. The suture as claimed in claim 24 wherein the different materials may be selected from any one or a combination of the following bioabsorbable or non-bioabsorbable materials including the set of: surgical gut; silk; cotton; polyamide; polyester; polyethylene terephthalate; polyethylene; ultrahigh molecular weight polyethylene; high molecular weight polyethylene; polypropylene; polyetheretherketone; polydioxanone; polytetrafluoroethylene; polyaramid; polyglycolic acid; polylactic acid.

26. The suture as claimed in any preceding claim wherein the axial, braided and core yarns comprise polyethylene terephthalate.

27. The suture as claimed in any preceding claim wherein the axial, braided and core yarns comprise ultrahigh molecular weight polyethylene.

28. The suture as claimed in any one of claims 1 to 25 wherein the braided yarns comprise polyethylene terephthalate and the axial and core yarns comprise ultrahigh molecular weight polyethylene.

29. The suture as claimed in any preceding claim wherein the braided yarns comprise a bioabsorbable material and the axial and core yarns comprise ultrahigh molecular weight polyethylene.

30. The suture as claimed in any one of claims 1 to 25 wherein the braided yarns comprise a bioabsorbable material and the axial and core yarns comprise polyethylene terephthalate.

31. The suture as claimed in any preceding claim wherein any one or a combination of the axial, braided and/or core yarns is coloured relative to other respective axial, braided or core yarns.

32. The suture as claimed in any one of claims 1 to 30 wherein any one or a combination of the axial, braided and/or core yarns comprise different colours.

33. The suture as claimed in claim 31 or 32 wherein at a cross section through the suture, any coloured axial and/or braided yarns are equally spaced from one another.

34. The suture as claimed in claim 31 or 32 wherein at a cross section through the suture, any coloured axial and/or braided yarns are unequally spaced from one another.

35. The suture as claimed in any one of claims 31 to 34 wherein coloured axial yarns create coloured stripes extending along the length of the suture.

36. The suture as claimed in any one of claims 31 to 35 wherein the coloured yarns are incorporated in the suture to create at least one repeating pattern extending over a region of the suture.

37. The suture as claimed in any preceding claim wherein the axial, braided and core yarns comprise parallel, twisted or braided fibres that form the respective yarns.

38. A suture comprising: an elongate tubular sheath formed from a plurality of braided yarn strands; a plurality of axial yarn strands overlapping the braided yarn strands and aligned with the longitudinal axis of the elongate tubular sheath and transverse to the braided yarn strands; wherein the axial yarn strands comprise a different denier to the braided yarn strands.

39. The suture as claimed in claim 38 wherein the axial yarns comprise a greater denier than the braided yarns.

40. The suture as claimed in claim 38 wherein the axial yarns comprise a smaller denier than the braided yarns.

41. A suture comprising: an elongate tubular sheath formed from a plurality of braided yarn strands; a plurality of axial yarn strands overlapping the braided yarn strands and aligned with the longitudinal axis of the elongate tubular sheath and transverse to the braided yarn strands; wherein the axial yarn strands comprise a different cross-sectional area to the braided yam strands.

42. The suture as claimed in claim 41 wherein the axial yarns comprise a greater cross sectional area than the braided yarns.

43. The suture as claimed in claim 41 wherein the axial yarns comprise a smaller cross sectional area than the braided yarns.

44. A suture comprising: an elongate tubular sheath formed from a plurality of woven yarn strands; a plurality of axial yarn strands overlapping the woven yarn strands and aligned with the longitudinal axis of the elongate tubular sheath; and a core positioned within the tubular sheath, the core formed from a plurality of yarn strands extending longitudinally within the tubular sheath.

45. A suture comprising: an elongate tubular sheath formed from a plurality of knitted yarn strands; a plurality of additional axial yarn strands overlapping the knitted yarn strands and aligned with the longitudinal axis of the elongate tubular sheath; and a core positioned within the said tubular sheath, the core formed from a plurality of yarn strands extending longitudinally within the tubular sheath.

46. A suture comprising: an elongate tubular sheath formed from a plurality of woven yarn strands; a plurality of axial yarn strands overlapping the woven yarn strands and aligned with the longitudinal axis of the elongate tubular sheath; wherein the axial yarn strands comprise a different denier to the woven yarn strands.

47. A suture comprising: an elongate tubular sheath formed from a plurality of knitted yarn strands; a plurality of axial yarn strands overlapping the knitted yarn strands and aligned with the longitudinal axis of the elongate tubular sheath; wherein the axial yarn strands comprise a different denier to the knitted yarn strands.

48. A suture set comprising a plurality of individual sutures wherein in at least some of the sutures comprise different mechanical/physical properties wherein the different sutures are distinguished from each other based on their respective mechanical/physical properties by incorporating coloured yarns in at least some of the sutures, the coloured yarns providing a different repeating pattern along a region of the length of the sutures to provide a means of visually distinguishing the sutures having different mechanical/physical properties.