Synthetic materials for absorbable sutures

Natural collagen-based absorbable sutures have largely been replaced by synthetic absorbable sutures. Synthetic absorbable sutures are made from aliphatic absorbable polyesters and contain one or more of the five basic building blocks glycolide,L-lactide,p-dioxanone, -caprolactone and trimethylene carbonate. With the exception of the trimethylene carbonate building block which results in amorphous polymers, the polymers from the other four blocks are semicrystaUine. 

The chemical structures of these five basic building blocks and commercial absorbable sutures are shown in Fig. 11.1a and 11.1b, respectively. Very recently, 4-hydroxybutyrate-based absorbable suture (TephaFlex) was approved by the FDA. TephaFlex is bioengineered from bacteria rather 

Dexon Dexon II, Dexon S, Bondek, Surucryl, Salil, Salil Quick, PolySyn FA 

Vicryl, Vicryl Plus, Vicryl Rapid, Pdysorb 

1 (a) Six building blocks to fabricate synthetic absorbable sutures, (b) Chemical structure of commercial synthetic absorbable sutures. 

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The first synthetic absorbable suture was made from a homopolymer of glycolic acid by Davis Geek Co. and manufactured with the tradename Dexon (1970). This suture was followed by a second material produced by Ethicon, Inc., in 1974, a copolymer of lactide and glycolide known as poly-glactine 910 or Vicryl. Both Vicryl and Dexon are made from polymer fibers, which are braided to produce sutures. In addition. Vicryl is Teflon coated for... 

An absorbable suture was one that lost a significant portion of its mechanical strength over a period of 2 months > hile a non-absorbable suture was one that maintained a significant portion of its strength longer than 2 months [4]. A suture may lose its toisile strength over a relatively short period of time, but require months or evoi years to absorb completely and be eliminated from the body. The prinuiry mode of degradation for natural materials is enzymolysis, vdiereas for synthetic absorbable materials it is hydrolysis [3]. 

The previous chapter provided a general overview of the properties of materials used for surgical sutures and of the desirable characteristics of such materials. This chapter considers absorbable and nonabsorbable materials in greater detail, looking within each category first at natural materials, and second at synthetic materials. In the section on absorbable materials, natural materials reviewed are ... 

Nonabsorbable sutures are divided into natural fibers (silk, cotton, linen), and man-made fibers. The latter include polypropylene, polyanfide, polyester, poly(ether ester), polytetrafluoroethylene (Gore-Tex ), polyvinylidine fluoride (PVDF), and stainless steel. Monofilament Dyloc (from Dynek, Australia) is unusual among synthetic nonabsorbable sutures because it is made from a nonconventional man-made fiber poly(ether ester) (Fig. 10.2). The main types of material for both absorbable and nonabsorbable sutures are discussed in Chapter 11. 

Sutures are also classified according to size. Currently, two standards are used to describe size USP (United States Pharmacopeia) and EP (European Pharmacopeia) (Chu et al., 1997). Appendix 2 at the end of this chapter provides a summary of these. In the USP standard, which is used most commonly, the size is represented by a series combination of two Arabic numbers a zero and any number other than zero, for example, 2-0 (or 2/0). The higher the first number, the finer is the suture material. Sizes larger than 0 (1/0) are denoted by 1,2,3 etc. This standard also varies with the type of suture material. In the EP standard, the code ranges from 0.1 to 10. The corresponding minimum diameter (mm) can be easily calculated by taking the code number and dividing it by 10. The EP standard does not separate natural from synthetic absorbable sutures as does USP. Table 10.A.2 in the Appendix at the end of this chapter outlines USP and EP suture size classification... 

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