Suture materials absorbable sutures

Herrman, J. B., Kelly, R. J., and Higgins, G. A., Polygly-colic acid sutures, laboratory and clinical evaluation of a new absorbable suture material. Arch. Surg., 100, 1970. 

An interesting legal case ensued in the English High Court [87], where Ethicon (Johnson Johnson) maintained, among other things, that the formation and hydrolytic behaviour of polyglycolide fibres were already known and that it was therefore obvious to use the material as an absorbable suture. The outcome was basically favourable to American Cyanamid. 

In general, absorbent sutures are composed of materials that are natural to mammals, such as catgut, and to materials that are either quite susceptible to hydrolysis and/or polymers derived from natural materials such as polyglactin, which is a copolymer of lactic and glycolic acid. Nonabsorbent sutures can be made from natural materials such as cotton, which is a plant material, polymers that range from being hydrophobic to hydrophilic, and steel. 

PGA has been known as a polymer capable of forming tough fibres however, due to its hydrolytic instability its use has initially been limited. Currently, PGA and its copolymers with either lactic acid or with e-caprolactone are widely used as a material for the fabrication of absorbable sutures. 

The polyester named Lactomer is an alternating copolymer of lactic acid and glycolic acid. Lactomer is used for absorbable suture material because stitches of Lactomer hydrolyze slowly over a two-week period and do not have to be removed. The hydrolysis products, lactic acid and glycolic acid, are normal metabolites and do not provoke an inflammatory response. Draw the stmeture of the Lactomer polymer. 

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... 

Polydioxanone (PDS) was produced in the early 1980s as an absorbable suture material [33] ... 

McCarthy, W. H., A new synthetic absorbable suture material a clinical trial of polyglycolic acid suture in general surgery, Aust. NZ J. Surg., 39, 422, 1970. 

As with other types of braided sutures, an absorbable coating which improves suture handUng and knot formation has been added to the absorbable braids. To minimize the risk of infection and tissue drag that are sometimes associated with braided sutures, four types of monofilament sutures have been commercialized. The absorbable monofilaments were designed specifically to approach the engineering compliance of braided sutures, by combining appropriate materials to achieve low moduli, for example, polydioxanone and copolymers of glycolide with caprolactone or trimethylene carbonate. 

Loh IH, Lin HL, Chu CC. Plasma surface modification of synthetic absorbable sutures. In Proceedings, Clemson University Conference on Medical Textiles and Biomedical Polymers and Materials 1996. 

Sutures remain the most common method of tpproximating the divided edges of tissue (1). Sutures are categorised by size, material, design and behaviour. Absorbable and nonabsorbable materials are further divided into synthetic versus natural products, some of vdiich can be fabricated in braided and/or monofilament form. Non-absorbable sutures have played an important role in the development of surgical procedures, generally made of silk, polyamide, polyester, polypropylene, polyethylene and poly(tetrafluoroethylene) (2). 

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]. 

Poly (hexamethylene adipimide) is also known as Nylon 6,6 since its repeat unit has two six-caibon sequences. Nylon is tough, abrasion resistant, and has a low coefficient of friction, making it a popular suture material. Nylon 6,6 is hydrophilic and absorbs water when placed in tissues or in humid environments (9 to 11 percent water when fully saturated ). Absorbed water acts as a plasticiser, increasing the ductility and reducing the modulus of Nylon 6,6. Nylon bioerodes at a very slow rate. Nylon 6,6 implant in dogs lost 25 percent of its tensile strength after 89 days and 83 percent after 725 days. ... 

Polymers in the group of polyesters, specifically the family of polyflactic acid) (PLA), polyfglycolic acid) (PGA), and copolymers of lactic and glycolic acids (PLGAs), as well as poly(P-hydroxybutyric acid) (PHB) most closely fulfilled the criteria outlined above, including biocompatibility, processability, and controlled degradation [8]. These polymers, many descendant of absorbable suture materials developed a couple of decades ago, were approved for in vivo use by the Food... 

The third reason why biocompatibility cannot be equated with inertness is that there are several, and indeed an increasing number, of applications which involve intentionally degradable materials. The two most widely quoted situations here are absorbable sutures and implantable drug delivery systems but many more circumstances where degradable scaffolds and matrices could form an essential component of a device are envisaged. If biocompatibility is predicated on inertness, then degradable materials cannot, by definition, be biocompatible. This clearly does not make sense and suggests that the concept of biocompatibility needs to be altered. 

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