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Non-Absorbable Sutures

Chapter 4: Table of Contents

Non-Absorbable Sutures

Non-absorbable suture materials are either used in areas that allow easy removal after healing (e.g. skin closure) or when long term suture strength is required (e.g. specific orthopaedic procedures, to appose tissue that is expected to heal very slowly, or that is under great tension). By definition, non-absorbable suture materials will retain a significant amount of tensile strength for greater than 60 days after implantation. It is important however to note that despite being classified as non-absorbable, some materials such as silk can still be resorbed and lose significant amounts of strength overtime. Non-absorbable suture materials exist in natural, synthetic and metallic forms. For example, silk is a natural non-absorbable material. It is recognized for its good handling characteristics but it causes a marked tissue reaction after implantation. Silk loses its tensile strength after 6 months and is ultimately absorbed (especially in cats) over a number of years. Because of its braided structure, silk can promote bacterial infections. Synthetic suture materials include polypropylene, polymerized caprolactam, nylon, etc. These suture materials have a high tensile strength and tend to induce a minimal tissue reaction (except for silk which induces significant tissue reaction). Stainless steel suture is the main representative of the metallic form. It was used mainly due to its high tensile strength, excellent knot security and reduced tissue reaction. However, stainless steel is difficult to handle, requires minimal handling in order to prevent bending and breakage and may cut tissues. It is rarely used in modern surgery. 

Non-Absorbable Suture Material

Silk:  Silk is a natural fiber used to manufacture a multifilament (braided) nonabsorbable suture material.  Silk suture is often considered to possess the best handling characteristics of all suture material.  It has weaker tensile strength and knot security than its synthetic counterparts, and elicits more tissue reaction.  Despite its classification as nonabsorbable, silk does absorb over time (complete absorption after 2 years) and loses half of its tensile strength after approximately 1 year.  Silk suture is sometimes coated with a wax mixture to reduce tissue drag during implantation; this can also reduce relative knot security. 

Polyester (Mersilene):  Polyester is a synthetic, nonabsorbable multifilament (braided) suture material that is available in various sizes (5 to 11-0) as well as plain (Mersilene) and coated (Ethibond) forms.  The plain polyester suture material has significant tissue drag, coating reduces this drag but also knot security.  Polyester suture material has excellent initial and prolonged tensile strength, but compared to other synthetic nonabsorbable sutures, it elicits more tissue reaction and has poor knot security.  A surgeon’s throw is often required for the first throw in order to maintain tension during knot placement.  In addition, temporary clamping (using a mosquito forceps) of the knot during placement of the second throw is frequently performed to prevent loosening while tying.  Mersilene is often used to stabilize unstable joints because it is strong and non elastic. 

Polypropylene (Surgipro®/Prolene®):  Polypropylene is a synthetic, nonabsorbable monofilament suture material that is available in various sizes (5 to 8-0).  This monofilament suture is more difficult to handle because of it’s high memory, but it has minimal tissue drag.  It possesses good tensile strength and excellent knot security (due to plastic deformation during tying) and may also be steam sterilized.  It is often favoured for cardiovascular surgeries because it has reduced thrombogenic potential. 

Polymerized Caprolactum:  Polymerized caprolactum is a synthetic, nonabsorbable multifilament (twisted) made from polyamide suture enclosed in a proteinaceous material.  The coating frequently cracks and degrades causing a significant foreign body reaction.  This suture material possesses good tensile strength and fair knot security.  It’s use is typically limited to skin closure.      

Polyamide Nylon:  Polyamide or nylon suture is a synthetic, nonabsorbable suture material available in a monofilament and multifilament (braided) form.  It possesses good initial tensile strength although some strength is lost after implantation (15-20% per year).  Nylon suture is noted as having a high degree of elasticity, which can be useful in edematous tissue and in skin closure.  If nylon is stretched beyond its elastic phase, it will quickly break causing suture failure.  The multifilament nylon suture has better handling characteristics than its monofilament counterpart, but loses its tensile strength after 6 months and may allow for bacteria to persist in its pores within the braiding. 

Polybutester:  Polybutester is a synthetic, nonabsorbable monofilament suture material available in various sizes (2 to 10-0).  It possesses moderate initial tensile strength but is highly elastic (more than nylon) and can be useful in tissues that are likely to become edematous.  Polybutester causes minimal tissue reaction and has minimal tissue drag.  It does not lose any of its initial tensile strength after implantation and has moderate knot security.  Polybutester can be used in slow healing tissues and tissues that requires some elasticity during healing but is generally reserved for skin closure.   

Stainless Steel:  Stainless steel is the most commonly used metallic suture, usually composed of a 316L alloy stainless steel.  It is available in a monofilament and multifilament (twisted) form and in various sizes (7 to 10-0).  It is the most inert and strong nonabsorbable suture material and it has the best knot security.  Stainless steel suture is difficult to handle, it can easily cut tissue and can weaken if bent inappropriately.  It is still used in orthapedic surgery and in infected wounds due to its strength and inertness, but it has mostly been replaced by synthetic suture materials.  

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