Lab 4 . Part 5 - Suture materials

• wide variety of sutures materials and brands available
• need to be familiar with the important characteristics of the ones you use
• a small sample of some classic and commonly used materials are detailed to demonstrate important considerations in selection - the list is by no means exhaustive

For each suture that you use, you need to know:

• absorbable or nonabsorbable
  • if absorbable, how rapidly
• monofilament or multifilament (braided)
• amount of tissue reaction that it stimulates
• knot security and ease of handling
• unique properties of that material

(significant loss of tensile strength by 14 days)

Chromic Gut

• derived from sheep intestinal submucosa and bovine intestinal serosa
• treated with formaldehyde
• chromic Gut: treated with chromic salt
  • increases strength
  • slow loss of tensile strength
  • decreases tissue reaction
•  absorbed by phagocytosis
• rapidly absorbable
  • loses tensile strength (33% in 7 days, 67% in 28 days)
  • complete removal from tissue prolonged (can be found encapsulated at previous sites years later)
  • rapid premature loss of strength in infected wounds, after exposure to digestive enzymes (eg. stomach), in highly vascular tissue, and protein-depleted patients
• causes significant foreign body reaction
• relatively good handling characteristics
  • stiff in larger sizes
  • good knot security
    • minimum of 3 throws are recommended for a secure knot
    • four throws for starting knot and five throws for ending knot on continuous patterns
  • ends need to be left 3-5 mm long as tend to untie when wet
• should NOT be used to close the abdominal wall because of rapid, unpredictable loss of strength
• economical
• use largely been replaced by synthetic materials

characteristics summary

• natural
• rapidly absorbable
• multifilament
• reactive in tissue

Polyglycolic acid (Dexon)

• made of a glycolic acid polymer
• absorbed by hydrolysis
• rapidly absorbable
  • most of its tensile strength lost within 2 weeks of implantation
  • removed from the body within 3-4 months
  • more rapid absorption in alkaline environment (eg. urinary bladder)
•  significant tissue drag
  • may cut delicate tissues
  • available with coating
    • decreases drag
    • poorer knot security (need extra throws)
•  comparison with chromic gut:
  • stronger
  • more predictable strength loss
  • less reactive
  • more rapid and complete removal from body
•  can be used to close clean tissue layers that regain sufficient strength within 7-10 days

Characteristics summary

• synthetic
• rapidly absorbable
• braided multifilament

Polyglactin 910 (Vicryl)

• composed of copolymer of glycolide and epsilon-caprolactone
• rapidly absorbable by hydrolysis
  • loses tensile strength quickly (50 % within 7 days)
  • completely removed from body within 4 months
• initially very strong (strongest of absorbable)
  • initial strength allows selection of 1-2 sizes smaller than would normally
• minimal tissue reaction
• soft, pliable material with excellent handling
  • minimal tissue drag
• good knot security
  • required throws for secure knot formation is unknown (follow those for polydioxanone)
  • 4 throws for a secure knot
  • 5 throws at the start and 6-7 at end of continuous pattern
• used for soft tissue suturing when prolonged wound support is not necessary (eg. subcutaneous and intradermal layers) 

Characteristics summary

• synthetic
• rapidly absorbable
• braided multifilament

Poliglecaprone 25 (Monocryl)

• composed of copolymer of glycolide and epsilon-caprolactone
• rapidly absorbable by hydrolysis
  • loses tensile strength quickly (50 % within 7 days)
  • completely removed from body within 4 months
• initially very strong (strongest of absorbable)
  • initial strength allows selection of 1-2 sizes smaller than would normally
• minimal tissue reaction
•  soft, pliable material with excellent handling
  • minimal tissue drag
• good knot security
  • required throws for secure knot formation is unknown (follow those for polydioxanone)
  • 4 throws for a secure knot
  • 5 throws at the start and 6-7 at end of continuous pattern
•  used for soft tissue suturing when prolonged wound support is not necessary (eg. subcutaneous and intradermal layers) 

Characteristics summary

• synthetic
• rapidly absorbable
• monofilament
• strong
• minimally reactive

(significant strength remains for at least 30 days but lost by 60 days)

Polydioxanone (PDS II)

• composed of paradioxanone polymers
• absorbed by hydrolysis
• slowly absorbable
  • over 50% strength remains after 6 weeks
  • complete removal from the body up to 6 months
  • strength maintained in alkaline environment (suitable to close urinary bladder)
• strong
• minimal tissue reaction
• acceptable handling qualities but larger sizes are stiff
• minimal tissue drag
• reasonable knot security
  • 4 throws for secure knot
  • 5 throws at start and 6-7 at end of continuous pattern
  • popular choice for general soft tissue suturing
  • recommended when prolonged tissue support desired.

Characteristics summary

• synthetic
• slowly absorbable
• monofilament
• strong
• minimally reactive

• composed of glycolic acid and trimethylene carbonate
• absorbed by hydrolysis
• slowly absorbable
  • 50% tensile strength lost by 3 weeks
  • complete absorption takes 6-7 months
  • retains strength in alkaline environment (can use for urinary bladder closure)
• strength similar to polydioxanone
• minimal tissue drag
• stiff
  • tends to conform tissues to suture rather than conforming to tissues
• good knot security when extra throws placed
  • 4 throws for secure knot 5 throws at start and 6-7 at end of continuous pattern
• more economical than PDS
• handling characteristics have limited use in small animals but could be selected for most soft tissue suturing

Characteristics summary

• synthetic
• slowly absorbable
• monofilament
• strong
• minimally reactive

Silk

• derived from silkworm cocoon
• technically nonabsorbable
  • slowly loses tensile strength over 6 months
  • may be completely absorbed after 2 years
  • not recommended if prolonged strength or persistence is desired (e.g. securing a prosthetic device)
• induces significant tissue reaction
•  excellent handling characteristics
• good knot security
• economical
• should NOT use in infected or contaminated areas
  • potentiates infection (less bacteria required to induce infection)
  • harbor bacteria within braid leading to persistent infection
• uncommonly used
• use largely replaced by synthetic monofilament materials

Characteristics summary

• natural
• nonabsorbable (absorbed over several years)
• multifilament
• reactive

Polymerized caprolactum (supramid)

• composed of synthetic twisted multifilament polyamide encased in a smooth sheath
• very strong
• somewhat stiff to handle
• reactive when used in skin (increased if casing breaks)
• should NOT be buried because of high rate of draining tract formation
• economical
• primarily used as a skin suture in food animals

Characteristics summary

• synthetic
• nonabsorbable
• multifilament
• coated
• very reactive

Polyesters (Mersilene, Ethibond)

• composed of synthetic multifilament polyester
• very strong
• retains tensile strength when implanted
• significant tissue drag
  • coating improves but decreases knot security
• moderate tissue reaction when implanted
• contraindicated in infected or contaminated wounds
  • potentiates infection
  • bacteria reside within braid leading to persistence of infection and chronic draining tracts
• primarily used for tendon and ligament repairs because of excellent strength
  • eg. extracapsular cruciate repairs
  • results in significant incidence of chronic draining tracts
  • use gradually being replaced by monofilament options

Characteristics summary

• synthetic
• nonabsorbable
• multifilament
• strong

Nylon (Dermalon or Ethilon)

• available as both monofilament or multifilament
• composed of a polyamine
• monofilament form (Ethilon)
  • inert
  • minimal tissue reaction
  • nonabsorbable by definition but loses 30% of strength within 2 years of implantation
• multifilament form (Dermalon)
  • essentially no strength after 6 months
  • somewhat stiff to handle
  • uncommonly used
• significant memory, especially in larger sizes
• knot security is relatively poor so care necessary to ensure secure knots
  • 4 throws required for a secure square knot
  • additional throws necessary for continuous patterns (5 on beginning knot and 6 on ending knot)
  • suture ends may be sharp so avoid in areas where could cause trauma
• mainly used as a skin suture, but can be buried if necessary

Characteristics summary

• synthetic
• nonabsorbable but strength loss over time
• minimally reactive
• available as monofilament or multifilament

Polybutester (Novafil)

• composed of a copolymer of polyglycol and polybutylene terephthalates
• good tensile strength
• strength maintained when implanted
• slippery to handle
• more flexible and elastic than polypropylene or nylon
• minimal tissue reaction
• reasonable knot security but need to ensure throws adequately tightened
• nice handling qualities once experience gained with knots
• mainly used as a skin suture, but can be buried if necessary

Characteristics summary

• synthetic
• nonabsorbable
• monofilament
• minimally reactive

Polypropylene (Prolene)

• composed of a propylene polymer derived from propane gas
• not as strong as nylon
• retains initial strength when implanted
• minimal tissue drag
• minimal tissue reaction
• best knot security of synthetic monofilaments
• very nice handling qualities once experience gained with knots
• least likely of the monofilament nonabsorbable sutures to potentiate infection or induce thrombi
• used as skin suture and if need to permanently implant suture (eg. prosthetic device)

Characteristics summary

• synthetic
• nonabsorbable
• monofilament
• least reactive of sutures

Table 1: Summary of Characteristics of Commonly used suture materials

Table 2: Summary of Characteristics of Commonly used suture materials

** At least 4 throws recommended for all nonabsorbable materials. For continuous patterns, add one additional throw for the beginning knot and 2 additional throws for the ending knot.