suture and biomaterials

what are ideal suture properties?

•Easy to handle

•Minimal reactivity with tissue

•Inhibits bacterial growth

•Holds securely when knotted

•Resists shrinking in tissue

•Is absorbed with minimal reaction once the tissue is healed

•Non-capillary

•Non-allergenic

•Non-carcinogenic

•Non-ferromagnetic

Inexpensive

suture characteristics to consider

•Suture size

•Flexibility and Memory

•Surface characteristics and coating

capillarity

knot tensile strength

relative knot security

patient factors to consider

•Type of tissue sutured

•Expected healing time of tissue

•Presence or absence of infection

•Presence or absence of neoplasia

•Presence or absence of medications prescribed

•Presence or absence of endocrine disorders

•Patient nutritional status

suture sizes

12 - 0 (smallest) to 7 (largest)

thickness of human hair

0.017-0.18 mm

flexibility often refers to

memory

inherent capability of suture to return to, or maintain, its original gross shape

memory

____ ____ & ____ also play a part in flexibility of the material

torsional stiffness and diameter

least flexible

steel

most flexible

silk

important to ____ tissue drag

decreaase

•– the amount of friction created as suture is pulled through the tissue

drag

greater the drag the more

micro trauma to the tissue

___ suture drags more than ____

braided, monofilament

braided suture often coated to reduce _____ but it also promotes a smoother surface

capillarity

•The degree to which absorbed fluid is transferred along a suture.

capillarity

•It is the process by which fluid (and potentially bacteria) are carried into the interstices of multifilament fibers

capillarity

monofilament sutures are considered

noncapillary

What effect does coating have on the capillarity of sutures?

Coating reduces capillarity.

What types of coatings may be used on sutures?

Coatings may be water soluble or insoluble.

What antibacterial coating is used on Vicryl Plus and PDS Plus sutures?

Triclosan.

What is created around the suture when using Triclosan?

A zone of inhibition.

- a measurement of the ability of a material (or tissue) to resist deformation and breakage

tensile strength

tensile strength diminishes over time as suture is ____, ____, and has constant ____ applied to it

absorbed, stretches, load

as tissue heals ___ ___ returns and the load is transferred from the suture to the tissue

tensile strength

holding capacity of the suture

relative knot security

What is relative knot security?

The strength required to break or untie a tied knot.

What is the tensile strength of suture material?

The strength required to break an untied knot.

Which type of material generally has better knot security?

Braided material.

What effect do instruments have on suture tensile strength?

Suture tensile strength is micro-damaged by instruments, causing the suture to weaken.

What should you NEVER do with suture?

Grasp suture with an instrument.

•the degree to which suture will deform under stress or load and return to its original form when the load is removed

elasticity

•the degree to which suture will deform without breaking and will maintain its shape after removal of the deforming force

plasticity

•– the ease of handling and the ability of the suture to change shape

pliability

- tendency of a suture to slowly and permanently deform under constant stress

creep

types of suture needles

•Cutting

•Taper

•Reverse cutting

•Trocar

•Blunt point

•Straight

•Micropoint

•Spatula

What are the different properties of degradation by absorbable suture material?

Different properties of degradation by material

What type of reaction does absorbable suture promote in tissue?

Promotes an inflammatory reaction in tissue

What happens to the tensile strength of absorbable suture as it stretches and degrades?

Loses tensile strength as suture stretches and degrades

What types of fibers can absorbable sutures be made from?

Natural and composite fibers

What is a characteristic of non-absorbable sutures regarding degradation?

Non-absorbable sutures do not degrade and become walled-off by the body.

What type of reaction do non-absorbable sutures promote in tissue?

Non-absorbable sutures promote an inflammatory reaction in tissue.

What happens to the tensile strength of non-absorbable sutures as they stretch?

Non-absorbable sutures lose tensile strength as they stretch.

What types of materials can be used to make non-absorbable sutures?

Non-absorbable sutures can be made from natural and composite fibers.

Absorbable suture defined as -

a suture that loses most of its tensile strength within 60-90 days in living mammalian tissue

2 types of natural fiber suture

silk and catgut

non-absorbable but does degrade after 2 years

silk

- manufactured from the small intestine submucosa of sheep

catgut

•delays absorption, decreases inflammation

•Chromium trioxide salts

chromic catgut

absorbable synthetic suture examples

•Polyglycolic acid (Dexon)

•Polyglactin 910 (Vicryl)

•Poliglecaprone 25 (Monocryl)

•Polydiaxanone (PDS)

•Polyglyconate (Maxon)

non absorbable synthetic suture examples

•Polyester (Nylon)

•Polypropylene (Prolene)

•Stainless steel

most sutures degrade by

hydrolysis

Cleavage of chemical bonds by the addition of wat

hydrolysis

Catgut degrades by

proteolysis

Breakdown of proteins into peptides and amino acid

proteolysis

suture degradation

so which suture do i use?

Absorbable for buried sutures

Suture not needed after the tissue is healed

Non-absorbable for skin

Suture promotes an inflammatory reaction

Less suture material is better as long as it does the job

Use smallest suture necessary to do the job

so which suture do i use?

Smaller knots leave less for inflammatory reaction

But not at the expense of suture failure

Suture failure is usually due to knot failure

As strong as the tissue that it is holding to heal

Tensile strength reduction corresponds to gain in tissue strength

Strength comes from the tissue holding the suture, not the suture holding the tissue

examples of biomaterials

•Plates/screws

•Other metallic implants

•Allograft material

•Absorbable mesh

•Xenograft material

•Non-absorbable mesh

•Adhesives

•Cyanoacrylate

•Polymers

•Composites

•Ceramics

•Metals (staples)

What is the purpose of surgical mesh?

Used to augment surgical repair of slow healing tissue

What materials can surgical mesh be made from?

Synthetic polymers or biologically derived materials

What is one common synthetic material used in surgical mesh?

Polypropylene

What does SIS stand for in the context of surgical mesh?

Porcine small intestine submucosa (xenograft)

How is surgical mesh typically constructed for strength?

Woven or knitted

What characteristic of surgical mesh affects its mechanical properties?

Different mechanical properties

What is the effect of small pore size in surgical mesh?

Inhibits ingrowth of capillaries and fibroblasts

What type of glue is used as a tissue adhesive?

Cyanoacrylate glue

In what form is tissue adhesive typically found?

Liquid monomer form

What triggers the polymerization of tissue adhesive?

It polymerizes when it encounters anions in the moisture around a wound edge

How does tissue adhesive bond to the skin?

It bonds to skin cells and is sloughed when those cells die

What is the correct application method for tissue adhesive?

Pinch skin edges together and apply to surface on top of skin

What should you NOT do when applying tissue adhesive?

DO NOT place drop into incision and then pinch skin

What reaction can occur due to improper application of tissue adhesive?

Creates a foreign body reaction and inflammation results secondary to elution of toxic byproducts

skin staples

stainless steel

circular staples

EEA

linear staples

TA

GIA

LDS

name basic suture patterns

•Simple Interrupted pattern

•Simple Continuous pattern

•Cruciate pattern

•Horizontal Mattress pattern

•Buried Interrupted and Continuous patterns

simple interrupted pattern

•Easiest pattern to learn

•Appositional

•Provides secure closure

•Avoid excessive tension on tissue

simple interrupted

simple continuous pattern

simple continuous pattern

•Appositional

•Tied off only at ends

•Saves time and suture material

•Not generally used for skin

•Avoid over-tightening

•Provides secure closure

cruciate pattern

cruciate pattern

•Appositional

•Too much tension will cause tissue to invert

•Faster than simple interrupted

•Gives a strong closure

Horizontal mattress pattern

horizontal mattress pattern

•Tension relieving pattern

•Distributes forces away from the incision

•Too much tension will cause tissue to evert and damage blood supply to incision

buried patterns

buried patterns

•Absorbable suture material

•Appositional

•Closes dead space

•Skin sutures support this layer of closure

Knot is always at deepest layer

___ knot has better knot security

surgeons knot

___ ___ knot for tighter closures

half hitch

types of knots

How tight should you tighten a suture when tying a knot?

Just enough to appose tissue

What should you avoid when tying a knot to prevent tissue damage?

Crushing the tissue and damaging the blood supply

What is the minimum number of throws required when tying a suture knot?

4 throws

What may be needed when using large suture?

More than 4 throws

How long should the suture ends be cut after tying a knot?

Leaving ~3-5mm tags

What should you avoid when handling the suture?

Handling the suture with instruments

What type of knots should be ensured when tying sutures?

Square knots, not slip knots