Lecture 10: Suture Materials and Patterns

choosing suture material

size and chemical make-up

natural vs synthetic

think:

strength of closure —> how long does it need to last?

choosing suture material

absorbable vs nonabsorbable

think:

inside or outside of body?

inflammatory response?

choosing suture material

monofilament vs multifilament

think:

wound contamination

how to choose suture material for LA:

same options as SA, only BIGGER!

Typitcally use 2-0 for SQ and 2 or 3 for linea alba!

suture selection principles:

• suture should be as strong as the normal tissue through which it is placed

• tensile strength reduction over time should correspond to healing of the affected tissue

• suture is not needed after the wound is healed

• the strength of the wound is more dependent on the tissue’s ability to hold the suture than the suture material itself

suture with elasticity is ideal for?

skin closure (adapts to wound edema)

suture with high stiffness is chosen for what?

abdominal closure, herniorraphy, prosthesis, etc

what will oversize suture do to your closure?

it will WEAKEN it! due to excessive tissue rxn

• bigger is not always better!

what to do with wounds under tension

increasing the number of sutures (or using a tension relieveing suture pattern) is better than increasing suture size

suture strength needs to do what?

last to support healing tissueand withstand physiological forces during recovery

how long do internal organs and subQ take to heal?

relatively fast

few days

full strength in a couple of weeks

how long does fascia take to heal?

slowly

couple weeks

full strength in a couple months

• linea alba: baseline strength at 8 weeks

how long does skin take to heal?

seals within 1 day

primary incision heals in 10 - 14 days

full strength < 30 daysb

better apposition —>

decreased healing time

commonly used suture in large animals

if you can’t remove it, what suture do you use - absorbable or nonabsorbable?

use absorbable

SubQ, organs, ligatures

if you can remove it, what suture do you use?

non-absorbable

skin

ideally should be inert —> reduces inflammation = speeds healing

what is needed for suture absorption in absorbable suture?

inflammation

increase suture size = increase volume of knot which is important to know why?

this is more important than number of throws on knot when it comes inflammation

increased volume of knots =

increased inflammation

increased inflammation =

weaken closure

• use the smallest suture possible!!!

which needle is the most commonly used in vet med?

3/8 or ½ circle

• more ergonomic to use

¼ circle = opthalmologic surgery

5/8 circle: confined or deep locations

needle sizes

determinent for picking a needle for a wound:

want to be able to reaach across both sides of the wound with the needle

taper point needle

round needle shaft does not enlarge hole as it passes through

good for delicate tissue

reverse cutting needle

cutting edge on the convex (outer) side

• makes needle stronger than conventional cutting

• less risk of tissue cut out

• skin, fibrous tissue

conventional cutting

uncommon

taper point needle

reverse cutting needle

conventional cutting needle

Buhner needle

special needle in LA sx

used to purse string prolapses

buhner needle

S needle

special needle in LA sx

• used to close cow skin

• negates need for needle drivers

• easier to punch through thick skin

• use suture on a reel

S needle

Buehner needle and suture vaginal prolapse

DEEP path

starts and ends under the vulva

minimize exposed suture

S needle usage

suture without needle holders

closing ruminant skin

good for thick skin!!

knot tying techniques

knot = weakest point in the suture pattern

• even if its perfect!!

important to do this correctly to prevent dehiscence of incision

wound dehiscence. Ouchie

simple throw

half a knot

square knot

2 simple throws that are reversed

surgeon’s throw

placed when a square throw is slipping

• more friction

• more suture material left in the wound

granny knot: 2 throws, NOT reversed

NOT secure, do NOT do this

half hitch

pulling up on the suture end instead of across

NOT secure

types of knots

knot security

suture type:

memory and coefficient of friction

• body fluids contact suture and can change the frictional behavior of suture

knot security

number of throws:

2-0 PDS (polydiaxanone) or nylon: 4 throws are needed for a secure ligature

larger suture = needs 5 throws!

#2 or #3 Vicryl (polyglactin 910) or #2 PDS (polydioxanone)

for knot security, how long should the tag length be?

at least 3mm in length

when tying loops, how can you create knot security?

need knot security!

increasing suture size =

decreasing knot security!

monofilament for skin suturing =

decrease bacterial transport into deeper tissues

nonabsorbable suture we like to use in the skin:

polypropylene (Prolene)

nylon

common suture pattern for skin:

simple interrupted with no tension (USP 2-0)

• ± tension relieving patterns (;arger suture: 0, 1 or 2)

specifics on how to suture skin:

apposition of tissues edges or slight eversion

bites about 5mm from skin edge

• collagenase activity within 5mm of wound —> sutures may pull through

• wounds may require suture to be further away

sutures for fascia

most common in LA - linea alba!

species difference: bites 15mm away from cut edge

• extra suture needed to combat potential abdominal distension

suture to close fascia:

polyglactin 910 (Vicryl), Polydioxanone (PDS)

size: #2-7 (#2 or #3 most common)

what type of suture do we commonly use in cattle to close fascia?

catgut! It’s cheap!

• don’t use in horses, too much inflammation

suture specific for delicate tissue like subcutaneous, GI organs:

PDS (polydioxanone), Vicryl (polyglactin 910), Monocryl (poliglecaprone)

typically use USP 2-0

Suture pattern for GI tract:

inverting suture patterns

• Lembert

• Simple continuous oversewn with a Cushings

suture for contaminated wounds:

monofilament only!
nonabsorbable suture - inert

elastic - allows for tissue swelling

all wounds in horses are contaminated!!!

suture to use in farm animals

ideally same suture as other animals ——>

to reduce cost:

• chromic cat gut

• suture on a reel

  • supramid

    • braided nylon

  • braunamid

    • braided polyamide

when to remove sutures

10 - 14 days

what is staging removal for wounds under tension?

take out every other suture or every 1/3 initially

most common absorbable suture:

polydiaxanone - PDO/PDS

polyglactin 910 - Vicryl

poliglecarpone 25 - Monocryl

polyglyconate - PGA/Dexon

most common non-absorbable suture:

polypropylene - Prolene

polybutester - Novafil

coated polyster - Ethibond Excel

nylon - Ethilon

skin staplers facts

stainless steel

• inert

fast to put in

stable remover or hemostat to remove

• patient recheck opportunity

wounds with NO tension

• appose wound edges

skin staplers

stable removal can be:

tough!

NOT for mini colics

foals are really tough too!!!

large animal suture patterns are:

the same as small animal (:

few that are more common in large animal though.

inverting tissue pattern

more common in LA

• invert the tissue edges to help make a seal

• uses: uterus, GI tract, urinary bladder

• suture does NOT come out the tissue edge

  • adjacent to the edge to fold in some tissue

• examples: Utrecht, Cushing, Lembert

inverting suture pattern

Utrecht is commonly used on which organ?

uterus!

Utrecht suture pattern

Cushing pattern is commonly used on which organ?

GI, urinary bladder

• often combined with a simple continuous first

Cushing suture pattern

Lembert suture pattern is commonly used on:

GI or urinary bladder

• be careful not to make a “cuff” of tissue deep to your suture line

Lembert suture pattern

suturing wound under tension

tension impedes healing

impairs blood supply

prevents perfect apposition

• shear stress on wound

Langer’s lines:

relaxed skin tension lines

incision parallel = least tension

incision perpendicular = most tension

LA and SA langer’s lines are:

different!

preferable why to suture wounds under tension:

use limb immobilization

add more sutures

use tension-relieving techniques

what is not preferable when suturing wounds under tension?

using bigger suture

wound/limb immobilization

splint/bandaging as wound/limb immobilization

tension relieving techniques

release incisions

walking sutures

tension relieving suture patterns

• ± use of stent

• ± combo patterns

• skin tension lines

relief incisions

close the primary wound and leave the relief incisions to heal by second intention

tension relieving pattern

walking sutures

• using your suture to “pull” the skin over the top of the defect

• even out tension

• obliterate dead space

• no closer than 2-3 cm apart

  • can increase inflammatory response with extra suture

tension relieving pattern

stents

distribute tension more evnely along suture to prevent pull-through

staged removal if needed

avoid using a stented closure on its own

• always a combo of stents and other suture patterns

stents

walking sutures

tension relieving pattern

vertical mattress

less impingement of blood supply compared to horizontal mattress

good apposition, but some eversion

interrupted only

bites are perpendicular to cut edge

vertical mattress

tension relieving pattern

horiztonal mattress

strong tension relieving - will not tear through tissue

• but tends to impede blood supply

• RARELY use without stents

most eversion possible

can apply in continuous pattern

visible bites are parallel to cut edge

horizontal mattress

tension relieving pattern

near-far-far-near

excellent apposition and tension relief

interrupted only

most suture in wound

near-far-far-near

special suture pattern

ford interlocking

• mild tension relieving continous pattern

• reduces suture disruption if one part breaks

• good apposition

• commonly used to close skin on cow flank incision

Ford Interlocking Pattern

mesh for large defects

polyglactin 910 - Vicryl

Polypropylene - Prolene

differences from small animals

punching through skin - much thicker

• practice!

tightness on skin sutures

• snug!

more frquently use surgeon’s throws

PDS II NOT preferred for closing linea alba

RARELY use intradermal patterns