Sutures

transcript

Sutures

Briefly…

Definition of suture:1. A strand of material that is used to approximate tissues or to ligate blood

vessels during the wound-healing period (Ratner et al. 2004).2. A stitch or row of stitches holding together the edges of a wound or

surgical incision (Oxford Dictionary).

Tools:1. Needle2. Suture material

The Needle…• Traditionally used stainless steel alloys 300 and 420• Modern needle uses 455 for superior properties (Ratner et.al. 2004)

Chemical Composition 420 300 455

Fe Majority Majority 73%

C < 0.15% < 0.08% < 0.05%

Cr 12 – 14% 17.5 – 20% 11.8%

Ni 8 – 11% 8.5%

Cu, Nb, Ti 2, 2, 1.1 %

Mn < 1% < 2% < 0.5%

Si < 1% < 1% < 0.5%

P < 0.04% < 0.045% < 0.004%

S > 0.03% < 0.03 % < 0.03%

Density (kg/m3) 7750 8000 7800

Elastic Modulus (Gpa) 200 193 200

Specific Heat (J/kg.K) 460 500 N/A

Tensile Strength (Mpa) 655 205 965

Source: Azom.com

The Needle…

Source: Suture Technical Specifications, Demetech (http://www.demetech.us/suture-specs.php)

Classifying Suture Material…

Sutures

Origin

Natural

Synthetic

Absorption

Absorbable

Nonabsorbable

Fiber construction

Multifilament

Monofilament

Source: Ratner et al. 2004

SilkNatural, non-absorbable

VicrylSynthetic, Absorbable

Classifying Suture Material…

Fiber construction

Source: Suture Technical Specifications, Demetech (http://www.demetech.us/suture-specs.php)

Classifying Suture Material…Suture Types Generic Structure Classification Representative

Product/BrandCatgut Collagen from animal

intestinesNatural, absorbable, twisted multifilament (mono.)

Surgical Gut, Chromic Gut

Silk Fibroin from silkworm Bombyx mori

Natural, non-absorbable, braid multifilament

Perma-Head, Softsilk

Polypropylene Isotactic crystalline stereoisomer of PP

Synthetic, non-absorbable, monofilament

Prolene, Surgipro

Polyamide Nylon 6 and nylon 6,6 Synthetic, non-absorbable, monofilament

Ethilon, Dermalon

Stainless steel 316L (low carbon) stainless steel alloy

Metal, non-absorbable, mono and multifilament

Ethisteel, Flexon

Polyglycolic acid/ Polylactic acid

90% PGA, 10% PLA Synthetic, absorbable, braided multifilament

Vicryl, Vicryl Rapide

Polydioxanone Polyester p-dioxanone Synthetic, absorbable, monofilament

PDS II

Polyglycolic acid/ Polytrimethylene carbonate

Copolymer of glycolic acid and trimethylene carbonate

Synthetic, absorbable, monofilament

A Truly, Ideal Suture Material?

Does Not Exist, BUT…

Sterile, highly uniform tensile strength, predictable performance, non-capillary, non-allergic, easy to

handle, minimal tissue reaction, absorbed completely

Properties of Suture Material…

Properties

Physical

Tensile Strength, Dimension, Knot-pull

strength, Knot security, Stiffness

Handling

Knot-tie down, First throw hold, Tissue

drag, Package memory, Suppleness

Biological

Tissue reaction, Absorption,

Biocompatibility, Tensile strength loss

• All standards, test procedures and product specifications are set by U.S. Pharmacopeia (U.S.P.)

Properties: Size and Dimension• Smallest diameter possible to minimize the amount of

material drawn on tissue• Size ranges from #5 (largest) to #11-0 (smallest)

USP Synthetic: Diameter (mm)

Collagen: Diameter (mm)

11-0 0.01 – 0.019

10-0 0.02 – 0.029

9-0 0.03 – 0.039 0.04 – 0.049

8-0 0.04 – 0.049 0.05 – 0.069

7-0 0.05 – 0.069 0.07 – 0.099

6-0 0.07 – 0.099 0.1 – 0.149

5-0 0.1 – 0.149 0.15 – 0.199

4-0 0.15 – 0.199 0.2 – 0.249

USP Synthetic: Diameter (mm)

Collagen: Diameter (mm)

3-0 0.2 – 0.249 0.3 – 0.349

2-0 0.3 – 0.349 0.35 – 0.399

0 0.35 – 0.399 0.4 – 0.499

1 0.4 – 0.499 0.5 – 0.599

2 0.5 – 0.599 0.6 – 0.699

3 0.6 – 0.699 0.7 – 0.799

4 0.8 – 0.899

5 0.70 – 0.799

Source: US Pharmacopeia (http://www.pharmacopeia.cn/v29240/usp29nf24s0_m80190.html)

Properties: Knot pull tensile strength• Maximum tensile stress that can be applied on the ears of a

knot (Ratner et al. 2004)• The larger the diameter, the higher the knot pull tensile

strentgh

USP Synthetic Collagen*

10-0 0.24

9-0 0.49

8-0 0.69 0.44

7-0 1.37 0.69

6-0 2.45 1.76

5-0 6.67 3.73

4-0 9.32 7.55

USP Synthetic Collagen*

3-0 17.4 12.2

2-0 26.3 19.6

0 38.2 27.2

1 49.8 37.3

2 62.3 44.2

3 71.5 57.8

4 68.6

*Based on limit on average minimumSource: US Pharmacopeia (http://www.pharmacopeia.cn/v29240/usp29nf24s0_m80190.html)

Properties: Tensile Strength Loss…• The loss of tensile strength as a function of time (Ratner et al.

Properties: Absorption…• Enzymatic and/pr hydrolytic breakdown of a strand followed

by elimination (Ratner et al. 2004)

Properties: Strain, Stiffness• Strain: Ratio of the change in length of a material to the initial

unstressed reference length (Helmenstine 2012)• Stiffness: Resistance of an elastic body to deflection or deformation by

an applied force (Engineering Toolbox)

Source: Najibi et al. 2001

PGA/PLLA

Properties: In summary…

Suture Types Knot pull strength

Knot security

Handling Tissue reactivity

In vivo strength loss

Catgut Poor Poor (plain)Fair (chromic)

Fair High 7-10 days (plain), 21-28 days (chromic)

Silk Fair Good Very good High 1 year

Polypropylene Fair Poor Poor Low Indefinite

Polyamide Fair Fair Good Low 1.5 – 2.5% /year

Stainless steel High Good Poor Low Indefinite

PGA/PLLA Good Fair -good Good Low 10 days – 4 weeks

Polydioxanone Fair -good Poor-fair Fair-good Low 10 days – 6 weeks

• Knot security: Force that a knot can withstand before slipping or untying (Ratner et al. 2004)

Wound Healing…Wound healing

Primary Intention

Usually clean, uninfected, surgical wound

Secondary Intention

Cell or tissue loss more extensive due to injury, malignancy or infection

Source: Dunn 2007

Tissue Reaction• Immune system considers all suture threads to be foreign bodies• Inflammatory response occurs is similar to any reaction towards

foreign body• Reaction depends on the type of suture, texture, degree of tissue

trauma and length of implantation (Braun & Aesculap t.th)

(Postlethwait et al. 1975):• Catgut >> encourage formation of thin connective tissue, histiocytes

and lymphocytes and cellular infiltrations >> complete absorption leaves

• Silk >> formation of fibrous tissue capsule with variety of giant cells presence, with latter invasion of histiocytes and fibtoblasts

• Nylon >> narrow fibrous tissue zone, least reaction seen

Interaction with Biological System + Host Reaction

(Source: Postlethwait et al. 1975)

GIl Y, Gut 11 years, vaginal cuff closure. No absorption or reaction.

GlOD, Gut 10 days, gastroenterostomy. Essentially no reaction.

G19D, Gut 19 days, subcuitaneotus. Absorption beginning, mainly by monocytes. Serrations at edges and one cleft in suture.

Grades of Tissue Reaction

Coated Vicryl Rapid ®, 7 days, presence of multinucleated giant cells between filaments of suture

SEM of Coated Vicryl Rapid ®, Series of absorption occurs (A) implantation (B) 7 days post and (C) 14 days post.

Source: Andrade & Weissman 2005

Suture Types Tissue reactivity In vivo strength loss

Catgut High 7-10 days (plain), 21-28 days (chromic)

Silk High 1 year

Polypropylene Low Indefinite

Polyamide Low 1.5 – 2.5% /year

Stainless steel Low Indefinite

PGA/PLLA Low 10 days – 4 weeks

Polydioxanone Low 10 days – 6 weeks

Let’s Recap on the Biological Properties

Risks & Side Effects…

1. Suture knot slipping• Inability of the suture to retain until wound healing complete• Common in absorbable suture

2. Re-infection• Site for microbial growth causing re-infection• the need for suture with antimicrobial activity

3. Failure of wound healing• Improper suturing technique does not allow collagen formation

Future Development• Limited to products that can demonstrate a

performance benefit due to cost-constrained market

• Continue development of multifilament braid coatings to provide the best suture possible

• Need to have an ideal absorbable suture should only degrades rapidly following loss of tensile strength

• Development of more suture with antimicrobial properties:• Vicryl Plus (contains triclosan or 5-

chloro-2-(2,4-dichlorophenoxy)phenol)• More commercialized non-suture products

like tissue sealant made of fibrin glue

INNOVATION

PROSPECT

DEMAND

References1. Andrade, M.G.S. & Weissman, R. 2005. Tissue Reaction and Surface Morphology of

Absorbable Sutures after In Vivo Exposure. Journal of Material Science: Material Medicine 17:949-961.

2. Braun & Aesculap. 2006. Suture Glossary.http://www.themonofilamentadvantage.com/documents/Training/Glossary_Sutures_neu.pdf

3. Chrimax. 2001. Non-absrobable Materials: Reaction in Tissue. http://www.chirmax.cz/chirmax_multi/index.php?stranka_id=21&jazyk=3j

4. Dunn, D.L. 2007. Wound Closure Manual. Johnson & Johnson. http://surgery.uthscsa.edu/pediatric/training/woundclosuremanual.pdf

5. Engineering Toolbox. 2012. Stiffness. http://www.engineeringtoolbox.com/stiffness-d_1396.html

6. Helmenstine, A.M. 2012. Strain. About.com Chemistry. http://chemistry.about.com/od/engineeringglossary/g/strain-definition.htm

7. Najibi, S., Banglmeier, R., Matta, J.M. & Tannast, M. 2001. Material Properties of Common Suture Materials in Orthopaedic Surgery. The Iowa Orthopaedic Journal 30:84-88.

8. Postlethwait, R.W., Willigan, D.A. & Ulin, A.W. 1975. Human Tissue Reaction to Sutures. Annals of Surgery 181(2):144-150

9. Ratner, B.D., Hoffman, A.S., Schoen, F.J. & Lemons, J.E. 2004. Surface Properties and Surface Characterization of Materials. Biomaterial Science: An Introduction to Material in Medicine. 2nd Edition. San Diego: Elsevier

10. Salhan, S & Dass, A. 2012. Textbook of Gynecology. New Delhi: Jaypee Brothers Medical.11. US Pharmacopeia. http://www.pharmacopeia.cn/v29240/usp29nf24s0_m80190.html

Sutures

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