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Biomaterial discussion on classification, properties and biological reaction

Biomaterial discussion on classification, properties and biological reaction

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Sutures Sutures Presentation 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 455Fe 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 7800Elastic Modulus (Gpa) 200 193 200Specific Heat (J/kg.K) 460 500 N/ATensile 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… Natural Origin Synthetic Absorbable Sutures Absorption Nonabsorbabl e Multifilament Fiber construction Monofilament Source: Ratner et al. 2004
  • Classifying Suture Material…Vicryl SilkSynthetic, Absorbable Natural, non-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 Natural, absorbable, twisted Surgical Gut, intestines multifilament (mono.) Chromic GutSilk Fibroin from silkworm Natural, non-absorbable, Perma-Head, Bombyx mori braid multifilament SoftsilkPolypropylene Isotactic crystalline Synthetic, non-absorbable, Prolene, Surgipro stereoisomer of PP monofilamentPolyamide Nylon 6 and nylon 6,6 Synthetic, non-absorbable, Ethilon, Dermalon monofilamentStainless steel 316L (low carbon) stainless Metal, non-absorbable, Ethisteel, Flexon steel alloy mono and multifilamentPolyglycolic acid/ 90% PGA, 10% PLA Synthetic, absorbable, Vicryl, VicrylPolylactic acid braided multifilament RapidePolydioxanone Polyester p-dioxanone Synthetic, absorbable, PDS II monofilamentPolyglycolic acid/ Copolymer of glycolic acid Synthetic, absorbable, MaxonPolytrimethylene and trimethylene carbonate monofilamentcarbonate Source: Ratner et al. 2004
  • 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 Handling Biological Knot-tie down, First Tissue Tensile Strength, throw hold, Tissue reaction, Absorptio Dimension, Knot- drag, Package n, Biocompatibility, pull strength, Knot memory, Tensile strength security, Stiffness Suppleness 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: Collagen: USP Synthetic: Collagen: Diameter Diameter Diameter Diameter (mm) (mm) (mm) (mm) 11-0 0.01 – 0.019 3-0 0.2 – 0.249 0.3 – 0.349 10-0 0.02 – 0.029 2-0 0.3 – 0.349 0.35 – 0.399 9-0 0.03 – 0.039 0.04 – 0.049 0 0.35 – 0.399 0.4 – 0.499 8-0 0.04 – 0.049 0.05 – 0.069 1 0.4 – 0.499 0.5 – 0.599 7-0 0.05 – 0.069 0.07 – 0.099 2 0.5 – 0.599 0.6 – 0.699 6-0 0.07 – 0.099 0.1 – 0.149 3 0.6 – 0.699 0.7 – 0.799 4 0.8 – 0.899 5-0 0.1 – 0.149 0.15 – 0.199 5 0.70 – 0.799 4-0 0.15 – 0.199 0.2 – 0.249 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* USP Synthetic Collagen* 11-0 3-0 17.4 12.2 10-0 0.24 2-0 26.3 19.6 9-0 0.49 0 38.2 27.2 8-0 0.69 0.44 1 49.8 37.3 7-0 1.37 0.69 2 62.3 44.2 6-0 2.45 1.76 3 71.5 57.8 5-0 6.67 3.73 4 68.6 4-0 9.32 7.55 *Based on limit on average minimum Source: 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. 2004) Source: Ratner et al. 2004
  • Properties: Absorption…• Enzymatic and/pr hydrolytic breakdown of a strand followed by elimination (Ratner et al. 2004) Source: 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) PE PET PETPGA/PLLA Source: Najibi et al. 2001
  • Properties: In summary…• Knot security: Force that a knot can withstand before slipping or untying (Ratner et al. 2004)Suture Types Knot pull Knot Handling Tissue In vivo strength strength security reactivity lossCatgut Poor Poor (plain) Fair High 7-10 days (plain), Fair 21-28 days (chromic) (chromic)Silk Fair Good Very good High 1 yearPolypropylene Fair Poor Poor Low IndefinitePolyamide Fair Fair Good Low 1.5 – 2.5% /yearStainless steel High Good Poor Low IndefinitePGA/PLLA Good Fair -good Good Low 10 days – 4 weeksPolydioxanone Fair -good Poor-fair Fair-good Low 10 days – 6 weeks Source: Ratner et al. 2004
  • Wound Healing… Usually clean, Primary Intention uninfected, surgical woundWound healing Cell or tissue loss more extensive due to Secondary Intention injury, malignancy or infection Source: Dunn 2007
  • Interaction with Biological System + Host Reaction 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 Grades of Tissue Reaction (Source: Postlethwait et al. 1975)GlOD, Gut 10 days, G19D, Gut 19 days, GIl Y, Gut 11 years,gastroenterostomy. subcuitaneotus. vaginal cuff closure.Essentially no Absorption beginning, No absorption or mainly by monocytes. reaction.reaction. Serrations at edges and one cleft in suture.
  • Interaction with Biological System + Host 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
  • Interaction with Biological System + Host Reaction Let’s Recap on the Biological Properties 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 Source: Ratner et al. 2004
  • Risks & Side Effects…1. Suture knot slipping • Inability of the suture to retain until wound healing complete • Common in absorbable suture2. Re-infection • Site for microbial growth causing re-infection • the need for suture with antimicrobial activity3. 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: INNOVATION • Vicryl Plus (contains triclosan or 5- chloro-2-(2,4-dichlorophenoxy)phenol) PROSPECT• More commercialized non-suture products DEMAND like tissue sealant made of fibrin glue Source: Ratner et al. 2004
  • 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.pdf3. Chrimax. 2001. Non-absrobable Materials: Reaction in Tissue. http://www.chirmax.cz/chirmax_multi/index.php?stranka_id=21&jazyk=3j4. Dunn, D.L. 2007. Wound Closure Manual. Johnson & Johnson. http://surgery.uthscsa.edu/pediatric/training/woundclosuremanual.pdf5. Engineering Toolbox. 2012. Stiffness. http://www.engineeringtoolbox.com/stiffness- d_1396.html6. Helmenstine, A.M. 2012. Strain. About.com Chemistry. http://chemistry.about.com/od/engineeringglossary/g/strain-definition.htm7. 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):144-1509. 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: Elsevier10. Salhan, S & Dass, A. 2012. Textbook of Gynecology. New Delhi: Jaypee Brothers Medical.11. US Pharmacopeia. http://www.pharmacopeia.cn/v29240/usp29nf24s0_m80190.html