Suture Characteristics

If an ideal suture material could be created, it would be :
  • Sterile
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  • Highly uniform tensile strength, permitting use of finer sizes
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  • High tensile strength retention in vivo, holding the wound securely throughout the critical healing
        period, followed by rapid absorption

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  • Consistent uniform diameter
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  • Predictable performance
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  • Non-capillary, non-allergenic, and non-carcinogenic
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  • Easy to handle, ties down well, provides optimum knot security
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  • Minimally reactive in tissue and not predisposed to bacterial growth
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  • Capable of holding tissue layers throughout the critical wound healing period securely when
        knotted without fraying or cutting

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  • Resistant to shrinking in tissues
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  • Absorbed completely with minimal tissue reaction after serving its purpose
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    However, because the ideal all-purpose suture does not yet exist, the surgeon must select a suture that is at least as close to the ideal as possible
     
    Personal Suture Preference :

    Most surgeons have a basic "suture routine," a preference for using the same material(s) unless circumstances dictate otherwise. The surgeon acquires skill, proficiency and speed in handling by using one suture material repeatedly-- and may choose the same material throughout his or her entire career
    A number of factors may influence the choice of materials :
  • His or her area of specialization
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  • Wound closure experience during clinical training
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  • Professional experience in the operating room
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  • Knowledge of the healing characteristics of tissues and organs
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  • Knowledge of the physical and biological characteristics of various suture materials
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  • Patient factors (age, weight, overall health status and the presence of infection)
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    Size and Tensile Strength :
    Size denotes the diameter of the suture material

    The accepted surgical practice is to use the smallest diameter suture that will adequately hold the mending wounded tissue. This practice minimizes trauma as the suture is passed through the tissue to effect closure. It also ensures that the minimum mass of the foreign material is left in the body
     

    Suture size is stated numerically; as the number of 0's in the suture size increases, the diameter of the strand decreases. For example, size 5-0, or 00000, is smaller in diameter than size 4-0, or 0000. The smaller the size - the less tensile strength the suture will have

     

    Knot tensile strength is measured by the force, in Kilograms force (Kgf), which the suture strand can withstand before it breaks when knotted
     

    The tensile strength of the tissue to be mended (its ability to withstand stress) determines the size and tensile strength of the suturing material the surgeon selects. The accepted rule is that the tensile strength of the suture need never exceed the tensile strength of the tissue. However, sutures should be at least as strong as normal tissue through which they are being placed
     

    If the tissue reduces suture strength over time, the relative rates at which the suture loses strength and the wound gains strength are important. If the suture biologically alters the healing process, these changes must also be understood
     
    Monofilament vs. Multifilament Strands
    Sutures are classified according to the number or strands of which they are comprised
     
    Monofilament sutures are made of a single strand of material

    Because of their simplified structure, they encounter less resistance as they pass through tissue than multifilament suture material
    They also resist harboring organisms which may cause suture line infection
    These characteristics make monofilament sutures well-suited to vascular surgery
    Eg : Polyamide (Nylon), Polypropylene
     
    Multifilament sutures consist of several filaments, or strands, twisted or braided together
    This affords greater tensile strength, pliability, and flexibility

    Multifilament sutures may also be coated to help them pass relatively smoothly through tissue and enhance handling characteristics
    Eg : Polyglycolic Acid (PGA), Silk, Polyester
     

    Note : Catgut is multifilament in construction, however due to polishing gives a finish of Monofilament
     

    CLASSIFICATION ON THE BASIS OF ABSORPTION :
    Absorbable sutures may be used to hold wound edges in approximation temporarily, until they have healed sufficiently to withstand normal stress
     
    Natural Absorbable sutures :
    These sutures are prepared either from the collagen of healthy mammals

    Some are absorbed rapidly, while others are treated or chemically structured to lengthen absorption time ( Chromic )
    Absorbed/ digested by body enzymes which attack and break down the suture strand
    Plain sutures are absorbed in 70 days measurable tensile strength for 7-10 days
    Chromic sutures are absorbed in over 90 days with measurable tensile strength for 14-21 days
     
    Synthetic Absorbable sutures :

    They are made of polymer strands which are braided and impregnated or coated with agents that improve their handling properties and colored with an FDA approved dyes to increase visibility in tissue
    Synthetic absorbable sutures are hydrolyzed -- a process by which water gradually penetrates the suture filaments, causing the breakdown of the suture's polymer chain
    Absorption normally completes in 60-90 days

    Compared to the enzymatic action of natural absorbables, hydrolyzation results in a lesser degree of tissue reaction following implantation
     
    Two varieties of Synthetic Absorbable sutures -
    Polyglactin 910 ( Vicryl™) ETHICON Company- Polymer of Glycolide and Lactide Polyglycolic Acid (PGA) Polymer of PGA
     
    Non absorbable Materials :

    Non-absorbable sutures are those, which are not digested by body enzymes or hydrolyzed in body tissue
     
    They may be used in a variety of applications :
  • Exterior skin closure - to be removed after sufficient healing has occurred
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  • Within the body cavity, where they will remain permanently encapsulated in tissue
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  • Patient history of reaction to absorbable sutures, keloidal tendency or possible tissue hypertrophy

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  • Prosthesis attachment (i.e., defibrillators, pacemakers, drug delivery mechanisms)
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  • Where lifelong support is required like in Cardiovascular surgeries
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    These sutures may be uncoated or coated, uncoloured or naturally coloured or dyed with FDA approved dyes to enhance visibility
     

    Note : VICRYL™ is the Registered Trade Mark of Johnson and Johnson Company, USA

     

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