Neurosurgery notes/Sutures

Sutures

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General cranial procedures

General

  • The ideal suture should
    • Allow the healing tissue to recover sufficiently to keep the wound closed together once they are removed or absorbed
    • The smallest possible to
      • Produce uniform tensile strength,
      • Securely hold the wound for the required time for healing, then be absorbed.
    • Be predictable, easy to handle, produce minimal reaction, and knot securely.
  • Regardless of suture composition, the body will react to any suture as a foreign body, producing a foreign body reaction to varying degrees.
  • Time it takes for a tissue to no longer require support from sutures will vary depending on tissue type:
    • Days:
      • Muscle
      • Subcutaneous tissue
      • Skin
    • Weeks to Months:
      • Fascia
      • Tendon
    • Months to Never:
      • Vascular prosthesis
  • Example
    • A mass closure of a midline laparotomy may warrant use of PDS
    • A vascular anastomosis will probably require prolene
    • A hand-sewn bowel anastomosis may need vicryl
    • Securing a drain may need a silk suture.
  • Absorbable vs Non-Absorbable
      • Fig 1 - The different classifications and sub-classifications of suture materials.
    • Absorbable Sutures
      • Broken down by the body via enzymatic reactions or hydrolysis.
        • The time in which this absorption takes place varies between material, location of suture, and patient factors.
      • Absorbable sutures are commonly used for deep tissues and tissues that heal rapidly;
        • They may be used in small bowel anastomosis,
        • Suturing in the urinary or biliary tracts,
        • Tying off small vessels near the skin.
      • For the more commonly used absorbable sutures, complete absorption times will vary:
        • Vicryl rapide = 42 days
        • Vicryl = 60 days
        • Monocryl = 100 days
        • PDS = 200 days
    • Non-Absorbable Sutures
      • Non-absorbable sutures are used to provide long-term tissue support,
      • Remaining walled-off by the body’s inflammatory processes (until removed manually if required).
      • Uses include for tissues that heal slowly, such as fascia or tendons, closure of abdominal wall, or vascular anastomoses.
  • Raw origin: Synthetic vs Natural
    • Natural
      • Made of natural fibres
      • e.g. silk or catgut
      • Tend to provoke a greater tissue reaction.
      • Suturing silk is still utilised regularly in the securing of surgical drains.
    • Synthetic
      • Comprised of man-made materials
      • e.g. PDS or nylon
      • More predictable than the natural sutures, particularly in their loss of tensile strength and absorption.
  • Structure: Monofilament vs Multifilament
    • Monofilament suture
      • A single stranded filament suture
      • e.g nylon, PDS*, or prolene
      • They have a lower infection risk
      • Poor knot security and ease of handling.
    • Multifilament suture
      • Made of several filaments that are twisted together (e.g braided silk or vicryl).
      • They handle easier and hold their shape for good knot security,
      • Can harbour infections.
  • Suture type and structure
      • Suture Type
      Absorbable
      Non-absorbable
      Monofilament
      Multifilament
      Vicryl
      ✓
      ㅤ
      ㅤ
      ✓
      PolyDioxanone suture
      ✓
      ㅤ
      ✓
      ㅤ
      Monocryl
      ✓
      ㅤ
      ✓
      ㅤ
      Nylon
      ㅤ
      ✓
      ✓
      ㅤ
      Prolene
      ㅤ
      ✓
      ✓
      ㅤ
      Silk
      ㅤ
      ✓
      ㅤ
      ✓
      Type
      Example sutures
      Braided/non-absorbable
      Silk, Ethibond
      Braided/absorbable (breakdown time)
      Coated vicryl (4.5 weeks), Vicryl rapide (2 weeks)
      Monofilament/non-absorbable
      Ethilon, Prolene
      Monofilament/absorbable (breakdown time)
      Undyed monocryl (3 weeks), Dyed monocryl (4 weeks), PDS (9 weeks), Catgut

Surgical Needles

  • Ideal surgical needle should be
    • Rigid enough to resist distortion,
    • Flexible enough to bend before breaking,
    • As slim as possible to minimise trauma
    • Sharp enough to penetrate tissue with minimal resistance, and be stable within a needle holder to permit accurate placement.
  • Surgical needles
    • Are stainless steel.
  • They are composed of:
    • The swaged end connects the needle to the suture
    • The needle body or shaft is the region grasped by the needle holder.
    • Needle bodies can be
      • Round
        • Used in friable tissue such as liver and kidney
      • Cutting
        • Triangular in shape,
        • Have 3 cutting edges to penetrate tough tissue such as the skin and sternum,
        • A cutting surface on the concave edge
      • Reverse cutting
        • A cutting surface on the convex edge, and are ideal for tough tissue such as tendon or subcuticular sutures, and have reduced risk of cutting through tissue
  • The needle point acts to pierce the tissue, beginning at the maximal point of the body and running to the end of the needle, and can be either sharp or blunt:
    • Blunt needles
      • Are used for abdominal wall closure, and in friable tissue,
      • Can potentially reduce the risk of blood borne virus infection from needlestick injuries.
    • Sharp needles
      • Pierce and spread tissues with minimal cutting,
      • Used in areas where leakage must be prevented.
  • Needle shape
    • Vary in their curvature and are described as the proportion of a circle completed
      • The ¼, ⅜, ½, and ⅝ are the most common curvatures used.
    • Different curvatures are required depending on the access to the area to suture.