How many throws are recommended for an absorbable suture (absorbable thread used for wound closure)?

Recommended Number of Throws for Absorbable Sutures

For absorbable sutures, a minimum of 5 throws is recommended to ensure optimal knot security and prevent knot slippage, with certain materials like FiberWire requiring 6 throws.

Factors Affecting Knot Security

The number of throws needed for an absorbable suture depends on several key factors:

Suture Material

• Different absorbable materials have varying knot security properties:
  • Vicryl (polyglycolic acid) demonstrates the greatest knot security among common absorbable materials 1
  • Slowly absorbable sutures are preferred over rapidly absorbable ones for wound closure 2
  • Monofilament sutures are recommended over multifilament for midline laparotomy closures 2

Knot Technique

• The surgeon's knot technique provides greater security than square knots and sliding knots 1
• For surgeon's knots, at least 4 throws are generally indicated 1
• For sliding knots, at least 5 throws are generally needed 1

Suture Size

• Interestingly, knot security does not significantly depend on suture size (3-0,4-0, or 5-0) 1
• However, the appropriate suture size should be selected based on the tissue being closed

Evidence-Based Recommendations

Based on biomechanical testing:

• A minimum of 5 flat square throws should be used for most absorbable sutures to achieve optimal knot security (95% confidence interval 0.84 to 1.0) 3
• 4 throws may be sufficient in some cases (95% confidence interval 0.76 to 0.99) 3
• Special materials like FiberWire require 6 flat square throws per knot for security 3

Important Considerations

• Adding more than 5 throws generally does not contribute to additional knot security 1
• 2 throws are never indicated for absorbable sutures as they provide inadequate security 1
• The environment affects knot security - testing in saline solution to simulate the moist environment of tissues shows different results than dry testing 1
• When using synthetic absorbable sutures, their retained strength and low tissue reactivity make them suitable for many procedures where non-absorbable materials were traditionally used 4

Pitfalls to Avoid

• Using too few throws (less than 4) significantly increases the risk of knot slippage
• Synthetic monofilament materials tend to untie more easily than multifilament sutures 5
• Different knot techniques require different minimum numbers of throws - don't apply the same standard to all knot types
• Tensile loading decreases the maximum tensile load of absorbable sutures over time, particularly with chromic catgut 5

For optimal outcomes in wound closure with absorbable sutures, using 5 throws with proper technique will provide reliable knot security in most clinical scenarios.