title: A Biomechanical Comparison of Different Knots Tied on Fibrewire Suture.
abstract: BACKGROUND
  Synthetic sutures such as Fiberwire used in flexor tendon repairs have high tensile strength. Proper application allows early mobilisation, decreasing morbidity from repair rupture and adhesions while preserving range of motion. Suture stiffness can cause poorer knot holding, contributing to gapping, peritendinous adhesions or rupture. Previous studies recommended more throws in knots tied on Fiberwire to prevent knot slippage. These larger knots are voluminous and prominent. In tendon repairs they can cause "catching", increase friction and work of flexion. Other studies advocated certain complicated knots as being more secure. We evaluated several knots and their biomechanical properties with the aim of finding a compact knot with less potential for slippage to maximise strength potential of flexor tendon repairs using Fiberwire.
  
  
  METHODS
  A series of different knots tied on Fiberwire 4-0 sutures were pulled to failure on a mechanical tester. Mean tensile strengths, knot volumes and tensile strength to knot volume ratios were compared.
  
  
  RESULTS
  Tensile strengths and knot volume increased with more throws and loops. Four variations of the square knot (the 4=4=1, 2=2=2=2, 1=1=1=1=1, 2=1=1=1=1 knots) had tensile strengths greater than 35N. The specialised anti-slip knot had highest tensile strength and suture volume but lower strength-to-volume ratio.
  
  
  CONCLUSIONS
  The anti-slip knot had highest tensile strength but it also had the highest volume. The greater strength of repair may not translate into improved clinical outcome. The 1=1=1=1=1 knot has superior knot strength-to-volume ratio with good knot strength adequate for early active mobilisation in flexor tendon repairs.
authors.affiliation: * Department of Hand Surgery, Singapore General Hospital, Singapore, Singapore.
authors.forename: Jackson
authors.initials: J
authors.lastname: Jiang
authors.affiliation: † Biomechanics Laboratory, Singapore General Hospital, Singapore, Singapore.
authors.forename: Ita Suzana
authors.initials: IS
authors.lastname: Mat Jais
authors.affiliation: * Department of Hand Surgery, Singapore General Hospital, Singapore, Singapore.
authors.forename: Andrew Kean Tuck
authors.initials: AK
authors.lastname: Yam
authors.affiliation: * Department of Hand Surgery, Singapore General Hospital, Singapore, Singapore.|‡ Duke-NUS Medical School, Singapore, Singapore.
authors.forename: Duncan Angus
authors.initials: DA
authors.lastname: McGrouther
authors.affiliation: * Department of Hand Surgery, Singapore General Hospital, Singapore, Singapore.|‡ Duke-NUS Medical School, Singapore, Singapore.
authors.forename: Shian Chao
authors.initials: SC
authors.lastname: Tay
mesh_terms: D001696:Biomechanical Phenomena; D004867:Equipment Design; D006801:Humans; D008422:Materials Testing / Q000379:methods*; D013536:Suture Techniques / Q000295:instrumentation*; D013537:Sutures; D013710:Tendons / Q000601:surgery*; D013718:Tensile Strength
keywords: Biomechanical phenomenon; Suture technique; Tendon injuries