title: Tie hard 2- an in-vitro comparison of first throw tension holding in twisted v straight-first throws; using Polyglycolic acid (Dexon S), Polyglactin 910 (Coated Vicryl).
abstract: OBJECTIVE
  To compare the first throw tension holding properties of twisted versus straight first throws in two commonly used Oculoplastic braided absorbable sutures.
  
  
  METHODS
  An in-vitro experimental model.
  
  
  METHODS
  Variable loads were applied to the first double throw of a surgical knot - either in straight-line configuration or twisting the knot using both 6/0 Polyglycolic acid (Dexon S) and 6/0 Polyglactin 910 (Coated Vicryl). Each suture was tested to the point of knot slipping and the critical tension recorded. Two variations of the experiment were undertaken: Experiment 1 - two metal loops were brought together by the test suture, experiment 2 - two strips of tissue (Permacol - cross-linked porcine dermal collagen) were brought together by the test suture.
  
  
  RESULTS
  Experiment 1 straight: Polyglycolic acid 12.2g (11-13.5), Polyglactin-910 2.5 g (2.5- no range). Experiment 1 twisted: Polyglycolic acid 13.33 g (10-15), Polyglactin 910 3 g (2-5). Experiment 2 straight: Polyglycolic acid 33g (30-35), Polyglactin 910 25g (25 - no range). Experiment 2 twisted: Polyglycolic acid 35 (30-40), Polyglactin 910 25g (20-30).
  
  
  CONCLUSIONS
  Twisting the suture adds only a modest increase in first throw knot security. Polyglycolic acid (Dexon S) braided absorbable suture has significantly better first throw knot security when compared with Polyglactin-910 (coated Vicryl). This is an important property when suturing tissues under tension as it minimises slippage before the locking throw is tied.
authors.affiliation: Ophthalmology Department, University of Auckland, New Zealand. thomaskersey@doctots.net.uk
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Kersey
authors.forename: Vladamir T
authors.initials: VT
authors.lastname: Thaller
mesh_terms: D020341:Absorbable Implants; D020099:Coated Materials, Biocompatible; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D011098:Polyglactin 910 / Q000737:chemistry*; D011100:Polyglycolic Acid / Q000737:chemistry*; D013314:Stress, Mechanical; D013536:Suture Techniques; D013537:Sutures; D013718:Tensile Strength
chemical_list: D020099:Coated Materials, Biocompatible; D011100:Polyglycolic Acid; D011098:Polyglactin 910