title: The Stress Relaxation Process in Sutures Tied with a Surgeon's Knot in a Simulated Biological Environment.
abstract: BACKGROUND
  The exact characteristics of sutures are not only the basis for selecting from among different types of suture, but also provide the necessary information for the design of new surgical sutures. Apart from information relating to the breaking load of a suture reported in pharmacopoeias, the viscoelastic properties of sutures can be an additional selection criterium - one that influences stitching quality, especially when there is a risk of wound dehiscence.
  
  
  OBJECTIVE
  The aim of the study was to assess the stress relaxation process for 3 polymeric sutures in an environment simulating the conditions in a living organism and (for comparison) in room conditions.
  
  
  METHODS
  Stress relaxation testing was carried out on 3 polymeric sutures: polypropylene (PP), polydioxanone (PDS) and polyglycolic acid (PGA). To identify the mechanical properties of the sutures, uniaxial tensile tests were conducted according to the Polish Pharmacopoeia. The relaxation test was carried out in room conditions and in the bath simulating a biological environment. The sutures being tested were tied with a surgeon's knot.
  
  
  RESULTS
  The PP suture exhibited the greatest stress relaxation (18% of the initial stress in room conditions and 21% of the initial stress in the bath). The PGA suture exhibited the least stress relaxation (approximately 60% of the initial stress in room conditions and 59% of the initial stress in the bath). The PDS suture was tested at a lower strain level and showed stress relaxation similar to the PGA suture (approximately 63% of the initial stress in room conditions and 55% in the bath).
  
  
  CONCLUSIONS
  Multifilament braided absorbable (PGA) sutures and monofilament absorbable (PDS) sutures had a higher stress relaxation ratio over time than monofilament non-absorbable (PP) sutures. These findings may indicate higher stress maintained over time in PDS and PGA sutures, and thus higher tension at wound edges, sufficient to resist wound dehiscence.
authors.affiliation: Institute of Applied Mechanics, Cracow University of Technology, Kraków, Poland.
authors.forename: Aneta
authors.initials: A
authors.lastname: Liber-Kneć
authors.affiliation: Institute of Applied Mechanics, Cracow University of Technology, Kraków, Poland.
authors.forename: Sylwia
authors.initials: S
authors.lastname: Łagan
mesh_terms: D008422:Materials Testing; D016687:Polydioxanone; D011100:Polyglycolic Acid; D011126:Polypropylenes; D013537:Sutures; D013718:Tensile Strength
chemical_list: D011126:Polypropylenes; D011100:Polyglycolic Acid; D016687:Polydioxanone
keywords: mechanical properties; polymeric sutures; residual stress; stress relaxation; surgeon’s knot