title: Mechanical testing of different knot types using high-performance suture material.
abstract: OBJECTIVE
  This laboratory study aimed to evaluate the loop security, knot security, cyclic loading resistance and load-to-failure rate of three different knot types with establishing a new experimental set-up. Additionally, the mode of failure of each knot was evaluated.
  
  
  METHODS
  With the use of nonabsorbable, braided polyethylene sutures, USP size No. 2 [Hi-Fi®; ConMed Linvatec], the arthroscopic knot types Dines, SMC as well as the surgeon's knot were tested using a material testing machine. The knots were tied openly as well as arthroscopically. The set-up enables testing of knot configurations while eliminating friction between knot loop and its suspension points. Including all test procedures, a total of 216 knots were tested.
  
  
  RESULTS
  All openly tied knot types and ten of each type of arthroscopically tied knots resisted against cyclic loading of 1,000 cycles. With subsequent load-to-failure testing, openly tied knot types achieved significantly higher values of tensile strength than arthroscopically tied knots. Regarding clinical failure, defined as an elongation of 3 mm, Dines knot reached highest loop as well as knot security. Knot slippage was the most common failure mechanism at an elongation of 3 mm, whereas suture breakage was evaluated most at an elongation of 6 mm.
  
  
  CONCLUSIONS
  The new experimental set-up confirms the loop security of arthroscopic knot types. Using a knot pusher clinically is a key factor to attain this as compared to openly hand-tied techniques. The Dines knot presented the highest reliability. It may provide a secure tissue healing during rehabilitation and consequently can be recommended for clinical application.
authors.affiliation: Department of Orthopaedic Surgery, University of Göttingen Medical Centre (UMG), Georg-August-University, Robert-Koch-Str. 40, 37099, Göttingen, Germany. mbaums@t-online.de.
authors.forename: M H
authors.initials: MH
authors.lastname: Baums
authors.affiliation: Department of Orthopaedic Surgery, University of Göttingen Medical Centre (UMG), Georg-August-University, Robert-Koch-Str. 40, 37099, Göttingen, Germany.
authors.forename: Ch
authors.initials: C
authors.lastname: Sachs
authors.affiliation: Department of Orthopaedics, Trauma Surgery and Rheumatology, Katholisches Krankenhaus Dortmund-West, Dortmund, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Kostuj
authors.affiliation: Department of Trauma and Orthopaedic Surgery, Trauma Center Frankfurt/Main, Frankfurt, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Schmidt-Horlohé
authors.affiliation: Department of Orthopaedic Surgery, University of Göttingen Medical Centre (UMG), Georg-August-University, Robert-Koch-Str. 40, 37099, Göttingen, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Schultz
authors.affiliation: Department of Orthopaedic Surgery, University of Göttingen Medical Centre (UMG), Georg-August-University, Robert-Koch-Str. 40, 37099, Göttingen, Germany.
authors.forename: H-M
authors.initials: HM
authors.lastname: Klinger
keywords: Biomechanics; Cyclic loading; Security; Suture knots; Ultra-high molecular weight polyethylene