title: The twist-lock concept of tissue transport and suture fixation without knots: observations along the Hong Kong skyline.
abstract: OBJECTIVE
  To evaluate the load to failure and the mode of failure of a novel suture anchor construct that does not require knots (the "twist-lock" construct) and to compare it with a standard suture anchor construct (Corkscrew; Arthrex, Naples, FL).
  
  
  METHODS
  Biomechanical single-pull load-to-failure study comparing the twist-lock construct to the Corkscrew suture anchor construct.
  
  
  METHODS
  The twist-lock construct is a suture anchor system that does not use knots, instead using 3 consecutive twists between suture limbs to enhance internal interference between the suture limbs. This system maximizes internal interference by 2 mechanically verifiable friction-multiplier mechanisms: the cable friction effect and the wedge effect. After theoretically verifying the strength characteristics of the twist-lock system, the authors tested and compared its strength in vitro to that of a standard screw-type suture anchor system (Corkscrew). Unicellular polyurethane, which has been shown to accurately mimic the properties of cancellous bone, was used for implantation of suture anchors for the purpose of comparing the load to failure of 10 identical constructs in each of the 2 anchor systems. Axial single-pull loading to failure was performed with an Instron 5565 testing machine (Instron, Canton, MA).
  
  
  RESULTS
  The average load to failure for the twist-lock group was 137.2 N, and the average for the Corkscrew group was 123.0 N, a difference of 14.2 N. This study shows that the twist-lock anchors failed at a load that was 12% higher than that of the Corkscrew group (P =.02).
  
  
  CONCLUSIONS
  The twist-lock system is a suture anchor system that achieves suture fixation of soft tissue to bone without the need to tie knots. It shows single-pull loads to failure that are significantly higher than those of a standard suture anchor system.
authors.affiliation: Department of Orthopaedic Surgery, The University of Texas Health Science Center at San Antonio, The San Antonio Orthopaedic Group, San Antonio, USA. ssburkhart@msn.com
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Burkhart
authors.forename: Kiriacos A
authors.initials: KA
authors.lastname: Athanasiou
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D008422:Materials Testing; D011093:Polyethylene Terephthalates; D011140:Polyurethanes; D019736:Prostheses and Implants; D017006:Rotator Cuff / Q000601:surgery; D013314:Stress, Mechanical; D013536:Suture Techniques / Q000295:instrumentation; D013718:Tensile Strength
chemical_list: C014534:Ethibond; D011093:Polyethylene Terephthalates; D011140:Polyurethanes