title: Primary stability of rotator cuff repair: can more suture materials yield more strength?
abstract: It remains unclear if the increased biomechanical stability of the double-row repair is solely a result of the technique itself or due to the greater number of utilized materials. This study analyses the various rotator cuff (RC) repair interfaces and the influence of doubling the number of suture knots, stitch techniques and suture anchors on the primary stability of the RC reconstruction.
  
  
  
  Established cyclic testing protocols were used to test the primary stability of the knot interface with a Duncan loop and Roeder knot, the tendon-to-suture interface with a single-stitch and Mason-Allen-stitch and the anchor-to-bone interface with OPUS Magnum 2® and BioCorkscrew® anchors. After doubling the materials, the interfaces were tested again and compared to the yielded solitary values. The maximum failure loads (Fmax), clinical failure (CF), system displacement (SD) and modes of failure were recorded.
  
  
  
  Doubling the amount of knots, stitches and suture anchors improved almost all interface parameters. For example, Fmax, CF and SD of the Roeder knot could be significantly improved from 142.5 N to 256.7 N, from 82.5 N to 155.0 N and from 0.45 mm to 0.20 mm, respectively. The Mason-Allen stitch's Fmax improved from 196.4 N to 324.9 N, and CF from 94.25 N to 139.8 N, with almost identical SD of 0.81 mm and 0.84 mm. Bio-Corkscrew® Fmax improved from 232.5 N to 317.5 N, CF from 182.5 N to 210 N, and SD from 0.85 mm to 0.64 mm.
  
  
  
  Doubling the number of knots, stitches and suture anchors increases the primary stability of the various RC repair interfaces and may result in RC rerupture rate reduction. Furthermore, this study suggests that a suture anchor loaded with two or three sutures may yield the same primary stability as two or three suture anchors loaded with a single suture. This in vitro biomechanical study focuses solely on the rotator cuff interfaces at time zero; the biological healing process was therefore not analysed and requires further investigation.
  
  
  
  Improved primary stability by increased number of suture materials may reduce rate of RC rerupture.
authors.affiliation: Department of Orthopaedic Surgery, Physical Medicine and Rehabilitation, Medical Center of the University of Munich, Munich, Germany. mehmet.guelecyuez@med.uni-muenchen.de.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Gülecyüz
authors.affiliation: Department of Trauma Surgery and Sports Traumatology, A.Ö. BKH Kufstein, Kufstein, Austria.
authors.forename: Hannes
authors.initials: H
authors.lastname: Bortolotti
authors.affiliation: Department of Orthopaedic Surgery, Physical Medicine and Rehabilitation, Medical Center of the University of Munich, Munich, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Pietschmann
authors.affiliation: Department of Orthopaedic Surgery, Physical Medicine and Rehabilitation, Medical Center of the University of Munich, Munich, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Ficklscherer
authors.affiliation: Department of Orthopaedic Surgery, Physical Medicine and Rehabilitation, Medical Center of the University of Munich, Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Niethammer
authors.affiliation: Department of Orthopaedic Surgery, Physical Medicine and Rehabilitation, Medical Center of the University of Munich, Munich, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Roßbach
authors.affiliation: Department of Orthopaedic Surgery, Physical Medicine and Rehabilitation, Medical Center of the University of Munich, Munich, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Müller
mesh_terms: D001178:Arthroplasty; D001696:Biomechanical Phenomena; D006801:Humans; D066298:In Vitro Techniques; D017006:Rotator Cuff / Q000601:surgery*; D000070636:Rotator Cuff Injuries / Q000601:surgery*; D053441:Suture Anchors; D013536:Suture Techniques; D013537:Sutures
keywords: Biomechanics; Double row; Primary stability; Rotator cuff; Single row; Suture anchors; Sutures