title: Biomechanics of a new technique for minimal-invasive coracoclavicular ligament reconstruction.
abstract: OBJECTIVE
  To evaluate the biomechanical properties of a new coracoclavicular (CC) ligament reconstruction using a subcoracoidal flip button and a tendon graft compared to an augmented tendon loop and a synthetic coracoclavicular ligament reconstruction.
  
  
  METHODS
  A porcine metatarsalia model was used to assess supero-inferior fixation strength of (1) a new technique using an augmented tendon graft and a subcoracoidal flip button in a lifting block fashion, (2) an augmented tendon loop around the coracoid base and (3) a synthetic coracoclavicular ligament augmentation technique. Cyclic loading from 20 to 70 N for 1,000 cycles was performed, followed by a load-to-failure protocol.
  
  
  RESULTS
  All specimens of the three different groups survived the cyclic loading protocol. The maximum loads to failure under superior loading conditions were 760 ± 78 N for group 1, 702 ± 48 N for group 2 and 1117 ± 91 N for group 3. The synthetic coracoclavicular ligament augmentation technique revealed significantly higher maximum loads compared to the other groups (p < 0.001). The augmented tendon graft/flip button construct had higher maximum loads than the augmented tendon loop (n.s.). No significant differences were found for stiffness and elongation behaviour among the 3 tested groups.
  
  
  CONCLUSIONS
  The results suggest that the described technique is an alternative option to reconstruct the CC ligaments in AC joint instability in a minimal-invasive technique. Under superior loading conditions, the biomechanical properties exhibited by this novel technique were comparable to those of the tendon loop around the coracoid base.
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, University Hospital Münster, Waldeyerstraße 1, 48149, Münster, Germany. benedikt.schliemann@gmail.com
authors.forename: Benedikt
authors.initials: B
authors.lastname: Schliemann
authors.forename: Simon
authors.initials: S
authors.lastname: Lenschow
authors.forename: Peter
authors.initials: P
authors.lastname: Schürmann
authors.forename: Mike
authors.initials: M
authors.lastname: Schroeglmann
authors.forename: Mirco
authors.initials: M
authors.lastname: Herbort
authors.forename: Clemens
authors.initials: C
authors.lastname: Kösters
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Raschke
mesh_terms: D000173:Acromioclavicular Joint / Q000293:injuries*; D000818:Animals; D001696:Biomechanical Phenomena; D004195:Disease Models, Animal; D004204:Joint Dislocations / Q000601:surgery*; D008023:Ligaments, Articular / Q000503:physiopathology / Q000601:surgery*; D019060:Minimally Invasive Surgical Procedures; D019651:Plastic Surgery Procedures; D013552:Swine; D013710:Tendons / Q000637:transplantation