title: The biomechanical influence of the deltotrapezoid fascia on horizontal and vertical acromioclavicular joint stability.
abstract: BACKGROUND
  Many studies have investigated the biomechanical influence of the acromioclavicular (AC) and coracoclavicular (CC) ligaments on the stability of the acromioclavicular joint (ACJ). It has been shown that augmentation of the CC ligaments alone can result in residual horizontal instability. Our hypothesis was that the DTF would have a significant stabilizing effect on horizontal ACJ stability.
  
  
  METHODS
  In a biomechanical in vitro study a sequential injury of the ACJ was created on eight shoulders from full body, which were placed in an upright sitting position. The translation and rotation of the clavicle were measured in relation to the acromion using an optical navigation system in various states during thoracic-humeral elevation, abduction, and horizontal adduction. The three states were: an intact shoulder, complete sectioning of the AC ligaments, and a circular lesion of the DTF.
  
  
  RESULTS
  Compared to the intact state we found a significant increase in anterior rotation of the clavicle of 1.11° (p = 0.012) and a tendency in lateral translation of 2.71 mm (p = 0.017) in relation to the acromion, with a combined lesion of AC ligaments and DTF. No significant differences were found between the intact state and the isolated dissected AC ligaments as well in adduction as elevation.
  
  
  CONCLUSIONS
  A combined lesion of the AC ligaments and the DTF resulted in a quantitatively small but significant increase in anterior rotation and a tendency in lateral translation of the clavicle in relation to the acromion. These differences were quantitatively small, so that the clinical relevance of the stabilization effect of combined AC ligaments and DTF injuries is questionable.
authors.affiliation: Department of Orthopaedic Surgery, Medical School Hannover, Anna-von-Borries Straße 1-7, 30625, Hannover, Germany.
authors.forename: M F
authors.initials: MF
authors.lastname: Pastor
authors.affiliation: Department of Orthopaedic Surgery, Medical School Hannover, Anna-von-Borries Straße 1-7, 30625, Hannover, Germany.
authors.forename: A K
authors.initials: AK
authors.lastname: Averbeck
authors.affiliation: Laboratory of Biomechanics and Biomaterials, Medical School Hannover, 30625, Hannover, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Welke
authors.affiliation: Department of Orthopaedic Surgery, Medical School Hannover, Anna-von-Borries Straße 1-7, 30625, Hannover, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Smith
authors.affiliation: Department of Orthopaedic Surgery, Medical School Hannover, Anna-von-Borries Straße 1-7, 30625, Hannover, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Claassen
authors.affiliation: Department of Orthopaedic Surgery, Medical School Hannover, Anna-von-Borries Straße 1-7, 30625, Hannover, Germany. Mathias.Wellmann@ddh-gruppe.de.
authors.forename: M
authors.initials: M
authors.lastname: Wellmann
mesh_terms: D000173:Acromioclavicular Joint / Q000293:injuries / Q000502:physiology*; D001696:Biomechanical Phenomena; D005205:Fascia / Q000293:injuries / Q000502:physiology*; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000209:etiology / Q000503:physiopathology; D007593:Joint Instability / Q000209:etiology / Q000503:physiopathology; D008023:Ligaments, Articular / Q000502:physiology; D008297:Male; D016059:Range of Motion, Articular / Q000502:physiology; D012399:Rotation
keywords: Acromioclavicular joint; Deltotrapezial fascia; Dislocation; Vertical and horizontal instability