title: The cortical ring sign: a reliable radiographic landmark for percutaneous coracoclavicular fixation.
abstract: BACKGROUND
  For treatment of acute acromioclavicular separations, we have been using a reproducible radiographic view of the coracoid-the cortical ring sign-that we believe allows for placement of percutaneous coracoclavicular fixation safely and reliably in the center of the coracoid base, while avoiding the coracoid tip. This study evaluates the coracoid anatomy that the cortical ring sign represents, its utility for guiding fixation trajectory, and the proximity of neurovascular structures to this proposed trajectory.
  
  
  METHODS
  Kirschner wires were used to measure the orientation of the fluoroscopic beam in relation to the scapula and the proposed fixation trajectory using this radiographic view.
  
  
  RESULTS
  The cortical ring sign is achieved by first directing the x-ray beam perpendicular to the medial border of the scapula in the parasagittal plane and 49 degrees off the axis of the scapular spine in the axial plane, then fine-tuning until the coracoid cortical ring becomes evident. The nearest neurovascular structures to the fixation trajectory are the suprascapular artery and nerve (< 2 cm).
  
  
  CONCLUSIONS
  The cortical ring sign view targets the coracoid base and, as such, allows reliable, safe, percutaneous fixation in the center of the coracoid base.
  
  
  METHODS
  Basic Science.
authors.affiliation: Division of Orthopaedic Surgery, Duke University Medical Center, Durham, NC 27710, USA. garri016@mc.duke.edu
authors.forename: Grant E
authors.initials: GE
authors.lastname: Garrigues
authors.forename: Milford H
authors.initials: MH
authors.lastname: Marchant
authors.forename: Gemma C
authors.initials: GC
authors.lastname: Lewis
authors.forename: Anil K
authors.initials: AK
authors.lastname: Gupta
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Richard
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Basamania
mesh_terms: D000173:Acromioclavicular Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000601:surgery*; D001182:Arthroscopy / Q000379:methods*; D002102:Cadaver; D002968:Clavicle / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery; D005260:Female; D005471:Fluoroscopy; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods; D006801:Humans; D008297:Male; D019060:Minimally Invasive Surgical Procedures / Q000379:methods; D011336:Probability; D012540:Scapula / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery; D013679:Technology, Radiologic / Q000379:methods