title: Acromioclavicular joint reconstruction: a comparative biomechanical study of three techniques.
abstract: BACKGROUND
  Acute acromioclavicular joint dislocations indicated for surgery can be treated with several stabilization techniques. This in vitro study evaluated the acromioclavicular joint stability after 3 types of validated repair techniques compared with the native situation.
  
  
  METHODS
  Nine pairs (right-left) of intact cadaveric shoulder specimens were assigned to 3 study groups with randomly distributed samples according to the coracoclavicular distance. The groups were instrumented with acromioclavicular and coracoclavicular cerclages (CE), a Twin Tail TightRope (TR), or a locking compression superior and anterior clavicle plate (CP). Native and instrumented specimens were tested quasi-static nondestructively (superior: 70 N; anteroposterior: ± 35 N, 10 mm/min) and cyclically until failure (superior, valley load: 20 N; initial peak load: 70 N; increment: 0.02 N/cycle).
  
  
  RESULTS
  The TR study group showed the highest (in N/mm) superoinferior (73.77 ± 14.04) and anteroposterior (29.58 ± 1.52) stiffness, followed by CE (superoinferior: 59.73 ± 10.33; anteroposterior: 24.31 ± 4.14) and CP (superoinferior: 24.08 ± 5.29). Instrumentation generally led to increased superoinferior and anteroposterior stiffness in each study group but to a significant superoinferior stiffness reduction for CP (P = .029). Significantly lower coracoclavicular displacement at valley load after 1 and 500 cycles was observed for TR (P = .018) and CE (P = .041) compared with CP. Cycles to failure were significantly higher in CE (7298 ± 1244 cycles, P = .011) and TR (4434 ± 727 cycles, P = .031) compared with CP (1683 ± 509 cycles).
  
  
  CONCLUSIONS
  The CE and TR techniques led to similar biomechanical performances. The CE repair might mimic the native acromioclavicular joint stiffness better than the other 2 setups, leading to more physiological stabilization.
authors.affiliation: Division of Orthopaedics and Trauma Surgery, Department of Surgery, Geneva University Hospitals, Geneva, Switzerland. alexandre.laedermann@hcuge.ch
authors.forename: Alexandre
authors.initials: A
authors.lastname: Lädermann
authors.forename: Boyko
authors.initials: B
authors.lastname: Gueorguiev
authors.forename: Bojan
authors.initials: B
authors.lastname: Stimec
authors.forename: Jean
authors.initials: J
authors.lastname: Fasel
authors.forename: Stephan
authors.initials: S
authors.lastname: Rothstock
authors.forename: Pierre
authors.initials: P
authors.lastname: Hoffmeyer
mesh_terms: D000173:Acromioclavicular Joint / Q000503:physiopathology / Q000601:surgery*; D000368:Aged; D000369:Aged, 80 and over; D001178:Arthroplasty / Q000379:methods*; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000503:physiopathology / Q000601:surgery*; D007593:Joint Instability / Q000601:surgery*; D008297:Male