title: Biomechanical evaluation of a novel reverse coracoacromial ligament reconstruction for acromioclavicular joint separation.
abstract: BACKGROUND
  Enhancing anterior-posterior (AP) stability in acromioclavicular (AC) reconstruction may be advantageous.
  
  
  OBJECTIVE
  To compare the initial stability of AC reconstructions with and without augmentation by either (1) a novel "reverse" coracoacromial (CA) ligament transfer or (2) an intramedullary AC tendon graft.
  
  
  OBJECTIVE
  Reverse CA transfer will improve AP stability compared with isolated coracoclavicular (CC) reconstruction.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Six matched pairs of cadaveric shoulders underwent distal clavicle resection and CC reconstruction. Displacement (mm) was measured during cyclic loading along AP (±25 N) and superior-inferior (SI; 10-N compression, 70-N tension) axes. Pairs were randomized to receive each augmentation and the same loading protocol applied.
  
  
  RESULTS
  Reverse CA transfer (3.71 ± 1.3 mm, standard error of the mean [SEM]; P = .03) and intramedullary graft (3.41 ± 1.1 mm; P = .03) decreased AP translation compared with CC reconstruction alone. The SI displacement did not differ. Equivalence tests suggest no difference between augmentations in AP or SI restraint.
  
  
  CONCLUSIONS
  Addition of either reverse CA transfer or intramedullary graft demonstrates improved AP restraint and provides similar SI stability compared with isolated CC reconstruction.
  
  
  CONCLUSIONS
  Reverse CA ligament transfer may be a reasonable alternative to a free tendon graft to augment AP restraint in AC reconstruction.
authors.affiliation: Department of Orthopaedic Surgery, Stanford University, CA, USA.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Shu
authors.forename: Tyler
authors.initials: T
authors.lastname: Johnston
authors.forename: Derek P
authors.initials: DP
authors.lastname: Lindsey
authors.forename: Timothy R
authors.initials: TR
authors.lastname: McAdams
mesh_terms: D000173:Acromioclavicular Joint / Q000293:injuries / 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 / Q000601:surgery*; D007593:Joint Instability / Q000601:surgery; D008023:Ligaments, Articular / Q000601:surgery* / Q000637:transplantation; D008297:Male; D008875:Middle Aged; D011897:Random Allocation; D013314:Stress, Mechanical; D013710:Tendons / Q000637:transplantation; D016474:Weight-Bearing