title: Effect of Coracoid Drilling for Acromioclavicular Joint Reconstruction Techniques on Coracoid Fracture Risk: A Biomechanical Study.
abstract: To biomechanically compare the stability of the coracoid process after an anatomic double-tunnel technique using two 4-mm drill holes or a single-tunnel technique using one 4-mm or one 2.4-mm drill hole.
  
  
  
  For biomechanical testing, 18 fresh-frozen cadaveric scapulae were used and randomly assigned to one of the following groups: two 4-mm drill holes (group 1), one 4-mm drill hole (group 2), or one 2.4-mm drill hole (group 3). After standardized coracoid drilling, load was applied to the conjoined tendons at a rate of 120 mm/min and ultimate failure load, along with the failure mode, was recorded.
  
  
  
  There was no significant difference between groups regarding load to failure. Mean load to failure in group 1 was 392 N; group 2, 459 N; and group 3, 506 N. The corresponding P values were .55, .74, and .20 for group 1 versus group 2, group 2 versus group 3, and group 1 versus group 3, respectively. However, the failure mode for the group with one 4-mm drill hole and the group with two 4-mm drill holes was coracoid fracture, whereas the group with one 2.4-mm drill hole showed 5 tears of the conjoined tendons and only 1 coracoid fracture (P = .015).
  
  
  
  Although there was no significant difference regarding load-to-failure testing between groups, the failure mechanism analysis showed that one 2.4-mm drill hole led to less destabilization of the coracoid than one or two 4-mm drill holes.
  
  
  
  Techniques with small, 2.4-mm drill holes might decrease the risk of severe iatrogenic fracture complications.
authors.affiliation: Department of Orthopaedic Sports Medicine, Klinikum rechts der Isar, TU Munich, Munich, Germany; Center for Shoulder and Elbow Surgery, ATOS Clinic Munich, Munich, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Martetschläger
authors.affiliation: Trauma Center Murnau, Berufsgenossenschaftliche Klinik Murnau, Murnau, Germany; Institute of Biomechanics, Berufsgenossenschaftliche Unfallklinik Murnau, Murnau, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Saier
authors.affiliation: Department of Orthopaedic Sports Medicine, Klinikum rechts der Isar, TU Munich, Munich, Germany.
authors.forename: Annabelle
authors.initials: A
authors.lastname: Weigert
authors.affiliation: Department of Orthopaedic Sports Medicine, Klinikum rechts der Isar, TU Munich, Munich, Germany.
authors.forename: Elmar
authors.initials: E
authors.lastname: Herbst
authors.affiliation: Institute of Biomechanics, Berufsgenossenschaftliche Unfallklinik Murnau, Murnau, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Winkler
authors.affiliation: Institute of Biomechanics, Berufsgenossenschaftliche Unfallklinik Murnau, Murnau, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Henschel
authors.affiliation: Institute of Biomechanics, Berufsgenossenschaftliche Unfallklinik Murnau, Murnau, Germany; Institute of Biomechanics, Paracelsus Medical University, Salzburg, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Augat
authors.affiliation: Department of Orthopaedic Sports Medicine, Klinikum rechts der Isar, TU Munich, Munich, Germany. Electronic address: imhoff@tum.de.
authors.forename: Andreas B
authors.initials: AB
authors.lastname: Imhoff
authors.affiliation: Department of Orthopaedic Sports Medicine, Klinikum rechts der Isar, TU Munich, Munich, Germany.
authors.forename: Sepp
authors.initials: S
authors.lastname: Braun
mesh_terms: D000173:Acromioclavicular Joint / Q000601:surgery*; D000368:Aged; D001182:Arthroscopy / Q000009:adverse effects / Q000379:methods*; D001696:Biomechanical Phenomena; D002102:Cadaver; D000070597:Coracoid Process / Q000293:injuries*; D005260:Female; D050723:Fractures, Bone / Q000209:etiology / Q000517:prevention & control*; D006801:Humans; D007049:Iatrogenic Disease; D008297:Male; D008875:Middle Aged; D009984:Orthopedic Fixation Devices