title: Acromioclavicular joint dislocations: coracoclavicular reconstruction with and without additional direct acromioclavicular repair.
abstract: OBJECTIVE
  To evaluate different stabilisation techniques for acromioclavicular (AC) joint separations, including direct AC repair, and to compare the properties of the stabilised and native joints.
  
  
  METHODS
  An established in vitro testing model for the AC joint was used to analyse joint stability after surgical reconstruction [double TightRope (DTR), DTR with AC repair (DTR + AC), single TR with AC repair (TR + AC), and PDS sling with AC repair (PDS + AC)]. Twenty-four human cadaveric shoulders were randomised by age into four testing groups. Joint stiffness was measured by applying an axial load during defined physiological ranges of motion. Similar tests were performed for the native joints, after dissecting the coracoclavicular and AC ligaments, and after surgical reconstruction. Cyclic loading was performed for 1000 cycles with 20-70 N and vertical load to failure determined after cyclic testing.
  
  
  RESULTS
  Axial stiffness for all TR groups was significantly higher than for the native joint (DTR 38.94 N/mm, p = 0.005; DTR + AC 37.79 N/mm, p = 0.015; TR + AC 45.61 N/mm, p < 0.001 vs. native 26.05 N/mm). The axial stiffness of the PDS + AC group was similar to that of the native joint group (21.4 N/mm, n.s.). AC repair did not significantly influence rotational stiffness. Load to failure was similar and >600 N in all groups (n.s.).
  
  
  CONCLUSIONS
  Reconstruction of AC dislocations with one or two TRs leads to stable results with a higher stiffness than the native joints. For the PDS + AC group, axial stiffness was similar to the native situation, although there might be a risk of elongation. Direct AC repair showed no significantly increased stability in comparison with reconstructions without direct AC repair. Thus, a direct AC repair seems to be dispensable in clinical practice, while TRs or PDS cerclages appear to provide sufficiently stable results.
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, Hamburg-Eppendorf University Medical Center, Martinistrasse 52, 20246, Hamburg, Germany. l.weiser@uke.de.
authors.forename: Lukas
authors.initials: L
authors.lastname: Weiser
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, Hamburg-Eppendorf University Medical Center, Martinistrasse 52, 20246, Hamburg, Germany.
authors.forename: Jakob V
authors.initials: JV
authors.lastname: Nüchtern
authors.affiliation: Institute of Biomechanics, TUHH Hamburg University of Technology, Hamburg, Germany.
authors.forename: Kay
authors.initials: K
authors.lastname: Sellenschloh
authors.affiliation: Institute of Forensic Medicine, Hamburg-Eppendorf University Medical Center, Hamburg, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Püschel
authors.affiliation: Institute of Biomechanics, TUHH Hamburg University of Technology, Hamburg, Germany.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Morlock
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, Hamburg-Eppendorf University Medical Center, Martinistrasse 52, 20246, Hamburg, Germany.
authors.forename: Johannes M
authors.initials: JM
authors.lastname: Rueger
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, Hamburg-Eppendorf University Medical Center, Martinistrasse 52, 20246, Hamburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Hoffmann
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, Hamburg-Eppendorf University Medical Center, Martinistrasse 52, 20246, Hamburg, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Lehmann
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, Hamburg-Eppendorf University Medical Center, Martinistrasse 52, 20246, Hamburg, Germany.
authors.forename: Lars G
authors.initials: LG
authors.lastname: Großterlinden
mesh_terms: D000173:Acromioclavicular Joint / Q000601:surgery*; D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000601:surgery*; D007593:Joint Instability / Q000601:surgery; D008023:Ligaments, Articular / Q000601:surgery*; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D009984:Orthopedic Fixation Devices; D011897:Random Allocation; D053832:Surgical Tape; D016474:Weight-Bearing
keywords: AC joint dislocations; AC reconstruction; AC repair; PDS sling; TightRope