title: Biomechanical Comparison of Fracture Risk Created by 2 Different Clavicle Tunnel Preparations for Coracoclavicular Ligament Reconstruction.
abstract: BACKGROUND
  An anatomic reconstruction of coracoclavicular (CC) ligaments typically requires drilling tunnels in the clavicle. An increase in fracture complications has been associated with graft tunnel position. A method of drilling clavicle tunnels that would better re-create anatomic function of the CC ligaments without increasing fracture risk would be an improvement.
  
  
  OBJECTIVE
  To evaluate the feasibility of a novel single anterior-to-posterior tunnel technique and compare the biomechanical properties to the 2-tunnel technique in CC ligament reconstruction. The hypothesis was that the single tunnel will yield similar loads to failure as the 2-tunnel technique and better reproduce the native anatomy of the conoid and trapezoid ligaments.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Eight fresh-frozen matched pairs of human clavicles underwent testing. In 1 specimen of the matched pair, 2 bone tunnels were created as previously described. In the other, a single tunnel was placed obliquely from anterior to posterior. The relative position of the tunnels in relation to the conoid tuberosity was recorded. Specimens were tested on a materials testing machine. The ultimate load to failure, linear stiffness, distance of the conoid tuberosity to the conoid tunnel exit point, and mode of failure were recorded.
  
  
  RESULTS
  The ultimate load to failure in the single-tunnel group and the 2-tunnel group was 457.2 ± 139.8 and 488.8 ± 170.6, respectively. There was no significant difference (P = .5). The linear stiffness in the single-tunnel group and the 2-tunnel group was 94.6 ± 31.3 and 79.8 ± 33.5, respectively. There was no significant difference (P = .2). The 2-tunnel group had a significantly longer average maximum distance from the conoid tuberosity to the conoid tunnel exit point than the single-tunnel group (6.0 ± 2.1 vs 0.8 ± 1.9 mm; P = .05). The single-tunnel group was consistently more anatomic with regard to its relationship to the conoid tuberosity than the 2-tunnel group.
  
  
  CONCLUSIONS
  The single anterior-to-posterior clavicle tunnel had similar biomechanical properties to the 2-tunnel technique. However, the single-tunnel technique better reproduced the anatomic footprint of the conoid ligament. Utilizing this single-tunnel technique may yield an anatomic advantage that may also reduce the rate of complications caused by posterior wall blowout.
  
  
  CONCLUSIONS
  Acromioclavicular joint injuries are common in collision sports. Surgical management is often indicated to reconstruct the joint. This study assesses the feasibility of a novel surgical approach.
authors.affiliation: Orthopaedic Biomechanics Laboratory, Veterans Administration Long Beach Healthcare System, Long Beach, California, USA. ; University of California, San Francisco-Fresno, Fresno, California, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Nuzzo
authors.affiliation: Orthopaedic Biomechanics Laboratory, Veterans Administration Long Beach Healthcare System, Long Beach, California, USA. ; Congress Medical Associates, Pasadena, California, USA.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Adamson
authors.affiliation: Orthopaedic Biomechanics Laboratory, Veterans Administration Long Beach Healthcare System, Long Beach, California, USA.
authors.forename: Thay Q
authors.initials: TQ
authors.lastname: Lee
authors.affiliation: Orthopaedic Biomechanics Laboratory, Veterans Administration Long Beach Healthcare System, Long Beach, California, USA.
authors.forename: Michelle H
authors.initials: MH
authors.lastname: McGarry
authors.affiliation: University of California, San Francisco-Fresno, Fresno, California, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Husak
keywords: acromioclavicular joint injuries; anatomic reconstruction; biomechanics; coracoclavicular ligaments