title: Biomechanical Consequences of Coracoclavicular Reconstruction Techniques on Clavicle Strength.
abstract: BACKGROUND
  Lateral clavicle fractures have been reported after coracoclavicular (CC) ligament reconstructions with bone tunnels through the clavicle.
  
  
  OBJECTIVE
  To biomechanically compare clavicle strength following 2 common CC reconstruction techniques with different bone tunnel diameters.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Testing was performed on 2 groups of matched-pair cadaveric clavicles. Clavicles were prepared with either 2.4-mm tunnels and cortical fixation button (CFB) devices or 6.0-mm tunnels with hamstring tendon grafts (TGs) and tenodesis screws; contralateral clavicles were left intact. A 3-point bending load was applied to the distal clavicles at a rate of 15 mm/min until failure. Ultimate failure load and anterior-posterior width of the clavicles 45 mm medial from the lateral border were recorded. Strength reduction was determined as the percentage reduction in ultimate failure load between paired intact and surgically prepared clavicles. Relative tunnel size was determined as the quotient of tunnel diameter and clavicle width, reported as a percentage.
  
  
  RESULTS
  The TG technique significantly reduced clavicle strength relative to intact (P = .011) and caused significantly more strength reduction (mean, -30.7%; range, 8.1% to -62.5%) than the CFB technique (mean, -3.8%; range, 34.2% to -28.1%; P = .031). The CFB technique was not significantly different from intact (P = .314). There was a significant correlation between clavicle width and strength reduction (τ = -0.36, P = .04) and between relative tunnel size and strength reduction (τ = 0.51, P = .005).
  
  
  CONCLUSIONS
  The TG reconstruction technique with 6.0-mm tunnels, grafts, and tenodesis screws caused significantly more reduction of clavicle strength compared with the CFB technique with 2.4-mm tunnels and CFB device. Additionally, relative tunnel width correlated highly with the strength reduction.
  
  
  CONCLUSIONS
  This information can influence intraoperative decision making based on the individual clavicle width and might influence postoperative treatment protocols. Large bone tunnels may predispose patients to clavicle fractures after anatomic CC reconstructions.
authors.affiliation: Steadman Philippon Research Institute, Vail, Colorado, USA Department of Trauma and Reconstructive Surgery, University of Leipzig, Leipzig, Germany.
authors.forename: Ulrich J
authors.initials: UJ
authors.lastname: Spiegl
authors.affiliation: Steadman Philippon Research Institute, Vail, Colorado, USA.
authors.forename: Sean D
authors.initials: SD
authors.lastname: Smith
authors.affiliation: Steadman Philippon Research Institute, Vail, Colorado, USA Department of Trauma Surgery and Sports Medicine, Medical University Innsbruck, Innsbruck, Austria.
authors.forename: Simon A
authors.initials: SA
authors.lastname: Euler
authors.affiliation: Steadman Philippon Research Institute, Vail, Colorado, USA.
authors.forename: Grant J
authors.initials: GJ
authors.lastname: Dornan
authors.affiliation: Steadman Philippon Research Institute, Vail, Colorado, USA The Steadman Clinic, Vail, Colorado, USA.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Millett
authors.affiliation: Steadman Philippon Research Institute, Vail, Colorado, USA cwijdicks@sprivail.org.
authors.forename: Coen A
authors.initials: CA
authors.lastname: Wijdicks
mesh_terms: D000173:Acromioclavicular Joint / Q000601:surgery*; D001178:Arthroplasty / Q000379:methods; D002102:Cadaver; D002968:Clavicle / Q000601:surgery*; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D004204:Joint Dislocations / Q000601:surgery*; D008023:Ligaments, Articular / Q000601:surgery*; D019651:Plastic Surgery Procedures / Q000379:methods; D012540:Scapula / Q000601:surgery
keywords: acromioclavicular dislocation; clavicle strength; clavicle width; coracoclavicular ligament reconstruction; tunnel size