title: Biomechanical analysis of fixation of middle third fractures of the clavicle.
abstract: OBJECTIVE
  This biomechanical study compares four different techniques of fixation of middle third clavicular fractures.
  
  
  METHODS
  Twenty fresh-frozen clavicles were randomized into four groups. Each group used a different fixation device (3.5 Synthes reconstruction plate, 3.5 Synthes limited contact dynamic compression plate, 3.5 Synthes locking compression plate, and 4.5 DePuy Rockwood clavicular pin). All constructs were mechanically tested in bending and torque modes both with and without a simulated inferior cortical defect. Bending load to failure was also conducted. The four groups were compared using an analysis of variance test.
  
  
  RESULTS
  The plate constructs were stiffer than the pin during both pure bending and torque loads with or without an inferior cortical defect. Bending load to failure with an inferior cortical defect revealed that the reconstruction plate was weaker compared with the other three groups. The limited contact and locking plates were stiffer than the reconstruction plate but demonstrated statistical significance only with the cortical defect.
  
  
  CONCLUSIONS
  As hypothesized, the 3.5 limited contact dynamic compression plate and 3.5 locking compression plate demonstrated the greatest resistance to bending and torque loads, especially in the presence of simulated comminution of a middle third clavicular fracture. The reconstruction plate demonstrated lower stiffness and strength values compared with the other plates, especially with a cortical defect, whereas the pin showed poor resistance to bending and torque loads in all modes of testing. This information may help surgeons to choose the most appropriate method of fixation when treating fractures of the middle third of the clavicle.
authors.affiliation: Bioengineering Research Lab, Hand and Upper Limb Centre, St. Joseph’s Health Care, 268 Grosvenor Street, London, Ontario, Canada. ddros@mac.com
authors.forename: Darren S
authors.initials: DS
authors.lastname: Drosdowech
authors.forename: Stuart E E
authors.initials: SE
authors.lastname: Manwell
authors.forename: Louis M
authors.initials: LM
authors.lastname: Ferreira
authors.forename: Danny P
authors.initials: DP
authors.lastname: Goel
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Faber
authors.forename: James A
authors.initials: JA
authors.lastname: Johnson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D002968:Clavicle / Q000293:injuries* / Q000503:physiopathology* / Q000601:surgery; D019245:Compressive Strength; D003198:Computer Simulation; D055119:Elastic Modulus; D005260:Female; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods*; D050723:Fractures, Bone / Q000503:physiopathology* / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D013718:Tensile Strength