title: Biomechanical comparison of fixation techniques in midshaft clavicular fractures.
abstract: OBJECTIVE
  The purpose of this study is to evaluate the biomechanical properties and the stability among a locking clavicle plate (LCP), a dynamic compression plate (DCP) and an external fixator (Ex-fix) in an unstable displaced clavicle fracture model under torsional and three-point bending loading.
  
  
  METHODS
  Forty-eight human adult formalin-fixed clavicles were paired according to their bone mineral density homogeneously into three groups: LCP, DCP, and Ex-fix. Each specimen was osteotomized at the midshaft. Torsional and three-point bending forces were performed for 1000 cycles with stiffness recorded at 10 cycles (initial) and then at 100-cycle intervals thereafter. Initial stiffness, failure loads, and the percentage of initial stiffness at the various intervals were compared using analysis of variance.
  
  
  RESULTS
  The mean initial stiffness values (Nmm/deg) for torsion were 703.2 (LCP), 448.1 (DCP), and 365.2 (Ex-fix). The mean failure moments (Nmm) for torsion were 7671.7 (LCP), 4370.3 (DCP), and 2999.7 (Ex-fix). The mean initial stiffness (Nmm) for bending were 32.6 (LCP), 23.4 (DCP), and 20.6 (Ex-fix). The mean failure loads (N) for bending were 213.2 (LCP), 131.1 (DCP), and 102.7 (Ex-fix). For both torsion and bending, an overall significant difference among the three constructs in terms of failure loads and also a significant difference between the locking plate and the other two models only in terms of initial stiffness was seen. For torsion and bending, at all cyclic intervals, there was a significant difference between the locking plate and the other two models. After 700 cycles, a significant difference was also detected between the DCP and Ex-fix in torsion, but no difference was found between these groups at any cyclic interval in bending.
  
  
  CONCLUSIONS
  The locking plate is significantly more stable than DCP and Ex-fix under torsional and bending cyclic loading in a displaced fracture clavicle model.
authors.affiliation: Department of Orthopaedics and Traumatology, Istanbul Medical Faculty, Istanbul University, Istanbul, Turkey. demirhan@istanbul.edu.tr
authors.forename: Mehmet
authors.initials: M
authors.lastname: Demirhan
authors.forename: Kerem
authors.initials: K
authors.lastname: Bilsel
authors.forename: Ata Can
authors.initials: AC
authors.lastname: Atalar
authors.forename: Ergun
authors.initials: E
authors.lastname: Bozdag
authors.forename: Emin
authors.initials: E
authors.lastname: Sunbuloglu
authors.forename: Aysin
authors.initials: A
authors.lastname: Kale
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D040761:Biomimetic Materials; D015519:Bone Density; D001860:Bone Plates; D002968:Clavicle / Q000293:injuries* / Q000378:metabolism / Q000503:physiopathology; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D050723:Fractures, Bone / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D016268:Internal Fixators; D008875:Middle Aged; D010027:Osteotomy; D018583:Pliability; D011475:Prosthesis Failure; D013314:Stress, Mechanical; D054159:Torsion, Mechanical; D016474:Weight-Bearing