title: [A biomechanical comparison of Acutrak headless compression screw and AO cannulated lag screw for the fixation of Hoffa fracture].
abstract: OBJECTIVE
  To compare the stability, strength of Letenneur type I Hoffa fractures fixed by Acutrak headless compression screws and AO cannulated lag screws.
  
  
  METHODS
  12 models of Letenneur type I Hoffa fractures were randomly divided into 4 groups, which were fixed with two AO cannulated lag screws or Acutrak headless compression screws anteroposteriorly or posteroanteriorly. The stress between two fragments of all specimens was tested. Axial compression test, the cycle load test and the limit load test were successively performed in every specimen.
  
  
  RESULTS
  In axial compression test, displacement of Acutrak headless compression screw groups was lower than that of AO cannulated lag screw anteroposteriorly (P < 0.05). The load to failure for Acutrak headless compression screw groups was higher than that of AO cannulated lag screws (P < 0.05), no matter in anteroposterior or posteroanterior direction.
  
  
  CONCLUSIONS
  The strength and stability of Letenneur type I Hoffa fractures fixeded with Acutrak headless compression screw were superior to those provided by AO cannulated lag screw. The direction of screw affects the initial stability for AO cannulated lag screw, other than Acutrak headless compression screw.
authors.affiliation: Department of Orthopedics, West China Hospital, Sichuan University, Chengdu 610041, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Peng
authors.forename: Shu-Liang
authors.initials: SL
authors.lastname: Zhang
authors.forename: Pin
authors.initials: P
authors.lastname: Feng
authors.forename: Yong
authors.initials: Y
authors.lastname: Jiang
authors.forename: Chang
authors.initials: C
authors.lastname: Zou
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.forename: Chong-Qi
authors.initials: CQ
authors.lastname: Tu
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D002102:Cadaver; D005264:Femoral Fractures / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006801:Humans