title: Analysis of fixation methods for vertical shear fractures of the medial malleolus.
abstract: OBJECTIVE
  To evaluate 4 different fixation methods used to treat vertical shear fractures of the medial malleolus.
  
  
  METHODS
  Eighty polyurethane models of the distal tibia were osteotomized in a reproducible manner to create a vertical shear fracture of the medial malleolus. Twenty specimens were then randomly assigned to 1 of 4 fixation groups. Two fixation groups used a neutralization plate, whereas 2 groups were screw-only constructs. Ten of the specimens in each group were then randomly assigned to undergo either offset axial or offset transverse loading.
  
  
  RESULTS
  The construct using a neutralization plate with 2 screws in the distal fragment exhibited greater stiffness in offset axial loading compared with the screw-only constructs placed an equivalent distance from the tibial plafond. All specimens in the group with the properly applied neutralization plate exhibited elastic deformation, whereas the majority of the specimens in all other groups showed residual displacement or catastrophic failure of the construct.
  
  
  CONCLUSIONS
  Fixation of vertical shear fractures of the medial malleolus with a properly applied neutralization plate offers a significant mechanical advantage over screw-only constructs.
authors.affiliation: mdumigan@yahoo.com
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Dumigan
authors.forename: Dwight G
authors.initials: DG
authors.lastname: Bronson
authors.forename: John S
authors.initials: JS
authors.lastname: Early
mesh_terms: D016512:Ankle Injuries / Q000601:surgery*; D000843:Ankle Joint / Q000601:surgery*; D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D005592:Fracture Fixation / Q000379:methods*; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D016268:Internal Fixators; D008953:Models, Anatomic; D011140:Polyurethanes; D011897:Random Allocation; D033081:Shear Strength; D013314:Stress, Mechanical
chemical_list: D011140:Polyurethanes