title: Medial support by fibula bone graft in angular stable plate fixation of proximal humeral fractures: an in vitro study with synthetic bone.
abstract: BACKGROUND
  Failure to achieve stable fixation with medial support in proximal humeral fractures can result in varus malalignment and cut-through of the proximal screws. The purpose of this study was to investigate the influence of an intramedullary fibula bone graft on the biomechanical properties of proximal humeral fractures stabilized by angular stable plate fixation in a bone model under cyclic loading.
  
  
  METHODS
  Two fixation techniques were tested in 20 composite analog humeri models. In group F- (n = 10), fractures were fixed by an anatomically formed locking plate system. In group F+ (n = 10), the same fixation system was used with an additional fibular graft model with a length of 6 cm inserted in an intramedullary manner. Active abduction was simulated for 400 cycles by use of a recently established testing setup. Fragment gap distance was measured, and thereby, intercyclic motion, fragment migration, and residual plastic deformation were determined.
  
  
  RESULTS
  The addition of a fibular graft to the fixation plate led to 5 times lower intercyclic motion, 2 times lower fragment migration, and 2 times less residual plastic deformation. Neither screw pullout, cut-through, nor implant failure was observed.
  
  
  CONCLUSIONS
  Medial support with an intramedullary fibular graft in an angular stable fixation of the proximal humerus in vitro increases overall stiffness of the bone-implant construct and reduces migration of the humeral head fragment. This technique might provide a useful tool in the treatment of displaced proximal humeral fractures, especially when there is medial comminution.
authors.affiliation: Division of Trauma Surgery, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Georg
authors.initials: G
authors.lastname: Osterhoff
authors.forename: Daniel
authors.initials: D
authors.lastname: Baumgartner
authors.forename: Philippe
authors.initials: P
authors.lastname: Favre
authors.forename: Guido A
authors.initials: GA
authors.lastname: Wanner
authors.forename: Hans
authors.initials: H
authors.lastname: Gerber
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Simmen
authors.forename: Clément M L
authors.initials: CM
authors.lastname: Werner
mesh_terms: D001696:Biomechanical Phenomena; D001858:Bone Nails; D001860:Bone Plates; D001863:Bone Screws; D016025:Bone Transplantation / Q000379:methods*; D002102:Cadaver; D005360:Fibula / Q000637:transplantation*; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006801:Humans; D019736:Prostheses and Implants; D011474:Prosthesis Design; D012784:Shoulder Fractures / Q000601:surgery*