title: A nickel-titanium shape memory alloy plate for contactless inverse dynamization after internal fixation in a sheep tibia fracture model: A pilot study.
abstract: BACKGROUND
  Inverse dynamization has recently been proposed for the treatment of tibia non-unions. Nickel-titanium (NiTi) shape memory alloys (SMAs) may provide an opportunity for contactless non-invasive alteration of the stiffness of an implant after surgery.
  
  
  OBJECTIVE
  The aim of this pilot study was to analyze the feasibility of the one way shape memory effect in a large animal as well as the feasibility of our ovine large animal fracture model.
  
  
  METHODS
  A tibia osteotomy was performed in three sheep, followed by NiTi plate osteosynthesis in two cases and standard locking compression plate (LCP) osteosynthesis in one sheep. Contactless induction heating was performed after 3 weeks in order to alter the stiffness of the NiTi plates. Euthanasia was followed by biomechanical analysis after 8 weeks.
  
  
  RESULTS
  Successful change of configuration through contactless induction heating was shown in both SMA plates by image intensifier control. Although large differences in bending and torsional stiffness were observed between the operated and contralateral tibia, the sheep ambulated almost normally at six weeks post-operative.
  
  
  CONCLUSIONS
  We were able to trigger the one way shape memory effect which non-invasively altered the stiffness of the plate osteosynthesis.
authors.affiliation: Trauma Department, Hannover Medical School, Hannover, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Decker
authors.affiliation: Laboratory for Biomechanics and Biomaterials, Hannover Medical School, Hannover, Germany.
authors.forename: Manuel
authors.initials: M
authors.lastname: Krämer
authors.affiliation: Trauma Department, Hannover Medical School, Hannover, Germany.
authors.forename: Anna-Katharina
authors.initials: AK
authors.lastname: Marten
authors.affiliation: Laser Zentrum Hannover e.V., Hannover, Germany.
authors.forename: Ronny
authors.initials: R
authors.lastname: Pfeifer
authors.affiliation: Laser Zentrum Hannover e.V., Hannover, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Wesling
authors.affiliation: Trauma Department, Hannover Medical School, Hannover, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Neunaber
authors.affiliation: Laboratory for Biomechanics and Biomaterials, Hannover Medical School, Hannover, Germany.
authors.forename: Christof
authors.initials: C
authors.lastname: Hurschler
authors.affiliation: Trauma Department, Hannover Medical School, Hannover, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Krettek
authors.affiliation: Trauma Department, Hannover Medical School, Hannover, Germany.
authors.forename: Christian W
authors.initials: CW
authors.lastname: Müller
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001860:Bone Plates; D005593:Fracture Fixation, Internal / Q000379:methods*; D009532:Nickel; D010027:Osteotomy / Q000379:methods; D010865:Pilot Projects; D012756:Sheep; D013977:Tibia / Q000601:surgery*; D013978:Tibial Fractures / Q000601:surgery*; D014025:Titanium
chemical_list: C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: Sheep model; fracture repair; inverse dynamization; nickel-titanium; plate osteosynthesis; shape memory alloy