title: Auxetic polymeric bone plate as internal fixator for long bone fractures: Design, fabrication and structural analysis.
abstract: BACKGROUND
  Injuries cover about 11% of World's Disease Burden depicting fractures to be the leading severe consequence of trauma. Fractures occur due to force impact or osteoporosis. Fracture healing is a complicated process. Fracture fixation techniques focus on imparting reduction to fractured fragments and induce healing. When considering possible fixation methods, the aspect of micro-movement is an important one, as this induces callus formation which tends to be a crucial step for fracture healing. Internal fixation of long bone fractures using metallic plates has been carried out since decades and recently advancements have been in synthesizing biodegradable plates as well. The purpose of this research was to fabricate an Auxetic Polymeric Bone Plate that can be used as an internal fixator for long bone fracture; this bone plate renders micro-movement due to its counter intuitive behavior, has the potential to reduce the effect of stress shielding and allow the same range of motion as that of natural bone.
  
  
  METHODS
  Polyurethane was chosen as a material for the fabrication of the Auxetic device because of its biocompatibility and non-toxic effects. The plate was then tested for mechanical properties such as Tensile and Compression testing to determine the strength.
  
  
  CONCLUSIONS
  The tensile testing of the Auxetic polyurethane specimens showed that the mean of the Poisson's ratio of the samples lies between -0.68 and -0.87 at different uni-axial tensile load values. The Auxetic structure of our device has the potential to allow for efficient fixation because its negative Poisson's ratio offers micro-movement, thereby causing fixation with relative stability rather than absolute stability. The Auxetic bone plate can be superior to contemporary plate fixation systems, as it demands meaningfully small contact points. The suitable mechanical properties might lessen stress shielding effects that are normally caused by rigid bone plates. The Auxetic nature of the bone will help align and sustain the bone fragments with small fracture gaps in order to impart appropriate assembly to accomplish bone healing.
authors.forename: Seemab
authors.initials: S
authors.lastname: Mehmood
authors.forename: Murtaza Najabat
authors.initials: MN
authors.lastname: Ali
authors.forename: Umar
authors.initials: U
authors.lastname: Ansari
authors.forename: Mariam
authors.initials: M
authors.lastname: Mir
authors.forename: Munezza Ata
authors.initials: MA
authors.lastname: Khan
mesh_terms: D001696:Biomechanical Phenomena; D001860:Bone Plates; D005593:Fracture Fixation, Internal / Q000379:methods*; D006801:Humans; D008422:Materials Testing; D011140:Polyurethanes
chemical_list: D011140:Polyurethanes
keywords: Bone plate; auxetic; bone fracture; internal fixation; polymeric; rigid fixation