title: Comparative evaluation of in vitro mechanical properties of different designs of epoxy-pin external skeletal fixation systems.
abstract: OBJECTIVE
  To compare in vitro biomechanical properties of different designs of epoxy-pin external skeletal fixator (ESF) constructs.
  
  
  METHODS
  Mechanical testing study.
  
  
  METHODS
  Four epoxy-pin ESF design constructs (uniplanar [EU], multiplanar-I [EM-I], multiplanar-II [EM-II], and circular [EC]) were mechanically tested in compression, bending, and torsion.
  
  
  METHODS
  Four different designs of free-form epoxy-pin external fixator constructs were developed using 1.5 mm K-wires and epoxy resin mounted in an ultra-high density polyethylene rod (20 mm diameter). Three-point fixation was done in each fragment, and the distance between fixation wires, and between the rod and the side bars was kept constant in all the designs. A 5 mm gap was maintained at the center of the fixation rod to simulate an unstable fracture condition. The fixator constructs (n = 12 of each design) were subjected to mechanical testing in axial compression, bending, or torsion. Load-deformation curves were generated and mechanical properties were compared between construct types.
  
  
  RESULTS
  EU was the weakest design. Under compression, constructs EM-I, EM-II, and EC were similar. Under bending, EM-I and EM-II had similar strength, whereas EC was strongest. Under torsion, EC was strongest, followed by EM-II, EM-I, and EU; EM-II provided double the rotational stability of EM-I.
  
  
  CONCLUSIONS
  Overall, EC followed by EM-II epoxy-pin fixator designs had better mechanical strength.
authors.affiliation: Division of Surgery, Indian Veterinary Research Institute, Bareilly, Uttar Pradesh, India.
authors.forename: Surbhi Kuldeep
authors.initials: SK
authors.lastname: Tyagi
authors.forename: Hari Prasad
authors.initials: HP
authors.lastname: Aithal
authors.forename: Prakash
authors.initials: P
authors.lastname: Kinjavdekar
authors.lastname: Amarpal
authors.forename: Abhijit Motiram
authors.initials: AM
authors.lastname: Pawde
authors.forename: Tuhin
authors.initials: T
authors.lastname: Srivastava
authors.forename: Kanti Prakash
authors.initials: KP
authors.lastname: Tyagi
authors.forename: Shongsir Warson
authors.initials: SW
authors.lastname: Monsang
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D004285:Dogs; D016267:External Fixators / Q000662:veterinary*; D050723:Fractures, Bone / Q000601:surgery / Q000662:veterinary*; D008422:Materials Testing / Q000662:veterinary