title: A new, low cost, locking plate for the long-term fixation of a critical size bone defect in the ratfemur: in vivo performance, biomechanical and finite element analysis.
abstract: BACKGROUND
  The optimum fixation device for the critical size bone defect is not established yet.
  
  
  OBJECTIVE
  A reliable, feasible and low-cost fixation device for the long-term maintenance of a critical bone defect.
  
  
  METHODS
  A custom-made plate made of poly-methyl-methacrylate was used for the fixation of a critical defect of rats' femurs. The screws were securely fixing both on the plate and the bone. A three point bending test, aimed to resemble the in vivo loading pattern, a Finite Element Analysis and a 24-week in vivo monitoring of the integrity of the plate fixation were utilized.
  
  
  RESULTS
  The plate has linear and reproducible behavior. It presents no discontinuities in the stress field of the fixation. Its properties are attributed to the material and the locking principle. It fails beyond the level of magnitude of the normal ambulatory loads. In vivo, 100% of the plates maintained the bone defect intact up to 12 weeks and 85% of them at 24 weeks.
  
  
  CONCLUSIONS
  This novel locking plate shows optimal biomechanical performance and reliability with high long-term in vivo survival rate. It is fully implantable, inexpensive and easily manufactured. It can be qualified for long term critical defect fixation in bone regeneration studies.
authors.affiliation: Department of Orthopaedic Surgery, University of Ioannina, Ioannina, Greece.
authors.forename: George I
authors.initials: GI
authors.lastname: Mataliotakis
authors.affiliation: Department of Mechanical Engineering, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Alexander
authors.initials: A
authors.lastname: Tsouknidas
authors.affiliation: Department of Mechanical Engineering and Aeronautics, University of Patras, Patras, Greece.
authors.forename: Sofia
authors.initials: S
authors.lastname: Panteliou
authors.affiliation: Department of Orthopaedic Surgery, University of Ioannina, Ioannina, Greece.
authors.forename: Marios D
authors.initials: MD
authors.lastname: Vekris
authors.affiliation: Department of Orthopaedic Surgery, University of Ioannina, Ioannina, Greece.
authors.forename: Grigorios I
authors.initials: GI
authors.lastname: Mitsionis
authors.affiliation: Department of Materials Science and Engineering, University of Ioannina, Ioannina, Greece.
authors.forename: Simeon
authors.initials: S
authors.lastname: Agathopoulos
authors.affiliation: Department of Orthopaedic Surgery, University of Ioannina, Ioannina, Greece.
authors.forename: Alexander E
authors.initials: AE
authors.lastname: Beris
mesh_terms: D000818:Animals; D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D002484:Cementation / Q000379:methods; D003198:Computer Simulation; D017076:Computer-Aided Design; D003362:Cost-Benefit Analysis; D019544:Equipment Failure Analysis; D005264:Femoral Fractures / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D020342:Finite Element Analysis; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods; D017276:Friction; D008297:Male; D008954:Models, Biological; D011474:Prosthesis Design; D051381:Rats; D017208:Rats, Wistar; D013718:Tensile Strength; D016896:Treatment Outcome
keywords: Bone tissue engineering; animal models; critical size defect; fixation device; plate; segmental bone defects