title: Ex vivo torsional properties of a 2.5 mm veterinary interlocking nail system in canine femurs. Comparison with a 2.4 mm limited contact bone plate.
abstract: OBJECTIVE
  To evaluate the torsional properties of the Targon®Vet Nail System (TVS) in small canine femurs and to compare these properties to those of the 2.4 mm LC-DCP®plates.
  
  
  METHODS
  Thirty-six cadaveric femurs were allocated to three groups (n = 12). In all bones, points just distal to the lesser trochanter and just proximal to the fabellae were marked and a midshaft transverse osteotomy was performed. Group 1: bones were fixed with the 2.5 mm TVS with the bolts applied at the pre-identified marks. Group 2: A TVS system with 25% shorter inter-bolt distance was used. Group 3: A 7-hole 2.4 mm LC-DCP®plates were applied. All constructs were tested non-destructively for 10 cycles, followed by an acute torsion to failure.
  
  
  RESULTS
  Torque at yield was 0.806 ± 0.183 and 0.805 ± 0.093 Nm for groups 1 and 2 and 1.737 ± 0.461 Nm for group 3. Stiffness was 0.05 ± 0.01, 0.05 ± 0.007, and 0.14 ± 0.015 Nm/° for groups 1 to 3 respectively. Maximal angular displacement under cyclic loading was 16.6° ± 2.5°, 15.6° ± 2.1°, and 7.8° ± 1.06° respectively. There was no significant difference for any of the parameters between groups 1 and 2. Both torque at yield and stiffness were significantly greater between group 3 and groups 1 and 2.
  
  
  CONCLUSIONS
  The TVS had approximately half the torsional strength and approximately 1/3 of the stiffness of the 2.4 mm bone plate. Slippage of the locking mechanism was probably the cause of the early failure. The system should be considered as a low-strength and low-stiffness system when compared to bone plates.
authors.forename: Aline S
authors.initials: AS
authors.lastname: Macedo
authors.affiliation: Noel M.M. Moens, University of Guelph, Ontario Veterinary College, Clinical Studies, Gordon St, Guelph, ON N1G 2W1, Canada, E-mail: nmoens@uoguelph.ca.
authors.forename: Noel M M
authors.initials: NM
authors.lastname: Moens
authors.forename: John
authors.initials: J
authors.lastname: Runciman
authors.forename: Tom W G
authors.initials: TW
authors.lastname: Gibson
authors.forename: Bruno W
authors.initials: BW
authors.lastname: Minto
mesh_terms: D000818:Animals; D001858:Bone Nails / Q000662:veterinary*; D001860:Bone Plates / Q000662:veterinary*; D004285:Dogs / Q000601:surgery*; D005269:Femur / Q000601:surgery*; D054159:Torsion, Mechanical
keywords: Biomechanics; dogs; experimental research; fracture fixation; orthopaedic implants