title: A cadaveric simulation of distal femoral traction shows safety in magnetic resonance imaging.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the safety of a distal femoral traction pin subjected to a 1.5-T magnetic resonance image (MRI) with regard to pin migration and implant heating in a cadaveric model.
  
  
  METHODS
  Deflection angles of various traction pins as well as a Bohler-style Steinmann Pin Tractor Bow (tractor bow) and a Kirschner wire bow subjected to a 1.5-T clinical MRI were measured. Tractions pins were placed into a cadaveric femur and the tractor bow was attached to the most distal pin to simulate distal femoral traction. Temperature and migration were measured after subjecting the cadaveric leg to a "worst-case scenario" MRI sequence for 30 minutes.
  
  
  RESULTS
  All traction pins and bows showed deflection. The Kirschner wire bow showed a hazardous level of deflection and was immediately removed from further testing. The pin temperature changes were not significantly different than the changes in the MRI room temperature and a conduction loop was not seen in the combination pin and tractor bow. There was no significant migration of any pin nor was there objective loosening from pin vibration.
  
  
  CONCLUSIONS
  Implant-quality stainless steel traction pins show no signs of adverse heating or pin migration when subjected to 1.5-T MRI clinical scanning. Kirschner bows are highly ferromagnetic and should not be used unless individually tested for safety. Steinmann Pin Tractor Bows that show weak ferromagnetism preliminarily appear safe to use during a 1.5-T MRI and do not produce a conduction loop with excessive heating in a cadaveric model, although further testing is indicated.
authors.affiliation: Vanderbilt Department of Orthopaedics, Nashville, Tennessee, USA.
authors.forename: Alfred
authors.initials: A
authors.lastname: Mansour
authors.forename: Jake
authors.initials: J
authors.lastname: Block
authors.forename: William
authors.initials: W
authors.lastname: Obremskey
mesh_terms: D001858:Bone Nails; D002102:Cadaver; D019544:Equipment Failure Analysis; D005548:Foreign-Body Migration; D006358:Hot Temperature; D006801:Humans; D016268:Internal Fixators / Q000009:adverse effects*; D008279:Magnetic Resonance Imaging / Q000009:adverse effects* / Q000379:methods; D011474:Prosthesis Design; D012449:Safety; D013193:Stainless Steel; D014143:Traction / Q000295:instrumentation*
chemical_list: D013193:Stainless Steel