title: Distal femoral fixation: a biomechanical comparison of retrograde nail, retrograde intramedullary nail, and prototype locking retrograde nail.
abstract: BACKGROUND
  Distal femur fractures continue to be a complex surgical problem for which the incidence is increasing. Presently, there is a need for different constructs to address these complex fractures. This study attempts to define the biomechanical properties of several implants.
  
  
  METHODS
  A novel, prototype locking retrograde intramedullary nail and the Russell-Taylor femoral retrograde nail were tested at non-destructive, physiological, axial mode load strength using a young, synthetic bone model for a medial segmental shaft defect in the supracondylar region of the distal femur (medial gap of 10mm, 65mm proximal to the distal joint and parallel to the knee axis). Each specimen was compressively loaded and unloaded to the peak load for 80,000cycles at a 0.5Hz frequency. These were compared to the results from the same lab of the retrograde Trigen intramedullary nail. Motion and peak displacement were measured across the fracture site as a reflection of construct stability.
  
  
  RESULTS
  Previous testing demonstrated that Trigen intramedullary nail had significantly less motion across the gap and increased overall stiffness of the construct (P<0.05) compared to both Russell-Taylor and prototype nails.
  
  
  CONCLUSIONS
  Locking technology used in a nail biomechanically appears to lead to more micro-motion across the fracture gap and to less stiffness in this construct. Further research needs to be invested into intramedullary, locking technology before introducing it into clinical practice.
authors.affiliation: University of Toledo Medical Center, 3000 Arlington Avenue, Toledo, Ohio 43614, USA. jakeheiney@ameritech.net
authors.forename: Jake P
authors.initials: JP
authors.lastname: Heiney
authors.forename: Suneel
authors.initials: S
authors.lastname: Battula
authors.forename: Jill A
authors.initials: JA
authors.lastname: O'Connor
authors.forename: Nabil
authors.initials: N
authors.lastname: Ebraheim
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Schoenfeld
authors.forename: Gregory
authors.initials: G
authors.lastname: Vrabec
mesh_terms: D001858:Bone Nails; D001860:Bone Plates; D055119:Elastic Modulus; D019544:Equipment Failure Analysis; D005264:Femoral Fractures / Q000503:physiopathology* / Q000601:surgery*; D005594:Fracture Fixation, Intramedullary / Q000295:instrumentation* / Q000379:methods*; D007718:Knee Injuries / Q000503:physiopathology* / Q000601:surgery; D009038:Motion; D011474:Prosthesis Design; D013718:Tensile Strength; D016896:Treatment Outcome