title: A biomechanical comparison of unlocked or locked reamed intramedullary nails in the treatment of mid-third simple transverse femoral shaft fractures.
abstract: BACKGROUND
  Despite that a mid-third simple transverse femoral shaft fracture has been traditionally treated with an unlocked reamed intramedullary nail, recently a static locked reamed intramedullary nail has been favored by some orthopedists to avoid missing extended fracture lines. A prospective comparison of both nails was conducted to investigate the superiority between the nails from biomechanical viewpoints.
  
  
  METHODS
  Seven pairs of fresh healthy cadaver femora underwent mid-third transverse osteotomy. Consequently, all seven left femora were stabilized using Kuntscher nails and all seven right femora, static Russell-Taylor locked nails. Finally, all 14 femora were tested using a Material Testing System (MTS) machine to investigate the sustained mechanical loads, the maximal failure load, and the relative fragment displacement.
  
  
  RESULTS
  The locked nails produced the larger mechanical loads (p = 0.02). The unlocked nails had the larger fragment displacement (p = 0.02) and the higher maximal failure load (6090 verse 5590 newtons, p = 0.02). All tests ended due to basal neck oblique fractures.
  
  
  CONCLUSIONS
  Biomechanically, an unlocked nail, being a load-sharing device, is superior to a static locked nail, being a load-bearing device, in the treatment of a mid-third simple transverse femoral shaft fracture. Clinically, careful investigation of the fracture types and adequate selection of the nail type should be performed in treating these types of fractures.
authors.affiliation: Department of Orthopedics, Chang Gung Memorial Hospital, Chang Gung Institute of Technology, Taipei. ccwu@mail.cgu.edu.tw
authors.forename: Chi-Chuan
authors.initials: CC
authors.lastname: Wu
authors.forename: Ching-Lung
authors.initials: CL
authors.lastname: Tai
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D001858:Bone Nails; D005260:Female; D005264:Femoral Fractures / Q000503:physiopathology / Q000601:surgery*; D005594:Fracture Fixation, Intramedullary / Q000379:methods*; D006801:Humans; D008297:Male