A biomechanical comparison of unlocked or locked reamed intramedullary nails in the treatment of mid-third simple transverse femoral shaft fractures.
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.
Wu
Chi-Chuan
CC
Department of Orthopedics, Chang Gung Memorial Hospital, Chang Gung Institute of Technology, Taipei. ccwu@mail.cgu.edu.tw
Tai
Ching-Lung
CL
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