[Biomechanical evaluation of the gliding nail in trochanteric fractures].
OBJECTIVE
The purpose of the present study is to evaluate wether the gliding nail with it's double-t-shaped geometry is appropriate in the stabilization of unstable trochanteric fractures or not and if this evaluation can be performed with a static finite element simulation.


METHODS
Surface-Reconstruction with CT database of a proximal femur and reconstruction with CT based density data was done. After modelling of geometry, isotropic material behaviour and load application during one leg standing in slow walking was done with a limited dataset of relevant muscles. Two relevant fractures are modelled.


RESULTS
FE-simulation shows a movement of the femoral head distally, medially and posteriorly. Maximum bending strain is in the femoral diaphysis medial compression and lateral tension strain. In the proximal part we find a nearly homogeneous strain distribution. The clinical effect of lateralization of the proximal main fragment is also result of the simulation. In the area of the modelled fractures there is much more compressive stress than shear stress.


CONCLUSIONS
Elastomechanical behaviour of the gliding nail is demonstrated with correlation of clinical observed effects. In both simulated fracture areas there is a bone union supporting compressive stress. This means in the FE-simulation the gliding nail is appropriate in the stabilization in unstable trochanteric fractures.
Helwig
P
P
Department Orthopädie und Traumatologie, Albert-Ludwigs-Universität Freiburg, Germany. peter.helwig@uniklinik-freiburg.de
Faust
G
G
Hindenlang
U
U
Suckel
A
A
Kröplin
B
B
Südkamp
N
N
D001696:Biomechanical Phenomena; D001858:Bone Nails; D003198:Computer Simulation; D019544:Equipment Failure Analysis; D005272:Femur Neck / Q000503:physiopathology / Q000601:surgery; D020342:Finite Element Analysis; D005594:Fracture Fixation, Intramedullary / Q000295:instrumentation*; D017102:Fracture Healing / Q000502:physiology; D006620:Hip Fractures / Q000503:physiopathology / Q000601:surgery*; D006621:Hip Joint / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D011183:Postoperative Complications / Q000503:physiopathology; D013718:Tensile Strength; D014057:Tomography, X-Ray Computed; D016474:Weight-Bearing / Q000502:physiology