Subtrochanteric fixation stability depends on discrete fracture surface points.

Fixation of subtrochanteric femur fractures may present complications, including malunion, delayed union, or nonunion, and is thought to be related to early fracture stability. To examine the initial stability of subtrochanteric fracture fixation, we investigated construct stiffness, interfragmentary gaps, and overall and point-wise interfragmentary motion (ie, axial and shear displacements) in synthetic composite femurs fixed with a cephalomedullary nail or condylar blade plate. Simulated stable and unstable subtrochanteric femur fractures were created in composite femurs, anatomically reduced, fixed with either a long Gamma nail or a blade plate, and subjected to combined axial, bending, and torsional loading.