Using flexible nails to improve stabilization of proximal femur fractures in adolescents.

Intramedullary fixation as a treatment for adolescent femur fractures has increased in popularity. We investigated the varus stability of 3 fixation techniques--the standard 2-nail configuration (2 retrograde nails), a 3-nail configuration (standard 2-nail configuration plus 1 antegrade nail), and a retrograde/antegrade 2-nail configuration--in synthetic femurs with 2 simulated fracture patterns (transverse, butterfly). A varus moment was applied to the specimens until 20 degrees of varus angulation was obtained. The varus angular stiffness of the construct defined varus stability. The 3-nail configuration had the most varus angular stiffness with both fracture patterns. The varus stability of the 3-nail configuration was statistically higher than that of the standard 2-nail configuration with the transverse fracture pattern only. Adding 1 antegrade nail to 2 retrograde nails significantly increased resistance to varus deformity of reduced proximal-third transverse femur fractures in the synthetic femur model.