This cadaveric study tested 5 trochanteric antegrade femoral nails at 3 different AP starting points in a reverse obliquity subtrochanteric fracture model. The goal was to identify a universal optimal entry site that minimizes fracture malalignment regardless of nail design.
Subtrochanteric fractures routinely look well reduced on the fracture table, then shift into varus the moment you advance the nail. This paper explains why: the eccentric trochanteric entry combined with the nail's proximal bend predictably deforms the fracture if your start is even 2-3 mm off.
The practical rule is simple. On AP fluoroscopy, start at the tip of the trochanter or 2-3 mm medial. Never lateral. A lateral start produced varus and lateral cortex gapping with every nail in this study, and varus malalignment is not just a cosmetic problem — nail failures from varus have been reported in clinical series.
When you are nailing a reverse obliquity subtrochanteric fracture and the reduction looks good before nail insertion, verify your starting point before you ream. The lateral cortex gap is your intraoperative warning sign that the start drifted lateral.
This study also establishes that nail geometry cannot rescue a bad starting point. Entry point dominates alignment; nail design does not compensate for positional errors.
This cadaveric study tested 5 trochanteric antegrade femoral nails at 3 different AP starting points in a reverse obliquity subtrochanteric fracture model. The goal was to identify a universal optimal entry site that minimizes fracture malalignment regardless of nail design.
Subtrochanteric fractures routinely look well reduced on the fracture table, then shift into varus the moment you advance the nail. This paper explains why: the eccentric trochanteric entry combined with the nail's proximal bend predictably deforms the fracture if your start is even 2-3 mm off.
The practical rule is simple. On AP fluoroscopy, start at the tip of the trochanter or 2-3 mm medial. Never lateral. A lateral start produced varus and lateral cortex gapping with every nail in this study, and varus malalignment is not just a cosmetic problem — nail failures from varus have been reported in clinical series.
When you are nailing a reverse obliquity subtrochanteric fracture and the reduction looks good before nail insertion, verify your starting point before you ream. The lateral cortex gap is your intraoperative warning sign that the start drifted lateral.
This study also establishes that nail geometry cannot rescue a bad starting point. Entry point dominates alignment; nail design does not compensate for positional errors.