Plate position on the femur / tension band principle
As a general rule the plate should be positioned on the lateral aspect of the femur.
A plate acts as a dynamic tension band when applied to the tension side of the bone and when a cortical contact is present on the opposite side to the plate.
With vertical load, the curved femur creates a tensile force laterally and a compressive force medially.
A plate positioned on the side of the tensile force resists it at the fracture site, provided there is stable cortical contact opposite to the plate.