PI correction changes femur height by?

• A. +2 mm per 5 mm
• B. -2 mm per 5 mm
• C. +5 mm per 5 mm
• D. No change

Answer: (B)

PI correction changes the femur height by a small amount in the opposite direction. When you adjust the pelvis to correct PI, the pelvis tilts and the hip joints reposition slightly, which shifts the vertical position of the femoral heads. In this context, for every 5 units of PI correction, the femur height decreases by about 2 units. So the change is negative and relatively small, not a large or zero shift.