It is very important to restore the biomechanical axis of the lower limb.
The normal biomechanical axis follows a line from the center of the femoral
head, through the center of the proximal tibia and then through the center of
the ankle joint. This axis can be checked intraoperatively by using a piece of
cable, such as the diathermy cord, to give an approximate estimate of the axis,
The biomechanical axis must be restored and care should be taken to ensure
that there is no malrotation of the distal femur on the proximal femur.