The shape of legs can be estimated as “perfect” by the presence of three spindle-shaped spaces of the inner outline of the legs, limited by the perineum, closed up knee joints, and soft tissues in the region of calf muscles and ankles.

The “O” -shape occurs when a spindle-shaped defect of the inner outline from the perineum to the closed up ankles is present.
The “X” -shape occurs when it is impossible to close up the ankles when the knees are closed.

There is no constant femur / tibia ratio in humans and it varies considerably between women and men, different ethnic groups and countries, but does fall within a normal range.  However, we believe that legs can be estimated as a proportional when distance between trochanter major to the knee joint and from knee joint to the internal malleolus is equal as it is shown in the picture.
perfect legs_in_armenia