Two common leg types, so-called "O-leg" and "X-leg", are named Geno Varum and Geno Valgum, which can also be translated as "genu varum" and "genu valgum".

Then how to distinguish? Generally speaking, the way to distinguish them is to look at the angle between thigh and calf and tibia.

Generally, the included angle is about 15 degrees, greater than 20 degrees (X-leg, knee, ankle) or less than 10 degrees (O-leg, knee, ankle).