Look at that tibia.

An abnormally small angle is known as coxa vara and an abnormally large angle as coxa valga .

The hock, or gambrel, is the joint between the tarsal bones and tibia of a digitigrade or unguligrade quadrupedal mammal, such as a horse, cat, or dog.

Because changes in shape of the femur naturally affects the knee, coxa valga is often combined with genu varum (bow leggedness), while coxa vara leads to genu valgum (knock knees).