knee and ankle joint

Dear AnyBody:

I have a very basic question. Both knees and ankles are defined as hinge joints, why are there three JRF and two moments (lateral and axial) produced at the knee, while there are three JRF and one moment (axial) at the ankle? Additionally, I have an impression that “knee was defined as a hinge joint, with a small amount of patella rotation.” What is meant by "a small amount of patella rotation?

Thank you,