[ashe]

I'f like to first offer the caveat that I'm unclear on the spiraling of the joints in the legs myself but a few points;

I have to split hairs with the classification of the wrist as a hinge joint (think about all the ways you can articulate your hand. In fact I remember watching something on PBS that attributed our ability to do things like play piano to the shape of a single bone in our wrist (compared to chimps). While it's true that the wrist has a much greater range of motion through extension and flexion, there is a significant ROM through radial and ulnar deviation (which is why we need to be convex-convex when we want to create convex energy for example). That same range of motion in more than one plane is just not present in a hinge joint.

I think some of the confusion about spiraling in the lower body (my confusion) is that even in the upper body, if you're drawing circles with the elbow, the motion really happens in the shoulder and is just reflected in the elbow, but the hips don't move as freely, especially with the feet on the ground.

I THINK I'm starting to feel the spin at the ankle clearly, but I've thought that before about other things and have been wrong, so...
Anyway, the spin at the knee seems fairly straightforward in the saggital plane but seems like it would put a lot of shearing force on the joint horizontally and seems impossible in the frontal.

I think its one of those things that I can "just do" to a certain extent but can't explain it or demonstrate clearly since I don't understand it clearly enough myself.