Multiple Lattice Joint Deformation Drivers?

Hi all,

So I’m trying to animate a basic humanoid leg. I normally just use a weight painted rig to do my character animation, but I want a better looking joint deform for this project. I’m currently using a large lattice for the entire leg, and it worked great until adding the foot flexion into the mix. When the calf is flexed and the foot rotation is added the foot stretches and shrinks wildly, but only while the calf is raised. With the calf down it works fine because that’s were I created the IPO’s for the foot animation.

My question: How do I go about fixing this / What approach does everyone else use for this?

Here’s what I’m talking about: legDeform.blend (277 KB)

Thanks for any help forthcoming!