Basic design. Articulating ankle which allows limited rotation in dorsiflexion, plantarflexion, inversion, and eversion. Each value of rotation was approximated then fine tuned by actual testing to maintain wheel contact and imitate natural function.
I modified the skate by installing an aluminum plate which matches the contour of the boot sole. The four bolts which attach the truck plate to the boot pass through the boot and into this aluminum plate. In this manner the prosthetic ankle mounts in concert with the truck plate and not just the boot, thus minimizing flexing and maximizing skate control.
Quicktime movie (5.6MB!) of me at the rink during one of my skate tests.