Physiotherapy with skies

Here I saw for the first time the advise of using skies for physiotherapy exercising.

The walking with skies makes the patient to flex his knees in order to rise a leg higher, but, more important to activate all the ankle movements to avoid the over-crossing of the skies. The exercises may be performed while hording the parallel bars.
The skies are 50-70 cm long and fixated firmly along all the sole to a shoe.
Also weights may be added. I think the weights may be moved along skies or may be located asymmetrically.