ankle a first pair of side by side slots 16 and a second pair of side by side slots 17 are equally spaced on opposite sides of the aperture 13 the crescent shaped medial shell 12 shown in fig1 and 4 is adapted to fit beneath and upwardly about the tibial malleolus it is of symmetrical configuration and can be used on either the left or the right ankle it includes a first pair of side by side slots 18 at one end and a second pair of side by side slots 19 at its opposite ends between those pairs of slots is a wider central slot 20 the foot shell 11 is adapted to underlie the rear foot and extend forwardly beyond the tarsal joint it is in the form of a contoured stirrup which includes an upper lateral side portion 21 a slot 22 is defined in the lateral side portion of the foot shell 11 forwardly of the upper lateral side portion 21 a rivet 23 provides pivot means connecting the lower end portion 14 of the lateral shell 10 to the upper side portion 21 of the foot shell 11 the rivet 23 is affixed to the foot shell side portion 21 and extends outwardly through a larger hole in the overlapping lateral shell lower end portion 14 a head 25 on the rivet 23 holds the overlapping side and end shell portions 21 and 14 together and at the same time permits angular movement of the foot shell 11 relative to the lateral shell 10 about an axis substantially coincident with the functional axis of the talocrual joint formed in the.