Fig. 3

a illustrates a tibial plane model, with normal lines drawn perpendicular to tangential lines intersecting contact points for the tibial sesamoid and proximal phalanx. Their point of intersection determines its CR. b illustrates the fibular plane model, with specific contact points for the proximal phalanx and fibular sesamoid. Again, the intersecting normal lines define its CR. Since the fibular sesamoid contact point is more proximal, point C is also positioned more proximal (relative to the distal metatarsal edge) than point B in a