A heel cup can be inserted into a shoe in order to define a posterior upward projection and lateral wings which surround the posterior and lateral faces of the calcaneum and which, through lateral notches, define a preferential deformation zone at, and in the direction of, the subtalar cone of the tibiotarsal joint. Moreover, a sufficiently-rigid connecting zone connects the posterior upward projection and the lateral wings, thus providing the shoe with good stability while enabling inversion and eversion foot movements. In this way, comfort is increased considerably, while the risk of articular injuries is reduced since the subtalar articulation is contained correctly upon reaching the limit thereof.