A covering shell for a prosthesis of a given limb, the shell having at least two zones of different flexibility. The arrangement of the zones of the covering shell in relation to one another corresponding to the arrangement of the parts of the given limb having different hardnesses. An exoskeletal structure, having preferably a tubular shape, of a prosthesis of a given limb. The exoskeletal structure being designed to provide a connection between a socket and a hand prosthesis or between a socket and a foot prosthesis, in order to form the prosthesis of the limb. The exoskeletal structure having at least two zones of different flexibility. The arrangement of the zones of the exoskeletal structure in relation to one another corresponding to the arrangement of the parts of the given limb having different hardnesses.

A prosthesis or orthosis for a joint, such as an ankle, which includes a first body, a second body, and an articulated joint between the first and second bodies, the articulated joint allowing the rotation of the first and second bodies with respect to one another around a joint rotation axis. It further includes a locking mechanism configured to selectively lock the rotation between the first and second bodies in one direction, when it is in a locked configuration, and a transmission mechanism such that a rotation of the joint rotation axis generates a movement of a lockable part of the locking mechanism. The axis of the movement of the lockable part is shifted relative to the joint rotation axis and the transmission mechanism includes a reducer configured to reduce effort to lock the rotation of the first body with respect to the second body.