Bionic joint and a prosthesis for replacing an elbow joint

A prosthesis, the prosthesis comprising:

• a first rigid link;
• a second rigid link;
• a joint arranged between an end of the first rigid link and an end of the second rigid link and configured to enable a rotational movement between the first rigid link and the second rigid link with respect to each other;
• a first string section and a second string section extending from the first rigid link to the second rigid link, being both fixed to the second rigid link, and arranged on opposite sides of the joint,
• a spindle arranged in the first rigid link and coupled to a first pulley and a second pulley connected to the first string section and the second string section, respectively, the first string section and the second string section being wound on the respective pulley in opposite winding directions, such that rotating the spindle winds up one of the first string section and of the second string section on the respective one of the first pulley and the second pulley and unwinds the other one of the first string section and of the second string section from the respective other one of the first pulley and the second pulley, for driving a rotation of the first rigid link and the second rigid link with respect to each other around the joint, wherein first rigid link is configured as an upper arm prosthesis or part thereof, wherein the end of the first rigid link corresponds to a distal portion of the humerus, and the second rigid link is configured as a lower arm prosthesis or part thereof and the end of the second rigid link corresponds to a proximal portion of the ulna and radius.

A passive joint prosthesis comprising

• a first rigid link,
• a second rigid link,
• a pair of cross-flexural pivots extending between the first rigid link and the second rigid link for defining a cross flexural hinge with a principal plane of rotation, the cross-flexural pivots being spaced along the normal of the principal plane of rotation from each other, the normal being the vector which is perpendicular to the principal plane of rotation and points out of the principal plane of rotation;
• wherein each of the cross flexural pivots comprises a first elastic bar and a second elastic bar extending between the first rigid link and the second rigid link, wherein the first elastic bar and the second elastic bar cross each other, when viewed along the normal of the principal plane of rotation;
• and
• a locking mechanism for selectively restraining a rotation of the first rigid link with respect to the second rigid link in the principal plane of rotation.