Ellipsoidally-shaped humerus head prosthesis

A humerus head implant comprising:

• a head cap and a fixing component,
• the head cap having a body enclosed between (i) an outer curved articulating surface that defines a half-ellipsoidal shape of the head cap and (ii) an inner surface that defines a conical recess in the body and that includes an extension surface surrounding said conical recess,
• wherein, when a local coordinate system is chosen such that a z-axis is transverse to and directed from the extension surface to the outer curved articulating surface and an x-axis and a y-axis are in a plane of the extension surface:
• a) an intersection of the z-axis with the outer curved surface represents a center of the outer curved articulating surface that, in operation of the implant, is aligned along the z-axis with a first point chose to represent a center of humerus, and
• b) a center axis of the conical recess is transverse to the extension surface and is displaced along the y-axis from the z-axis such that the body is asymmetric with respect to the z-axis
• and
• wherein a ratio of an x-extent of the head cap along the x-axis to a y-extent of the cap along the y-axis is in a range from 0.8 to 0.95,
• the fixing component comprising:
• a conical section dimensioned to fit into the conical recess and to allow for rotation of the head cap relative to the fixing component, and
• a bone-screw component.