Attachment element for a prosthesis of the shoulder for the articulation of a humerus in a scapula of a shoulder having a glenoid cavity. The prosthesis comprises a first articulation element associated with the top of the humerus, and a second articulation element associated with the glenoid cavity. The attachment element comprises a first part for removable anchorage to the first or second articulation element, and a second part for attachment of the prosthesis to the bone part of the scapula in a position outside the bulk of the first and second articulation element.