A base member (508) for a stemless humeral shoulder assembly and prosthesis comprises a proximal end (524) comprising a peripheral member and a central portion configured to form at least partly a recess into which a mounting member of an anatomical or reverse joint interface is received when the mounting member is advanced within the base member. The base member further comprises a distal end (520) configured to be embedded in bone and a plurality of spaced apart arms (528) projecting from the proximal end to the distal end, each of the plurality of spaced apart arms comprising a plurality of openings.
