A humerus implant has a stem (400, 410), cup shaped body (100) and a locking adapter (200). The cup shaped body is locked to the stem by a key-slot mechanism. The cup shaped body has a center portion and a plurality of flexible first sidewall segments (120) and second sidewall segments (130), with gaps (140) between neighbored sidewall segments. The first sidewall segments have a plurality of locking fins (122) while the second sidewall segments having a plurality of recesses (131) and holes (132). The locking adapter has means for fixing the locking adapter to the cup shaped body and a locking ring (205) for locking the sidewall segments into their final positions.
