The invention proposes a modular reverse shoulder prosthesis (1), comprising:a stem (10) having a proximal taper (14) and a primary stem axis (110), the proximal taper extending from the stem about a metaphyseal axis (143), the metaphyseal axis at an angle with respect to the primary stem axis；a metaphysis (20； 20') having a proximal end (22), a distal end (21), an aperture (23) in the distal end configured to be placed over the proximal taper, and first interlocking means (24； 25； 25') at the proximal end having an insert axis that is eccentrically offset from the metaphyseal axis (290), the metaphysis configured for attachment to the stem at a plurality of rotational positions of the metaphysis about the metaphyseal axis； anda reverse insert (30； 30'； 30"), the reverse insert having a proximal end (39； 39') and a distal end (31； 31'), wherein the proximal end comprises a concave cup (38； 38') formed about a cup axis (380； 380'； 380") and configured to receive a glenosphere, and wherein the distal end comprises second interlocking means (36, 37； 36', 37'； 36", 37"),wherein an interface surface between the first and second interlocking means has a rotational symmetry about the insert axis (290).
