A modular humeral implant for an inverted shoulder prosthesis includes a humeral stem having, on the one hand, a diaphyseal keel of elongate shape, extending along a diaphyseal axis and shaped to be engaged in a medullary cavity of a humerus, and, on the other hand, a metaphyseal portion. A humeral spacer is mounted on the metaphyseal portion of the humeral stem and has a lower face facing the metaphyseal portion, the lower face having a peripheral portion projecting laterally from the metaphyseal portion and covered at least partially with a porous or rough metal surface coating promoting an osseointegration. A humeral insert is fastened on the humeral spacer and has a hemispherical cap shaped to receive a glenosphere of a glenoid implant.
