The present invention relates to a reinforcing element (200) for a circular mesh, comprising a plurality of fingers (201) which, at rest, form a conical structure (202) that can open out when the reinforcing element is placed under axial stress, each finger comprising a vertex segment (201a) and a peripheral segment (201b) defining a vertex part (202a) and a peripheral part (202b) of the said conical structure, the said reinforcing element comprising, for each finger, means (201c, 205 402 502) of misaligning the said vertex segment and the said peripheral segment, at least when the said reinforcing element is under axial stress, the said misalignment means making it possible, in the said position under axial stress, firstly for the peripheral part of the said conical structure to adopt a planar configuration, and secondly, for the said vertex part of the said structure to maintain a conical shape. The invention also relates to a prosthesis (300) comprising such a reinforcing element (200) associated with a mesh (1).
