A blocking ring (20) is for a threaded holding pin (18) to be screwed into a portion of a bone (14), said ring including a first portion (22) having an axial bore (24) for receiving said holding pin, the periphery of said first portion being threaded so as to interact with a holding plate (12), wherein said ring is characterised in that the same further comprises, as an extension to said first portion, a second deformable portion (28) having a thickness less than the first portion and having a similar axial bore (30), and in that the shearing of the pin (18) and the ring at the join between the first portion (22) and the second portion (28) deforms the remaining portion (34) of the second portion (28) of the blocking ring (22) towards the pin (18) in such a way as to block the pin (18) in relation to the blocking ring (22) by crimping.
