Device for immobilishing an osteosynthesis pin in a bone part

A device used to immobilise a threaded support pin ( 21 ) in relation to a fixed element ( 1, 34 ), the pin being screwed into a bone part ( 3, 3 a , 3 b) along an axis (yy'). The device includes a locking sleeve ( 13 ) which can be solidly screwed to the fixed element ( 1, 34, 7 ) and which is provided with an axial bore ( 19 ) in order to receive the pin ( 21 ). The axis (zz') of the sleeve screw thread is angularly and/or laterally offset in relation to the axis (yy') of the pin ( 21 ) when the latter is in place on the bone part ( 3, 3 a , 3 b), and/or the axis of the bore ( 19 ) of the locking sleeve ( 13 ) is angularly and/or laterally offset in relation to the screw thread axis ( 6 ).